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Re: Trainwreck clones --WHich Schematic?

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9/9/2000 4:57 PM

Re: Trainwreck clones --WHich Schematic?

quote:
"One tip mentioned here anonymously was to use a .001uF poly cap in parallel with a .001uF ceramic cap as the coupling cap after the second stage"

That trick works good actually.. I've used that in some amps, where i was out of .02 caps, but had .01u ceramic disks, paralleled them and the tone really opened up for me, but yur milage may vary, and it just throws one more wrench into the works of 'the tone' I wonder if anye has used paralleled ceramic disk and silver mica caps for small values? you'd get some of the sparkle of the SM and the warmth of the ceramic disk.... hmmmmm more ideas

9/11/2000 11:27 PM

quote:
"One tip mentioned here anonymously was to use a .001uF poly cap in parallel with a .001uF ceramic cap as the coupling cap after the second stage"

Tried it here and the loss of clarity due to phase problems was severe. The frequency response was about the same as an equal value single capacitor but the sound lost all of it's focus. Used a 715P .001 poly and a NOS Spraque 1000v .001 ceramic that sounds awesome by itself. Really weird how they interact.

..Joe L

9/12/2000 3:47 PM
Bruce	So what are you saying JOe? The poly/ceramic parallel combo didn't work? I've been using plastic caps across power supply E-caps for years and that does work OK. Bruce

9/12/2000 4:51 PM

Bruce,
The plastic caps accross the E-caps. Does this serve to lower the ESR of the E-cap? If so, what kind of tonal differences does it afford to the amp. Is there a formula/ration for determining the appropriate cap value? What value would you use for say a 50uf cap. I'm curious about this. I've read that it makes a big difference but I've never found any technical articles that really explain what is happening in the circuit when you parallel a film cap with a power supply electrolytic. I've used motor start/run caps in some amps and the amp had maybe a little tighter bass respons, but the hum remained about the same. Of course the amps are extremely quiet to begin due to layout and star grounding.

Peter S

9/12/2000 10:22 PM

quote:
"The poly/ceramic parallel combo didn't work?"

No, not for me it didn't. It sounded like a blanket was draped over the amp but yet the tone balance was the same as a single .002uF. Kind of like throwing a pig at a chain link fence at 600mph. What comes out the other side of the fence is still mostly pig, but it sure doesn't oink.

And I'm not surprised that paralleling works in power supply filtering and _maybe_ even bypass usage. But not in direct coupling where any phase shift differences between the two caps can combfilter the main signal. That sound is totally different and undesirable from what I hear when a ceramic by itself is used.

..Joe L

9/13/2000 1:04 AM
BWilliamson	Just curious if you built up a 'Wreck clone or tried it in a different amp? And if in another amp where in the circuit? bw

9/13/2000 1:21 AM
Joe L	It's a 'wreck! Used a SF Bassman that I love torturing. ..Joe L

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