Liverpool: It's alive...HELP!!

[geetarpicker]

The presence control bleeds off some of the negative feedback in the high end, meaning less cancellation of highs effectively giving you more audible high end when you "turn up" the presence knob. That said, I'm pretty sure without the presence control at all the amp will sound the same as having one, but like it is set to 0.

Yes the lower the feedback resistor the more opposing feedback will be injected into the circuit, giving you more cancellation and basically less net high end. To much is probably not healthy for the output tubes and OT but others may know how low you can go. Try 100k (stock value) for starters.

Others may know better the best way to have the feedback circuit wired up when you don't actually have any presence pot at all. I'm not sure if you will have to have a fixed resistor in place of where the pot would be or not. You might need a 5k resistor to ground on the feedback wire after it ties into the PI, to mimic the stock circuit with the presence set "off".

Others?

[M Fowler]

I ground the tail resistor put in 25kL cut pot and the amp sounds way better to me. No feed back loop.

[JoeCon]

Mark

That is exactly how I have it now. Is your amp "bright"?
I'm liking the aggressive nature the LP has, way different from the Rocket types, but it is very treble weighted. Bass control works great but I can't use much treble and the cut is really turned down and this is with humbuckers, single coils are too much....

I have to check the pots and see what I put in there...

Thanks.

[M Fowler]

No it is not bright that was my intention to get rid of the NFB and presence pot to lower the brightness and it worked. The cut control was added so I could get more lows.

I still have a bright switch.

[geetarpicker]

The loop in itself (without the presence control) will reduce PI and output stage gain and improve the headroom for better cleans. It shouldn't make it any brighter.

[hans-jörg]

@JoeCon,
I really don`t understand why you don´t even try the NFB (after you swapped the OT sec. for sure). This Thread could be much shorter
I have the cut too (because of PPIMV which don´t like so much Presence).

Hans-Jörg

[JoeCon]

Hans,

LOL, I will, I will!! Life got in the way...
Plus have to find a nice way to get those parts in there, man. No shorting out please!

I'll see if I can swap the OT primes and then get those resistors in there tonite or tomorrow nite.

Thanks for the concern!!

[hans-jörg]

Hi,
what I found out here is, that I want to try out a switch for NFB: 100k/Non/33k.
Let live diversity!

Hans-Jörg

[JoeCon]

Hans

Yes! Choices in life...good stuff!!
That's what I get from TAG, choices on how to build "my" amp. Great ideas from a number of different sources let me get what I ultimately want.
Feedback or No Feedback...nice!

[JoeCon]

Glen, Hans, Mark,

Thanks guys for your help. I think it's under control now although right on the edge a bit. Sounds nicer, not so hairy and wild but still can growl when turned way up.

So swapped the OT primaries, 100k and 4k7 NF loop, moved ground connection for PS caps and voila! Quiet, not too bright, plenty of useable gain, not just a feedback machine. Even the Tele sounds good thru it. Time to...
Play on!!

Once again thanks for steering me in the right direction.

OK who's up for a Plexi 6V6?? Anyone?

[hans-jörg]

Hi,

good news, wish you plenty pleasant hours with it!

Hans-Jörg

[joeboo88]

Hi Joe: i was wondering if you still like your build: I was thinking of attempting the same build.
Is it much different than your 2 hole Rocket?
is the gain that much different?

I'm still unsure what to build a Rocket or a Liverpool ( 2el84's)

[JoeCon]

Joe

Oh yeah the Liverpool is quite different than the Rocket. The LP is a real "lead guitar amp". It cuts thru great and has that overdrive lead tone I was looking for. And it's loud with just the 2 EL84's too.
I put a switch for the V1a bypass cap to cut the gain a bit so I get two different ranges. It cleans up some with the guitar volume but not like the Rocket.
If you want a better all around amp I'd go with the Rocket for sure, I still really like that amp overall, especially the Rockster version I built with 2 KT66, but if you want a great lead amp the LP is it. Well until I build an Expresss anyways...LOL!

[joeboo88]

thanks for the info

[RJ Guitars]

So how about an Express with a pair of KT-66's... or if that is not loud enough, a pair of KT-88's??