Getting More Highs from #124 build

[JammyDodger]

Hey All,

I had finished by build based on #124 a few months ago. A have loaned it out on a number of occasions to fellow players to get there feedback. To a man, they have all said it needs for highs. One guy with a Tele said it was O.K. for him but all the others, using a strat, 335, and a Les Paul said that it need more treble.

Is there a way to do this? cap values maybe?

Oh, by the way... it is usually played throught a 2x12 cabinet with Celestion 30 and a greenback

Best Regards, Mike

[dogears]

Did you use a 250Ka drive pot? If so, use a 100K.

Also, try the "standard" pre-od network. 220K feeding 100K trimmer.

Hey All,

I had finished by build based on #124 a few months ago. A have loaned it out on a number of occasions to fellow players to get there feedback. To a man, they have all said it needs for highs. One guy with a Tele said it was O.K. for him but all the others, using a strat, 335, and a Les Paul said that it need more treble.

Is there a way to do this? cap values maybe?

Oh, by the way... it is usually played throught a 2x12 cabinet with Celestion 30 and a greenback

Best Regards, Mike

[Structo]

Also what value treble cap did you use.
Bright cap on master?

[JammyDodger]

The treble cap is .002 uF with a 390 pf 'Bright cap'.

The OD drive is a 100k pot with a 150k resistor.

All pretty much exactly like the #124 schematic.

Thanks!

[skyboltone]

The treble cap is .002 uF with a 390 pf 'Bright cap'.

The OD drive is a 100k pot with a 150k resistor.

All pretty much exactly like the #124 schematic.

Thanks!

Not the bright cap but the cap across the Master Volume. 390 would be waaaaay too large for a MV cap.

[Structo]

I think the bright cap he is referring to is the one on the bright switch.
The treble cap would be the ceramic that is connected to the right leg of the treble pot.
Typically 270-330pf.

[JammyDodger]

I used 30pF across the MV.

Best Regards, Mike

[ayan]

I used 30pF across the MV.

Best Regards, Mike

I use 30pF in mine as well. A very good sounding 124-like amp used a 47pF cap, which actually measured 39pF. To me, the master volume brightness cap is mandatory on all these amps to give the clean channel soem life to it. In amps with a single master volume, like 124 and all non HRMs, that means that perhaps one will have to tame the brightness of the overdrive a bit.

Gil

[dogears]

I meant the OD level pot. #124 used a 250K. This is a very unique feature to just that amp. Try a 100Kb. That is the standard in most. Also, the pre-od network is unique. Try the 220K into 100K. You don't know what the iron sounded like in 124. Chances are Dumble made those unique changes to compensate for something. Go with the standard values and then tweak.

And listen to Gil

The treble cap is .002 uF with a 390 pf 'Bright cap'.

The OD drive is a 100k pot with a 150k resistor.

All pretty much exactly like the #124 schematic.

Thanks!

[ayan]

I meant the OD level pot. #124 used a 250K. This is a very unique feature to just that amp. Try a 100Kb. That is the standard in most. Also, the pre-od network is unique. Try the 220K into 100K. You don't know what the iron sounded like in 124. Chances are Dumble made those unique changes to compensate for something. Go with the standard values and then tweak.

And listen to Gil

And listen to Scott. If you do that, you will follow his advice and in addition to changing the 250K pot, etc -- mandatory change, IMNSHO -- you will listen to me. Of course, if you listen to me, you will go back to the beginning of this paragraph and listen to Scot. I am getting dizzy. Really truly, go with the stock stuff, the deviations seen in 124 didn't sound right in my version of it.

Gil

[scotto]

And once you've done what Scott and Gil suggest, think about a speaker change. I've tried that combination and found it to be lacking in high frequency definition. I found that an EV will bring that range back into focus, even when used with a 12 65 which I also find a bit dark when used by itself. I use these 2 in combination or just the EV if it's a small venue.

[bluesfendermanblues]

I used 30pF across the MV.

Best Regards, Mike

I use 30pF in mine as well. A very good sounding 124-like amp used a 47pF cap, which actually measured 39pF. To me, the master volume brightness cap is mandatory on all these amps to give the clean channel soem life to it. In amps with a single master volume, like 124 and all non HRMs, that means that perhaps one will have to tame the brightness of the overdrive a bit.

Gil

I've tried 47p, but with Sovtek 12ax7wa...outch it was rippin my head off, when using a TubbyTon Hempcone alnico same with 2x12 celestion H30.
39pf was far better ( with the master on 9 o'clock)

So, try out various preamp tubes and find the ones to your liking, prior to messing with pf's on your master vol.