Liverpool bass reduction?

[Ledvedder5150]

I'm curious about ways to reduce the bass a bit in the Liverpool. Don't get me wrong, the amp sounds killer as is, but I like to experiment. I've tried a few things, but I'm wondering if anyone has tried other options. I've tried a 0.68uF bypass cap across the 2nd stage, instead of the standard 22-25uF. I've also tried a 22nF at the PI input, instead of the standard 100nF.

[Reeltarded]

Is the amp at full drive and you backed the guitar volume down and this bass bubble still exists?

[Reeltarded]

Ok. I think I have the overall answer to your whole list of things. It's this simple.

You need more midrange authority in your tone stack. This is done with the treble cap. Is it still 50p?

That 68k is just above the knee of gain that flattens EL84s. Consider this when changing your treble cap to 330p/500p range and probably dropping the 68k to 56k.

This opens up the headroom between the preamp and output enough for the larger treble authority to be effective at a similar output volume.

I would return the large bypass you changed to .68u and get this other thing worked out before changing the bypass.

[Ledvedder5150]

I wouldn't call it a bass bubble. It works great with the 500pF bright cap, but I'm preferring 100pF bright cap. It seems to clean up better with the guitar volume. And it's not a ridiculous amount of bass. I just prefer a bit leaner tone. Comes from my Marshall background I suppose. Or more likely that I always prefer HB guitars. Maybe it's an EL84 characteristic? I feel the same way about an AC30 clone that I've built. I'm always dialing back the bass with that too.

I'll test the tone cap suggestions. Thanks!

[Littlewyan]

What coupling cap and resistor have you got between the 2nd and 3rd stages?

[bepone]

1nF to the PI input,
otherwise change output transformer for better

[Reeltarded]

I wouldn't call it a bass bubble. It works great with the 500pF bright cap, but I'm preferring 100pF bright cap. It seems to clean up better with the guitar volume. And it's not a ridiculous amount of bass. I just prefer a bit leaner tone. Comes from my Marshall background I suppose. Or more likely that I always prefer HB guitars. Maybe it's an EL84 characteristic? I feel the same way about an AC30 clone that I've built. I'm always dialing back the bass with that too.

I'll test the tone cap suggestions. Thanks!

NOT BRIGHT CAP

TREBLE CAP



Yes. There is a gain factor with 84s. Once you are driving them you have about 1 volt of headroom to do all your tone changes. lol Once they are fully driven THEY ARE the whole character of the curve. You can't do anything about it. You either like it or not.

Change the actual treble cap to 500p to gain mid/treble authority. The treble cap that feeds the treble control off the slope resistor that is para to the mid and bass caps. The actual treble. This will force the output to eat more mids and treble before getting stuffed with bass. You might need to tweak the 68k resistor to 56k once you do this to give you a little more room under the 84 whine.

[Reeltarded]

1nF to the PI input,
otherwise change output transformer for better

He isn't wrong. Try this idea if swapping the treble cap to 500p doesn't produce exactly what you wanted.

[Ledvedder5150]

I was talking about the switchable bright cap when I said I prefer 100 over 500.

[Ledvedder5150]

What coupling cap and resistor have you got between the 2nd and 3rd stages?

2.2nF and 68k.

[Reeltarded]

I was talking about the switchable bright cap when I said I prefer 100 over 500.

Yes I was talking about tone stack treble cap when I suggested 330-500p lol

[Littlewyan]

What coupling cap and resistor have you got between the 2nd and 3rd stages?

2.2nF and 68k.

Try replacing the 2.2nF with 1.5nF or even 1nF, see if that takes you in the right direction. I'm not sure what configurations Liverpools generally have if I'm honest, just that it ranges from .001uF - .01uF and 33K - 150K. So basically it could be anything!

[LOUDthud]

What coupling cap and resistor have you got between the 2nd and 3rd stages?

2.2nF and 68k.

Try replacing the 2.2nF with 1.5nF or even 1nF, see if that takes you in the right direction. I'm not sure what configurations Liverpools generally have if I'm honest, just that it ranges from .001uF - .01uF and 33K - 150K. So basically it could be anything!

It's interesting to put a pot in place of the resistor. It's kind of a subtle tweek that if it was on the front panel, you'd set it to one place you like it and leave it there. 68K is on the low side, too much load on the previous stage IMHO. Reduce cap to 1nF and try resistor from 100K to 500K.

[Ledvedder5150]

Well, I tried increasing the treble cap to 500pF and decreasing the 68k to 56k. I liked the result, but I'm not sure if I want to keep it this way. I feel like any little change away from the original circuit designed by KF takes a little something away from the magic of it. Sure, maybe I have to turn the bass all the way down and run the treble high to get the tone I want with humbuckers, but at least I can get that tone.

But, something that's been bugging me is that I can't really get exactly the tone that Pete Thorn gets in his Chante video. That's the video that made me want a Liverpool. I have the exact guitar he's using, along with a Greenback loaded cab. I see he has the volume at noon, treble and mid around 1, bass around 10, presence around 1 in his video. That tone is just amazing. Maybe it's the tubes running in that amp. I'm running JJ power tubes, and a combination of RFT and Sovtek LPS preamp tubes. I guess tone really is in the hands of the player.

[Littlewyan]

How about this clip? Does your Liverpool sound similar to this? (Bear in mind I think he might be using a G12H cab here)

https://youtu.be/3aP4yFdejSo?t=276