AudioCircle
Industry Circles => Audio by Van Alstine => Topic started by: avahifi_lj on 21 Sep 2016, 04:40 am
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Hello,
I recently had the foam surround replaced on my speaker woofers. I mentioned to Frank what I was doing, and he asked if I had thought of doing his speaker damping mod before reinstalling the woofer. For those not familiar with the mod, it involves applying a bit of modeling clay to the speakers. Check out the following Audio Basic article for details:
http://www.avahifi.com/images/avahifi/root/audio_basics/ab_pdf/ab1982.pdf
In the Audio Basic article Frank suggests Plast-i-Clay, but he told me that any non-hardening modeling clay will work. I could not find Plast-i-Clay, but did find Plastalina at my local Michaels (appears to be their house brand). Plastalina comes in a variety of colors, and is fairly cheap. The key thing to remember is that you need to use non-hardening modeling clay.
The basket/frame of my woofers are stamped steel, which frankly surprised me as I was expecting a cast aluminum basket/frame. Adding the clay was pretty easy, and it added a lot of dampening to the basket/frame. I didn’t add clay to the magnet assembly simply because it was already very substantial, and I felt that if any part of the speaker was going to have issues with vibration it was going to be the basket/frame. Note that it’s important to not get any clay on the speaker cone or any of the moving parts (spider, wires, etc).
Once I got both speakers coated with clay (about ¾ of a pound per speaker) I installed them back into the cabinet, and fired up the system. What I immediately noticed was a more controlled low end. The bass didn’t necessarily go any deeper, but it sure was a lot more solid and defined.
The project is fairly easy, and well worth the time.
Larry
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I can attest to what Larry is saying, having done the suggested mods in times past with several sets of speakers, also turntables. The difference is significant on everything I've tried it on, including (scaled down) my Sennheiser HD650 headphones. As Neil DeGrasse Tyson says, "Science doesn't depend on you believing in it to work". The science behind why it works is explained in the linked file. The improvement you get if you do as Larry (and others, including myself) have done far exceeds what you would ever get from boutique cabling for a tiny fraction of the price.
Would love to hear from others who have tried this low-buck, high-yield mod. The laws of physics being what they are, it works just as well now as it did "back in the day".
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Modded my old VR-2's with clay. The sound became clearer, less colored, quicker, and smoother. For some obscure reason the woofer magnet was surrounded by a steel bowl shaped shield that rang like a bell when tapped so I wrapped it with VB-2 vibration damping material.
(http://www.wghwoodworking.com/av/VR2_speaker_damping.jpg)
Wayne
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That shield is no doubt to manage the magnetic field so as not to interfere with the CRT monitors nobody uses anymore. I see the edges are wrapped but if its characteristics are as described, it could no doubt benefit from a coating of plastic clay as well.
I got mine from Michael's also when i did my HD650 headphones. They had it in a very dark grey color which is almost impossible to see without a flashlight. It's worth noting that AVA's modded Grado phono carts also make use of this material. Here are before-and-after shots of the Senns. I neatened up things before closing them back up. The foam areas are open so I left them alone.
(http://www.audiocircle.com/image.php?id=150748)
(http://www.audiocircle.com/image.php?id=150749)
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Cool stuff!
I have read of this before, but I have not yet tried it.
Thanks! :thumb:
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There are also cabinet resonances and funny how I was fooling around with this on Tuesday evening. I had put some sorbothane dots on top of my Dynaco A25XL CBDs and thought I noticed a change in the sound field (wider, cleaner), but could not believe my ears, so I'm experimenting with my ARs.
'ner
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Would this mod also fork for subwoofers?
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Yes.
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If I recall correctly, to quote Frank, "Meatballs don't bounce". This mod was one of my earliest encounters with AVA (aka Frank and the Jensen (sic) Stereo Shop). Worked well for my ESS PS8 speakers. I am now a planar man so don't use the plasticlay but Audio Basics is a wonderland archive of information. :thumb:
Cheers,
Mark
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Would this mod also fork for subwoofers?
Absolutely. Just follow the guidelines in the document. I have used it on several pairs of speakers, several turntables, even my open back headphones (scaling down the amount applied).
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Be mindful of the price of Plasti Clay if looking around online. This stuff is only $4.50 per pound from the manufacturer, (yet, oddly, $117.00 for 25 pounds). http://www.amaco.com/products/clay-modlg-6k-gray-1?taxon_id=448 (http://www.amaco.com/products/clay-modlg-6k-gray-1?taxon_id=448)
It works!
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Hello Audio Experts!
I used to use an epoxy product called "Supermend" on all my stamped steel driver frames. I liked that it got 'semi-hard' & thought that might be better than clay...!?
https://www.amazon.com/Eclectic-Products-5330031-Supermend-Epoxy/dp/B000BPB15C?th=1
Murf
(http://www.audiocircle.com/image.php?id=150918)
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The reason for plasticlay is that it absorbs vibrations very well. An epoxy based product will be too hard to work well.
The test is my old "meatballs don't bounce" observation.
Frank
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There seem to be a lot of mods that come and go in popular awareness while losing none of their underlying value. Maybe someone could start a "doomsday book" thread compiling tweaks of yore?
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An epoxy based product will be too hard to work well.
Frank
Also not reversible if necessary, as plasticlay is, very easily.
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There seem to be a lot of mods that come and go in popular awareness while losing none of their underlying value. Maybe someone could start a "doomsday book" thread compiling tweaks of yore?
If it works, it works, and this worked then and works now, the laws of physics having changed little since 1982. This isn't like painting the edges of your CDs with green sharpies.
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The reason for plasticlay is that it absorbs vibrations very well. An epoxy based product will be too hard to work well.
The test is my old "meatballs don't bounce" observation.
Frank
Yes, but I don't think that test is really definitive! Supermend can be gouged with my soft fingernails when hard. I also wanted to strengthen stamped frames. So, strength plus dampng was my thinking.
I think I'm all 'cast frame' now, so stopped messing with the pretty things. But I do have some clay somewhere.... :scratch:
(http://www.audiocircle.com/image.php?id=150986)
These are my observations!
Murf
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If you want to try this, do only one speaker of s pair first, then compare them with the system set to mono.
When you hear the improvements, you will be sure to do the other speaker of the psit.
Frank
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Hi Frank,
Have you done this mod to any of those fancy Seas drivers you were playing around with?
Murf
Trans Lab tweet
Seas Excel M15 mid
Seas Prestige L26 woof
(http://www.audiocircle.com/image.php?id=151000)
(http://www.audiocircle.com/image.php?id=151001)
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Frank, did you mod the Biro speakers with this method while in production?
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Yes, the plasticlay coated woofer baskets were standard production with the Biro L/1 speakers.
Frank
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THANKS FRANK. I DID NOT KNOW THAT. I am not sure if it was even mentioned in the ad during it's production years. If it was mentioned, I missed it. That saves me a lot of work. Thanks again.
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This is from a speaker builder forum:
"I have been using Permagum on baskets for years. Specially stamped ones. The effect is measurable, specifically from 100Hz to about 800Hz. I don't put pounds. Enough to damp the tink-then-ring when you flick it to a dull thump is enough. Works for cast frames too. Just because a driver has a cast frame does not mean it is designed well and wont ring. "
"Adding mass to lower resonant frequency is not always a bad thing either. In general, a more flexible and non-hardening product will add more damping to the structure, whilst still adding the mass to lower the resonance freq."
"I have found stamped steel frames to ring a good bit, when out in open, but when screwed down into enclosure, most of the ringing vanishes.
I tried damping a few older frames, but was not sure if I really could tell a difference or not. The "rap on it" test sounded better, out of box, but not much different than the screw it down good into box with gasket sound.
Enclosure damping, much more so. "
"I use some of that peel and stick stuff, a generic version of Dynamat"
"I believe ... has been doing this in the full range discussion board for a while.... He used the press and stick window caulking rope. I think frost king makes it and calls it finger caulk. It is a non hardening clay. I have used it with good results."
"A very inexpensive alternative is to go to Lowes and pick up some "flashing."
Epoxy will work great. Try making a pencil out of epoxy and see how well it "rings" when struck.
They make putty epoxy which would really be easy to apply as well."
"I use Mortite as well...."
The concept seems fairly well accepted, but the product is debated! FWIW, Frank probably spoke with Mr. Salk & some other speaker experts.
But:
"I've tried this on a couple of stamped midbass/midrange drivers using duct seal compound and it made no difference in measurements or subjectively once secured into place. YMMV though."
"This is where the rubber meets the ring, so-to-speak. If you can't measure the difference between raw and treated driver, you will not hear a difference, of that I have no doubt. This type of mod lends itself well to measurement. Mounting a driver on a baffle substantially reinforces it. I've made mods to driver frames that were very easily measured (cavity fill) and some (primarily damping) that made absolutely no measured difference. It's probably going to be more of an issue with large drivers IMO. All of my tests were not performed in boxes, they were on my 2mx2m test baffle, no box influence after mounting."
You pays yer money & makes yer choice.
Murf
(http://www.audiocircle.com/image.php?id=151173)
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I had a pair of Sequerra 2 + 2W speakers back in the 1980's. All the speakers were covered on the back with putty. The mid was a Phillips with it's own tube like enclosure. It was heavily coated as well.
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I remember the plasticlay mod in Audio Basics at the time. And in 1987 I bought a pair of B&W DM 330i. A great speaker that can be improved. I've tried different tweeters over the years, as the original tweeter was a bit hard sounding. For two years now I have used the Vifa XT25TG-30/04 tweeter and it works without mod to the crossover. Many years ago I changed the capacitors for Panasonic polypropylene that I bought from Frank. And later on I stuffed the box with polyester damping material in order to damp unwanted reconances. I did tune it by ear - too much and it didn't play low bass. I will try the plasticlay mod one day.
Ola
Norway
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(http://www.audiocircle.com/image.php?id=74367)
Hi. I use Franks idea for my speaker mounting gaskets. This one is about 1/2 inch thick. I used a rolling pin and trimmed around the speakers frame with a credit card used as a knife. No vibes to the enclosure here....Mark Korda
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This is from a speaker builder forum:
"This is where the rubber meets the ring, so-to-speak. If you can't measure the difference between raw and treated driver, you will not hear a difference, of that I have no doubt. This type of mod lends itself well to measurement. Mounting a driver on a baffle substantially reinforces it. I've made mods to driver frames that were very easily measured (cavity fill) and some (primarily damping) that made absolutely no measured difference. It's probably going to be more of an issue with large drivers IMO. All of my tests were not performed in boxes, they were on my 2mx2m test baffle, no box influence after mounting."
You pays yer money & makes yer choice.
Murf
Unless you have the specialized equipment to make time-domain measurements, you will not 'measure' a difference- amplitude response is not affected unless you do something wrong, like use way too much material (affecting cabinet tuning) (possible with really small minimonitor cabs) or accidentally block a driver vent hole etc. IN my experience, speakers sound 'faster' because transient response is cleaner. Frank's suggestion in the original article to do one speaker and then compare to the other is a good idea. (Might want to use a mono recording or switch your system to mono for the comparison, so both speakers are playing the exact same signal- and pan with the balance control.) That will tell you whether your ears will find it worthwhile. I found it very worthwhile and have used it on speakers, TT's, even headphones (obviously scaling down the amount used).
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I have always recommended doing one speaker first and then compare them, side by side, with the system set to mono. Have someone else run the balance control back and forth. For best resullts, also have that someone scramble the speakers before you listen so you won't know which you are listening to.
Then, if you hear a useful difference, it won't be because of anticipation bias.
Frank