Search found 758 matches

by jjman
Sun Jan 08, 2023 12:32 am
Forum: Fender Discussion
Topic: Fender Reverb Values
Replies: 12
Views: 1542

Re: Fender Reverb Values

I would replace the 1meg grid leak on the driver tube with a 1meg pot, creating a send control. Then switch to 2 resistors after you determine the setting that sounds good. Also make sure the 500pf capacitor there is 500pf.
by jjman
Sun May 08, 2022 12:44 am
Forum: Technical Discussion
Topic: Trying mystery NOS tubes out - no tube tester nearby
Replies: 11
Views: 1374

Re: Trying mystery NOS tubes out - no tube tester nearby

That spread of idle results is not large to me. I allow 1 small pop, 1 time.
by jjman
Thu Apr 15, 2021 10:43 pm
Forum: Technical Discussion
Topic: Deluxe Reverb Buzzing
Replies: 12
Views: 1761

Re: Deluxe Reverb Buzzing

Some time after I removed the anti-oscillation caps (aka tone-suckers) from the 6v6 grids of my ’71 DR, a similar issue arose. I changed those grid wires to shielded resolving the issue. You could install the caps as a test. ~1200pf
by jjman
Mon May 11, 2020 2:11 am
Forum: Fender Discussion
Topic: Question about voltages on Dual Showman
Replies: 5
Views: 978

Re: Question about voltages on Dual Showman

Scheme shows the plug in and switched on. We know it's oscillating so Fender must have shown an average figure for the voltage. Same behavior on my Fender.
by jjman
Sun Dec 29, 2019 10:13 pm
Forum: Fender Discussion
Topic: 5C2 princeton schematic
Replies: 1
Views: 2064

Re: 5C2 princeton schematic

Plugging in 2 instruments provides the ground reference thru each 75k then thru the instruments then to ground. Not normal practice nowadays for sure. You can use a 1 meg. Or 500k for increased peace of mind.
by jjman
Sun Dec 29, 2019 9:26 pm
Forum: Trainwreck Discussion
Topic: New Express build!!! Some troubleshooting required.
Replies: 18
Views: 5484

Re: New Express build!!! Some troubleshooting required.

Sounds like you may have touched both pins 2 & 3 simultaneously. This triggers an arc. I did it once and it blew the heater-to-ground virtual CT resistors. Sounds like your arc self perpetuated via the carbon.
by jjman
Mon Nov 11, 2019 2:03 am
Forum: Technical Discussion
Topic: Vibro Champ Reverb Amp?
Replies: 22
Views: 4347

Re: Vibro Champ Reverb Amp?

Trem before vs after reverb is important and a personal choice. Experimenting with pedals could be fruitful.
by jjman
Sun Sep 08, 2019 1:36 am
Forum: Fender Discussion
Topic: Jumpering Channels with Blackface Reverb Amp
Replies: 7
Views: 3003

Re: Jumpering Channels with Blackface Reverb Amp

Also the Vib channel has the secrete bright cap and the Normal does not.
by jjman
Sun Sep 08, 2019 1:23 am
Forum: Technical Discussion
Topic: Effect loop level
Replies: 8
Views: 2054

Re: Effect loop level

I recently checked my pedals that “should” be used in a loop. My Digiverb doesn’t clip until it sees 3.8Vp-p. Boss DM-3 at 3.6Vp-p. I then recalibrated my “send” which is actually a ‘wet” on mine since it is parallel. With the tube recovery stage, the wet side can now be stronger than the dry side i...
by jjman
Fri Jun 07, 2019 1:53 am
Forum: Trainwreck Discussion
Topic: FX Loop for Express; Two Rock?
Replies: 10
Views: 2703

Re: FX Loop for Express; Two Rock?

I went to assess the pedals’ input capacity and realized I should not assess by feeding them a clipped signal even if clipped only on one half. I injected a sign wave into each pedal directly from my Heathkit generator with a total load on the pedals' outputs of about 500k. Model.................Out...
by jjman
Sat Jun 01, 2019 4:05 pm
Forum: Technical Discussion
Topic: Series/parallel fx loop: really simple or what?
Replies: 7
Views: 599

Re: Series/parallel fx loop: really simple or what?

The way BF/SF reverb works in Fenders can be looked at as a parallel loop. However, they have reduced bass and a transformer in the "loop" path. And the spring tank itself which is the "effect" in the "loop."
by jjman
Thu May 23, 2019 3:31 am
Forum: Trainwreck Discussion
Topic: FX Loop for Express; Two Rock?
Replies: 10
Views: 2703

Re: FX Loop for Express; Two Rock?

All this loop talk got me thinking about mine and how it has been a little too weak in its ver 2 setup. All have been parallel and Ver 1 had a “blend” control going into the PI (with a phase flipping trans on the wet to preserve phase.) Although that allowed for very wet settings I did not want to g...
by jjman
Sun Mar 31, 2019 12:48 am
Forum: Fender Discussion
Topic: Vibrochamp insanity!
Replies: 17
Views: 2564

Re: Vibrochamp insanity!

The later VCs added a cap from the grid to the cathode of the 6v6. I removed mine since it was surely sucking tone. The result was a buzzy oscillation riding most notes. I changed the grid wire to that 6v6 to shielded and the buzz went away. Mine is 1974.
by jjman
Wed Dec 26, 2018 3:03 am
Forum: Trainwreck Discussion
Topic: Expression trouble, need help
Replies: 34
Views: 5984

Re: Expression trouble, need help

Is the chassis paint removed below all the ground-wire connections?
by jjman
Sun Dec 23, 2018 3:29 am
Forum: Fender Discussion
Topic: Blackface Princeton Reverb clone, el84 reverb driver mod
Replies: 17
Views: 2496

Re: Blackface Princeton Reverb clone, el84 reverb driver mod

The 135watt Twin shows 9ma thru the reverb driver on the schematic, doing the math. Same tranny sku as when under lower current from older generations. 12at7 can idle much more current than 12ax7. I also could not find a spec on the max dc current of that tranny when I was looking a few years ago.