Search found 231 matches

by mojotom
Fri Nov 18, 2022 7:58 am
Forum: Dumble Discussion
Topic: Dumble chassis
Replies: 17
Views: 3231

Re: Dumble chassis

rootz wrote: Fri Nov 18, 2022 1:30 am Something like this Mark?
I’d like one too !!

Edit: like Guy I wouldn’t mind a Reverb send control on the back but OD Drive and Level on the front along with a global Master as I use them a lot (especially pushing the OD Level and lowering the Master as the Reverb mixer sits in between).
by mojotom
Mon Sep 05, 2022 7:10 pm
Forum: Technical Discussion
Topic: how to blackface a twin ?
Replies: 15
Views: 1483

Re: how to blackface a twin ?

I like Silverface mods, well not all of them but the Silverface PI is nice and well suited to a 12AT7 tube. I did rebuild a lot of them and my advise would be to remove caps to ground on power tubes and wire a regular bias pot then change the polarized capacitors (filter, bypass on cathodes and bias...
by mojotom
Wed Aug 24, 2022 7:26 am
Forum: Dumble Discussion
Topic: tweaking JM/SSS style amps for more mojo
Replies: 10
Views: 1217

Re: tweaking JM/SSS style amps for more mojo

Well I did build a 50W JM with a tube rectifier and an AC30 OT (smaller OT) and tweaked it a lot since I build it. I like it, especially the reverb, but still not 100% satisfied by it. Not so long ago I was rebuilding a Vibrolux for a friend, really like that amp (I'm a huge SuperReverb fan tbh) and...
by mojotom
Wed Aug 17, 2022 11:59 am
Forum: Dumble Discussion
Topic: Loud Speaker polarity ... again !
Replies: 50
Views: 8951

Re: Loud Speaker polarity ... again !

It can be quite noticeable when you hit your string as it will change the onset of attack (push vs pull) imo. If I remember correctly the 5F6 Bassman used Jensen Speaker for a push configuration and was copied by Marshall but he used a Celestion speaker with an inverser polarity so a pull configurat...
by mojotom
Wed Aug 17, 2022 6:45 am
Forum: Technical Discussion
Topic: Ampeg V4 60 Cycle Hum - Pronounced When Reverb is Turned Up
Replies: 27
Views: 1418

Re: Ampeg V4 60 Cycle Hum - Pronounced When Reverb is Turned Up

May be check your hum balance pot, I had issue with noise and buzz on mine, send it to a tech but they didn’t find the issue. I then change the hum pot and hum was gone. If a tube go bad it can bring down that hum pot. And reverb become almost unusable due to hum. At least something to check on thos...
by mojotom
Thu Jul 21, 2022 12:07 pm
Forum: Dumble Discussion
Topic: Hey Robben, where's your Dumble?
Replies: 75
Views: 15919

Re: Hey Robben, where's your Dumble?

What filter caps do you think are more suitable ? IMO , honestly anything but F&T . I personally like sprague, ARS, and Vishay BC. I cant say what would work best, just what doesn’t work for me . That is quite interesting. I noticed quite a change soundwise when I compare JJ caps to F&T on the firs...
by mojotom
Tue Jun 28, 2022 10:33 am
Forum: Dumble Discussion
Topic: TR Traditional Clean Circuit
Replies: 19
Views: 3883

Re: TR Traditional Clean Circuit

I guess I shouldn’t have use the term "brighter" comparing the JM and the TR. When I build that JM amp as a test mule I tried a lot of tonestacks, various preamp voltages, etc. I did settled with a classic tonestack with 250k bass pot and 1k8 tail and wired a presence control. I like the amp, the re...
by mojotom
Sat Jun 25, 2022 1:51 pm
Forum: Dumble Discussion
Topic: TR Traditional Clean Circuit
Replies: 19
Views: 3883

Re: TR Traditional Clean Circuit

I did rewire my JM style amp to a TR clean to test that circuit and wire it back to JM specs a few days later to have a back and forth point of view (quite easy to do btw). I noticed the JM got more volume and gain available, The TR is almost only clean even when maxed and overall volume felt lower....
by mojotom
Fri Jun 24, 2022 12:55 pm
Forum: Fender Discussion
Topic: Tweed twin HP 6v6 Build
Replies: 5
Views: 1133

Re: Tweed twin HP 6v6 Build

I had the same issue with Tung Sol 6V6, either red plating or failure at 400V. The JJ will work and last week if you pass a few weeks and are not noisy/microphonic. Good tubes, more like a 6L6 soundwise, or a cross between V and L. I found the EH 6V6, if available these days, to work quite nicely at...
by mojotom
Fri Apr 22, 2022 7:56 pm
Forum: Dumble Discussion
Topic: My TR TS-1 is both too thick and too bright on the OD
Replies: 8
Views: 1618

Re: My TR TS-1 is both too thick and too bright on the OD

Hi Ian, thanks for the reply I’ve not played with the OD trimmer as yet, so worth a shot for sure - the amp is really in dirty cleans territory until OD level is up to about 6 as it stands, which I’m assuming is already on the lean side? V2 - tried a lot of tubes and currently running a 60s Holland...
by mojotom
Tue Mar 01, 2022 4:55 pm
Forum: Fender Discussion
Topic: 1965 Bandmaster hum
Replies: 93
Views: 11993

Re: 1965 Bandmaster hum

Take a look at the solder joint on the lower left on you filter caps photo, I will check that one and resolder if necessary but like I said earlier I would put some new 100uF 350V and check on hum. If it’s fine you can even resolder the current ones but at least you’ll know. Then check caps on the s...
by mojotom
Sat Feb 26, 2022 11:37 am
Forum: Fender Discussion
Topic: 1965 Bandmaster hum
Replies: 93
Views: 11993

Re: 1965 Bandmaster hum

I have noticed on some already serviced amps that a new cap job can really help hum reduction. I had one 64 Vibroverb I worked on with some issues and I kept the first two serie filter caps as they looked new and fine but once everything was done I still had a bit of hum and changing those two reall...
by mojotom
Thu Feb 24, 2022 5:06 pm
Forum: Technical Discussion
Topic: Required training
Replies: 4
Views: 642

Re: Required training

did v4 restauration, complete , removed all the wires, components, cleaned carbonised pcbs , reinstalled al new, painted chassis new etc, one month job :mrgreen: Should be a nice amp after the restauration ! But lots of work. I love those, especially the « Distortion » models (even if you don’t wan...
by mojotom
Sun Feb 20, 2022 8:41 pm
Forum: Dumble Discussion
Topic: Troubleshooting reverb circuit - solved
Replies: 77
Views: 8492

Re: Troubleshooting reverb circuit

Did you use isolated RCA connectors ?

If not that could be something to try.
by mojotom
Mon Feb 14, 2022 7:27 pm
Forum: Dumble Discussion
Topic: HRM in a Tweedle Dee?
Replies: 15
Views: 1577

Re: HRM in a Tweedle Dee?

The easiest would be to insert the HRM board between V1 and V2, take a look at Divided by 13 CJ11, just like a BF Fender with a volume control after the stack but it does only work with one channel, not 2 like the 5E3 amp (more like a 5F11 Vibrolux for exemple). Maybe with a higher value slope resis...