The Amp Garage

for cathode biased amps you subtract the cathode voltage from the plate voltage to get the actual voltage the plate "sees"-----so you can always run them a little hotter than you think with cathode bias. i'm guessing you have around 20v on the cathodes here, give or take. rh

brian wallace from marstran stocks the heyboer express trannies----and his powers have export taps, so there is a 240v tap. rh

http://www.marstran.com/MISC.htm
http://www.marstran.com/Wiring%20Diagrams.htm

ken worked at ampeg for a while. ampeg put the diode string in their bigger amps in the 70's. they thought it was a good idea and he probably did as well, since i'm sure he probably learned a good bit while working there. rh

it's just like the diagram in rj's reply. except the addition of a 5v winding for 5v tube rect. heaters. rh

...esp the fb loop as is. leave it alone. i still like it best for guitar as is---with just a couple of minor changes (fb loop cap and lower snubbers in the earlier stages). i think it sounds pretty good----jut my tastes perhaps. rh Hi Robert, thanks for the reply If you mean the stage 1 snubbers o...

I've been cleaning up what I thought was an AA165. I had trouble biasing it last night and remembered that they used up old tube charts...wasted time. Here's the oddity, the guy is bassist. He has a pile of quirky bass amps, and changing it for the best guitar tone isn't the plan. I've modded the b...

the part number for the ones i had heyboer make is hts-6607 if you do a search for brian may and dave peterson you can find the big pdf file on his mods (somehow my browser won't load it anymore) also aschematic is on greg fryer's site---he was involved as well http://fryerguitars.wordpress.com/2009...

it's not that large size wise----i think it's the same open frame size as a pro/bandmaster/18w marshall output trannie but with a bit thicker stack. i'll post my heyboer part number when i get home and you guys can feel free to order some. i bought a batch, but i believe they were about $30ea as one...

i've built several ac30's with the "brute force" front end (cap-choke-cap) with some chokes i had heyboer make for me 7h/300ma. brian may's amps were changed in this fashion. it allows you to use the lower filtering (and have that kind of feel) without all the ghosting that comes with lower filtered...

yeah just a normal lytic. and it's part of the whole presence and p.i. circuit so you need to change the whole thing around it for effect. note the use of a nfb cap and not resistor. these are probably dark amps by some people's standards.
rh

i've built several naylor sd60 type amps. (both the pre 96 and post 96 circuits). i have a few transformer sets to build these if anyone here is interested. i like the pre 96 circuit a lot, but both are good. i also add a a switch for an extra parallel treble cap for more upper mids if needed. the ...

i've built several naylor sd60 type amps. (both the pre 96 and post 96 circuits). i have a few transformer sets to build these if anyone here is interested. i like the pre 96 circuit a lot, but both are good. i also add a a switch for an extra parallel treble cap for more upper mids if needed. the p...

DR.Z wrote:That was one quarters worth.
I order 100 of the tung-sol 12AX7's a month.
So the 135 failed was from 300 I purchased in 3 months.

DR.Z

hopefully mr. matthews won't decide those you sent back are ok and sell them to me next time i order 10-20pcs. rh

I am going to order a couple of the Classis Tone outputs and see how they look and sound. I can't bring myself to go for the Power Trannies since they are bit more expensive than Heyboer and I have plenty of stock in Heyboer and Pacific at the moment. I am curious if anyone else would be interested...

the correct value is 365-0-365 at idle (maybe 30 -40ma current draw on each tube) on the hv sec. you can add about 3 or 4 volts extra on the total for the unloaded ac. value---so call it 368-0-368. the wire for the winding will be rated at 250 - 300ma, so figure 27ga wire. essentially any higher vol...