Liverpool treble cap differences

[Ledvedder5150]

I'm noticing different treble cap values used on some different schematics. Some show 47pF, which is what my build currently has. Others show a 500pF cap. Does this make a dramatic difference?

[Reeltarded]

YES

The treble cap moves the midband down the larger it is, leaving the 1kHz dip wider with a smaller treble cap and very steep and narrow by comparison with a 500p. I can't imagine any control on the amp doing much with a 500p treble cap.

I turn mids.. amp maxed.. treble.. amp maxed.. bass is an off switch at the bottom and there isn't a clean sound with volume above .3!

47p is somewhat balanced to my ears. The treble authority is in control.

[guitarmike2107]

Be careful when comparing schematics, the 50pf cap works with the 1M treble control (classic Vox values). the 500pf cap is often used with a 250k pot. So you might not be comparing apples with apples.

For treble caps, doubling the cap value gives an obvious change in hi mid response that you may or may not like. I would try a 100p or put another 50pf on a switch in parallel to see if you like it.

On the liverpool amp though I do think the 2.2nf coupling cap feeding the 68k grid leak gives a fixed treble and high mid boost so that you don't need to boost the high mids in the tone stack. happy for you to prove me wrong!

[Ledvedder5150]

Be careful when comparing schematics, the 50pf cap works with the 1M treble control (classic Vox values). the 500pf cap is often used with a 250k pot. So you might not be comparing apples with apples.

For treble caps, doubling the cap value gives an obvious change in hi mid response that you may or may not like. I would try a 100p or put another 50pf on a switch in parallel to see if you like it.

On the liverpool amp though I do think the 2.2nf coupling cap feeding the 68k grid leak gives a fixed treble and high mid boost so that you don't need to boost the high mids in the tone stack. happy for you to prove me wrong!

Yep, I realized that after looking at the pot values! It's obviously the sum of all parts. But that makes me wonder why a 1M was used in the Liverpool, but a 250k was used in the Express. I wonder if it was just the Vox vs Marshall origins of both circuits?

[guitarmike2107]

Could be, I was surprised about it when putting the kit together. I am sure Ken had his reasons

If you haven't already, you should download the tone stack calculator and plug in the values to get an idea how cap changes affect the tone stack.

[Reeltarded]

Be careful when comparing schematics, the 50pf cap works with the 1M treble control (classic Vox values). the 500pf cap is often used with a 250k pot. So you might not be comparing apples with apples.

For treble caps, doubling the cap value gives an obvious change in hi mid response that you may or may not like. I would try a 100p or put another 50pf on a switch in parallel to see if you like it.

On the liverpool amp though I do think the 2.2nf coupling cap feeding the 68k grid leak gives a fixed treble and high mid boost so that you don't need to boost the high mids in the tone stack. happy for you to prove me wrong!

Yep, I realized that after looking at the pot values! It's obviously the sum of all parts. But that makes me wonder why a 1M was used in the Liverpool, but a 250k was used in the Express. I wonder if it was just the Vox vs Marshall origins of both circuits?

250k pot with 47p will put you at the end of rotation trying to get more. 1M and 500p you would be asking how to cut highs after hitting 1 on the dial.

Liverpool is lacking headroom for control changes to affect much with volume up anyhow. It's all 84 by the time it's driven. Wrrrrrrrrr

[Mark]

I'm noticing different treble cap values used on some different schematics. Some show 47pF, which is what my build currently has. Others show a 500pF cap. Does this make a dramatic difference?

It makes a huge difference. Ken Fischer has built a Liverpool with the 500pF. 50pF (47pF) is typical, the 50pF sounds smoother, the 500pF (470pF) sounds fatter.

[Mark]

Be careful when comparing schematics, the 50pf cap works with the 1M treble control (classic Vox values). the 500pf cap is often used with a 250k pot. So you might not be comparing apples with apples.

For treble caps, doubling the cap value gives an obvious change in hi mid response that you may or may not like. I would try a 100p or put another 50pf on a switch in parallel to see if you like it.

On the liverpool amp though I do think the 2.2nf coupling cap feeding the 68k grid leak gives a fixed treble and high mid boost so that you don't need to boost the high mids in the tone stack. happy for you to prove me wrong!

Yep, I realized that after looking at the pot values! It's obviously the sum of all parts. But that makes me wonder why a 1M was used in the Liverpool, but a 250k was used in the Express. I wonder if it was just the Vox vs Marshall origins of both circuits?

The Liverpool and the Express both use 1M pots, the Komet amp uses 250K pots.

Use 0.0047uF instead of 0.0022uF it sounds better.

[Ledvedder5150]

Be careful when comparing schematics, the 50pf cap works with the 1M treble control (classic Vox values). the 500pf cap is often used with a 250k pot. So you might not be comparing apples with apples.

For treble caps, doubling the cap value gives an obvious change in hi mid response that you may or may not like. I would try a 100p or put another 50pf on a switch in parallel to see if you like it.

On the liverpool amp though I do think the 2.2nf coupling cap feeding the 68k grid leak gives a fixed treble and high mid boost so that you don't need to boost the high mids in the tone stack. happy for you to prove me wrong!

Yep, I realized that after looking at the pot values! It's obviously the sum of all parts. But that makes me wonder why a 1M was used in the Liverpool, but a 250k was used in the Express. I wonder if it was just the Vox vs Marshall origins of both circuits?

The Liverpool and the Express both use 1M pots, the Komet amp uses 250K pots.

Use 0.0047uF instead of 0.0022uF it sounds better.

For me, it's already bassy enough with the 2n2 cap.

[Mark]

Yep, I realized that after looking at the pot values! It's obviously the sum of all parts. But that makes me wonder why a 1M was used in the Liverpool, but a 250k was used in the Express. I wonder if it was just the Vox vs Marshall origins of both circuits?

The Liverpool and the Express both use 1M pots, the Komet amp uses 250K pots.

Use 0.0047uF instead of 0.0022uF it sounds better.

For me, it's already bassy enough with the 2n2 cap.

What cab and speakers are you using?
I haven’t had issues with the amp having too much bass.

[Ledvedder5150]

The Liverpool and the Express both use 1M pots, the Komet amp uses 250K pots.

Use 0.0047uF instead of 0.0022uF it sounds better.

For me, it's already bassy enough with the 2n2 cap.

What cab and speakers are you using?
I haven’t had issues with the amp having too much bass.

A Suhr 2x12 with greenbacks.

[Mark]

For me, it's already bassy enough with the 2n2 cap.

What cab and speakers are you using?
I haven’t had issues with the amp having too much bass.

A Suhr 2x12 with greenbacks.

Looking at Suhr’s range of 2 X 12” cabs, there are two that are open backed and two that are closed back. I assume you have the closed back cab.

[Ledvedder5150]

What cab and speakers are you using?
I haven’t had issues with the amp having too much bass.

A Suhr 2x12 with greenbacks.

Looking at Suhr’s range of 2 X 12” cabs, there are two that are open backed and two that are closed back. I assume you have the closed back cab.

Yes sir! PT15-212, https://www.suhr.com/electronics/amplifiers/pt15-2x12/