Gretsch Amps

Modding my G5222. What do you suggest?

1

There were some great G5222 modding threads from years ago lost in the crash.

I bought a G5222 with the intention on modding it and only got as far as changing out the grill cloth and upgrading the speaker.

I find that my amp is very dark sounding when playing through it with a humbucker equipped guitar so I've decided it's time to dive into the amp and mod the circuit.

A few mods I've read about are;

  • Either removing the R19, or doubling the value.
  • Removing the R7 resistor (NFB)

What are some great/useful mods you've done to yours?

2

Here's the schem (assuming it's the same as the champ 600): http://support.fender.com/s...

Interesting tone stack for an amp with no tone knobs. There's a lot you could do in there. I'll play around with it later today.

3

I would start by replacing R18 with a 6k8, to get the tone stack in line with Blackface Deluxe spec. You can also play with this value (it is the "Mid" knob from a Blackface Fender). Then it's just a matter of playing with the "Treble" knob (determined by the ratio between R21 and R20) and the "Bass" knob (determined by the value of R22). You could even temporarily install potentiometers to determine the optimal values.

Something a little more crazy (and a lot more fun) would be to bypass the tone stack entirely with a coupling cap (maybe a 203 or 103 for a brighter sound).

4

To put it in better terms, you have a full Fender Blackface era tonestack inside this seemingly simple amp, but the knobs are in fixed positions. Changing the values of those resistors R19-R22 is equivalent to turning the Treble Middle Bass knobs. If you have any other amps with that tonestack (pretty much any Fender or Marshall from the 60s-70s, or their derivatives) and have a 'favorite' position for them, you can easily calculate the ideal values for those resistors.

You could also use something like Duncan's Tone Stack Calculator to play around with the values.

One quick trick you could do that doesn't cost a dime is to switch R20 and R21. This would be equivalent to turning the Treble knob from 3 to 7. If you want even more treble after that then put a jumper across R21, which would be equivalent to turning the Treble knob up to 10.

You could make the amp brighter and cleaner by reducing the value on C3, the cathode bypass cap on the first stage. Try 1uf or 500nf.

I still prefer the option to bypass the tone stack entirely, like the Tweed Champ. To do this just remove R19, or put it on a switch.

5

I may try that last suggestion on my Champ 600, Otter. As most tone stacks are cut only, this R19 switch idea makes the amp run wide open. If you need to adjust tone, use the knob on the guitar. Simplicity.

6

As you might expect, it's going to give you a lot more of everything: distortion, bass, hum. You might not like it, so maybe best to just lift one end of that resistor.

7

Bass couldn't hurt at all, especially with a 6" speaker. Distortion, not too bad either. Hum? I play single coils, so I'm used to it. I like the switch idea, actually---best of both worlds.

8

Interesting, so the designers of this amp literally 'locked in' a specific sound into the wiring. Good read guys. The option of temporarily installing potentiometers to find your desired values sounds like quite a bit of fun.

9

Or, you could gut the whole thing and using the original chassis and transformers, build one of these.

10

.....and make a cabinet big enough to house something larger than a 6" speaker. BTW, that certainly isn't the chassis from a G5222 or a Fender 600. Those are just an L shaped piece of metal.

11

Well, I would argue that it's a proper "C" shaped chassis, and that I've done this exact thing in a Fender 600. Actually I think it was a 5F1 circuit, but I definitely squeezed it into the stock chassis/cabinet. I just find it easier to start from scratch than to muck around with PCB's.

12

Stock Fender 600

13

Fender 600 chassis with 5F1 circuit

14

Grill cloth and a better speaker make a big difference. The stock grill cloth is pretty mufffled.

At least some 8" speakers will fit, barely. I think Paul Setzer got one in.

15

I looked into fitting an 8" speaker in, Bax. It would require nibbling away at the chassis metal some to fit the speaker flange in, but, it could be doable as the circuit board would clear. The bigger problems would be clearing the magnet structure with the power tube, and finding a 4 ohm 8" speaker. Back in the day, Fender made a 6"-600, 8"-800, and a 10"-1000 model. Changing the rubber printed grille cloth on the G5222 helps a lot as it muffles the sound. There was a '50s Gretsch amp with that cloth on it, so there's an historic aspect to it. The Fender version has a very thick fuzzy cloth on it that muffles the sound as well, but not ass bad as the Gretsch version. It's much like the white fuzzy grilles found on some '50s Gretsch amps as well. I like the Gretsch tweed covering better, but, the Fender two tone Tolex isn't bad. You can easily swap tubes to something better than the stock ones to improve sound quality. I've got a whole $80 in mine, so I can't complain at all. It's the amp I use the most---power switch and a volume control. Simplicity!

Powdog, those rebuilds are sweet. Nicely done! What's the finish on that two tone cab? Is that all wood?

16

Thanks Slim. Yea, the two tone cab is Mahogany and Maple, oil finish. I was going for the 50's Gibson GA cabinet look. I had been asked to make the smallest tube amp I could. I made 3, all 5F1 circuits with SS rectifiers. This one was the largest of the 3, and is the same dimensions as the Fender 600. This one is sporting an old Jensen C69R speaker (6x9 oval). I think when I rebuilt the Fender 600 I shoehorned in an 8" Weber. I did make a new baffle out of 1/4" plywood to make it clear the chassis, which made a pretty big difference.

I've taken in a couple Fender 600's, Blues Jr's and Valve Jr's as payment, in trade, etc. I have no real investment in them, so I have no qualms over tearing them apart and rebuilding point to point circuits. And I just plain don't like working on PCB's if I don't have to (big hands). As far as the Fender 600 and Gretsch are concerned, short of pulling out the PCB, the biggest improvements I've heard are to make a new baffle out of thin plywood, more transparent grille cloth, better speaker and some nice tubes. WGS/Jupiter make a sweet little 8" speaker with a small diameter ceramic magnet. Pretty sure you could sneak one of those in there.

17

Grill cloth and a better speaker make a big difference. The stock grill cloth is pretty mufffled.

At least some 8" speakers will fit, barely. I think Paul Setzer got one in.

– Baxter

When I first bought the amp I put in a Weber 8" ceramic speaker and a some real grillcloth

18

Slim, instead of cutting a new baffle I recall just rotating it so that the new 8" would miss the components.

19

Slim, instead of cutting a new baffle I recall just rotating it so that the new 8" would miss the components.

– Setzer

Yeah, that's what I did too

20

New grille cloth and tubes for mine.

21

Or, you could gut the whole thing and using the original chassis and transformers, build one of these.

– Powdog

That's a good idea powdog. I got as far as getting the board and components for a 5f1, but kind of lost interest when I got around to spending money on chassis/transformers/cabinet. Will try keep an eye out for an old champion 600/g5222.

22

When I first bought the amp I put in a Weber 8" ceramic speaker and a some real grillcloth

– MacStevenXIII

This. And NOS tubes.

If after changes of the speaker, cloth and preferably tubes you're still not pleased with the sound I'd only then played with resistor/cap values but I have a feeling that you wouldn't need to do that.

23

This. And NOS tubes.

If after changes of the speaker, cloth and preferably tubes you're still not pleased with the sound I'd only then played with resistor/cap values but I have a feeling that you wouldn't need to do that.

– Mil

I put some NOS tubes in there too when I got the amp.

It helped but I need to modify some resistor/cap values. It's still a very dark sounding amp.

24

I had a local amp tech/friend mod mine. Not sure what he did but it really opened it up.

25

I put some NOS tubes in there too when I got the amp.

It helped but I need to modify some resistor/cap values. It's still a very dark sounding amp.

– MacStevenXIII

Try the amp through a better cab, anything you have should beat that 6" driver. You'll see if the tiny speaker is a culprit or not. Nothing on the schematic for Champion 600 seems to have out of ordinary values. I'm not familiar with the amp, these are really only general recommendations.

One way to let more treble in (or better to cut bass) would be to cut values of cathode caps (C3 and C10). Your total volume would be less but for this small home practice amp that might be a good thing. You could use the "Marshall" 0.68 uF value or look at this handy on-line calculator to show you how the changes of caps influence the frequencies.

I'd start with 0.68 uF for C3 and get rid of C10 altogether and see how it sounds. Your ears should be the judge. But again, I doubt that you could be pleased with the stock speaker regardless of the mods.


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