2024 Monkeymatic Liverpool (nontraditional)

[dorrisant]

Nice!

[bepone]

Those radial caps are not made to be hanging on their leads.. also i dont like gluing elcos to chassis..theit plastic envelope will be broken one day.. and then? They can be mechanically mounted very nice, holders exiting on the market. Also vote against use of this sockets.

From my point of view this is just experimental amp with lower reliability rate.

[dorrisant]

Those radial caps are not made to be hanging on their leads.. also i dont like gluing elcos to chassis..theit plastic envelope will be broken one day.. and then? They can be mechanically mounted very nice, holders exiting on the market. Also vote against use of this sockets.

From my point of view this is just experimental amp with lower reliability rate.

With respect, how do you explain point to point construction... without a turret board? I've seen very old devices that have outlive their electrolytics, yet when they are replaced, most all is very well.

[maxkracht]

Looks like gravity and glue are holding those caps. I see a fair number of failures when heavy caps are hanging only from their leads, but laying down with some silicone, no problems. The larger snap in cap looks slightly precarious, but it has gravity, glue, and stranded wires stopping it from tipping.

[xtian]

I have 3M double sided, 1mm thick tape holding the reservoir cap down--it's very firmly attached. When I build an amp for NASA, I'll meet the spec. Until then, I do it my way, baby.

[Reeltarded]

Where did you end up on the third stage? I have no idea why the hell a 150k would be suggested other than joking about sustain and getting 100w peak transients out of a 35w amp. The high end response on my amp taps the stops on my meter. My 60w amps don't. Red light scares me.

Do you know the Scorpions tune "Catch Your Train?" Turn the lil LP up to about 5-6 and put a flat drive in front of it with very little gain but output way up. I used a Marshall umm.. is it Drivemaster.. omg it's just like it. It sounds like the Sun is melting.

It is. Hendrix. His black strat melted the Sun,

[Reeltarded]

Hey Aaron, I just built my Liverpool for the second time. I used the 68k instead of the 150k per Miles suggestion. Mine has the high gain hiss but
No extra noise. I also can crank the amp to 2 than after that it’s way too loud. I guess these amps are like the express as a lot of the volume comes on very early on. I use mine with a home made attenuater exclusively.. it sounds great… not muddy with the attenuator.
Good luck. Joe

First time I flipped the switch I thought something was broken! 150k had to be an April 1st mod.

I rarely play off a load box and reamped, but this is the loudest a quad of 84 type tubes can be. Liverpool easily flattens a Marshall 4 input amp. It stands up to the 100 and wipes a 50. Playing it into 2 cabs takes a little hate off the high mids, but even I can't take the volume. The peak in the mids loves to play though.

[xtian]

I changed that 150K to 33K, and changed gNFB resistor from 100K to 50K. Still way too bright. I'll have to spend more time tweaking.

I'm getting 12 watts into 8R with these Fender OEM transformers. Can only imagine the mayhem with solid Trainwreck iron!

[Reeltarded]

I changed that 150K to 33K, and changed gNFB resistor from 100K to 50K. Still way too bright. I'll have to spend more time tweaking.

What are you playing into it? You should try 68k. That is what was intended. The coupler is too small to make meat, but with all that gain.. I actually use the 100p brite. That is with humbuckers @7.75k-ish. Controls V from 4-7, T 5-7, M 5-8, B 4-6. Pres set to take the stab off the face per setup. Bleed with me.

BEST PRESENCE CONTROL IN THE BIZ!

You must ride the wild monkey and learn to love the bomb.

I want to understand your instrument setup and have some clue about how the LND handles the clean to dirt. Does it splat when it's amping small signals.. hmm.

I need to read some more about it.

[cdemike]

Build finished, fired up successfully. 316v plates – 10.3 cathode = 306v plate-to-cathode, 10.3v across 130R cathode resistor = 80mA, or almost exactly 100% dissipation, so that's nice.

I have a LOT of noise at idle. It's not the gNFB, it's just a huge amount of gain following the Volume pot. If I ground the input of the PI, I get silence. But if I ground the input of the prior stage (the triode with 10K catohde), white noise is very loud. In play testing, the amp is extremely loud with the Volume pot just barely above zero. Clearly, I've got to dump a bunch of gain somewhere. Is this a common Liverpool observation?

Photos to come.

I'm new to solid state and have been doing a deep dive after your first thread exploring the idea, so take this as you will, but it appears to me based on what I've been able to glean about gain calculations that you'll have quite a bit more gain than a 12AX7 gain stage there. With a 100K drain resistor and a 130R source resistor, you're looking at a gain factor of about 88.5. I'm basing that based off this thread: https://electronics.stackexchange.com/q ... -in-mosfet

The specific formula I'm using from there is gain factor = Rd/((1/gm)+Rs) where Rd is the drain resistor value and Rs is the source resistor value. So that could be part of the reason why you're seeing the unexpected gain and could also explain some of the noise. As for values for the protective coupling cap at the input, I think 100nF should give you basically all the usable information you'd need for a guitar signal (I used the Amp Books calculator and assumed a "worst case scenario" minimum of 125K "output impedance" based on Fender volume/tone pot values).

Edit: it's been a while since I've looked at a Strat wiring diagram and mis-remembered there being two volume controls and one tone control, but point still stands if you're using 10% tolerance 300k pots on, say, a newer Les Paul with factory pots.

[xtian]

Last step required to manage gain was to replace both 12AX7s with 12AT7s. Very happy now. Playing thru an EVM12S. Amp can be way too bright—can't turn on bright switch, and Presence is too much. But tone stack controls are really responsive. This demo is recorded with: Treble 3, Mid 3, Bass 5. This is a very fast-attack amp (remember I put a 220uF reservoir in there!), but I like it—works great for early Zeppelin with my Barncaster.

https://youtu.be/u_lO-q4a-24?si=bEfGJhVedlWuj0qJ

[xtian]

Another improvement: The 1uF bypass on the FET's source ("cathode") was a mistake. I just cut it out and left the 1K2 resistor unbypassed. This removed some mid-high harshness.

The FET is sounding like a fine choice as a preamp. The only oddity I've noticed is that, when playing a power chord during power down (as I do sometimes to drain the caps quickly, sometimes just to enjoy the fading distortion as the voltage drains), the FET sputters and shuts off abruptly. No heaters in that little guy.

[Reeltarded]

It sounds fun and you subverted the soul of Liverpool. Congrats lol

[Guy77]

Last step required to manage gain was to replace both 12AX7s with 12AT7s. Very happy now. Playing thru an EVM12S. Amp can be way too bright—can't turn on bright switch, and Presence is too much. But tone stack controls are really responsive. This demo is recorded with: Treble 3, Mid 3, Bass 5. This is a very fast-attack amp (remember I put a 220uF reservoir in there!), but I like it—works great for early Zeppelin with my Barncaster.

https://youtu.be/u_lO-q4a-24?si=bEfGJhVedlWuj0qJ

Sounds great! Hopefully the Trainwreck ghost and goblins will not be awaken lol.
Love the smoothness of that EVM speaker.
I will try my LND150 preamp Single ended ODS I built to see if it does the same thing yours does when shutting down and hitting a power cord.

What's that cool looking device partially seen below your oscilloscope?

Cheers
G

[ViperDoc]

"LND Zeppelin". Nice, dude!