***Desktop Speakers***

0 Members and 1 Guest are viewing this topic. Read 29606 times.

Peter J

  • Full Member
  • Posts: 1129
  • Hmmmm
Re: ***Desktop Speakers***
« Reply #20 on: 23 Feb 2012, 03:07 pm »
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?

skeeter99

Re: ***Desktop Speakers***
« Reply #21 on: 23 Feb 2012, 03:29 pm »
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

Danny Richie

  • Facilitator
  • Posts: 12074
    • http://www.gr-research.com
Re: ***Desktop Speakers***
« Reply #22 on: 23 Feb 2012, 04:44 pm »
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.

Peter J

  • Full Member
  • Posts: 1129
  • Hmmmm
Re: ***Desktop Speakers***
« Reply #23 on: 23 Feb 2012, 04:51 pm »
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?

Danny Richie

  • Facilitator
  • Posts: 12074
    • http://www.gr-research.com
Re: ***Desktop Speakers***
« Reply #24 on: 23 Feb 2012, 05:02 pm »
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.

WC

Re: ***Desktop Speakers***
« Reply #25 on: 23 Feb 2012, 05:17 pm »
Danny,

Should you run them in series or parallel? Would it sound different?

Danny Richie

  • Facilitator
  • Posts: 12074
    • http://www.gr-research.com
Re: ***Desktop Speakers***
« Reply #26 on: 23 Feb 2012, 05:29 pm »
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. 

Peter J

  • Full Member
  • Posts: 1129
  • Hmmmm
Re: ***Desktop Speakers***
« Reply #27 on: 24 Feb 2012, 02:04 am »
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!


planet10

  • Industry Participant
  • Posts: 1396
  • Frugal-phile (tm)
    • planet10-hifi
Re: ***Desktop Speakers***
« Reply #28 on: 24 Feb 2012, 06:18 am »
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.



It works well and the idea can easily be incorporated.

dave

planet10

  • Industry Participant
  • Posts: 1396
  • Frugal-phile (tm)
    • planet10-hifi
Re: ***Desktop Speakers***
« Reply #29 on: 24 Feb 2012, 06:29 am »
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

Peter J

  • Full Member
  • Posts: 1129
  • Hmmmm
Re: ***Desktop Speakers***
« Reply #30 on: 26 Feb 2012, 05:40 am »
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?




Peter J

  • Full Member
  • Posts: 1129
  • Hmmmm
Re: ***Desktop Speakers***
« Reply #31 on: 27 Feb 2012, 03:37 pm »
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:

skeeter99

Re: ***Desktop Speakers***
« Reply #32 on: 27 Feb 2012, 04:21 pm »
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

skeeter99

Re: ***Desktop Speakers***
« Reply #33 on: 27 Feb 2012, 04:28 pm »
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

Danny Richie

  • Facilitator
  • Posts: 12074
    • http://www.gr-research.com
Re: ***Desktop Speakers***
« Reply #34 on: 27 Feb 2012, 05:25 pm »
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.

skeeter99

Re: ***Desktop Speakers***
« Reply #35 on: 27 Feb 2012, 05:34 pm »
I just plugged in the specs into WinISD and it came back with this, roughly .293 ft^3.


Peter J

  • Full Member
  • Posts: 1129
  • Hmmmm
Re: ***Desktop Speakers***
« Reply #36 on: 27 Feb 2012, 11:04 pm »
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?


skeeter99

Re: ***Desktop Speakers***
« Reply #37 on: 27 Feb 2012, 11:15 pm »
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

Peter J

  • Full Member
  • Posts: 1129
  • Hmmmm
Re: ***Desktop Speakers***
« Reply #38 on: 28 Feb 2012, 08:00 am »
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...




jcotner

  • Jr. Member
  • Posts: 179
Re: ***Desktop Speakers***
« Reply #39 on: 28 Feb 2012, 08:36 am »
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: