Tube Amps / Music Electronics
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|4/14/2000 2:32 PM|
|peter||Re: Trainwreck amps|
Excellent, thanks for that.
Something I ought to have mentioned for
Nathan's benefit is, don't be put off the
amp by my experience, there are so many
variables (guitar, speakers, output
transformer etc etc) that my amp
may not be "representative".
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|4/19/2000 2:02 AM|
Peter, what did you use for a power supply? cap values and resistors. I've built one of these and am in the final tweaking stages.
|4/19/2000 3:04 PM|
Unfortunately all I had was a hammond 270bx,
which gives a plate voltage of 495 volts,
but I used a tube rectifier and added
three 15 volt zeners, so that the final plate voltage is 430 volts, dropping to about 390 at
full output. Can't remember the filter cap
values off hand, but I started smallish and
then made them bigger cos I didn't like the ripple.
A choke of 2 henries supplies the screens.
Following that I had a 10k resistor to feed the
PI. The PI supply was then about 380 volts.
I increased the 10k to 22k, dropping the voltage
to 330 or so. This also reduces the preamp supply
voltages, and I noticed a significant improvement in
sound this way.
So how would you describe the sound you are getting
out of yours?
|4/19/2000 3:29 PM|
Give me your email and I'll email you direct your voltages are to high.Mine sounds alot like the Van Halen first record distortion wise.
|4/19/2000 3:39 PM|
Check that 270BX... there is no way that tranny can deliver 495vdc in this amp!!
You either don't have a 270BX or you have no tubes in the chassis.
|4/19/2000 4:20 PM|
Right you are, Bruce, I made a typing
error, it is a 273BX, 350-0-350 at 175 mA,
weighs 8.8 lbs.
Now did you look that up, or did you just happen
to know that a 270BX is a wee thing, or is there
some code to understanding these numbers, that I don't know?
|4/19/2000 5:03 PM|
When you guys got your TW's put together did you have any oscillation problems, as in squeals when you cranked the treble and mid controls? thanks! Mark
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