Have you tried "doping" your speaker cones?

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!

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?

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.