The Amp Garage

An easier way might be to implement the switch shown in Mark Abbott's mods schematic in the Files here:

http://maximoaudio.com/download/schemat ... iation.jpg

This will lower the gain of the preamp and allow for more clean headroom.
markd

dobbhill wrote: Are the Mallory 150's metalized polyester or polyester film/foil?
Dobb

polyester film/foil.
http://mhuss.com/php/pix.php?p=MalloryYellow
markd

Also the 150K plate resistor used on the second stage should translate to more gain, but the following grid leak resistor is smaller, 56K vs 150k for the A1b, probably compansating. Ricks57, Like the man said, the grid resistor following the second gain stage is in parallel with the plate resistor ...

But now I've started wondering about applying some of the wreck ideas to this circuit, without losing some of the magic it currently has. I didn't want to move the tone stack, so I thought about just replacing the second gain stage's 820R cathode resistor with 10k like the third stage in a wreck. S...

the B+1 decoupling elcap is an 100µF/450V type with a 220k resistor across it. What is that resistor supposed to do? If you have two caps in series to up the voltage rating you need a 220k (or similar) resistor across each to provide equal charging. I see no purpose for that resistor on a single ca...

There is a post at the JTM45 site here: http://launch.groups.yahoo.com/group/JTM45/message/4349 that mentions the Two Rock guys are selling some Trainwreck type trannies, etc. Sounds interesting. If the link above doesn't work here is the text of the post. "I have really enjoyed learning about JTM45...

Now that I've seen the pictures and thought about it, a question has popped into my head. How do they use a tube rectifier (GZ34) and have what looks to be 160uF of capacitance for the first stage? I have read that the highest any rectifier tube can handle is 50uF. I assumed the caps were in parall...

Thanks for the reminder :) I'm sure I've bought from them way back in the past. Hmmm... there's only a handful of Solen values listed (mostly low uF values), but I'll drop them an email to see if they also do the others (filter cap values). The Solens filter caps also look good to me. I have built ...

I checked the voltages on one that was biased very cold(the owner felt it sounded best at that setting) and the plate voltage was well over 450v. If it ws biased at 70% it would have still been slightly above 450v, IMO, but I didn't rebias it. A Komet is set up where a non technical person can rebia...

Here's a guess. Even though hooking two 80uF caps in series gives you 40uF, it doesn't physically limit the ability of those caps to hold electrical charge. An 80 uF cap has larger plates than a 40uF cap. That larger plate area can hold twice as many electrons as the plates of the 40uF cap. Two 80uF...

I'm sure I'll have other questions when I fire up and debug the amp, but for now my main question is whether you guys have any favourite values for the cap and resistor between the 2nd and 3rd stage? I'm planning to start with .0022uF and 68K. Thoughts? As you know, the cap and resistor between the...

Matt,
Really like your 3D layout. When it is done will a viewer be able to change the perspective from which it is viewed? Great Job!
markd