Neither of my Trainwreck amps currently have the stock presence circuits. My Liverpool currently has no Presence or NFB and just has a cut control. My Express has the Naylor Presence circuit.
I was making a few clips of both amps a few days ago. I was pretty happy with my Express, except there is no option on the amp to reduce the high end harshness. I'm forced to dial back my guitar tone. I always run the bright switch full (500pF) so that I can get a nice clean to mean on the guitar. So, today, I added a standard cut control after the PI. I sacrificed the Naylor presence knob and put 2 values on a push pull pot of 2.35K and 3K (using a 4.7K resister that parallels with either a 4.7K or 8.2K resistor. They are very subtly different, so I will probably spread out the options a bit more. But, with the cut control, there is a bit more freedom there.
For the Liverpool, I do love the tones I get, but I realize the clean to mean is more gradual and the clean is significantly quieter than the full distortion. I realize this is partly due to the Express being overall better than that. But I also suspect I've exacerbated this difference by removing NFB from my Liverpool. So, now I want to experiment with adding NFB back into my Liverpool without giving up my cut control for a Presence control. I'm assuming I can just add back in the 100K NFB resister and a 4.7K tail resister and ignore the presence pot and cap. Has anyone played with this stuff in the Liverpool? I guess if I feel I need more sizzle, I could simulate a random presence setting with a cap and resistor.
Cut + Presence or NFB in Liverpool & Express
Moderators: pompeiisneaks, Colossal
Re: Cut + Presence or NFB in Liverpool & Express
So, my first reactions are pretty good. For the Liverpool, I also switched back to the 6k6 OT primaries. I think the clean and mean volumes are closer now. I switched from my 12ay7 in V1 back to a 12ax7... then switched back. I think I need something more in between like my 5751.
As far as the express goes, I am noticing a subtle high end crackle. I thought it was something with my speaker cab at first. I was checking around the room for things rattling, removed the amp from the cab entirely, but it's still there. It's similar to that static sound you can get if you've ever used an unshielded strat in the middle of winter (-40 degrees) in a super dry climate. The Cut control is definately nice to have, but even at full cut, I can still get a fair amount of brightness from the amp. You can hear above which frequency it is affecting. I'm tempted to switch back from the Naylor Presence circuit to the Stock Express Negative feedback situation to see if its complex/unorthodox methodology is causing that subtle crackle. I had left it so far because I feel like it had resolved the frustrating fizziness that my Express usually had. I guess we will find out. It's time to learn...
As far as the express goes, I am noticing a subtle high end crackle. I thought it was something with my speaker cab at first. I was checking around the room for things rattling, removed the amp from the cab entirely, but it's still there. It's similar to that static sound you can get if you've ever used an unshielded strat in the middle of winter (-40 degrees) in a super dry climate. The Cut control is definately nice to have, but even at full cut, I can still get a fair amount of brightness from the amp. You can hear above which frequency it is affecting. I'm tempted to switch back from the Naylor Presence circuit to the Stock Express Negative feedback situation to see if its complex/unorthodox methodology is causing that subtle crackle. I had left it so far because I feel like it had resolved the frustrating fizziness that my Express usually had. I guess we will find out. It's time to learn...
Re: Cut + Presence or NFB in Liverpool & Express
OK, so now both my Liverpool and my Express are pretty similar. They both have the stock 100k feedback resistor. Then I forgo the presence control and just have a 4.7K to ground off the PI tail resistor. Then they are both using a Cut control with a 250K pot and a 0.0047uF cap. I actually put a 180K Resistor across the Cut pot on the Express that I just switched over in order to get the sweep a bit more useable. I think the problem is mostly that I like the pot to cut highs as I turn it CCW, but I think I need reverse audio taper pots to make that work well.
Anyways, my immediate reaction is that I think I'm happy with this situation. I'll have to test them a bunch to see if I'm happy long-term. I've messed with these amps so much over the 15 years I've had them... but often circling back to roughly the stock circuits.
Anyways, my immediate reaction is that I think I'm happy with this situation. I'll have to test them a bunch to see if I'm happy long-term. I've messed with these amps so much over the 15 years I've had them... but often circling back to roughly the stock circuits.
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Re: Cut + Presence or NFB in Liverpool & Express
Hello Matt --
Tinkering with perfection. An excellent collegial process.
..
Tinkering with perfection. An excellent collegial process.
..
Re: Cut + Presence or NFB in Liverpool & Express
Ya, these have been my favourite couple amps for many years now... So it's worth it to try little tweaks that can make them more optimal.
I'm curious how others find in regard to whether the presence is needed for the equal clean to mean volume vs simply the NFB being there.
Re: Cut + Presence or NFB in Liverpool & Express
I've been pretty happy so far with both the amps using a Cut control, and just the NFB with no specific presence control.
I do have a question though. By having the 4.7K resister to ground off the PI tail with no Presence capacitor... does this mean I am simulating the presence being turned all the way up, or all the way down?
I originally assumed it was like having the presence all the way down, but the fact that I HAVE to use that cut control pretty heavily, now makes me wonder...
NFB circuits can get me confused sometimes because the way they are taking an out of phase signal; I get turned around a little.
Just to clarify, I realize I am talking about what used to be two different presence circuits.
This is what I did/ removed from each:
I do have a question though. By having the 4.7K resister to ground off the PI tail with no Presence capacitor... does this mean I am simulating the presence being turned all the way up, or all the way down?
I originally assumed it was like having the presence all the way down, but the fact that I HAVE to use that cut control pretty heavily, now makes me wonder...
NFB circuits can get me confused sometimes because the way they are taking an out of phase signal; I get turned around a little.
Just to clarify, I realize I am talking about what used to be two different presence circuits.
This is what I did/ removed from each:
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Re: Cut + Presence or NFB in Liverpool & Express
The cut control on the Express was really sucking. The pot was scratchy and I didn't feel like it could tame the potential harsh high-end enough even all the way down.
I swapped for a simple linear taper PEC 250K pot and doubled the cap value to 0.01uF. This seems to be working better so far and has more intervening power if wanted. We'll see how it plays out.
I must really hate presence since I use no presence cap at all and I still need an aggressive cut control... Although I gravitate toward single coils a lot, and I like to use the bright switch on full, so there's that.
I swapped for a simple linear taper PEC 250K pot and doubled the cap value to 0.01uF. This seems to be working better so far and has more intervening power if wanted. We'll see how it plays out.
I must really hate presence since I use no presence cap at all and I still need an aggressive cut control... Although I gravitate toward single coils a lot, and I like to use the bright switch on full, so there's that.
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