Master Volume, to cap or not to cap ?

[Rob Livesey]

Hi Chaps,

I've been experimenting with the "jzucker mods" to the Ceriatone Overtone which I think were developed with a lot of input from you guys here.

Anyway, the overall tone of the amp has improved dramatically, but I do think the amp lacks high end now and I can't help thinking that the cap (15pf) on the Master volume is something that I need.

How many of you guys run a cap on the pot and what values do you use?

The layout for the jzucker mods can be viewed here:
http://personalpages.manchester.ac.uk/s ... modded.pdf

Based on your experience and the current values in this amp I would like to hear your opinions.

Cheers,
Rob.

PS: I run the amp at about 3 - 4 on the Master so it would have some effect.

[dogears]

Anywhere from 10pf to 47pf depending on taste, volume levels, and whether you use the loop. Try a 33pf or 47pf and then use a cable in the loop. It simultaneously smooths and then brightens.

Many Dumbles have up to a 47pf there. Especially if the amp is used with a Dumbleator.

[Rob Livesey]

Anywhere from 10pf to 47pf depending on taste, volume levels, and whether you use the loop. Try a 33pf or 47pf and then use a cable in the loop. It simultaneously smooths and then brightens.

Many Dumbles have up to a 47pf there. Especially if the amp is used with a Dumbleator.

Hi Scott,

Thanks for the input, I'll try the lower values first and see how it goes.

Now, I am going to be using a Dumbleator Clone, what effect does the jzucker mod on the loop jacks have?

Cheers,
Rob.

[Fischerman]

Rob,
Are both channels a little lacking in highs or just one?
There are a couple of spots that I think might open it up a bit. These are pretty subtle:
The 470pF in parallel with the 220K at the V2b grid could be increased to 500pF. This ever so slightly increases the high mids and not really the treble per se. Very subtle but still there. Affects both channels.
The 180k grid stopper on V2b could be reduced to 150k. This will just slightly increase the high treble. Affects only the OD.

[ic-racer]

Anywhere from 10pf to 47pf depending on taste, volume levels, and whether you use the loop. Try a 33pf or 47pf and then use a cable in the loop. It simultaneously smooths and then brightens.

Many Dumbles have up to a 47pf there. Especially if the amp is used with a Dumbleator.

Hi Scott,

Thanks for the input, I'll try the lower values first and see how it goes.

Now, I am going to be using a Dumbleator Clone, what effect does the jzucker mod on the loop jacks have?

Cheers,
Rob.

I believe the jzucker mod is to remove the 220k/270p from the jacks. This makes it 'normal' and will work fine with the Dumbleator.

Like Scott pointed out, I have had very good results using various length patch cords in the effects loop with the series 220k/250p in the signal path.

This one is with a 6ft cable (15p on master). : http://soundclick.com/share?songid=6575515

Personally, if I had a Ceriatone, I might consider using the 50/100 switch hole in the back for a DPDT switch to bring a 'tone smoothing' circuit in and out of the signal path. I would use either the 220k/250p from #124 or copy Gill's tone network on his #124 based amp.

[ic-racer]

duplicate

[Structo]

The Ceratone layout I have shows a 15pf cap on the master.
Your's didn't come with one?

[jaysg]

hmm...pull pot?

[ic-racer]

The Ceratone layout I have shows a 15pf cap on the master.
Your's didn't come with one?

I think he is saying he took it off as part of the jzucker mod.

[bluesfendermanblues]

Try 39p on the master, going up or down in value depending on darkness/brightness og your preamp tubes and speakers character.

I've found Sovtek 12ax7Wa to be extremely bright and piersing in the amp, huh

Then I put two old mullards (not NOS, but OOS ) in V1 and V2...and the amp got quite dark and lacked touch. Probably not a big supprise to the more advanced/experienced tweakers in here..

Moral: Try different preamp tubes prior to messing too much with pf on your master!

In the past I've made (too) many mods, that could have been avoided, if I'd just experimented with the preamp tubes. This is the place to start.

Do you guys still recommend EH's in the Pre??