FWIW everyone be careful with what you put on your cones, their was always a few at car audio shows that would use Armor-All on their speaker cones, big mistake, the stuff soaks in, weighs down the cone and essentially ruins the speaker. They make noise but it isn't very pleasant, I stick to light dusting with a dry towel/cloth. So moral of the story is if you aren't sure DON'T DO IT, you don't want a heavy flimsy cone!! well I assume you don't any way
~Tim |
Twl,Damar varnish is not brand name,but a type of varnish typicaly used by artists who paint with oils. It would be available from an art supply store like "Daniel Smith" out of Seattle or from a company that makes art supplies like Windsor Newton. |
I should mention that the main reason I tried it was to tame a small peak in the upper midrange and to take a little "edge" off the highs that was causing sibilance. You should try one thin coat at a time,let dry, and listen test. You can go too far with this and it can "deaden" the highs, if you are not careful. With woofers and mids, though, I think there is less risk of going too far,because of their lower frequency nature. It really stiffens the cone and creates better piston type action and reduces any cone breakup modes you may have. I should add that this is for paper cones only. |
Everbody talks about light moving mass but many speaker manufaturers modify the drivers they use by adding damping material. An older Dalquast(sp) Moniter had some sort of putty on the front of the woofer. someone was marketing a doping mod for Mission 707s. One of the most highly rated speakers today use a "damping ring"(my term) applied to the back of magnesium mid-woofers. |
Twl, how could you do that ? What you did is both illegal and immoral. This is not to mention that you might have even gotten your drivers "hooked". For shame, for shame...
Actually, i've heard many positives about doing something like that. I can see how it could help in reducing cone break-up, flexing and distortion. As you mentioned, i think that it is most beneficial in the upper mids and treble.
Out of curiosity, does the driver that you are using have a whizzer cone and if you've done anything to work with that ? Sean
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Strange Sean, usually whizzer comes after too much alcohol, not dope. |
The big problem I see with this is that it is not reversible. What do you do if it sounds worse? If the drivers are cheap it might be worth a try.
You can get dope at your local hobby shop. Model airplane builders put it on the paper wings to make them stronger.
Twl, what kind of drivers are you doping? |
Sean, I've not only got my drivers "hooked" on doping, but I've got myself hooked at the same time. It really worked exactly as I thought. Great fine-tuning tweek. Only adds a few grains of weight, but alot of stiffening. About the whizzer cone mods, mine don't have any, but I've heard of 2 mods for them. They both are aimed at reducing the whizzer cone's propensity to vibrate out-of-control at the unsupported outer edge. This is the cause of the upper mid anomaly commonly known as "Lowther Shout", and some "tizzly" high end effects. One mod uses fiber glass insulation material, the other uses lamb's wool. In either case, a small amount of material is gently tucked in and lightly glued between the back of the whizzer cone and the main cone. All the way around. The idea being to support and damp the whizzer cone without adding any more mass than absolutely necessary. I have not tried this myself, and the Lowther people don't recommend it, but I have read many posts and articles that said it helped. This idea could be tried on any whizzer cone driver that is exhibiting peaky and irritating upper mids and highs. And if you don't like it you can take it out. That "glue stick" like kids use in school is good for temporary testing purposes. Albert - I guess this mod is how to get the "whiz" out of the whizzer! |
Those are good pointers from Herman and Maxgain as to a source for "doping compound".
As to the whizzers, the reason that i asked is that i've heard of some people using high density foam tucked between the main cone and the whizzer. Basically the same approach you've mentioned but with even less mass.
Not only were they concerned about flexing of the whizzer, they also mentioned nearfield reflection between the main cone and the whizzer. I could see how this could happen and how it could distort the frequency response / radiation pattern to a large degree. Obviously, some frequencies would be more affected than others.
According to what i've read, using the high density foam not only stiffened and supported the whizzer, it would tend to absorb some of the higher frequencies that might have otherwise been distorted. This should result in a measurably more linear response without affecting driver speed to any noticeable degree ( much like light doping ). I just wondered if you had any personal experience with a similar approach.
The reason that i ask is that my brother had attempted to build a full range TL ( transmission line ) using a Pioneer 8" with a whizzer. It was his first attempt at a TL and as such, he tried to make it "bigger and better" in every way imaginable. Needless to say, the initial results were not what he had hoped for, but we had both learned a lot along the way. We have since found out quite a bit about the specific driver and its' characteristics from other "full range tweakers" that have experimented with that model. From what i've seen, they've gotten pretty good results out of it but it did take a lot of work, measurements and tweaking.
Given the cost of the drivers ( not much at all ), i think that doping them is in order. This should at least help with the upper midrange "brittle-ness" that i noticed. Playing with damping on the rear of the whizzer cone also seems like a logical approach and may help tame other related problems. We might be able to salvage the original cabinets, but i'm not sure. He built them like a tank ( screwed and glued ) as if it was a final design rather than starting off with a basepoint and going from there. As one learns as they get older ( and hopefully wiser ), youthful enthusiasm has its drawbacks : ) Sean
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TWL: Doping is an online tweak for the paper drivers used in the little Radio Shack Minimus series of speakers (the ADS/Braun knock offs). I will try this when I get around to putting a small system together in our bedroom. The speakers were $5/pair @ a local thrift shop (so no big whoop). I will probably ring the cheap dome tweeter with felt as well. I also have some paper cone speakers (from an old RCA console) that I may try this with if I can repair the wire connections to the drivers/coils which are broken. I would like to mount these on small flat panels and use them @ the computer with a single ended EL84 based amp (from the same console). I don't have the balls to do this to expensive drivers though. Hope it works out in the long run. |
Herman, I've doped the Fostex FE-103's in my full range single driver speaker system. After numerous adjustments to the T-lines and other aspects, I've refined them quite well. The upper midrange peak and sibilance problems were about the only things I hadn't overcome. This helped, not only for those things, but improved the sound overall by reducing cone breakup modes. |
The best tweak I've tried is "doping" myself. Works every time. |
No, however have doped the wife so I could listen to my music. |
I know that Nancy Reagan isn't around to remind us but shouldnn't we still just say NO!?! |
Doping means applying any kind of liquid to the speaker cones to change their performance characteristics, not using airplane dope. Airplane dope is nitrocellulose dissolved in ether or other highly volatile solvent. It isn't stiff and the solvent would be hell on surrounds. Stay out of the hobby shop. Damar varnish is fir tree resin dissolved in turpentine. Very, very different from airplane dope, which was formerly used to coat fabric-covered wings and tail surfaces and, more recently, to coat fine silk for model airplanes. Dope-and-silk has been almost entirely replaced with heat-shrinkable plastic.
Will |
Bishopwill is correct, and is obviously no "dope."
Seriously, his comments are absolutely correct, even in the description of the formulation of these products. |
Thanks for the clarification Will. Sean
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Just to add a little to this topic, I rearranged my room and moved my speakers out further to get closer to the "typical" placement formula, and wow! I don't know if the doping gave more coherent phase info or what, or maybe it was just the placement diff, but the soundstage now is incredible! I played Madonna(Immaculate Collection) and the soundstage now ranges from about 6ft behind the rear wall to about 4ft in front of the speakers in depth, and about 4ft outside each speaker in width! This is about 13ft depth and about 20ft width. And the imaging is rock solid, well to the outside of the speakers. With this kind of depth, who needs surround sound? I know I'm raving, but I am flabbergasted. Really, guys, this is the first time I have ever gotten soundstage and imaging like that from a speaker. Oh, sure, you get imaging, but alot of times it is centered and smallish. And, you get big soundstage, but the image focus is lacking, but the combination of both is a real mind bender. And, having the speakers disappear while providing solid imaging thet's well outside the left and right boudaries that is "palpable", is alot different than having the speakers disapper and provide nice imaging within the left/right boudaries.I suppose this is why people spend $30k-50k on a set of speakers.Pardon my lunatic rantings, but I am really enjoying this. I feel like after all the speakers I built, I finally hit the bullseye. |
My apologies for the hobby shop suggestion, looks like I may be the dope. |
I doubt that Herman.
Looked like a practical suggestion to me. I doubt that any member at Audiogon can say that they have never posted a fragment of incorrect data.
Unless of course they have never posted :~) |
Herman, no need to apologize. You put forth what you thought was helpful information. Luckily, someone else caught it and was able to correct it. When we are too big to make mistakes or be corrected, THEN we need to start thinking about apologizing : )
Twl, sounds like you've just had an "audio revelation". It's great, isn't it ??? : )
You're finally hearing what a point source can do. Now if you could only get rid of the boxes and start doing some 360* radiation, you'd really see what width and depth was like. When things really start to cook, you'll take notice of image height too : ) Sean
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PS... Sometimes I have to silently laugh when people ( primarily salespeople ) talk about the "depth" of the soundstage on a system. I think that you may start doing the same. |
Sean, this is great fun. I am noticing large heighth improvements also. Sometimes, I think it might be too high. The drums are low, where they should be, and the instruments and voices are at middle height and about natural proportion and location, but sometimes tinkling bells and such seem to come from the ceiling. It's eerie, as my ceiling is vaulted to 16ft. Kind of a neat effect though. |
No need to apologize, Herman. If I had a nickel for every bit of misinformation I passed along I could buy a set of speakers like Albert has.... |
I gotta think that if this is such a good idea, the speaker manufacturers would have already done it. Of course, what the heck do they know, they only do it for a living... |
