Fender Super 5G4

[angelodp]

I just inherited this fine " Brown " amp circa 1960, the schematic is a bit hard to find. If anyone out there has any info on this amp please do let me know.

best ange

[Firestorm]

I just inherited this fine " Brown " amp circa 1960, the schematic is a bit hard to find. If anyone out there has any info on this amp please do let me know.

Go to the Fender Field Guide and download the schematics and layouts for the 5F4 and the 6G4. Yours will be close to one of those. This was a period when Fender was tweaking the hell out of everything and there a great many amps that don't quite match any published schematic. You'll have to see for yourself exactly what this one is. Please don't do anything irreversible to it -- these are very cool amps.

[angelodp]

Yes indeed, I intend to simply play it. I have one microphonic tube which i am about to swap out. It seems like the Vibrato is very subtle but lush. it is not at all like the Tremolo on my Tremolux. There i a sweet spot at 8 for speed and 10 for intensity. does this seem correct, or should there be a broader range of tweak with it. For example at low speeds i do not hear much at all, as in a tremolo?

thanks Ange

[Firestorm]

If you have Tremolo, that makes it a 6G4 or a 6G4-A rather than a 5F4.
The 6G4 and the 6G4-A had different Tremolo cicuits (both pretty wacky). You can tell by the number of preamp tubes -- the 6G4 has five and the 6G4-A has six.

In either case, weak tremolo is usually a cap problem: the cathode bypass caps need to be good in order for the oscillator (V3) to oscillate. The phase shift caps in this circuit (the .01s and the .02) are also suspect. These are likely Astron caps, which will be leaking their hearts out by now. High-voltage ceramics work better for this (but hang onto anything you replace because future buyers will be finicky). There's a also a .03 that will kill the oscillation if it's leaky. Also a .05 and a .25 that have to block the plate voltage from V3B and will screw things up if they're shot.

It's a major pain to test each one -- if you're not overly concerned with originality, you could just shotgun everything. You might wind up doing that anyway if the caps are Astrons. At least half of them are likely to have gone South by now.

[angelodp]

The amp has a 5G4 sticker inside ?? It does have vibrato.

Does a leaky cap have a specific physical characteristic or is it a question of lowered values.

ange

[Firestorm]

With poly caps or ceramics, there's usually no physical sign that they've gone bad. A cap is supposed to block DC, and when it starts leaking DC, all kinds of funky things can happen. With coupling/blocking caps, you need to disconnect the "cold" side of the cap (the side not connected to DC) and check to see if any DC is leaking through. Most meters will show a little DC on any cap when first connected but it will go away after a few seconds. If you see more than a volt or so after that, the cap is bad. I've seen some Astrons that would leak 40-50VDC.

[BluzMike]

The amp has a 5G4 sticker inside ?? It does have vibrato.

Does a leaky cap have a specific physical characteristic or is it a question of lowered values.

ange

Congrats to this rare find, Ange!

I own a pinkish brown Super with tweed era-style grill (maroon with yellow threads), normal order controls, Triad trannies (just as a tweed Super), a 5G4 tube chart stamped May 1960 and ... the 6G4 circuit.
Has yours the same unconnected Pulse hole in the back panel? What speakers sit in yours, P10Rs or Qs?

The trem should work more flexibly. Check those caps mentioned above. Actually I much prefer the tremolo of the 6GXAs, but find their tone inferior to the earlier and later amps. This is a matter of taste, though.

Astrons sound fantastic, but tend to leak. There is a guy in California offering Astron repros und er the name of Luxe caps (check ebay) that actually have Sprague Vitamin Qs inside. They are quite expensive, as they are labor intensive. But if you want to retain the old look with updated functionality, you might want o consider them.

Mike

[angelodp]

Hi Mike, yes same pinkish brown grill, 5G4 sticker, 6G4 circuit, P10R speakers. Triad tranny?? You mean Power T, Output T and choke right - yes i have that as well, Not sure what you mean by the unconnected pulse hole, what does that look like ( pic if you can ). Just rebuilt the intensity pot and put in a higher value 12ax7 in v3 so the vibrato seems to be more active, but still quite different than the standard tremolo of a tremolux. Had to change two small caps that were microphonic, used a vintage type. We also added a couple of 1 ohm resistors on the power tubes when we rebiased the amp... I can always take it back to stock... have it all documented. Sounds amazing. But i still have a few 12ax7's that are not at full value so I will replace them soon. Any more info you can share on this amp. I love it. Seems like we have the same amp.

pics will show 1 ohm resistors, then the replaced caps ( brown ), then the other pic shows the vibrato pots.... wondering if those caps look like they need to be replaced... guess i have to pull them and read them to know.

[IMG1152]http://i260.photobucket.com/albums/ii9/ ... G_1213.jpg[/img]
[IMG1152]http://i260.photobucket.com/albums/ii9/ ... G_1211.jpg[/img]
[IMG1152]http://i260.photobucket.com/albums/ii9/ ... G_1177.jpg[/img]
[IMG:768:576]http://i260.photobucket.com/albums/ii9/ ... 1211-1.jpg[/img]



best ange

The amp has a 5G4 sticker inside ?? It does have vibrato.

Does a leaky cap have a specific physical characteristic or is it a question of lowered values.

ange

Congrats to this rare find, Ange!

I own a pinkish brown Super with tweed era-style grill (maroon with yellow threads), normal order controls, Triad trannies (just as a tweed Super), a 5G4 tube chart stamped May 1960 and ... the 6G4 circuit.
Has yours the same unconnected Pulse hole in the back panel? What speakers sit in yours, P10Rs or Qs?

The trem should work more flexibly. Check those caps mentioned above. Actually I much prefer the tremolo of the 6GXAs, but find their tone inferior to the earlier and later amps. This is a matter of taste, though.

Astrons sound fantastic, but tend to leak. There is a guy in California offering Astron repros und er the name of Luxe caps (check ebay) that actually have Sprague Vitamin Qs inside. They are quite expensive, as they are labor intensive. But if you want to retain the old look with updated functionality, you might want o consider them.

Mike

[BluzMike]

Look at your back panel. In contrary to later versions you will only find a single speaker jack and another jack (hole) with Pulse written underneath. So far I have not heard about an amp where that Pulse jack was wired. How about yours?

Sorry for the typo, I meant Triad trannies, including the choke.

Mine has one original '60 dated blue P10R as well as a non-orig. reconed blue P10R from '62. Do not turn your amp up with these speakers, as you will blow them quickly. To play the amp out on higher volume settings than 3 or so, install higher wattage repalcements such as RI P10Qs, Webers etc. Do not use heavy speaker son the orig. baffle board, as it will break with 10" Altecs, JBLs or EVs.

PM me your e-mail adress and I will send all pics I have, and I will take some more if you like.

[Guitaro99]

Go and look at The Groove Tubes Amp Book. It has a schematic in there...
I have one I'm sellijng now...I've had it 20 years...cool amp ! Huh?!!!
What's funny about mine is it has tweed grille , yet the inside sticker says 6G4...I assume Fender ,who had NO quality control, must've had this in the shop a while, and decided to let it go later...