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Posted: Fri Dec 03, 2010 9:10 am
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A Super Reverb is capable of shaking the fillings right out of your teeth!

:mrgreen:

This amp runs at 2 ohms -- removing one speaker only raises that load to 2.6 ohms. It would still be pretty loud under those conditions. Disconnecting two drivers would represent a 4 ohm load, which is sufficient to decrease the available output power from 40 watts to approximately 28 or 30 watts......significantly diminished in terms of overall volume. However, this puts the speakers in use at risk since the factory drivers are rated for only 20-25 watts max. A less-perilous method for taming the volume would probably be the power soak method.

HTH

Arjay

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Posted: Fri Dec 03, 2010 9:51 am
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You won't ear any difference in volume ( db) unless you use a power attenuator.


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Posted: Fri Dec 03, 2010 11:30 am
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OK, attenuator/power soak it is then :-)

Back when I started this thread, I was trying to determine whether I had an early SF etc, yesterday's discussion about the inclusion of a 5U4 in my amp got me thinking again. I will ultimately do a full restoration on this amp and now am trying to figure out what to do about face panels etc.

So today I did a schematic comparison between the AB763 and the AB568 since the 763 had a standard GZ34 and the 568 had a standard 5U4 for rectifier.

Eyeballing the schematics and the layouts of both (and confirming from http://fenderguru.com/amps/super-reverb) I now know for certain that I have the AB763 circuit since I have none of the bias circuit changes. But I still have the 5U4. Would someone just have swapped the 5U4 in as a DIY mod along the way? I guess the whole BF vs SF topic was not much of an issue years ago and maybe the concept of BF vs SF and preference was not such an interesting topic as it is today.

So. back to restoration, given that I know I have the BF circuit, would I be crazy to get a new BF faceplate or should I get a new SF and keep it as it is. I guess what I am asking is, if you were going to restore my amp would you dress it up as BF or as SF. I don't have the drip edge and the original speaker options, but otherwise.....

So what would you do for restoration?


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Posted: Fri Dec 03, 2010 11:47 am
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taskerc wrote:
So. back to restoration, given that I know I have the BF circuit, would I be crazy to get a new BF faceplate or should I get a new SF and keep it as it is. I guess what I am asking is, if you were going to restore my amp would you dress it up as BF or as SF. I don't have the drip edge and the original speaker options, but otherwise.....

So what would you do for restoration?


Front panels for a Super Reverb, both blackface and silverface, are available here......

http://www.verelec.com/catalog/index.php?cPath=45_88

There's a vendor on Ebay that sells the aluminum drip-edge molding for around $3.00/foot. You'll be on your own for the corner pieces though -- they aren't available.

Whichever way you decide to proceed, in either case the amp would've had the early "snowman" type knobs -- the "8" on the skirt is shaped like a traditional snowman (unlike the current Fender knobs). Hopefully your amp still has its originals. Likewise, the original tilt-back legs -- early examples from the 67/68 time frame were still stamped "PATENT PENDING" and had a serial number imprinted on one of a matching pair.

The correct grill cloth for a drip-edge amp from '67 or '68 would be the silver/black/blue weave (this was supplanted by silver/white/metallic turquoise at the beginning of the '69 model year). Mojotone has both types of repro cloth available.

You can e-mail me direct if you wish for additional info.

HTH

Arjay

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Posted: Fri Dec 03, 2010 11:59 am
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I don't remember which year is your amps, I don't want to read all the post but some Silverface have Blackface circuit. So the Silverface panel could be original

About 5U4, you can put GZ34 , is not what I can say " a modification". GZ34 is a better tube. You won't need to make any modification to your amp for this tube. Plug in , that's it.


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Posted: Fri Dec 03, 2010 12:11 pm
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stratele52 wrote:
I don't remember which year is your amps, I don't want to read all the post but some Silverface have Blackface circuit. So the Silverface panel could be original

About 5U4, you can put GZ34 , is not what I can say " a modification". GZ34 is a better tube. You won't need to make any modification to your amp for this tube. Plug in , that's it.


Thanks Louis,

Transformers etc are dated 1967 so probably 1968 so SF faceplate is probably original. I understand GZ34 vs 5U4 now - thanks for your help on that one.

Chris


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Posted: Fri Dec 03, 2010 1:09 pm
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Yes Silverface panel is the original one


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Posted: Fri Dec 03, 2010 11:13 pm
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Just wondering what the B+ reading is with the rect tube in the amp ? Or has that tube been checked to be bad ? The power supply can't be verified without a rectified AC voltage. I don't think that I missed that check, but maybe I did. Art

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Posted: Sat Dec 04, 2010 4:49 am
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verelec.com Silverface front panel

I have customers with non original silverface panel it look the same as those sell by verelec.com

Not very good !

Why ? look at verelec, Silverface panel, we can see the half circles on aluminium. It look like brush aluminiun , This is not like original Fender.

My customer have the same panel and I see it, not bad but not very good. You buy it if your original is scrap or you ca'ts find a better one.


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Posted: Sat Dec 04, 2010 6:34 am
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aclempoppi wrote:
Just wondering what the B+ reading is with the rect tube in the amp ? Or has that tube been checked to be bad ? The power supply can't be verified without a rectified AC voltage. I don't think that I missed that check, but maybe I did. Art


Hi Art - I have not been able to check the tube on a tester. At which pin on the 5U4 can I get B+ measurement?

Chris


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Posted: Sat Dec 04, 2010 7:39 am
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Pin 8 to ground.


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Posted: Sun Dec 05, 2010 1:02 am
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Right, and after the rectified AC voltage, it becomes a DC voltage at pin 8 of the 5U4. So all of the power supply caps(positive side terminal) and tube socket plate pins would be measured on the DC meter scale. Stratele, correct me if I'm wrong. Art

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Posted: Sun Dec 05, 2010 1:12 am
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There may still be some slight AC component at pin 8, Art. However, at the negative terminal buss following the filter caps that voltage should be ripple-free.

Arjay

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Posted: Sun Dec 05, 2010 3:00 am
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Yes at pin 8 it's DC voltage. With ripple (AC)but we don't care about that now.

Retroverbial, I don't understand what you talking about when you write ;

"However, at the negative terminal buss following the filter caps that voltage should be ripple-free. "

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The negative !!! what negative ?


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Posted: Sun Dec 05, 2010 4:09 am
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Yeah for sure, Arjay, the ripple is right there. You know, Chris, if that #8 pin tests out to be around +480 DC or so, I'd call it good. Any more testing in the amp is probably not necessary, for now. Sometimes I exaggerate the inspection process. MY BAD ! Stratele, maybe he meant the positive side. BTW is your name Louis ? Mine is Art.

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