Guyatone Reverb Jazz (Fender Pro Reverb) conversion

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Synchu
Posts: 522
Joined: Sun Mar 11, 2012 5:24 am

Guyatone Reverb Jazz (Fender Pro Reverb) conversion

Post by Synchu »

Some time ago (alright, it might have been a bit more time ago), I got a call from a friend whether a good looking, vintage Guyatone Reverb Jazz is a good buy for Fender like clean sound.
Now, after a 20 second search it turned out that this is a clone of Fender Pro Reverb. A great amp by itself, but not too sure of the JP clone qualities.
After not too much thinking, though, we finally concluded that it is a good buy, especially as a mod platform. On the Internet, Amp's sound received
good praise over, so I thought it may work out a great two channel amp after some (well, more than some) time on the bench.

There have been some typical for the era of mass produced JP clones "implementations" - likes the obsessive use of 33uF bypass capacitors - they must have obtained a huge batch for cheap, quite bad pots and few other things, but the overall build quality was very good :)

Fast few months forward, between busy job, two kids and family, I dare to say that it turned very nice Dumble styled amplifier. While it follows
the topology, it's quite heavily tweaked.
My initial thought was to do a Ultraphonix sort of, but after (more than) few experiments another configuration turned out great.

So here is the short description of what it is now:
- Clean channel - V1A&B only, TR JM sig based clean channel (with 22M, 0.047, 22M local feedback network), 0.02uF coupling capcacitor to the drive stage.
- Drive channel - Dumble style, stacked - 180k/2.7k/4.7uF, 120k/1.8k/1uF, 0.002 coupling between V3&4, 47p/470K/180k/100k pot V3 entry. V2A&B - 240pf cathode to plate snubbers
- HRM tone stack (previous normal channel tone stack) - 33k slope, 250KA treble, 500KA bass, 50kb mid
- PI - Marshall/Bluesmaster based, 0.02uF coupling, SOZO blue, 47pf snubber
- reverb and tremolo went almost untouched
- pre PI master vol (clean channel only)
- 250pf bright Switch, Boost (Bass pot decoupling only), Deep switch, Mid boost (1000pF, Two Rock JM style)
- Jupiter caps for the tonestack, SOZO coupling, handpicked others for bet sound

Changed power tubes to TAD 6L6 new GE black plate style - and this has been the final touch - these do sound great. A bit on the expensive side, but worth the money.

I enjoyed the process quite a bit and it turned out a great amp to my ears.

Niki

Here are some pictures

Fancy a tweaking?
[img:500:375]https://c1.staticflickr.com/6/5835/3057 ... 6d5dbb.jpg[/img]

V2 (left) and V1 (right) tubes after mods
[img:500:246]https://c1.staticflickr.com/1/640/31256 ... 5694ab.jpg[/img]

Side top view
[img:500:377]https://c3.staticflickr.com/1/755/31256 ... 042be7.jpg[/img]

Overview
[img:500:273]https://c3.staticflickr.com/1/720/31256 ... 748665.jpg[/img]

PI, coupling view
[img:500:332]https://c3.staticflickr.com/1/590/30787 ... 19a81f.jpg[/img]

Here's the whole album of full resolution pictures for anyone who might want to look at them:
https://www.flickr.com/gp/synchu/Xj0D36

and (more than few) sounds. Guitars or any effects used are described in the Soundcloud track description.
Clean, strat:
https://soundcloud.com/synchu/slow-travel
Somewhat rockish sound (strat):
https://soundcloud.com/synchu/guya-test ... -tad6l6-ge
Cranked - with humbuckers:
https://soundcloud.com/synchu/guya-test-cranked-od-suhr
Slight drive - p90 type pickups:
https://soundcloud.com/synchu/guya-test ... lack-plate
Fuzz lead, crunchy backing (JB Fuzz FAce clone used for the lead, strat guitar)
https://soundcloud.com/synchu/guya-test ... ot-stacked

There are more than these, just check my soundcloud profile. I really enjoyed a lot how it turned out, hence a bunch of impro style recordings.
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