liverpool done but need some help

[gahult]

FWIW here is a copy of my Liverpool voltage readings.

3/31 The one I posted was not right. My eyes went south while re-entering the reading. These are the new readings.

Gary

[Normster]

From the pictures, the V2a cathode appears to be a 10k, but the grid load looks like 130k instead of 68k. Don't know if that would cause any problems, though. Also difficult to see, but how do you have the 4k7 PI tail wired?

[fishy]

When you check the V2 cathode out, may I suggest sure you check from the tube socket back to the buss to include the whole signal path for the cathode. The resistor might well measure 10k but your issue might be wiring / cold solder joint etc elsewhere in the cct between the cathode and ground.

[pinkmarkos]

hey everybody- i just got done completely going through the preamp of my liverpool and... it's working!! it definitely shakes the walls now- no question. thanks again for all who weighed in with ideas. i would like to express deep gratitude to all who hang out at the amp garage and help newbies like me build kicka** amps they could never find in a store. also- thanks again to allyn for the chassis, rj for the boards, and toneslut for the trannies.
now for what was wrong- i think my main problem was an open resistor at R8, and i think R9 was bad as well. they were both 1 watt, not 1/2 watt carbon- not sure why only the 1 watts would be bad. anyways, now this amp sounds like a beast, every bit as tough as the express. ironically, i really liked the tone i was getting from the amp when it was not working correctly. it was just too quiet. i wish i was able to replicate that in another amp. instead of breaking up around 9 o'clock like the liverpool/express does- it gradually broke up until it got to a nice med/mellow distortion when dimed. any liverpool owners do anything to tame the ferocious distortion sometimes? i was thinking either a 12at7 in either v1 or v3 and see what that does.

[fishy]

Cool.... so the cathode resistor was bad.

Don't forget to do a full voltage chart with the amp up and running. You never know when it might come in handy

Tube rolling can help.

You can also tune the R7 / C8 RC network into V2 to reduce gain. The schematic suggests you can go as low as 33k. A point to consider if you change R7 it will influence the frequency response. To compensate you adjust R7 and C8 together. Doubling C8 while reducing R7 by half will keep your frequency response as it is. I have 68k / .0047 in mine.
This is assuming you want to maintain the frequency response where it is now.

Your volume control on the guitar should be your friend here also. They should clean up when you roll the volume down although not to the extent the Express does.

[M Fowler]

Nice to hear that you got it up and running

You will like the liverpool more each time you play it. The only thing better is the Rocket.

Try different tubes until you get the tone you want. You can also wire the NFB to one of the other 4, 8, 16 ohm taps to back off the early gain. Do you really need the 33k on V1?

Mark

[pinkmarkos]

thanks guys- i already have 150K at R7 as this value in addition to the 33K grid stopper worked wonders with the express. 150K seemed to give me a nice fat bottom end. You (Fowler) suggest removing the 33K grid stopper? I could try it. Another thing I noticed is that over a week or so the express seemed to "break in". it got smoother the more i played it. i will definitely post my entire voltage chart when i have a chance to get an entire one together. BTW- i have a quad of EI el84's in the power section, and they sound very good. i haven't heard the saratov's yet although lots of other people seem to rave about those tubes. Mark

[pinkmarkos]

hello everyone- just an update on my newly birthed liverpool. i have to say that this amp is what i've been looking for for over 20 years now. the tone just blows my mind !! I changed C8/R7 to .0047 and 47K and that did the trick. i have the NFB tapped to 8 ohms, and I have 47pf/82K at C12/R15 on the PI per the layout suggestion. I'm getting a great clean tone up until about 10 o'clock then it blooms into this amazing harmonic distortion from about 12/1 o'clock on. I am using a quad of EI el84's (not JJ's) and they sound killer. I still haven't really upgraded the preamp tubes (still all 12ax7's) yet so hopefully it will even get a little better from where it is now. There is hardly any noise except when prescence and volume are both dimed. M Fowler- you are right that it sounds better every time I play it! I guess the only thing left is a Rocket for my TW trifecta. Can't wait to start it! BTW- will post some sound clips ASAP. Good luck to the other guys trying to get their amps up and running
Here are my upgraded voltages just in case anybody else wants 'em. They are just about the same as gahult's (thank you gahult)
B+1- 338
B+2- 316
B+3- 263
B+4- 248
B+5- 235
Mains- 525 VAC Heaters 6.3VAC
V1- pin 1 177, pin3 1.53, pin 6 156, pin 8 1.17
V2- pin1 222, pin3 2.32
V3- pin 1 200, pin2 42, pins3 and 8 57, pin 7 38
V4- V7 pin 3 10, pin 7 (plate) 337, pin 9 (screen) 312

[M Fowler]

pinkmarkos,

It is good to hear that you got the amp going and you are enjoying it thats the main thing. She should be cooked in good by now huh, playing it frequently!

Mark

[gahult]

Your voltages look fine.

Allyn gave me some of his findings on one of his builds and some of yours are closer to his than mine are. I would hazard a guess that you are spot on with what you should see on your readings given the variables of all the components.

I have had different readings in builds when changing tubes to find the "right" one so, that is to be expected too.

Next thing is sound clips.

Gary

[fishy]

Good job getting where you wanted to be......