Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: purpletele on February 02, 2018, 03:49:53 am
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A colleague had asked me to help him upgrade his Super Champ X2.
I was thinking, why? He is an excellent guitarist, his gig rig consist of 3 Champ amps, one BF Vibro Champ and two newer X2's
He runs a line out of a slave amp into his board and then into two Champs.
I am not sold on the rig, but I agreed to help.
The amp played very nice as a stock amp. Dave installed a new speaker which is ok.
My colleague Dave asked me to install a new OT in an effort to get the amp to be more responsive and be less farty.
Here is what I did:
1. I spoke with David Allen and he recommended the TO20 as an upgrade.
a. I installed the TO20 which was a dream, the holes matched and the chassis is threaded!.
b. I fired up the amp and it sounded distorted, but it felt more responsive.
c. I checked the bias expecting it to be low. It was set at 26 mV.
d. I adjusted the bias to 40 mV and it sounded much better, but not great.
e. I removed the GT 6 v 6 C and replaced them with JJ 6 v 6 S. Huge improvement
f. The amp still feels like it has an arrestor on it, very similar to the way the old Blues Juniors would be even after you install a new OT.
g. If I recall the sequence on the Blues Juniors, it was the Filter Cap Upgrade that made a huge difference as well as one of the tone caps.
2. The amp has a slight ghosting note on the lower scale when playing in the 2nd channel or FX channel. If I hit a clean B at the nut then it buzzes quite noticeably.
a. The amp is in a cradle and I am using a stand alone speaker, so I am not confusing that ghosting note with a new buzzing when the amp is in its case.
Question:
1. Any advice on the ghosting notes?
a. I have new tubes installed and they are biased correctly. The Preamp tubes was changed for testing and then reinstalled.
2. Does anyone know of any MOD formula that I should try, such as replace the filter caps and upgrade their values, etc..
3. I know Ben Fargen has a Hot Mod Blueprint for this amp but I don't know what he does to it.
4. I would much rather be working on the drawings for my own nice amps, but i'm into now and the Ghosting note is of concern.
5. https://reverb.com/item/87887-fender-fargen-hot-mods-superchamp-x2-2013 (https://reverb.com/item/87887-fender-fargen-hot-mods-superchamp-x2-2013)
Existing Filter Cap Values
C38 = 22 uF 450V
C40 = 22 uF 450V
C41 = 22 uF 450V
C53 = 4700 uF 16 V
C57 = 1000 uF 35 V
C60 = 1000 uF 35 V
Any advice would be very much appreciated.
BV