Help with Liverpool -no sound

[BLT]

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[martin manning]

I would reconfigure the bright switch and caps like this.

[hans-jörg]

+1

works perfect with me too.

Hans-Jörg

[Richie]

yep ,and turning the pot like some mention would shorten those 2 leads.

I also wondered[Express and Liverpool] why the long leads from the 2 .02 tone caps. they could be shorter if attached to the pot closest to them where the jumper wire is connected. The way they are, they go to the furthest point, and the jumper connections go back.

Maybe it was done for a reason, but looks like both could be much shorter, less wire,and then still has the jumper wires that connect the pots.

I think if you look, Ken changed some of the wiring in different amps a bit.

[Bob S]

Thanks Martin - that's what I meant.
Getting the TMB & Vol wiring right is the difference between a good amp & a great amp.
Oscillatious the enemy lives up there where the infant signal wanders.
The presence can be tricksy too.
But well worth the effort when you get it right.
Keep us posted.

[WinstonN]

I'm going to work these suggestions. They all make sense to me...now. Wouldn't have a week ago! Like you wrote Bob - "Oscillatious the enemy lives up there where the infant signal wanders" - so true! It's all happening up there in "V1-BrightSwitch-VolPot-ville".

Again, thanks again for taking me from a state of total frustration to discovery. I've learned more i the last few days about amps than in 40 years of playing! I can see how this can become a problem...er...passion.

[WinstonN]

...I should admit that I don't nearly, *completely* understand this stuff. I am reconfiging the bright switch per Martin's diagram, but I need to think about why it will work wired that way, other than the obvious elimination of excess lead length.

Question: This amp get to full volume by 9:00 to 10:00 on the volume - with *tons* of gain. After that it is mostly compressing. Is that typical?

Note on Presence - past 2 or 3:00 is a very high-pitch oscillation. Keeping it at 0 to 30% seems fine.

[Littlewyan]

Yes there is quite a bit of compression with the Express and the Liverpool amps.

With regards to the Presence could we get a better photo of the Presence wiring?

[martin manning]

I am reconfiging the bright switch per Martin's diagram, but I need to think about why it will work wired that way, other than the obvious elimination of excess lead length.

The original layout had longer leads, three runs between the pot and the switch, and one or all three of them were basically functioning as little antennas depending on the switch setting. In the revised scheme the two leads running close together will create a few pF of capacitance between them, and to ground if they are run close to the chassis.

[WinstonN]

I see. Would twisting the 2 wires help? Should they be as close to the chassis as possible?

Working on a presence wiring pic...

[WinstonN]

Presence...

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[Littlewyan]

No need to twist the wires, if they are run parallel to each other then that is the same as twisting anyway. When the amp starts squealing due to the presence being too high start moving wires to see what changes it. It will most likely be either the presence wire or tone control wires.

[M Fowler]

I use the same bright switch wiring as Martin Manning showed above and I twist the wires from switch center lugs to volume pot.

[hans-jörg]

Hi,
I twisted them too, but turned the pot 90 degree, so the wires get half of the length of before. I have there now 2cm twisted wire and no more antenna

Hans-Jörg

[JoeCon]

On my recent Liverpool build I turned the pot to make the wires as short as possible, like this picture...