Search found 682 matches

by rfgordon
Thu Oct 01, 2015 8:06 pm
Forum: Fender Discussion
Topic: Alessandro Deluxe Reverb Reissue Parasitic Oscillation?
Replies: 20
Views: 5556

Re: Alessandro Deluxe Reverb Reissue Parasitic Oscillation?

In a conventional Fender-style layout, the coupling cap from the plate of the reverb recovery stage is on the board, and that results in a fair amount of unshielded grid lead between it and the reverb pot. If you relocate that cap from the board to the tab on the pot, then that previous section of l...
by rfgordon
Tue Sep 15, 2015 7:46 pm
Forum: Fender Discussion
Topic: 69 Deluxe Reverb wiring
Replies: 16
Views: 3398

Re: 69 Deluxe Reverb wiring

The lead dress in some of these amps is so bad that you can move around one lead and interfere with the tremolo function and even kill the signal altogether with phase interference. If you were to tighten up the leads by taking out the slack, I'd bet you'd take over a foot of wire out there, easy. A...
by rfgordon
Wed Aug 26, 2015 8:30 pm
Forum: Marshall Discussion
Topic: need help with JCM800 restoration
Replies: 7
Views: 2558

Re: need help with JCM800 restoration

Turret, Thanks for your help. Functionally, the amp acts just like a JMC800, except that the PPIMV gets the PI overdriving more. It seems that it was put back to stock, but without using the original component spots on the board. I think I'm gonna get back to the owner to see what he's really after ...
by rfgordon
Sun Aug 23, 2015 8:05 pm
Forum: Marshall Discussion
Topic: need help with JCM800 restoration
Replies: 7
Views: 2558

Re: need help with JCM800 restoration

more
by rfgordon
Sun Aug 23, 2015 8:00 pm
Forum: Marshall Discussion
Topic: need help with JCM800 restoration
Replies: 7
Views: 2558

Re: need help with JCM800 restoration

more pics
by rfgordon
Sun Aug 23, 2015 7:59 pm
Forum: Marshall Discussion
Topic: need help with JCM800 restoration
Replies: 7
Views: 2558

need help with JCM800 restoration

A very early (I think) JCM 800 came to me to be restored back to the original topology. I think the date code on the choke is 11-82, which puts this as a late 82, early 83 amp. The back plate is long gone, so any serial number or other model info is gone. Back in 1986 the amp was modded in the extre...
by rfgordon
Tue Jun 30, 2015 1:40 am
Forum: Marshall Discussion
Topic: How to make the most pedal-friendly Plexi?
Replies: 11
Views: 3818

Re: How to make the most pedal-friendly Plexi?

The guy has been using a plexi style amp I made out of a Bassman 50 donor. It has nice headroom and sounds exquisite when played clean with verb and delay. That said, it's on the bright side, so I suspect some of the guy's pedals may sound a bit fizzy through it. I'm considering putting in a 6 way r...
by rfgordon
Fri Jun 26, 2015 1:24 pm
Forum: Marshall Discussion
Topic: How to make the most pedal-friendly Plexi?
Replies: 11
Views: 3818

How to make the most pedal-friendly Plexi?

I will soon have the task of building a Plexi style amp for a client. It's very important to him (he runs a small recording studio) that the amp be very overdrive/distortion pedal friendly. For y'all that have built Plexi type amps or variations, are there certain component values in certain places ...
by rfgordon
Mon Jun 15, 2015 12:37 am
Forum: Fender Discussion
Topic: Fendery amp built for Jimmy Fortune
Replies: 3
Views: 1618

Re: Fendery amp built for Jimmy Fortune

Yes, it helps control the splash on the initial note attack on the reverb. I especially helps as the amp's preamp gain is turned up. In a Fender style circuit, this increases the signal on the tank, which this control counters.
by rfgordon
Fri Jun 12, 2015 12:54 pm
Forum: Fender Discussion
Topic: AB763 Question
Replies: 6
Views: 1661

Re: AB763 Question

If you want to make the Fender circuit overdrive more easily, lower the preamp tube plate voltages to 120 - 150 VDC. That will make it a bit browner and spongier. The other thing you can play with, and you might be surprised at how much difference it makes, is changing the value of the 3M3 resistor ...
by rfgordon
Fri Jun 12, 2015 12:45 pm
Forum: Fender Discussion
Topic: Thinking ahead. Reverb question.
Replies: 8
Views: 1548

Re: Thinking ahead. Reverb question.

In a typical Fender reverb circuit, because the signal goes to the reverb driver after two gain stages (and the Vol and tone stack), the amount of signal sent increases as the volume/gain is increased. In practical terms, this means that as the amp is turned up, you have no way of controlling the sp...
by rfgordon
Fri Jun 12, 2015 12:36 pm
Forum: Fender Discussion
Topic: Fendery amp built for Jimmy Fortune
Replies: 3
Views: 1618

Re: Fendery amp built for Jimmy Fortune

I got and installed the faceplate and logo this week, so the amp is finished and ready to deliver. The cab is cypress with dovetailed corner joinery. I used Dutch oil on the finish. I started with a medium walnut, working in the first coat with 400 grit paper. Subsequent coats were natural, worked i...
by rfgordon
Wed Jun 03, 2015 12:29 am
Forum: Fender Discussion
Topic: Super Reverb continuing problem
Replies: 9
Views: 1680

Re: Super Reverb continuing problem

The vibrato channel has a lot of grid lead from the tone caps to the tone pots. This makes these amps subject to parasitic oscillation, aka Fenderitis. An easy fix to try is to simply move the tone caps from the board to the pot tabs. It's completely reversible. I've eliminated odd noises from sever...
by rfgordon
Tue May 26, 2015 2:16 pm
Forum: Fender Discussion
Topic: Which electolytic caps for a 1964 Deluxe non-reverb?
Replies: 14
Views: 2937

Re: Which electolytic caps for a 1964 Deluxe non-reverb?

The only filter cap issue I've come across is size. For example, I worked on an old Peavey Classic 50 and ordered the same brand/value filter caps. Well, sometime between the amp's manufacture and now the cap company (the brand on the sleeve is, after all, only that) changed sources for the actual c...
by rfgordon
Sat May 02, 2015 6:40 pm
Forum: Fender Discussion
Topic: Fendery amp built for Jimmy Fortune
Replies: 3
Views: 1618

Fendery amp built for Jimmy Fortune

Here's my latest Fendery reverb amp. I call the small ones built into PR chassis Americana. The bigger ones, built into BF Bassman chassis, are California. The Chassis if from Mojotone (I confess I am annoyed that they took out the bright switch holes from this batch of chassis without announcing su...