V1 replacement for controlled bass (lower bass response)

[gwEm]

I'm using JJ ECC83 (I think the non-S version) and Mullard reissue EL34 in my JMP50 Master Volume.

Modifications are removal of the treble bleed cap on the gain pot, and a 80s spec power transformer (higher plate voltage).

Bass response can sometimes be a little too strong/driven - I very muchbelieve that this is happening before the tone stack.

Reports on this forum (from HTH in particular) suggest that a high quality V1 might be a good idea in general to improve tone - but would it help in this case?

I dont suspect the power section since, although it helps a little, cranking doesn't change much.

I dont suspect the speakers since its pretty clear on the four speakers I tried it through - G12T150, G12H30, G12H100, Vintage 30.

It happens on my guitars with strong bass response - Dirty Fingers and A5 Mules. Dialling out some bass on the tone stack obviously removes the low end, which is fine, but i think it is being distorted before this.

Would re-insertion of the treble bleed cap help? (obviously with a lower value - i quite enjoy being able to use this control)

edit: a bit more gain wouldn't go a miss either, dont fancy changing to a 12AT7 or anything like that. also, dont want to use pedals just for this.

[Twinfan]

I think you'll find the 'problem' is the replaced output transformer.  My Superbass Klipp runs EL34s at 600v and has monster low end and a cleaner, more hi-fi sound.  For the traditionall Marshall sound you need the plate voltages around 450v-ish.  Do you know what voltages you're running?

I would guess swapping the preamp valves around is going to make very little difference to your bass issue.  Putting the treble bleed cap back will help a bit, but not cure the problem completely.

[gwEm]

thanks for the response twinfan

the output transformer is orginal - i changed the power transformer for an upgraded item to give higher plate voltage. it is a simdgen under 450v, orginally it was alot less. changing the power transformer did give noticably more controlled bass, but it is still 'uncontrolled' in some cases.

[Twinfan]

Sorry gwEm - my typo, I meant power transformer.  Doh!

If you're running 450v, then maybe the cathode bypass caps on V1 and V2 need changing to alter the tone a little?  A good tech should be able to sort that out for you.  I'd also switch to the JJ ECC83S valves at the same time as I've read that they're much nicer sounding than the old ones.  I have the new ones in my amps and they're great.

[gwEm]

i'll check what i have later.

i just noticed these:

http://store.metroamp.com/product_info.php?cPath=21_40&products_id=325

JJ ECC803S... meant to have higher gain, might give one a go (internet rumours suggest bass is more controlled - but who knows about them)

wonder also about fitting a 100W PT

[hamfist]

JJ ECC803S... meant to have higher gain, might give one a go (internet rumours suggest bass is more controlled - but who knows about them)

In my experience the 803S's usually actually have slightly LESS gain than the standard 83S.  Another point to bear in mind is that the 803S is also a long plate tube, and will be much more prone to microphonics if used for high gain at all.

Alan

[gwEm]

JJ ECC803S... meant to have higher gain, might give one a go (internet rumours suggest bass is more controlled - but who knows about them)

In my experience the 803S's usually actually have slightly LESS gain than the standard 83S.  Another point to bear in mind is that the 803S is also a long plate tube, and will be much more prone to microphonics if used for high gain at all.

Alan

In fact there seems to be some internet discussion over wether the 803S or 83S has more gain - thanks for clearing it up!

Anyway I checked and have the ECC83S valves, so I'm going to buy an 803S as a little experiment.

[Twinfan]

Old post I know, but did you try the ECC803S gwEm?

I've just tried one in my JTM45 and liked it very much.  Lower gain and less flubby bass than an ECC83S.  It sounds very similar to my old Brimars and Mazdas.....

[gwEm]

old post indeed ;)

anyway - i got hold of some NOS Mullard ECC83, which solved the problem.

later, at philkings place, we tried the JJs against other valve makes and found that though the JJs were good, there were several other better makes available. was impressed with new sensor reissue mullard ecc83. i'd be interested to A-B them with a NOS mullard - i don't think they'd be much difference.

[HTH AMPS]

That amp shouldn't be bass heavy, they're typically bright and crunchy.  Here's my checklist...

(1) when were the EL34s last changed
(2) when were the ECC83s last changed
(3) does the amp still have the original filter caps? - if so, it would be a good idea to change them out for new ones.

The mains transformer running 450v is fine for a 50w Marshall,  The problem could be none of the above and something like a leaky coupling cap, hard to say without seeing the amp in person.

What speaker cab you using it with and what settings on the amp?

[gwEm]

i think i just prefer my sound with as close to zero low-end as possible. its good, bright and crunchy as you can hear from the slowhand clip you commented on.