AudioCircle
Industry Circles => GR Research => Topic started by: Peter J on 21 Feb 2012, 01:16 am
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Hi all, indulge me here a little, I'm a better cabinetmaker than speaker designer.
I have this idea to build a pair of small speakers for desktop. My thought is to build a mini version of Danny's omni design. There was a thread a while back about using a Tang Band 3" in a small enclosure which got me thinking.... well you know how that goes.
This wouldn't be a critical listening setup, just a step up from the ho-hum HK 2.1 setup I have now. I'd probably use one of the little T-amps from Parts Express and an old Velodyne F10 sub I have. Mostly it gives me an excuse to build something cool looking, which is where my interest really lies.
Questions are; Is the idea at all viable? Does anyone here want to conspire on the design leading to the woodworking part, which is where my strength and interest are?
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If you want something that simple you could just get a pair of car stereo speakers.
Although I'm sure Danny has better ideas.
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What about picking up one of the Lepai amps from PE, I have one running my desktop setup now, and a couple pairs of the buyout Tang Band W3-881si's? I have two pair I'm breaking in down in the basement right now. Maybe build a small set of ported enclosures for them tuned to 100hz or so then cross them over to your sub. Could be a fun little project. :thumb:
Scott
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Build it, then build it again but better. The justification is simple...... because you can!!! LS-9 computer speakers. :D
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How big of speakers are you thinking about? Personally, I have been interested in making a smallish speaker using the Loki coax speaker. Would make a fine center channel too I would think...
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How big of speakers are you thinking about? Personally, I have been interested in making a smallish speaker using the Loki coax speaker. Would make a fine center channel too I would think...
My thinking was to use very small drivers (2"- 4")in a tall skinny enclosure, something less than 5" and probably 12-16" high, driver facing up. I'm thinking the difuse imaging would work better than trying to position front firing on a desktop.
The Loki looks like an interesting driver
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That is an interesting idea.
Facing one up and one forward would keep the highs from cancelling each other out and that is where the problem is when using more than one full range driver.
I have been thinking of this for a while, BTW.
The lows would couple and increase bottom end output, and that would give you back some of the baffle step loss.
If you build one and send it to me, Ill measure it for you so you can see what it does. You just have to cover the shipping cost.
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That is an interesting idea.
Facing one up and one forward would keep the highs from cancelling each other out and that is where the problem is when using more than one full range driver.
I have been thinking of this for a while, BTW.
The lows would couple and increase bottom end output, and that would give you back some of the baffle step loss.
If you build one and send it to me, Ill measure it for you so you can see what it does. You just have to cover the shipping cost.
I'm considering doing this exact same thing but with towers and using them as surrounds. I was thinking of doing the "cap trick" that you discussed here: http://www.audiocircle.com/index.php?topic=83025.msg802021#msg802021 and having the front facing driver be the one running the high frequencies, almost similar to the X-Omni's and your O-3's.
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That's a good trick, but the one covering the highs will have to face forward. The upward facing driver will act like a front firing driver with an inductor in line with it. As frequency increases the output level will drop right out.
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That's a good trick, but the one covering the highs will have to face forward. The upward facing driver will act like a front firing driver with an inductor in line with it. As frequency increases the output level will drop right out.
Yeah that's what I said, front facing the one running the high frequencies :D
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Yeah that's what I said, front facing the one running the high frequencies :D
Oh yeah. :oops:
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Oh yeah. :oops:
You definitely had me questioning what I said though. Did I say it right?? LOL! Anyway, didn't mean to hijack the thread, sorry about that!
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The design would be similar to the Samadhi Magic Cube or Allison Five or Six, no? My question is does the sound change when listening in the nearfield?
http://store.hifiauthority.com/magiccube_nc.html
http://www.positive-feedback.com/ambackissues/samadhi.htm
http://www.classicspeakerpages.net/library/allison/allison_one_series/allison_one_series_brochure_2/allison_models_five_six_bro/allison_models_five_six_bro.html
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That is an interesting idea.
Facing one up and one forward would keep the highs from cancelling each other out and that is where the problem is when using more than one full range driver.
I have been thinking of this for a while, BTW.
The lows would couple and increase bottom end output, and that would give you back some of the baffle step loss.
If you build one and send it to me, Ill measure it for you so you can see what it does. You just have to cover the shipping cost.
I'm down with that, Danny, but honestly, when I look at all the 3" full rangers on Parts Express I just don't know how best to evaluate them as good candidates, that's where I'm seeking guidance.
With some drivers it looks like price could get so high that it'd make more sense to build something bigger and likely better...my thought would be to keep it cheap and cheerful. Maybe it would help to define some parameters, price per driver could be a good place to start.
I guess I see this as a fairly simple build that perhaps many could do once a little design and prototyping is done. Where's the sweet spot, everybody? I'd like to see total material cost at something less than $150 give or take, is that doable?
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Dave at Planet 10 has been designing some enclosures for some of the larger full range drivers. He might have an idea of which drivers would be best.
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My favorite of the ones I tested weer these:
http://www.tb-speaker.com/detail/1208_03/w3-871sc.htm
No one carries them though.
These are a close second:
http://www.parts-express.com/pdf/264-819s.pdf
They are also pretty inexpensive.
Also pretty good:
http://www.parts-express.com/pdf/264-809s.pdf
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These ones are a tad more than the TB options but I'm running the 4 ohm versions on my desk right now and really like them. My dad has the 8 ohm version in some small towers and a center and they work fantastic as well. They're technically a 4" driver but they go pretty low and play plenty loud and I'm powering them with a little Lepai amp.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-352
Scott
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Check out some of the Mark Audio drivers at Madisound. There are a lot a builds at diyaudio with the CHR70 and the CHP70.
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Check out some of the Mark Audio drivers at Madisound. There are a lot a builds at diyaudio with the CHR70 and the CHP70.
The MA drivers are great. My front stage right now are the Alpair12's in SuperPensil cabinets and a Mar-Ken12 shallow center. If the OP wants a small speaker the flange may be an issue as they're pretty large. If its not a big issue the CHR or CHP drivers are supposed to be great bang for the buck.
Scott
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Timely thread as I'm looking for some office speakers and a small integrated. Anyone have cabinet/crossover designs for some of these drivers? Any worth integrating with a small sub (have an 8" XLS sub sitting doing nothing).
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Timely thread as I'm looking for some office speakers and a small integrated. Anyone have cabinet/crossover designs for some of these drivers? Any worth integrating with a small sub (have an 8" XLS sub sitting doing nothing).
Stay tuned, I'm going to build something and take Danny up on his offer to measure. I'll post progress here as it unfolds. The sub you have could certainly see use considering the drivers we're talking about.
On the topic at hand, assuming I'm using 2 identical drivers per side, one facing up and one forward, would it be better to double the theoretical cabinet volume and have both drivers within said space, or separate space for each? In other words, should I divide the cabinet into two separate spaces, one for each driver?
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Stay tuned, I'm going to build something and take Danny up on his offer to measure. I'll post progress here as it unfolds. The sub you have could certainly see use considering the drivers we're talking about.
On the topic at hand, assuming I'm using 2 identical drivers per side, one facing up and one forward, would it be better to double the theoretical cabinet volume and have both drivers within said space, or separate space for each? In other words, should I divide the cabinet into two separate spaces, one for each driver?
I would think having them share airspace would be preferred and much more simple to build. In Danny's "cap trick" that I posted the link to he stated you can have them share airspace so I would think whether your using a cap or not to modulate the highs you should be fine sharing the same space.
Scott
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So long as they are in phase then they can share the same air space.
Also, when you send it to me make it to where I can measure each driver individually. Then we can see what each one is doing on its own. It will also let me try various parts to see what is ideal or even what the changes are.
If you don't have a dual binding post cup don't worry about it. Just feed the leads from one out the port hole.
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So long as they are in phase then they can share the same air space.
Also, when you send it to me make it to where I can measure each driver individually. Then we can see what each one is doing on its own. It will also let me try various parts to see what is ideal or even what the changes are.
If you don't have a dual binding post cup don't worry about it. Just feed the leads from one out the port hole.
Thanks Danny, will do. The cabinet I send will be a mock up, I'll pretty it up later. Would there be any reason to run the two drivers out of phase?
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Thanks Danny, will do. The cabinet I send will be a mock up, I'll pretty it up later. Would there be any reason to run the two drivers out of phase?
There won't be a reason to run them out of phase, but if a large inductor value were put on one of them it would really shift the phase compared to the other one.
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Danny,
Should you run them in series or parallel? Would it sound different?
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Danny,
Should you run them in series or parallel? Would it sound different?
Oh yeah. It will be different. The impedance and sensitivity will be very different.
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Easy for me to get carried away on this kind of stuff, and that's where I was heading so I reined myself in and stuck to my cheap and cheerful path for this project. This will act as the polar balance to the high end monitor thread :lol:
Just ordered this;
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=310-302
And four of these;
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=264-819&scqty=4
I've been thinking about the cabinets. I don't really want them directly beside my monitor, but behind it a bit. I should probably make them tall enough that the front firing driver is a little above monitor, which would put them about 21". So really tall and skinny and likely some empty space at the bottom.
Could put 'em on stilts even...look like a little old-time water tower...or a fence post...or an obelisk. This is where my imagination gets cookin'. Crazy ideas welcomed...jump in!
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Facing one up and one forward would keep the highs from cancelling each other out and that is where the problem is when using more than one full range driver.
The version of the microTower that is configured this ways has become the most popular version amoungst DIYers.
(http://homepage.mac.com/tlinespeakers/FAL/images/castle-el70-800.jpg)
It works well and the idea can easily be incorporated.
dave
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I'm down with that, Danny, but honestly, when I look at all the 3" full rangers on Parts Express I just don't know how best to evaluate them as good candidates, that's where I'm seeking guidance.
There are lots of good 3" full ranges ... from personal experience my favourites are Mark Audio Alpair6P, Alpair6M, & Fostex FF85wk. Hard to pick an outright winner, each has a balance of strengths that would give it the edge in differing circumstances. Fountek FR88ex is a step down (and the cheap ceramic magnet version probably offers really good performance for near nothing). The Aura NS3 i have heard and is decent. Except for a unique proto pair of cast-basket neo i haven't run into any TBs that i really like, but they probably hold their own -- years ago when the W3-871 was one of the few available 3", it gave a real kick to one's beliefs of what a 3" FR could do -- i still have a couple pairof those kicking around. The HiVis seem to get decent comments. The ScanSpeak 3" also is highly regarded, when i got mine i was a little turned off because of the high cost, haven't done anything with them yet... i believe there is a Vifa or Peerless based on the same design,
Pick some you like the look of and go for it. (edit, looks like you did :))
dave
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Off I go into the unknown (for me). The vas for this driver is 0.06 cu.ft. so I'm doubling that for two drivers.
The concept drawing is using 5/8" material for top and sides, and 1 5/8" bottom to add weight to the bottom. Internal volume with these dimensions clocks in at about 0.12 cu. ft. Right so far?
Next I'd assume I need to figure port size, how does one figure that out?
(http://www.audiocircle.com/image.php?id=58575)
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I need help. I was using vas of driver to dictate box volume which I now think is wrong methodolgy.
Nosing around I found this;
http://www.diyaudioandvideo.com/Calculator/Box/
which suggests to me that the vas is but one parameter to determine box volume. When I run the numbers this calculator is telling me I need something like .15 cu ft. per driver, double that and I have a much bigger box than what I had drawn...something like 2.5 times larger.
So if I use the above I end up with a box that doesn't work for the intended application because of sheer size...that's where I'm stuck.
What would be the effect of using my "too small" box design? Would it be better to rethink the enclosure or perhaps the whole concept?
I think I need a plan B :scratch:
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I need help. I was using vas of driver to dictate box volume which I now think is wrong methodolgy.
Nosing around I found this;
http://www.diyaudioandvideo.com/Calculator/Box/
which suggests to me that the vas is but one parameter to determine box volume. When I run the numbers this calculator is telling me I need something like .15 cu ft. per driver, double that and I have a much bigger box than what I had drawn...something like 2.5 times larger.
So if I use the above I end up with a box that doesn't work for the intended application because of sheer size...that's where I'm stuck.
What would be the effect of using my "too small" box design? Would it be better to rethink the enclosure or perhaps the whole concept?
I think I need a plan B :scratch:
Download WinISD: http://www.linearteam.dk/default.aspx?pageid=winisd Its a free program and gives you pretty good results with box calculations. Its not as good as expensive PRO stuff that I'm sure Danny and others use but it does very good and LOTS of people use it. You can add in your own drivers and they're specs and build a box based on lots of different parameters. Its very easy to use and play around with.
Scott
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I need help. I was using vas of driver to dictate box volume which I now think is wrong methodolgy.
Nosing around I found this;
http://www.diyaudioandvideo.com/Calculator/Box/
which suggests to me that the vas is but one parameter to determine box volume. When I run the numbers this calculator is telling me I need something like .15 cu ft. per driver, double that and I have a much bigger box than what I had drawn...something like 2.5 times larger.
So if I use the above I end up with a box that doesn't work for the intended application because of sheer size...that's where I'm stuck.
What would be the effect of using my "too small" box design? Would it be better to rethink the enclosure or perhaps the whole concept?
I think I need a plan B :scratch:
Download WinISD: http://www.linearteam.dk/default.aspx?pageid=winisd Its a free program and gives you pretty good results with box calculations. Its not as good as expensive PRO stuff that I'm sure Danny and others use but it does very good and LOTS of people use it. You can add in your own drivers and they're specs and build a box based on lots of different parameters. Its very easy to use and play around with.
Scott
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The older version of that driver that I had needed .1 cubic feet (ported) per driver. Looks like the specs of this newer version are still real close.
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I just plugged in the specs into WinISD and it came back with this, roughly .293 ft^3.
(http://i81.photobucket.com/albums/j217/scott_lisa_day/ScreenShot058.jpg)
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I just plugged in the specs into WinISD and it came back with this, roughly .293 ft^3.
Thanks for doing that Skeeter, is that for one driver or two? That number is really close to what the calculator I linked to indicates for both in one space. That sends me back to the drawing board I guess.
I'm still curious what the effect of a too small enclosure would be. I can't help but wonder how it's done on commercially made mini speakers. Does it just limit the lower frequency output?
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Thanks for doing that Skeeter, is that for one driver or two? That number is really close to what the calculator I linked to indicates for both in one space. That sends me back to the drawing board I guess.
I'm still curious what the effect of a too small enclosure would be. I can't help but wonder how it's done on commercially made mini speakers. Does it just limit the lower frequency output?
That was for two drivers. How much airspace do you want to work with? WinISD figures the optimal but you can tweak it for the size you want and adjust port lengths to get the tuning you want.
Scott
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To get optimum volume (.3 cu.ft.) this is morphing into a pretty overbearing desk accessory...and looking more and more like a fence post...
(http://www.audiocircle.com/image.php?id=58689)
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I don't know. Maybe it could be a skinney tower. Do a stand to get it to the floor.
Then put in on either side of the desk. Takes no desk space at all that way.
I've got a drunk that keeps hitting my mailbox. Maybe I could build one of these
to put the mailbox on and have it make a dying sound when it hits it again. :roll:
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If you reduce the box volume the LF extension of the driver becomes less. From Skeeter's model looks like F3 is around 65Hz. If you mate this to a small sub that can go higher in frequency, you can make the box smaller. The issue is it will be easier to locate the sub audibly.
The program Bass Box will let you put in custom box dimensions after you have the Thiel-Small parameters for the driver, which looks like Skeeter has used in his model.
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If you reduce the box volume the LF extension of the driver becomes less. From Skeeter's model looks like F3 is around 65Hz. If you mate this to a small sub that can go higher in frequency, you can make the box smaller. The issue is it will be easier to locate the sub audibly.
The program Bass Box will let you put in custom box dimensions after you have the Thiel-Small parameters for the driver, which looks like Skeeter has used in his model.
Hal is correct and some simple adjustments to raise your f3 yields this:
(http://i81.photobucket.com/albums/j217/scott_lisa_day/ScreenShot061.jpg)
Less than half the space of the previous design and .141 ft^3. It yields a rising response with a peak around 152hz and up 2.2db but then has a fairly smooth roll off after that with an f3 of about 90hz. I just let the box builder figure "optimum" dimensions which are obviously easy to tweak either way. I can easily tweak it, what dims are you looking for?
Scott
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I don't know. Maybe it could be a skinney tower. Do a stand to get it to the floor.
Then put in on either side of the desk. Takes no desk space at all that way.
I've got a drunk that keeps hitting my mailbox. Maybe I could build one of these
to put the mailbox on and have it make a dying sound when it hits it again. :roll:
I'm thinkin' the sound of a siren might leave a bigger impression on the drunk...
I really want them to live on the desk...really the only way to go if I want them to face me. I'm warming to the idea of fence posts on desktop, and to tell the truth I like contemporary look and now my imagination is ramping up with some cool ways to finish.
I'm wondering how the upper driver will like being within 16-17" of the ceiling...kinda like Danny's AV-R's.
I'm excited to give this a shot.
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Scott,
Thanks for showing the FR change.
The issue is going to be the peaking in the 100Hz to 200Hz range is going to start making things sound nasal since it is not flat.
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Hal is correct and some simple adjustments to raise your f3 yields this:
(http://i81.photobucket.com/albums/j217/scott_lisa_day/ScreenShot061.jpg)
Less than half the space of the previous design and .141 ft^3. It yields a rising response with a peak around 152hz and up 2.2db but then has a fairly smooth roll off after that with an f3 of about 90hz. I just let the box builder figure "optimum" dimensions which are obviously easy to tweak either way. I can easily tweak it, what dims are you looking for?
Scott
Scott I appreciate your efforts, I did download WinISD, but try as I might, I couldn't seem to save the new driver info so I could continue. Any clues on that?
I found something to play with box volume here, but no FR graph like winISD;
http://www.hometheatershack.com/forums/enclosure-volume-calculator/
I've had to define my parameters better as design has progressed, priorities have evolved to:
1. 5"x5" footprint is ideal for area where they will sit
2. Keep the whole thing cheap and cheerful
3. I think I want to optimize box volume if at all possible, hence my latest design
4. I'll mock them up before commiting to a final finish
5. I think I've succumbed to the experimentation bug :o
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Scott,
Thanks for showing the FR change.
The issue is going to be the peaking in the 100Hz to 200Hz range is going to start making things sound nasal since it is not flat.
It definitely could. I have a rising response like that on my desktop speakers I built and its really not too bad since its minimal but other people have far better hearing than I do and it very well could cause issues for them. Very good point.
Scott
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Brain is going very slow today due to a cold. :(
I think Bass Box's crossover software will let you add a notch filter to EQ out the peak in the 100-200Hz range. That might help flatten things out if you want to use the small box.
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Scott I appreciate your efforts, I did download WinISD, but try as I might, I couldn't seem to save the new driver info so I could continue. Any clues on that?
I found something to play with box volume here, but no FR graph like winISD;
http://www.hometheatershack.com/forums/enclosure-volume-calculator/
I've had to define my parameters better as design has progressed, priorities have evolved to:
1. 5"x5" footprint is ideal for area where they will sit
2. Keep the whole thing cheap and cheerful
3. I think I want to optimize box volume if at all possible, hence my latest design
4. I'll mock them up before commiting to a final finish
5. I think I've succumbed to the experimentation bug :o
I readjusted the dims within WinISD and got a 5"x5"x16.23" box using 1/2" material. Port is 2"x4.42".
I don't know why you can't save your own drivers?? You click on "own drivers" in the new project tab then click the "new" button. It takes you to the "Driver Editor" window where you put in the driver name and all the specs. Once you're done you click OK. You then have to go back to the New Project window, click on "own drivers" again then pick your driver from the pull down menu.
Scott
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Brain is going very slow today due to a cold. :(
I think Bass Box's crossover software will let you add a notch filter to EQ out the peak in the 100-200Hz range. That might help flatten things out if you want to use the small box.
Oh I don't have Bass Box, maybe I should download it. I'm using WinISD.
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Changing the tuning frequency to 75hz smooths out the larger rise to a max rise of .6db centered at 200hz and a f3 of 94.63hz:
(http://i81.photobucket.com/albums/j217/scott_lisa_day/ScreenShot062.jpg)
This changes the port length to 9" which is pretty long but its all internal so it shouldn't matter.
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I'll model this in Bass Box later today. The port size though sound be quite small.
Also keep in mind that there will be some baffle step loss. This will be helped by using two woofers but maybe not completely.
So a bumped bottom end may in reality not be much of a bump.
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I'll model this in Bass Box later today. The port size though sound be quite small.
Also keep in mind that there will be some baffle step loss. This will be helped by using two woofers but maybe not completely.
So a bumped bottom end may in reality not be much of a bump.
Cool! I look forward to seeing what Bass Box comes up with :thumb: Its fun playing around with the program so it'll be cool to see what pro results look like!
Scott
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To get optimum volume (.3 cu.ft.) this is morphing into a pretty overbearing desk accessory...and looking more and more like a fence post...
(http://www.audiocircle.com/image.php?id=58689)
Do keep in mind that when you get to these kind of aspect ratios that a BR modeler won't do it. You have to use something like MJK's sheets to account for the quarter-wave inside.
dave
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Do keep in mind that when you get to these kind of aspect ratios that a BR modeler won't do it. You have to use something like MJK's sheets to account for the quarter-wave inside.
dave
Hmmmmmmmm...quarter wave? Dave, I'd love to keep it in mind, but you're dealing with a neophyte designer here, so the truth is, I don't understand what you're describing.
Any chance you could elaborate? What is BR and MJK's sheets may well be of interest, if only I knew where I might find them. I doubt we're talking bed sheets...
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Bass box shows these woofers need .1 cubic feet per woofer. And the port size is 1/2" in diameter by 7/16" long. This gives you a -3db of 71Hz.
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Bass box shows these woofers need .1 cubic feet per woofer. And the port size is 1/2" in diameter by 7/16" long. This gives you a -3db of 71Hz.
Thanks for doing that, Danny, it gets confusing with different results from various resources. Is the port size you mentioned considering 2 woofers or should that double?
The little app I linked to earlier was calling for port diameter of 1" with a length of 1 11/16" and a box volume of 1.5 per driver...dang, what a difference. For someone (me) who likes to make well considered decisions, it seems a bit wonky.
I'll run with your numbers, partly 'cuz I like the box size better, but mostly because I trust your judgement.
This quarter wave thing Dave mentioned has got me wondering
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Thanks for doing that, Danny, it gets confusing with different results from various resources. Is the port size you mentioned considering 2 woofers or should that double?
Double that for two woofers.
It is just a 3" woofer with .2mm of X-max. It can't move enough air to need a port that is very big.
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Round three!
.2 cu ft volume, 5"x 5" footprint using 5/8ths material, may go with 1/2" material, not sure that additional rigidity of thicker MDF would prove to be a benefit...opinions?
(http://www.audiocircle.com/image.php?id=58725)
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Round three!
.2 cu ft volume, 5"x 5" footprint using 5/8ths material, may go with 1/2" material, not sure that additional rigidity of thicker MDF would prove to be a benefit...opinions?
(http://www.audiocircle.com/image.php?id=58725)
For Danny's sim to be valid you need to shorten the box and at least increase the depth (increasing the width to reduce early reflections back thru the cone will help reduce midrange colouration). With that aspect ratio you have created a non-optimum mass loaded transmission line. I'd alo try to keep the drivers as close as possible.
You could readily get away with 1/2" quality plywood. MDF needs to be quite a bit thicker for the same stiffness.
dave
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Version #4. Got all the parts on hand now. Box volume .2 as Danny figured, using 1/2" material and also considering Dave's suggestions this is what I came up with.
Bottom 5 1/2" of box is separate and raises the front driver to get slightly above monitor. Could be legs or some kind of plinth, but I'll ponder that some. My intent is to keep the design simple so it would be easy for others to duplicate.
Never having messed around with little drivers like these, I'm impressed by their heft...they're stout little buggers.
(http://www.audiocircle.com/image.php?id=58942)
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That should work out pretty well.
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So how is this coming along? Eagerly anticipating your results :) I might be starting my double tower this weekend using the TB Buyout W3-881SI's with a similar configuration. I'm going to be using mine as surrounds though.
Scott
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I got the test box done today, this is what I'm sending you, Danny.
Final versions will have the riser attached to bottom instead of the plinth I put on this one. Wires are running out port holes, finished speakers will have binding posts:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=260-275
Sounds kinda weird running stereo signal into common box, little amp doesn't have a way to switch to mono. I'm pleased so far. They'll never rock the house, but weren't intended too anyway.
Question for Danny about stuffing. Should I stick some in there before sending to you and if so how much? The plinth is screwed on so it's easy to change.
(http://www.audiocircle.com/image.php?id=59187)
(http://www.audiocircle.com/image.php?id=59188)
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Nice they're looking good! So are you not doing them ported? I can't remember what you decided.
Scott
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Scott,
The wires are coming out the port holes. They are just not very big.
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I would load that thing with some loose poly fill or insulation.
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Scott,
The wires are coming out the port holes. They are just not very big.
Haha ok I'm a dork. Carry on :green:
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I don't know. I wouldn't have thought those were port holes.
My thinking was there was normally only one port in a box
anyway. But it is handy for getting wires out of the box. :wink:
They do look like nifty boxes though. Simplicity is always
a good thing.
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After building the test box that's going to Danny, I've been refining the Sketchup model to simplify box building and facilitate changing riser height to accomodate different needs. Also gives easier access to internal space should one want it. Larger hole in rear is for binding post cup mentioned earlier.
(http://www.audiocircle.com/image.php?id=59380)
(http://www.audiocircle.com/image.php?id=59381)
(http://www.audiocircle.com/image.php?id=59382)
Unless threre are changes that come about after Danny's measuring, this is how I'll build 'em. I'm happy to share the Sketchup model if anyone wants it, send me a PM with your email address. This was created in Sketchup Pro, but I'm pretty sure the freebie version will open it and manipulate any way you want.
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It's very interesting following this project.
In the photos of the box, I didn't notice any nails or screws holding it together. Did you simply glue the sides and top together? In the final version will it be necessary to apply some type of caulk on the inside at the intersections of all the joints, to make sure that it is completely air tight?
Never built speakers before myself & am interested in answers to my novice questions.
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It's very interesting following this project.
In the photos of the box, I didn't notice any nails or screws holding it together. Did you simply glue the sides and top together? In the final version will it be necessary to apply some type of caulk on the inside at the intersections of all the joints, to make sure that it is completely air tight?
Never built speakers before myself & am interested in answers to my novice questions.
I used Titebond and biscuits on the butt joints, although there are other methods that would be just as good structurally. Even a simple glued butt joint would probably suffice considering appliaction...it's not like we're parking cars on it. I often avoid metal fasteners at the joints 'cuz carbide tooling and steel are a bad mix and I've got some ideas for corners that would require machining.
I'm the original anti-caulk crusader, so I may be jaded :D The only reason I can see to use it would be if joints were somehow difficient and there were gaps that effectively increased port size. This is a ported speaker so airtight isn't really necessary.
I think this design could be further simplified for a novice by not rabbeting for driver flange. Considering the intended application, I'm just not sure that it would make an audible difference, but Danny could speak to that better than me.
My altruistic thought is that this would be a fairly easy build for a newcomer, but I imagine that could be good or bad. Once on that train its hard to get off...
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This is a ported speaker so airtight isn't really necessary
My thinking, and maybe it is not that critical, is that the port is tuned and
any other leakage in the box will alter that tuning. Sounds like your box
building techniques probably result is a pretty tight box already but I
don't know if you can just discount box leakage in a ported design. IMHO
And I modify my post because it looks like you somewhat say the same
things in the sentence before. When my sinuses get bad things aren't
always obvious to me.
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Okay, I measured your speakers and here is the deal.
The up firing woofer is too far back of the front woofer. In other words the acoustic center of the front woofer is about an inch back (center of the voice coil) while the acoustic center of the up facing woofer is about 4.25" back. So there is quite a bit more delay involved than if the upper woofer were at the front of the cabinet verses at the back edge of the cabinet.
Here is the effect.
(http://gr-research.com/mis/dual3b.jpg)
The green line is the front facing woofer. The Red line is the up facing woofer. And the blue line is the two of them together. As you can see there is cancellation going on in two places and a big peak at 3kHz.
So I started dropping parts on it. The parts used can correct for response errors and also shift phase.
(http://gr-research.com/mis/dual3c.jpg)
This one got a notch filter on the front facing woofer. It corrected it's peak, but the cancellation effects are still there and in the same places. The peak is still there too.
(http://gr-research.com/mis/dual3a.jpg)
Here is one with a little more of a notch filter on the front woofer. It is the light Blue line. It looks really good on its own. The green line is the up facing woofer with a 12mH inductor in line with it. This makes it do low duty only. Unfortunately it adds even more delay. The dark blue line is the two of them together. The upper woofer is actually cancelling out the lower one some. I could reverse the polarity of the upper woofer to cause it to add a little gain, but then they would be fighting against each other in that air space.
The solution looks like requires the upper woofer to be moved to the front edge instead of the back edge. This will leave only about 1.25" of offset delay. Hopefully the area of cancellation will then be high enough in the frequency range that the limited off axis response will limit interaction or cancellation.
-
You are also going to have to figure out a way to line the walls with insulation while leaving the middle open so that there is a clear path to the ports. A wad of poly fill stuffed down the center isn't going to work.
-
You are also going to have to figure out a way to line the walls with insulation while leaving the middle open so that there is a clear path to the ports. A wad of poly fill stuffed down the center isn't going to work.
Very interesting Danny. I was wondering how the placement of the top woofer would affect the frequency response. I thought the top one looked cooler that way but apparently it isn't working. I'm glad I haven't cut the holes of mine yet. So bringing the top woofer to the front edge should really help out the delay and cancellation?
Scott
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Very interesting Danny. I was wondering how the placement of the top woofer would affect the frequency response. I thought the top one looked cooler that way but apparently it isn't working. I'm glad I haven't cut the holes of mine yet. So bringing the top woofer to the front edge should really help out the delay and cancellation?
Scott
Yes. I'll just have to give it a try and see if it will work.
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Thanks Danny...it's pretty cool of you to do this.
It does raise some questions. Given what you've measured, would you say the idea of an up firing driver in this application is beneficial or is it just adding complexity and compromise?
Because of magnet structure on drivers, front one will need to move down to accomodate top one moving forward. Although it's not a problem from a woodworking standpoint, will it introduce any significant new elements?
I can figure out the stuffing I think, but am wondering if moving ports nearer top would be desireable. Seems like I've mostly seen them down low, but now wondering if drivers actually "see" port position or just cabinet volume.
From a a woodworking standpoint it wouldn't be too difficult to separate the cabinet into two cavities to facilitate reversing phase on top woofer, but would require moving front woofer down even more, and still keep design somewhat easy to build. Would this make any sense?
Yet another possibility would be to put them both on front baffle and add notch filter...perhaps this would be the path of least resistance?
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It does raise some questions. Given what you've measured, would you say the idea of an up firing driver in this application is beneficial or is it just adding complexity and compromise?
If implemented properly with the acoustic centers aligned then it should add realism to the presentation. It will give you more of an in the room with you experience verses a from the speakers effect.
Because of magnet structure on drivers, front one will need to move down to accomodate top one moving forward. Although it's not a problem from a woodworking standpoint, will it introduce any significant new elements?
Moving the front one down will add a little more surface reflection to the front woofer output, but it will be real minimum. I wouldn't expect to see much change in the response.
I can figure out the stuffing I think, but am wondering if moving ports nearer top would be desireable. Seems like I've mostly seen them down low, but now wondering if drivers actually "see" port position or just cabinet volume.
In a box this small the location will have a minimal effect. But if you get them too close to the driver then the driver tends to not use the air space in the box as well.
From a a woodworking standpoint it wouldn't be too difficult to separate the cabinet into two cavities to facilitate reversing phase on top woofer, but would require moving front woofer down even more, and still keep design somewhat easy to build. Would this make any sense?
I'd try the same air space and just move the front woofer down and the upper one forward.
Yet another possibility would be to put them both on front baffle and add notch filter...perhaps this would be the path of least resistance?
I did two of them on the front of the baffle for my kids computer speakers and added an inductor in line with the lower woofer to keep it from playing to high.
The response of these look different than the older version of this woofer that I had. So the best solution for a crossover will be different.
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Looking back on page two at these speakers makes me think that they will have similar response problems.
(http://homepage.mac.com/tlinespeakers/FAL/images/castle-el70-800.jpg)
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First test didn't fare as well as hoped, so on we go to round two. Danny suggested two things to improve upon the basic platform; move top driver forward and line the walls to reduce internal reflections.
This is the new improved version, top driver moved forward and front driver moved down. I'll make another test box so we can see how it measures up.
(http://www.audiocircle.com/image.php?id=59709)
Lining the cabinet is hampered a little by access to the inside once box is assembled...there's just not much room to work. Something that can be cut to size, maintains it's shape and can be glued in place. After some head scratching and a couple of phone calls I came up with this;
(http://www.audiocircle.com/image.php?id=59695)
(http://www.audiocircle.com/image.php?id=59696)
It's felt carpet pad, sometimes called rug pad. Often used under throw rugs on hard surfaces to keep them from sliding and give a little cushion. Danny, does that look like it will do the trick?
I edited the drawing to correct a dimensional error which I discovered while building box.
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How about using this UltraTouch Insulation from Creative Sound Solutions (http://www.creativesound.ca/details.php?model=UltraTouch%20Insulation) to line the cabinet?
(http://www.creativesound.ca/images/product/UT4.jpg)
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I used UltraTouch in some acoustical panels and used some I had left over to stuff a sub I just built. You can get it from Homedepot also.
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We almost exclusively use UltraTouch for our boxes. It is a joy to use and works very well.
There are 2 types -- the 1/2" felt Bob sells, and less dense bats as used for wall insulation (in various thickness -- i expect this is what Home Despot sells (only in the US, not in Canada)
We use the felt for lining reflex enclosures (and for near the drivers in other boxes). The insulation bats are good for sealed or aperiodic boxes.
dave
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hello,
i remember a while back listening to speaker that looks like the speaker you are making. i sure it is not the same but thought you may want to look at it.
http://www.6moons.com/audioreviews/fj/om.html
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hello,
i remember a while back listing to speaker that looks like the speaker you are making. i sure it is not the same but thought you may want to look at it.
http://www.6moons.com/audioreviews/fj/om.html
Wow, $4,000 a pair.
I have a kit along those lines for $249: http://gr-research.com/av-o.aspx
And then this one is a step above at $529: http://gr-research.com/o-3.aspx
And I still have completed X-Omni's with no grills for $275 a pair. http://www.audiocircle.com/index.php?topic=99297.0
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The FJ speakers are sold through dealers (in fact, a friend of mine carries their line); if they were sold direct, the $4,000 FJ Ohm would be apprioximately $2,000. To determine how the FJ Ohm compares sonically to Danny's speakers, one would have to hear them side by side; it would undoubtedly make for an interesting comparison!
Larry
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Danny I wonder if you could elaborate on the cancelation you mentioned in your measurements? I'm trying to wrap my head around it conceptually and reconcile with what I'm looking at in the graphs.
Does the cancellation you see take place where the different driver meaurement lines intersect? What's the sonic effect? Does it create a null at that frequency (frequencies) that makes it (them) inaudible?
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Okay, the green line is the front driver and the red line is the upper driver.
So looking at the blue line of the two of them playing together we see that they are coupling below 900Hz and we see an increase in output (1+1=2).
However, at 1,700Hz and 4,900Hz we see cancellation effects (1+1=-2). Funny math huh? At 1,700Hz it is a half of a wave length back and 180 degrees out of phase. At 4,900Hz it is likely 1.5 wavelengths back and out of phase.
2,300Hz to 4kHz they are in phase and creating gain again. In this range they are actually a wavelength apart but in time with one another.
(http://gr-research.com/mis/dual3c.jpg)
When they couple they are twice as loud and when they cancel they have less output than one woofer, sometimes less than half of the output of one woofer.
-
uhh... right. Just when I think I have a little handle on the cancelation and doubling, you go and introduce wavelengths and phase shifting... :o Funny math indeed.
Phase confuses me some, I guess I think of it in absolute polarity terms, which is what I know from simply hooking up speakers, but there appears to be much more to it. So phase shift can occur within crossover components?
You know, this makes me feel almost stupid, good thing I'm not sitting in your chair! I'm better off sticking to the wood parts.
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Waves superimpose upon themselves... in other words, their amplitudes add. Imagine that two waves approach one another. If the crest of one wave goes through the trough of another, the amplitude will cancel. It's the same kind of thing as when two woofers are hooked up wrong, with one wired backward. When one woofer kicks in, the other kicks out. One creates a pressure zone, and the other a vacuum zone. When they meet, they cancel. On the above graph, at about 1700 Hz, one woofer is kicking in where the other is kicking out. It happens again at around 5K Hz. If it weren't for phase shifts, we could all design crossovers like pros. They are tricky little devils, and a pain to deal with.
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Ok, but when I grow up, I want to go to Scott's class about building speakers. Having Scott and Danny as teachers sure would have been cool!
Maybe my designs would not have been so bad over the years! :D
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Isn't a benefit of this wave cancellation effect the "noise-cancelling headphone"?
The microphone in the headphone listens to the ambient noise and plays it back in the headphones 180 degrees out of phase -- thus cancelling the noise :o for the headphone wearer (as explained by Danny and Scott).
This has nothing to do with your cool speakers, I'm just tossing out another example that you may have experienced.
- David
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Wow, $4,000 a pair.
I have a kit along those lines for $249: http://gr-research.com/av-o.aspx
And then this one is a step above at $529: http://gr-research.com/o-3.aspx
And I still have completed X-Omni's with no grills for $275 a pair. http://www.audiocircle.com/index.php?topic=99297.0
I notice that the reviewer devotes a lot of space to flowery descriptions of the sound, but I'm not seeing anything in the review about the position of the speakers in the room. He mentions his room size, but nothing more than that. Nothing about how position in the room changed the sound or imaging. Position in the room is important for any speaker, but it seems especially critical with dipoles and omnis.
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Welcome to AC Atexanathome.
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Okay how's this?
One woofer is mounted right over the other now and the best response was obtained on axis with the front firing woofer. Green is the front facing woofer. Blue is the lower one, and red is the two together.
(http://gr-research.com/mis/d3a.jpg)
Because I am on axis with the front firing woofer and not dead center between the two of them, there is some cancellation going on in the 1.5kHz to 4kHz range but only a slight amount cause by a slight phase rotation. This is because the mic is slightly further away from the upper woofer. So it smoothed out the peak in the response of the front woofer. No notch filter needed. :D
Okay now how's this (below)? I added a .47mH inductor in line with the upper woofer to minimize how high it plays and to reduce upper frequency range interference a little. This time the light blue line shows them playing together.
(http://gr-research.com/mis/d3b.jpg)
Here is the response on a typical 10db scale like you see everywhere else.
(http://gr-research.com/mis/d3c.jpg)
Here is the horizontal off axis. Looks pretty smooth and consistent.
(http://gr-research.com/mis/d3d.jpg)
Here is the vertical off axis. As the mic moved up 4" per measurement you can see more coupling in the 1kHz to 3kHz range. Not too bad though.
(http://gr-research.com/mis/d3e.jpg)
Here are the impedance curves with and without the .47mH inductor on the upper woofer. Red is without the inductor and green is with it.
(http://gr-research.com/mis/d3f.jpg)
Another thought on this is that a rear firing ambiance tweeter could be added with a single small cap and resistor (adjustable) to give it back a little air. That will help with the over all sound since the top end is a little soft. It would also not effect the on axis response, just the overall in room response and balance. It will also lower the impedance in the top end and balance the impedance load.
These would be good speakers for a small untreated room, especially with the speakers placed well out into the room. They would create a pretty large sound field.
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Danny:
In the second graph I do not see the high frequency roll-off from the inductor in series. What am I missing (other than a brain! :) )
Larry
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Danny:
In the second graph I do not see the high frequency roll-off from the inductor in series. What am I missing (other than a brain! :) )
Larry
Check the bright Blue line in the top two graphs. Note that in the second graph the upper woofer (Blue line) does not play up as high.
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Aha, it's the lower woofer (dark blue line) that does not play as high in freuency.
When you wrote "I added a .47mH inductor in line with the upper woofer" you really meant the lower woofer, correct? Or am I still confused?
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Aha, it's the lower woofer (dark blue line) that does not play as high in freuency.
When you wrote "I added a .47mH inductor in line with the upper woofer" you really meant the lower woofer, correct? Or am I still confused?
No, it is the upper woofer (up facing woofer) that has the inductor in line with it.
-
But those responses look identical. I'm still confused.
-
But those responses look identical. I'm still confused.
Okay Larry,
I have copied the Blue line from the second graph (with the in line inductor) onto the first graph. Now do you see the difference in the two blue lines?
(http://gr-research.com/mis/difference.jpg)
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But those responses look identical. I'm still confused.
Larry, they look similar, but in the second graph the upper woofer (lowest on graph...dark blue) starts falling off a little sooner, around 800 Hz.
I'm actually getting to the point that I recognize a little more of what I'm looking at! The phase and wavelength thing still befuddle me...oh well.
Danny, I have to say that from my limited knowledge, moving that woofer forward made a significant difference, no?
I'm game to try the tweeter, do you have a recommendation?
While I appreciate your candor when you ask us,"Okay, how's this" , I sure don't feel qualified to say, " well Danny, that looks great!". Having just gotten my yellow belt in speaker design and all :) I know just enough to be dangerous!
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Danny, I have to say that from my limited knowledge, moving that woofer forward made a significant difference, no?
Yes it did.
And the response is very smooth.
You can use just about anything for a rear ambiance tweeter. It is only going to add a little air in the very top end. So just about any inexpensive dome tweeter would be good.
-
Danny:
Absolutely, the thick blue lines are quite different. But you said before those were the lower woofers, which is why I got confused:
Blue is the lower one
Larry
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Yes it did.
And the response is very smooth.
You can use just about anything for a rear ambiance tweeter. It is only going to add a little air in the very top end. So just about any inexpensive dome tweeter would be good.
Perhaps AV123 stuff, like what the X-LS has, or would that be overkill?
Mounted up near the top on rear, that's a lot of holes cut in a small area, do you think it would be wise to look at smaller diameter or maybe lower mounting?
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Danny:
Absolutely, the thick blue lines are quite different. But you said before those were the lower woofers, which is why I got confused:
Larry
Oh, sorry about that.
Perhaps AV123 stuff, like what the X-LS has, or would that be overkill?
Mounted up near the top on rear, that's a lot of holes cut in a small area, do you think it would be wise to look at smaller diameter or maybe lower mounting?
High mounting is fine.
-
Apology accepted. Someone's gotta' keep you on your toes. :)
-
Another thought on this is that a rear firing ambiance tweeter could be added with a single small cap and resistor (adjustable) to give it back a little air. That will help with the over all sound since the top end is a little soft. It would also not effect the on axis response, just the overall in room response and balance. It will also lower the impedance in the top end and balance the impedance load.
Danny, when you say adjustable, I'm assuming changing value of cap and resistor accomplishes the adjustment, correct? Where does one start with these values?
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Danny, when you say adjustable, I'm assuming changing value of cap and resistor accomplishes the adjustment, correct? Where does one start with these values?
The cap value will be pretty small to match the rear wave output. Then the level of the tweeter can be adjusted up or down via the resistor value.
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Question for those following this thread, (assuming any are still hangin' in!).
I'm soon to build a finished pair...pretty basic, with laminate as the final finish. Maybe mess with a rear tweeter later. If there's interest, I'll shoot pics along the way. What say you?
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Question for those following this thread, (assuming any are still hangin' in!).
I'm soon to build a finished pair...pretty basic, with laminate as the final finish. Maybe mess with a rear tweeter later. If there's interest, I'll shoot pics along the way. What say you?
I'm still following and would love more pics! I'm getting ready to cut holes in my towers :-)
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Absolutely, keep us updated with pics.
Thanks.
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More pics please! Thanks for sharing your expertise!
Pete
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Here we go...
Parts cut out. I tried to make constuction simple so design could be easily duplicated. All butt joints and glue.
(http://www.audiocircle.com/image.php?id=60299)
Sides and top glued and clamped, bottom left loose and used as a spacer
(http://www.audiocircle.com/image.php?id=60301)
Glue and clamp front and back, bottom still loose, you'll see why...
(http://www.audiocircle.com/image.php?id=60302)
Danny's Bass Box calcs called for two 1/2" dia. x 7/16" long ports. conversion to single port for same volume ended up with odd hole size that most people won't likely have, so this was path of least resistance. Removing material from inside to accomplish the 7/16" dimension in 1/2" material.
(http://www.audiocircle.com/image.php?id=60303)
Before and after
(http://www.audiocircle.com/image.php?id=60304)
Ready to clamp front and rear on. I did both at the same time, but might be easier one at a time if it's new to you.
(http://www.audiocircle.com/image.php?id=60305)
Clamped
(http://www.audiocircle.com/image.php?id=60306)
All flush trimmed and putting stop cleats in for bottom to land on
(http://www.audiocircle.com/image.php?id=60307)
Speaker and base the same except base has 3/4" top and bottom
(http://www.audiocircle.com/image.php?id=60308)
Next up laminating exteriors, stuffing interiors and final assembly...stay tuned!
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Wow, the cabinets are looking great! I have thoroughly enjoyed following this thread! Actually, your project has pushed me into giving it a try. The low cost of these drivers makes it pretty easy too.
Can you post the dimensions of your cabinets? I want to try to duplicate it.
Also, just curious, are you going to stain the cabinets or paint them?
Thanks again, Tom
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Wow, the cabinets are looking great! I have thoroughly enjoyed following this thread! Actually, your project has pushed me into giving it a try. The low cost of these drivers makes it pretty easy too.
Can you post the dimensions of your cabinets? I want to try to duplicate it.
Also, just curious, are you going to stain the cabinets or paint them?
Thanks again, Tom
Tom, I'm posting a some graphics that will give dimensions...hopefully all you need. I varied the base height from that shown to 8 3/4" because I wanted the front drivers to peek over my monitor...you'll see what I'm saying as I post more on this thread.
A few things to bear in mind;
The base has no function other than to raise the speaker, so it can be eliminated if you like.
If you want the whole Sketchup model, I can email it to you, shoot me a PM with your email addy and it's yours, and that goes for anyone else as well. Google has a free version of Sketchup that will (I'm pretty sure) open this and give you most if not all the capability I used to draw it. It's very cool and capable and FREE, so have fun.
http://sketchup.google.com/intl/en/download/
To make this build even easier, I think one could eliminate the rabbet for the driver flange to get them flush with cabinet without huge detriment to overall sound. Danny, can you speak to that?
(http://www.audiocircle.com/image.php?id=60321)
(http://www.audiocircle.com/image.php?id=60322)
Finish will be this laminate,
http://samples.wilsonartcontract.com/p-517-xanadu-7945.aspx
which is the same as I put on the receiver in this thread.
http://www.audiocircle.com/index.php?topic=104835.0
Let me know if there's something else that I've overlooked. Let's get those things started!
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pm sent.
Thanks,
Tom
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To make this build even easier, I think one could eliminate the rabbet for the driver flange to get them flush with cabinet without huge detriment to overall sound. Danny, can you speak to that?
You could probably get away with not flush mounting the top driver, but if you did that to the front facing one then it would add a little ripple to the response.
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Moving on with laminating and stuffing...
Parts ready, laminate cut to size
(http://www.audiocircle.com/image.php?id=60358)
Contact on opposite sides
(http://www.audiocircle.com/image.php?id=60359)
Ready to trim
(http://www.audiocircle.com/image.php?id=60360)
And a little painting, you'll see why
(http://www.audiocircle.com/image.php?id=60361)
Speaker cutout template, double sided tape 'cuz it's hard to clamp
(http://www.audiocircle.com/image.php?id=60362)
Round-under bit for holes
(http://www.audiocircle.com/image.php?id=60363)
Some black dye so there's no light showing
(http://www.audiocircle.com/image.php?id=60364)
Lined with "horse hair" felt
(http://www.audiocircle.com/image.php?id=60366)
Stayed back some from drivers so airflow isn't impeded
(http://www.audiocircle.com/image.php?id=60367)
And poly fill. Danny does this look like what you had in mind?
(http://www.audiocircle.com/image.php?id=60368)
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Approaching the end...
Inductors glued to bottoms
(http://www.audiocircle.com/image.php?id=60369)
soldering inductor to upper driver positive side
(http://www.audiocircle.com/image.php?id=60370)
Solder to binding post
(http://www.audiocircle.com/image.php?id=60371)
Screwed risers to speakers
(http://www.audiocircle.com/image.php?id=60372)
Sand baggie for ballast, the little drivers are hefty, so they're a little top heavy. Never really liked the look of plinths
(http://www.audiocircle.com/image.php?id=60373)
Riser bottom installed, gettin' close
(http://www.audiocircle.com/image.php?id=60374)
The vanity shot
(http://www.audiocircle.com/image.php?id=60375)
Backside shot
(http://www.audiocircle.com/image.php?id=60376)
And the obligatory installed shot
(http://www.audiocircle.com/image.php?id=60377)
Listening to the Prentenders "The Isle of View", Chrissie's sounding fine...
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Those look great.
Thanks for keeping us updated on their progress.
How do they sound?
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How do they sound?
Been thinking how to answer that genuinely . I’m not one to say something’s awesome just ‘cuz I own it, and I think one needs keep in mind the original concept. Low cost, easy to build, explore the possibilities of omni-polar in a desktop system and bettering my existing HK 2.1 system.
Along the way I get to learn a little something about speaker design and build something. The latter objective combines two things I really like…music and woodworking. It’s fun to share it with others of similar interest.
That being said, I’ll see if I can be objective about how these little guys perform. Without a doubt we bettered the system they replaced. They have surprisingly good bass response, it’s not high impact bass but it’s not absent. Kinda funny to watch the curtains behind them get puffed around by those little ports when I crank it up. The very bottom is being filled in with a Velodyne F-1000 servo sub that I already owned.
Mid-range is their strong suite; vocals are clear and crisp, guitars and piano full but not exaggerated. Drums have a nice snap and timbre. There is some slight chestiness or boxiness to the vocal presentation, but that could be the way I stuffed the boxes.
I think they’re largely accurate in the higher treble range, but lack some sparkle that I’ll bet could be addressed with a rear tweeter…maybe someday. I have to remember we’re dealing with 3” (effectively 2 ½”) full-range drivers that cost $12, so it’s unlikely I’ll shame some of the other gear in the house.
They’re easy to listen to, but I won’t tell you they they’re the last word in imaging and dynamics, but damn good for what they are used for. One thing I’ll say is that I’m limiting them is some ways. Danny suggested I listen to them 4 or 5 feet out from the back wall. Not really able to do that in my office, but I did set them up like that in the shop where they certainly threw a much larger sound stage, really defying their size. I wish I had more real estate on my desk to spread out and lower them so they weren’t behind my monitor. They noticeably flesh out when top edge of cabinet is just a tad below ear level. Right now they’re a good 12” higher than that and it kinda short circuits some of their strengths.
Overall a fun project that perhaps others will find interesting to build. It’s a fairly simple construction with low $$ investment for some pretty good returns.
A big thanks to Danny for his time and insight, too.
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There is some slight chestiness or boxiness to the vocal presentation
I have often found this to be caused by the side walls too close to the back of the driver.
dave
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Thanks, Peter.
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I have often found this to be caused by the side walls too close to the back of the driver.
dave
Interesting. Now that I think about it, many of the single driver designs I've seen have wider baffles that would give the backside of driver(s) more breathing space. I may experiment more.
After spending some time with these, I think I need to reinforce something I wrote in my assesments for anyone else that may build them. The difference in staging and fullness throughout their range is remarkable when I get my ears at or above the tops of speakers. Bass is more articulate and integrated. I questioned what I was hearing at first, but it's umistakably better.
I've been bouncing up and down between sitting and standing trying to figure out how rearrange desk to accomplish this. I briefly considered laying them down...it's that much of a difference! I think they might be surprisingly good in a more conventional setup (non-desktop), provided one doesn't overdrive them, they'll never be room shakers.
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When I measured and tested these the best response was on axis of the front facing woofer. That's your reference height.
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Well two months on and wondering how these are working out.
Interesting little speaker.
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Well two months on and wondering how these are working out.
Interesting little speaker.
Well, since they sit on my desk, I guess I'm best qualified to answer :)
My impressions now are much like I posted earlier. Ideally, they'd be positioned closer to ear level.
I did a little modification that seems to help my particular situation, but I can't speak as to why. I stood a CD case behind the upper woofer. I'm sure it introduces some reflection, but it gets them closer to the way they sound when my ears are in line with the top. I imagine I'm breaking some basic rule of speaker design, but the audio police haven't shown up, so life is good.
Don't get me wrong, they accomplished the goal, but I would be wrong to gush about their giant killer ability. I'm certain they perform better than any computer speakers I've heard. All in life is some kind of compromise, no? They would be better served in a bigger space, meaning less nearfield, but it is a desk after all.
Aside from the sound, I am really pleased with the way they look. Even cooler when paired with the reskinned receiver I posted about. So much do I like the crisp, contemporary style, that my next project will have the same look with a little twist...stay tuned.
If I were to build them again and had a little more space to work with, I might rotate them 90 degrees and center the drivers on wide side. I also think a rear mounted tweeter could add some sparkle, as Danny suggested.
Total dollar investment of around $100, I feel like I got more than my money's worth. I should add, though, that I already had the receiver and sub, so if starting from scratch that would be more.
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Peter Id like to say these look Fantastic! Your work is always top shelf as well as your execution of a project which many cant pull off. Most will be strong in their builds but lack in the finish or weak in the build but and strong in the finish, you have the ability to do both w/ ease. As far as the sound, Id love to hear them and Im glad you give an honest opinion on your take on them w/ out making out how earth shaking they are. Keep up the great work I always enjoy following your builds. R.K.
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I certainly agree with Randall...this was another interesting and educational thread! I look forward to following your next undertaking. Randall, I enjoy seeing your work...also top shelf! Are you two related?...twin artisans of different mothers? :)
Pete
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Aw shucks guys, :oops: :oops: how am I supposed to stay humble?
Randall, as I recall you're in California, right? If you're ever in Idaho, the door's open for a listen...and that invite extends to anyone who happens to be in the area.
Maybe I should build a traveling pair, although I'm not sure just how to implement that. Ideas anyone?
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Let Danny do them the way he demos speakers.
That seems to work pretty well and he can
secure a deposit so at least you get them back.
BTW what drivers do you finally end up using.
I checked what I thought you used and Parts
Express says no longer available, unless I
looked at it wrong.
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BTW what drivers do you finally end up using.
I checked what I thought you used and Parts
Express says no longer available, unless I
looked at it wrong.
Drivers here:
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=264-819&scqty=4
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Drivers here:
http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=264-819&scqty=4
Yeah I looked at that and it says they are no longer available.
Guess if anybody tried to duplicate this they will need to use a different driver.
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Yeah I looked at that and it says they are no longer available.
Guess if anybody tried to duplicate this they will need to use a different driver.
Well, duh I didn't see that...bummer. And here I was thinkin that this might be a good project for a newcomer. I guess that's a risk one takes with closeout drivers.
If someone is interested in recreating these with a different 3" driver, I would offer to draw and build a test cabinet for 'em, If Danny is still game to measure and give calcs and sage advice, it could be the .2 version.
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Randall, as I recall you're in California, right? If you're ever in Idaho, the door's open for a listen...and that invite extends to anyone who happens to be in the area.
No, sorry man I couldnt be farther from California Im in NC. :green:
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Danny, I wonder if you'd be game to help again?
I thought I'd get these tweeters for rear mounting when I order some other stuff from PE;
http://www.parts-express.com/pe/showdetl.cfm?partnumber=275-030
Would you be able to give me an idea of where to start capacitor and resistor wise to get me in the ballpark?
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Try starting with a 1uF or 1.5uF cap value. And try it first without a resistor. If it is too much then add resistance until it reaches the balance that you prefer. You might add 1 ohm or so at a time to reach that balance.