AudioCircle
Industry Circles => GR Research => Topic started by: Peter J on 26 Dec 2013, 03:48 am
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Danny, if this is too far astray from your circle, perhaps you can move it to appropriate place. Since you've got some full range drivers on the horizon, I thought this might be interesting to some.
Some time ago I bought 2 pairs of Mark Audio CHR-70s from a poster here. This was around the time Danny was helping me with Desktop speaker and I was kinda taken with full rangers at the time. They sat and sat...and sat. The idea's been cooking in the back of my mind for some time. Some of you know I sorta like contemporary looking stuff and the metal drivers just begged for this look...well, in my mind at least.
(http://www.audiocircle.com/image.php?id=91955)
I took this design,
(http://www.audiocircle.com/image.php?id=91953)
but wanted to give it a different look, so ordered some panels from a supplier for fronts and backs
(http://www.audiocircle.com/image.php?id=91954)
and changed the port to side slots, (probably violating some cardinal rule of speaker design)
(http://www.audiocircle.com/image.php?id=91956)
(http://www.audiocircle.com/image.php?id=91957)
(http://www.audiocircle.com/image.php?id=91958)
With prefinished material, the mating of parts is a little different. I machined a "furniture joint" to conceal the joint between box and front/rear.
(http://www.audiocircle.com/image.php?id=91959)
(http://www.audiocircle.com/image.php?id=91960)
(http://www.audiocircle.com/image.php?id=91961)
I prefer to cut driver rabbets and thru-holes with templates, here's a sequence of shots on how that's done. I make the template with Jasper Jig
(http://www.audiocircle.com/image.php?id=91962)
(http://www.audiocircle.com/image.php?id=91963)
(http://www.audiocircle.com/image.php?id=91964)
(http://www.audiocircle.com/image.php?id=91965)
(http://www.audiocircle.com/image.php?id=91966)
Assembly is a little different too. Can't have glue oozing all over, so a small bead of PL Premium and just enough glue in biscuit slots to get the job done
(http://www.audiocircle.com/image.php?id=91967)
(http://www.audiocircle.com/image.php?id=91968)
(http://www.audiocircle.com/image.php?id=91969)
More later as I progress.
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Man I sure do like your shop.
Of course it may be because we have a lot of the same tools. :D
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Peter...
There are amateurs, and then there are "Pros" Nice work :thumb:
With these single driver builds is there any electronics involved at all? Is it just speaker terminals wired directly to the binding posts?
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Man I sure do like your shop.
Of course it may be because we have a lot of the same tools. :D
I do like tools...
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Peter...
There are armatures, and then there are "Pros" Nice work :thumb:
With these single driver builds is there any electronics involved at all? Is it just speaker terminals wired directly to the binding posts?
Thanks!
I've run across some designs that have minor "control" electronics...perhaps low frequency cut-offs? but not crossovers in the strictest sense. In this case directly wired...binding posts to driver. I'm straying from original design in box damping and I added a brace as you can see. My knowledge is limited in the speaker design arena, but a box that contributes nothing seems intuitively right to me.
Stay tuned...
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I don't mind you posting that.
You'll have to build a pair with our new drivers and make a comparison though. :D
I tested that Enabled deal on a couple of my M-130's. I never could find any effect measured or heard. I am surprised it is still being done to drivers.
You build nice looking cabinets Peter.
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You'll have to build a pair with our new drivers and make a comparison though. :D
I tested that Enabled deal on a couple of my M-130's. I never could find any effect measured or heard. I am surprised it is still being done to drivers.
You build nice looking cabinets Peter.
I'm in for the comparison, Danny. I have way more want for new speakers than need it seems. Building them is some sort of Zen drug for me :o Needed a fix and had these drivers. I'm waiting to mainline with your upcoming open baffle designs.
I've eyeballed the drivers and read some of the theory on Enable-ing. It's one of those things in the audio world that kinda puzzles me... I just don't know what to make of it.
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I've eyeballed the drivers and read some of the theory on Enable-ing. It's one of those things in the audio world that kinda puzzles me... I just don't know what to make of it.
I have learned to be open minded to various tweaks. I have been surprised before. But in this case I found no evidence of any effect or change from the process. And I did many measurements that included spectral decay on and off axis. I found that it had about the same effect as drawing a smiley face on the cone with a magic marker.
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I found that it had about the same effect as drawing a smiley face on the cone with a magic marker.
You actually did that?
Couldn't resist, it's all the leftover Christmas candy. :hyper:
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Peter,
As far as the slits go for a port opening, I don't know for sure on speaker cabinets but when I am tuning a wooden flute I can cut the end off until I get the note I want or I can drill holes or cut slots at the proper spot on the sound chamber as long as the volume of the slots equals the diameter of the bore.
The same principle may apply to speaker cabinets
Mike
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Peter,
As far as the slits go for a port opening, I don't know for sure on speaker cabinets but when I am tuning a wooden flute I can cut the end off until I get the note I want or I can drill holes or cut slots at the proper spot on the sound chamber as long as the volume of the slots equals the diameter of the bore.
The same principle may apply to speaker cabinets
Mike
That's what I theorized, Mike, for better or worse. 1 1/4" x 6" = 5/16" x 6" x 4. I think I know that this might cause port chuffing, but can't imagine that much air volume and velocity coming from this driver, but that's seat-of-pants engineering and not really based in science....perfect for the audio world :icon_twisted:
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Moving right along...
I'm damping panels with this, gone up in price some since I last used it, $38 for 6 sq. ft.
(http://www.audiocircle.com/image.php?id=92020)
(http://www.audiocircle.com/image.php?id=92021)
And lining with this, I'll use some Dacron fill too, but stuff through driver hole, since there's no removable back like plan suggests...probably shooting my foot
(http://www.audiocircle.com/image.php?id=92022)
(http://www.audiocircle.com/image.php?id=92023)
(http://www.audiocircle.com/image.php?id=92024)
Gluing back just like front
(http://www.audiocircle.com/image.php?id=92025)
A new speaker is born...well, almost. Cool thing about prefinished materials is once it's assembled, it's close to being completed!
(http://www.audiocircle.com/image.php?id=92026)
(http://www.audiocircle.com/image.php?id=92027)
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Looking nice, hope it would sound nice too. :wave:
@Danny, pleasantly surprised that you are coming with single driver kits. What is the status and when are they expected?
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Houston, we have liftoff...
This shot sorta highlights the 3d grain in the sides, hard to see in photos
(http://www.audiocircle.com/image.php?id=92101)
The front and back come with a protective "peel coat", fun to pull off for the first time!
(http://www.audiocircle.com/image.php?id=92102)
(http://www.audiocircle.com/image.php?id=92103)
(http://www.audiocircle.com/image.php?id=92104)
And then
(http://www.audiocircle.com/image.php?id=92105)
playing to the messy shop, someone should clean it up :oops:
(http://www.audiocircle.com/image.php?id=92111)
I tried to get a shot of the grain in the metal look RTF, hard to capture
(http://www.audiocircle.com/image.php?id=92106)
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Larry PMed me about felt. Here's what and where for anyone else interested
http://www.ebay.com/itm/MULTIPLE-SIZES-Blue-Max-40-Ounce-Recycled-Felt-1-2-Thick-Area-RUG-PAD-/130869723608?pt=US_Tools_and_Accessories&var=&hash=item1e787181d8
With only 30 min. playing time, I imagine they've got some breaking in to do, but here are some initial impressions.
Two things strike me as noteworthy about the single drivers I've heard. First is coherence, there is something unique sounding about having all frequencies emanating from a single point. Second, bass. I'm truly surprised by the bass these and the desktop speakers I made produce. It's not tactile like a bigger driver, but it's certainly noticeable...heard but not felt, I guess would be a good way to describe. My slot ports seem to work fine, but like any other port, I don't think you'd want them against a side wall.
Within their limitations, they are pretty amazing. Won't rock the house or rumble the movie soundtrack, but for a smaller music system, I could easily live with 'em.
Looking forward to Danny's entry into this market.
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These are headed to Texas. Danny's agreed to measure their response and give some listening impressions, of which I'm curious.
After listening to them for a week, I've formed some impressions of my own, but won't go into that at this point. I'm interested in understanding how what I hear translates into measurable parameters. I know the sun doesn't rise and set there, but I'm hoping to gather yet another bit of knowledge. I'm just perpetually curious, I guess, and figure one can't learn too much about the hobby...right?
Also, having heard several of Danny's designs, I can say that our inclinations in speaker voicing seem to run parallel, and frankly, I trust his ears more than my own. I'll be building something with his new drivers and looking forward to comparing.
(http://www.audiocircle.com/image.php?id=92441)
The saga continues...
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I take it you built the crates for these too. How do you go about building crates to safely transport large speakers?
Mike
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I'm interested in the crate construction as well. I've been using cardboard boxes, styrofoam corners, and thin foam sheets. It works but a crate seems more durable.
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I'm a fan of crates, shipped some pretty big and heavy stuff around the country with no damage...knock on wood. (there's a pun there somewhere). It sometimes helps that I have scraps in the shop already, but in this case I bought a dozen 1x2 furring strips and a couple of sheets of 1/4" plywood underlayment. It's light and plenty strong. I had the foam. For bigger stuff I scale up to thicker ply and foam.
Essentially, I'm building a box that provides air space all around speaker and then hot gluing foam strips in this space. In this case I used 1 1/2" foam so my crate interior size was 3" larger that speaker in all dimensions. I like to put the frame on the outside like an exoskeleton so it gives hand holds to the shipping monkeys, in this case UPS. My thinking is that it will get dropped less if there's something to grab onto. Although I think it could survive a fair amount of abuse, I rather not test more than necessary. I glue and staple the all but the removable lid which is screwed on. At the very least, these will see two or three rounds of shipping.
I think the photos and graphics will do a better job explaining than more words...
First off, one needs a good helper for artistic inspiration and fitting purposes
(http://www.audiocircle.com/image.php?id=92444)
(http://www.audiocircle.com/image.php?id=92445)
EPS insulating foam is easy to come by and has worked well in the past
(http://www.audiocircle.com/image.php?id=92446)
And the crate itself, speaker is wrapped in dry cleaning bag, a roll of which I somehow ended up with :?
(http://www.audiocircle.com/image.php?id=92447)
(http://www.audiocircle.com/image.php?id=92448)
(http://www.audiocircle.com/image.php?id=92449)
(http://www.audiocircle.com/image.php?id=92450)
Here's an exploded view so I could exercise my limited Sketchup skills
(http://www.audiocircle.com/image.php?id=92451)
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Danny,
From what I've read efficacy of EnABL is driver dependent and intended for extended range drivers (not sure your M130 quite fills that bill). I had Bud Purvine (EnABL inventor) treat my Fostex F200A drivers and it improved midrange resolution and opened up the treble sound significantly.
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Hi Peter,
Are you a cabinetmaker? The speakers look fantastic.
Cheers Rod
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Hi Peter,
Are you a cabinetmaker? The speakers look fantastic.
Cheers Rod
Thanks Rod. I tell people I'm on my third career. Cut my teeth in a couple of cabinet shops, then moved into marine mechanics and later RV and boat sales. I currently make a little living remodeling homes. I truly enjoy what I do now, my work and hobby involve a lot of the same things!
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From what I've read efficacy of EnABL is driver dependent and intended for extended range drivers
Except for the Ohm Fs which were Bud's 1st experimental units, bud did not see a FR driver until i sent him a set of FE127e, so the 1st 10+ years of development were on multiway drivers. I am currently listening to a set of CSS MTM (cone + dome) that did indeed benefit from treatment.
dave
PS: very nice Pensils Peter. As an aside, there is a whole family of Pensil plans available http://frugal-phile.com/boxes-markaudio.html
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Peter,
Thanks for the info on the crate. Not as daunting as I thought but solid and protective.
Mike
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Danny,
From what I've read efficacy of EnABL is driver dependent and intended for extended range drivers (not sure your M130 quite fills that bill). I had Bud Purvine (EnABL inventor) treat my Fostex F200A drivers and it improved midrange resolution and opened up the treble sound significantly.
I can't see that it would be any different for an extended range driver. And I think the audible difference most people are noticing has more to do with driver burn in effects and not anything to do with painting dots on the cone.
The mid-range area (300Hz to 500Hz) is one of the most effected by burn in effects, and I have measured less stored energy in that range after sufficient driver burn in. I did not see any measured difference from the painted dots.
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Peter,
Thanks for the info on the crate. Not as daunting as I thought but solid and protective.
Mike
Yes too many speaker vendors whine about shipping costs, but after building cabinets, crates should be easy/cheap.
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I can't see that it would be any different for an extended range driver. And I think the audible difference most people are noticing has more to do with driver burn in effects and not anything to do with painting dots on the cone.
The mid-range area (300Hz to 500Hz) is one of the most effected by burn in effects, and I have measured less stored energy in that range after sufficient driver burn in. I did not see any measured difference from the painted dots.
My F200A's were 5 years old and listened to almost daily before Bud got them, so I'll dismiss burn-in issues. BTW it was upper mid-range and beyond (1,000 Hz and higher) that I was thinking of.
IMO 'real' science keeps questioning and investigating. Perhaps you simply don't have the time or the interest, no worries - to each their own.
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My F200A's were 5 years old and listened to almost daily before Bud got them, so I'll dismiss burn-in issues. BTW it was upper mid-range and beyond (1,000 Hz and higher) that I was thinking of.
IMO 'real' science keeps questioning and investigating. Perhaps you simply don't have the time or the interest, no worries - to each their own.
I am actually one of the guys that typically investigates tweaks from the subjective and objective view points. I am quite the listener first and then I look into the science of what is causing the difference I hear. And if I hear a difference but can't measure it then I am not measuring it rightly.
And I spent quite a bit of time on this one. I just could not hear any difference and could not measure any difference.
Plus, being part of the driver design process and having various changes made to a driver to minimize things like driver break up does give me some unique incite as to what it take to effect drivers in this way. Even changes in type of adhesives that hold the surround to the cone show some clear and present changes. And I have experimented with driver coatings and edge treatments. I have seen lots of effective treatments, but this is just not one of them.
I posted a thread on my findings. If you are interested I can search it and find it.
On my M-130 the mass (weight) was not enough to have any effect and the texture was not enough to have any effect. If the mass were greater and made from a softer material that was more of a damper then it might show some positive effect. It might also be more effective on the back side of the cone. Any effect in controlling resonances will show up in a spectral decay pretty easily. And I am real big about dissipation of stored energy and recovery speed or settling time. That is really where it's at.
My M-130 was also a paper cone with little resonance or break up issues to begin with. On a smaller driver that was a metal cone you might start seeing some real benefit, but the added mass needed (and in the right places) will likely need to be a little greater than painted dots.
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Here is a link to the testing I did.
http://www.audiocircle.com/index.php?topic=59575.msg530046#msg530046
I'd be glad to revisit it again.
Like mentioned early the M-130 is a paper cone driver with a really smooth response and very little break up or stored energy. My woofers had a little amplitude rise in the 5 to 6kHz range and only a very slight amount of stored energy there. This area is well down and well controlled by the crossovers used with them. If I were to try and tweak that out then I would start with adding some mass around the very edge of the cone where it meets the surround. But the Enabled painted dots were not even applied there.
(http://www.gr-research.com/images/enablepic.jpg)
These dots are just too small, and too light weight to do anything. A nice layer of dust stuck to the cone would have likely had more effect.
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Moving on to chapter two...
Danny was good enough to measure these Pensils, and here, my audio friends, are the results.
(http://www.audiocircle.com/image.php?id=92816)
(http://www.audiocircle.com/image.php?id=92814)
I withheld my initial impressions until I could see his results so I could try and couple the measurements with what I'm hearing. As I told Danny, trying to attach adjectives to sound from speakers is a difficult task. My recurring thought was "shiny". Not quite brassy, but not smooth and buttery. They sound a little like they look, oddly enough, somewhat metallic.
I imagine some would find that quality appealing. At first it seemed like fine detail retrieval, sort of an edge to things, but I do think it would get fatiguing in large doses of concentrated listening. I say that to contrast what happens around our house a lot of the time. Music is playing as we go about the day, in and out of living room where they live but audible throughout the house. I guess that kinda defines casual listening.
From the spectral decay, I think I can gather that at least some of what I'm hearing is ringing, which I guess is often the case with metal drivers. If I understand it right, the stiffness of the metal cone is desirable, but the resonances are the undesirable side effect. As was stated in another thread, designing a driver is about making compromises, you gets to pick your poison, but no poison isn't one of the choices.
I think I might be on a speaker building binge for a while. I'm anxious to try the LGKs and do some comparisons.
Speaker building, my drug of choice.
I suppose it could be worse...
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Here you go Peter. I designed a simple baffle step compensation circuit for it to flatten out the response. It only took one inductor and a resistor. Then I designed a pretty aggressive notch filter for the top end to kill some of that ringing. That only required two parts too and they are very small values. So the correction filter is pretty low cost.
Here is the before and after measurement. They are much smoother and more balanced now.
(http://gr-research.com/pics/ma3.jpg)
They still have the break up and ringing around 1.5kHz. I can't really fix that. But most of that heavy ringing up top is much more controlled.
(http://gr-research.com/pics/ma1.jpg)
I think I can listen to them now without them burning a hole in my head. I think you'll like them much better now. :thumb:
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Very cool Danny. I sure do appreciate your talents and don't want any holes burned in you head, for sure :o
Looking at the frequency graph, this must have been the speaker with the big spike around 10K, correct? Is that what the notch filter is addressing or is it more generalized? Assuming it's addressing the spike, what effect will the notch filter have on the one that was smoother in that area? Always the questions, questions and more questions, huh?
I like the looks of the "after" measurement and look forward to round two of listening.
Here's some food for thought for those following along. If one looks at the response graphs for this speaker and that of Danny's upcoming LGKs, you can see why he's jazzed about them. It appears to be a very smooth driver. I'm really interested to see what people will do with them.
To give me some points of reference I went back to this build:
http://www.audiocircle.com/index.php?topic=103789.0
and compared the response of those speakers
(http://www.audiocircle.com/image.php?id=93456)
And Danny's LGK
(http://www.audiocircle.com/image.php?id=93457)
Both appear to be smoother than the driver I used in this speaker. I think I'm getting a good idea why Danny's fond of paper drivers.
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Looking at the frequency graph, this must have been the speaker with the big spike around 10K, correct? Is that what the notch filter is addressing or is it more generalized? Assuming it's addressing the spike, what effect will the notch filter have on the one that was smoother in that area? Always the questions, questions and more questions, huh?
Yes, that speaker was the one with the larger spike at 9.5kHz.
Yes, the notch filter addresses that area.
The other one did not have as tall of a peak, but the spectral decay showed just as much stored energy there. So the notch filter will help it just the same.
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Peter,
Your Mark Audio speakers were sent back to you yesterday.
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Remember those seemingly bombproof shipping crates I built? Not so, it seems.
I put some blame on UPS (footprints on top of box tells me something), and some on me. I should've made the whole bottom solid and used thicker material rather than adding the skids. Looks like the skids became hooks and it ripped up the bottoms something fierce. And yes, that chunk of bottom was completely missing when delivered.
(http://www.audiocircle.com/image.php?id=94058)
(http://www.audiocircle.com/image.php?id=94059)
In spite of what you see on the crates the speakers were unscathed, a flippin' miracle. I must've used up a favor somewhere!
I assembled Danny's filters and installed in them behind drivers...it's the only access to the inside of cabinet.
I used this
(http://www.audiocircle.com/image.php?id=94060)
to install this
(http://www.audiocircle.com/image.php?id=94061)
I've been listening for the last couple of hours and have to say the difference in remarkable. I'd kinda chalked these up to a learning experience, but their character has changed enough to make me do a double take. Much smoother, much more natural sounding. Danny, I'm truly impressed but the most interesting thing I'm hearing is with the imaging...is that possible? Soundstage seems huge compared to what I remember. Is that the BSC or am I imagining things? I swear it almost envelopes me...does that sound nuts?
These had a sort of circuitous route back to me, so thanks to Mike Lundy for patching the crates up enough to get them back to Idaho.
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Anytime part of the frequency range is louder in relation to the rest of the frequency range, then it pushes it forward in the sound stage. A louder area is more in your face. And those drivers pushed a lot out in your face. With the response much more balanced now things will drop back into the sound stage where they are suppose to be, and imaging will improve.
Pretty cool huh?
Sorry about the ringing of that metal cone. That might still be a bit of an irritant. I can't fix that. But it is a lot more balanced now and you might enjoy curtain aspects of them.
BTW, the wire and connectors are also holding these back some in the resolution department.
Wait until you hear the new LGK's. :thumb:
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Peter,
WOW!!! I thought they looked bad when I got them. Plus they were solid and secure again when I left them at the UPS store. It took a fair amount of force to rip out the stales you secured the bottoms with and even more to rip out the screws I used. Looks like those gorillas from the old Samsonite commercials went to work for UPS!!
At least the speakers were intact.
Mike
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Footprints on the shipping crates....... :slap:
At least they showed up with no internal damage. :thumb:
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Have you put non-hardening putty or rope caulk in appropriate places on the driver?(basket and magnet areas) That might help a little.
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Anytime part of the frequency range is louder in relation to the rest of the frequency range, then it pushes it forward in the sound stage. A louder area is more in your face. And those drivers pushed a lot out in your face. With the response much more balanced now things will drop back into the sound stage where they are suppose to be, and imaging will improve.
Pretty cool huh?
Sorry about the ringing of that metal cone. That might still be a bit of an irritant. I can't fix that. But it is a lot more balanced now and you might enjoy curtain aspects of them.
BTW, the wire and connectors are also holding these back some in the resolution department.
Wait until you hear the new LGK's. :thumb:
Pretty cool is right...almost eerie what they're doing. I think it may have something to do with side ports and placement well into room.
I recognize I hamstring them some with my wire choice and the binding posts. Ultimately, these will bow to convenience more than absolute sound quality. I've talked to the guy I rent a spraybooth from about putting them in his house. If that happens they'll likely be playing Pandora from a laptop soundcard. He's not an audio goofball like me...
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Have you put non-hardening putty or rope caulk in appropriate places on the driver?(basket and magnet areas) That might help a little.
Well actually, they came that way. A fillet of putty between basket and magnet structure. I think this is stuff Dave at Planet 10 does as part of his optimization, perhaps he can confirm.
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What are the LGK speakers mentioned above?
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Well actually, they came that way. A fillet of putty between basket and magnet structure. I think this is stuff Dave at Planet 10 does as part of his optimization, perhaps he can confirm.
Yes.The stuff is ductseal (http://www.t-linespeakers.org/design/tweeks.html).
dave
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What are the LGK speakers mentioned above?
Jeff,
It's a small driver that Danny is bringing in... Peerless India??? See http://www.audiocircle.com/index.php?topic=120804.0
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Jeff,
It's a small driver that Danny is bringing in... Peerless India??? See http://www.audiocircle.com/index.php?topic=120804.0
This one is actually not being made by Peerless. Best sounding little full range driver I have ever worked with though. I can't wait to have them in stock.
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What are the LGK speakers mentioned above?
LGK stands for "Little Giant Killer"
This link is the same thread S Clark mentioned, just farther into the discussion. Scroll down to reply#306 for a picture of Danny's test speakers, desktop version.
http://www.audiocircle.com/index.php?topic=120804.300
Mike