Can I get more bass out of my Liverpool?

[fzfwyv]

Forever the tweaker, I'm now settling in to playing my Liverpool and was wondering if I can get a little more bass out of the 'Pool?

What about changing the value of the bass pot? Or changing a cap value?

I can eq the amp with less treble and mids but I think i'd want just a little more bass on tap.

Thanks,

-Rich

[Mark]

Dear Rich

The first question that comes to mind is what are you using for speakers?

I don't think the Express or the Liverpool like open back designs, I think they are strictly a 4 X 12" amp.

Mind you I did find the (my version) Rocket work quite well with an open back set up.

The next question is what value are you using for the coupling cap between the second and third stage (0.0047uF?)

Increasing the value of this component will result in an increase in bass response.

Hope this helps.

[tubedogsmith]

The 6.6k OT tap will give you more bass, if your not using 1 meg treble and bass pots put them in. 50pf treble cap? I'd stick with the .002 cap and a 68k resistor after the second stage. If you still want more bass try .047 or .1 caps in the phase inverter.

[krash]

yes I agree about the .002 cap even though I haven't built either an express or liverpool, in my hot rod PR anything bigger than .002 gets muddy, better off trying to chop off some top end rather than trying to cram more bass into that stage. it's all the same in the end. more bass = less highs. you might also consider bigger cathode bypass caps on the power tubes. i think .1uF caps in the PI are critical.

[paulruby]

The next question is what value are you using for the coupling cap between the second and third stage (0.0047uF?)

Increasing the value of this component will result in an increase in bass response.

Hope this helps.

Bingo. That is the component to play with to adjust the bass in a wreck preamp. Set your bass pot to 12 o'clock and tweak that cap to taste. Then the bass pot will be your fine tuner.

[fzfwyv]

So if I go adjusting this cap, should I change the bass pot to a 1M (from a 250K)?

Looks like I have some tweaking to do.

As far as cab & speakers, I am using a 2x12 closed back cab with Vintage 30s. The cab was made by Jeff Swanson and it is essentially a shrunken version of a 4x12 bottom cab. Dims are 24x24x12. This thing thumps. So I tend to believe it's not the cab/speakers.

To clarify my original question, it's not like there isn't enough bass, it's just my bass control is just about maxed. I would like to have a little more bass on tap, not muddiness, but just a little more bass frequencies.

So here goes another noob question...what cap is this exactly? I followed Mark A's schematic very closely so if you could identify if it is on page 1,2 or 3 that would help me greatly. Thanks, Rich

[Mark]

Try comparing the 5K primary impedence to the 6.6K primary impedence.

I've heard 6.6K was the original value that Ken Fischer used, but for reasons I don't understand, no one has tried it?

I still stick by using a cap between 0.002uF and 0.0047uF between the second and third stage.

Yours Sincerely

Mark Abbott