SV20h / 1959 / 1987 Plexi Bright Cap ?

[Mcentee2]

I've done a quick search and there is lots of info about the bright cap(s) but I haven't found a direct answer for this one:

I am getting to grips with my new SV20h and adore its full on crunch and drive, but the half my time is spent trying (and failing) to be David Gilmour

As such I seem to be spending quite a bit of time dialling in the SV20h to my liking to try and get the maximum possible clean headroom out of it *whilst still being EQ friendly*

I plug into Normal high or low, and then patch to Channel 1 (High Treble) - and there it is .... the expected brittle brightness at low Channel volume due to the bright cap. I can't turn it up too far where the bright cap is out of the circuit because then we are back into crunchy Plexi territory.

As a sort of test, I took the preamp FX out from my Laney L5t into the SV20v FX in to see what my 6ca7's made of it, and it got a pretty decent clean tone quite loud before breaking up, one that I can't quite get from the current SV20h preamp arrangement as it either farts out the Normal channel, or is ear-piercing on the High Treble

In the SV20h the bright cap is 2n2 nF, this is the one across the channel volume pot, *not* the one across the channel mixer 470k resistor.

So in order to tame this channel when all I want is to between off and about midday, without the searing high end, do I:

1) Snip it out completely and just let the channel flex up and down and bring the EQ with it (not sure if it will be too like the Normal channel but thinner due to the v1 bias/cap etc arrangement) ?

or

2) replace the 2n2 nF with say 500pF or 100pF, that does the same as now but only for a much higher band of high end thus somewhat taking the edge of it and making it more usable.

Whichever is best , it will be on a toggle with the standard 2n2 NF

Thanks

 

[Gene Ballzz]

@Mcentee2 ,
Try this. Plug into the Bright channel Hi and jumper from the Bright Lo to the Normal Hi. Now, bring the Bright Volume up to the maximum brightness that you will want your tone to have and bring the Normal Volume up to add bass, girth, body, etc. Kinda backwards from what you're currently doing and seemingly counterintuitive, but it's how many folks approach this at lower volume settings.
Just My $.02 & Likely Worth A Whole Bunch Less?
Gene

 

[Mcentee2]

@Mcentee2 ,
Try this. Plug into the Bright channel Hi and jumper from the Bright Lo to the Normal Hi. Now, bring the Bright Volume up to the maximum brightness that you will want your tone to have and bring the Normal Volume up to add bass, girth, body, etc. Kinda backwards from what you're currently doing and seemingly counterintuitive, but it's how many folks approach this at lower volume settings.
Just My $.02 & Likely Worth A Whole Bunch Less?
Gene

Tried it, and it's still pretty trebly whilst it restricts the volume.

Just a correction, the SV20 bright cap is 4n7 nF, not 2n2 as I said in my post above.

In addition, whilst checking the above I took note of the v1 cathodes.

They are split:

V1b 820r with 330uF (Channel 2, Normal)
V1a 820r with 0.68uF (Channel 1, High Treble)

 

[neikeel]

Unless you turn the volume up to 7-8!

Try 100pF / 4n7 in your toggle (or if space a push-pull pot)?

 

[Mcentee2]

Unless you turn the volume up to 7-8!

Try 100pF / 4n7 in your toggle (or if space a push-pull pot)?

Yep, Vol at 7-8 is too crunchy so has to be lower.

A on-off-on toggle seems to offer all 3 choices, so will probably go that way.

 

[MarshallDog]

@Mcentee2 ,
Try this. Plug into the Bright channel Hi and jumper from the Bright Lo to the Normal Hi. Now, bring the Bright Volume up to the maximum brightness that you will want your tone to have and bring the Normal Volume up to add bass, girth, body, etc. Kinda backwards from what you're currently doing and seemingly counterintuitive, but it's how many folks approach this at lower volume settings.
Just My $.02 & Likely Worth A Whole Bunch Less?
Gene

This is exactly what I do with my 4-holer and it works. I do have the brite cap at 100 pF!

 

[Mcentee2]

This is exactly what I do with my 4-holer and it works. I do have the brite cap at 100 pF!

Looks like 100pF seems to be the way folks do it rather than cut it completely.

 

[MarshallDog]

Looks like 100pF seems to be the way folks do it rather than cut it completely.

Yes, out completely leaves it lacking for sizzle IMO!

If you are doing a 3-way switch I would go with 100, 250 and maybe 500 pF or as close as you can get you can always tweak them.

 

[Mcentee2]

Follow up - I got a 100pF and TBH this is the one.

Temporary toggle now does 100pF, 100+200pF and 100pF+4.7nF.

I think I'll end up using just 100pF nearly all the time, so at some point may just solder that one in anyway and simplify it all again.

 

[Digital-Chris]

Mcentee2: what value did you end up settling on?