The Amp Garage

I tried the lower B+ and have to say that I like it better. I worked on my layout a bit and the distortion quality that was bothering me is much better. The amp is still extremely bright. I can play it with the treble turned off and it still has a good bit of high frequency content. I guess I just ...

I really like polypropylene 716 orange drops in my build. I've got something around 75 pf across my PI plates, though. What preamp tubes are you using?

Well, I use the transformer shunt method, myself, to measure current directly. Is the resistor EXACTLY 1 ohm? Your measurement is reliant upon the accuracy of that resistor. -5.7 volt bias voltage is far too hot for EL34's at that plate voltage. Forget the measurement of the current. Set the bias vo...

-5.7 on pin 5 of the power tubes doesn't sound like near enough bias voltage, to me. You say 70 mv, what you want to do is measure the current in miliamps. 70 ma seems reasonable for both tubes, but I would expect -30 to -38 or so at pin 5.

Thanks to David for sharing this information!

David, Did the guys at Two Rock say you couldn't post any info? If so, that would be pretty ironic! :roll: Omar Well, you've got to protect "proprietary" information...well, Ken's proprietary information, in this case. I'd post it, anyway without the loop and master, myself :twisted: . What really ...

I did a quick little experiment using some aligator clips to clip in a well broken in Mallory 150 and a fresh 716 between the source and amp on my hi fi. To my ear, the 716 does not make the source brighter, but sounds very close to no cap at all. The 150 sounded far worse, rolled off highs, less an...

I had switched the files around yesterday with a take which had more conventional noodling. I felt the first movie with the titles might have been a bit over the top. I put it back, though. I think it's at least evidence of the results of the layout tweak. I never would have believed that moving wir...

Well, I realized that while I don't have any recording gear at home, I do have my little digital camera which can shoot a movie. Hence, I have indulged my inner scorsese this evening. While not the highest quality recording, I think you'll get the picture in terms of the feedback. This is with 6V6's...

Jackie, Thanks for the great info. Can't wait to try this on my T-wreck clone. Btw, I know I've told you before, but your amp look fabulous!! :D Omar Omar, you're too kind. I think your wreck gets the fabulous prize, though. Nice clip on the other thread. Your plexi is wired impecibly, too! I think...

Dear Jackie I'm glad the info I provided was able to help. I do have an "exact" layout for an Express/Liverpool amp. I have been meaning to forward it on to Omar, but work is getting the better of me at the moment. Should you want a copy, just send me an email. there is also a layout of the Express...

So the harmonic feedback increased with the longer wires and pinning them against the chassis (just trying to get it straight)? Also, where did you get your board material? I like the brown. Yes, that's exactly what happened. I had previously been fiddling with the wires from the board to the pream...

WOW!! That little change made that much of a difference? :shock: I would guess because those are high impedance runs (which makes them more sensitive to small changes in length, position--like the wires to the pots in a Marshall). thanks for the report JT! What it looks like to me is that by laying...

Yes, it's a big, very real difference. I don't know why, either. The resistors are the Japanese Riken-Ohms. I got them from Angela Instruments. They sound pretty nice and are very quiet. I've got a Tungsram in the first preamp position, Mullards in the other two, and JJ 6V6's as power tubes at the m...

A couple days ago, there was a topic at the gearpage regarding building express clones. I had said that I felt my build was lacking in the harmonic feedback department, not that I've ever played a wreck. However, I've read they give a lot of feedback, etc. Anyway, Mark Abbott's layout diagram for th...