Transformers

[jimmynumber9]

I own a Fender the Twin red knob amp. The input and output transformers need replaced (don't ask, I bought it dirt cheap) Can I put any 100w transformers in it like from a plexi or do i need the exact same as the original?

Thanks

[backline]

As you know, the out tranny is a huge part of an amplifiers sound. If I were you, I would start talking to people like Hammond, Merc Mag, and Heyboer to name a few. Those guys do it for a living. Get their opinion on your situation.
Have you ever played through this amp? Those trannies are going to be a few hundred dollars. Do you have any idea what else that amp will need, caps, tubes, troubleshooting, miscellaneous parts replacement? Are you sure this will be worth it?
Good Luck

[jimmynumber9]

I have just ordered new tubes and am waiting to do a cap job until I figure what to do with the transformers. I don't mind the original tone from this amp (the plexi was just an example of a 100w transformer I could use) I am just wondering if any 100w will work or if I need other parts to make it not fry my amp.

Thanks

[Cleeve]

Weber has fender twin replacement transformers for a good price.
https://taweber.powweb.com/store/magnetic.htm

[Slow Reflexes]

Originally Posted by backline

As you know, the out tranny is a huge part of an amplifiers sound...

So... you're saying that with transformers, there's more than meets the eye?

[Wally]

Jimmy, the power trannie will have to fit the current draw and voltage requirements on the circuit. You have more leeway with the output tranny. However, if you liked the tone of the amp before, why not just go back with the 'proper' replacement? Cleeve's suggestion would be good for going back with 'what was there' at a reasonable price, imho. OTher places...Mojo, tubesandmore, and MERcury Magnetics for perhaps the most 'vintage' approach....but then the REd Knob is not such a vintage thing, is it? Mercury will be the priciest.

[Ben Harmless]

Originally Posted by Slow Reflexes

So... you're saying that with transformers, there's more than meets the eye?

Worst. Post. Ever.

As as been indicated, the power transformer is definitely not plug-and-play. They need to provide a specific voltage from a couple of different windings.

The output transformer is a different story, but I'd at least use one intended for a quad-6L6 amp. Other options would be considered experimental, and there's no guarantee that after shelling out a $100 or more for the iron, that you'll like what happens.

[jimmynumber9]

Thanks everyone, I have actually talked to a few of the people you have metioned and they do not make actual vintage transformers for the red knob twin. They have none of the numbers in records anywhere. (Guess that's what you get for buying an amp made right after a company sells... and before it sells) I just need to know what a good replacement would be and what numbers I need to look at to get one that will work with my amp, not against it.

[backline]

Those Red Knobs were not the most popular amps in the world, so I am not sure if there is a direct replacement these days. Try to find a company/companies that can get as close as possible to the original specs.
As others have said, the PT needs to supply the proper secondary so the amp will run as designed. So far as the Out Tranny... who knows what iron was in those Red Knob OT's. You seem to be pretty happy with these amps (I have a soft spot for them myself). So I think it would be worth a few phone calls to make sure you will get some squares that are reasonably close to what went in there the first time around.
Good Luck

[RomanS]

http://www.mercurymagnetics.com/page...MM_fender3.htm
- you'll have to scroll down a bit!
Definitely NOT inexpensive, though... (whodathunk, since it's from Mercury Magntics).

OT isn't that big of a deal, though - if you don't mind that with a replacement OT the amp might not sound EXACTLY the same as in original state, you might use any OT intended for 4x 6L6 amps, with a primary impedance of around 2000 ohms, and a secondary of 16 ohms (IIRC, on the red knob Twin, both 8 ohm speakers are wired in series, unlike on all other Twin amps, so a 16 ohm secondary impedance would be right; you might also get an OT that offers 4-8-16 ohm taps for the speaker, or a more common OT with only a 4 ohm tap - in that case, you'd have to change the speaker wiring on that Twin from series to parallel).
Some OT options:
Weber W022756 https://taweber.powweb.com/store/magnetic.htm
Heyboer [FONT=Arial][SIZE=2]HY022889
Hammond 1750W
Hammond 1650TA or 1650T

As for the PT I can't help, those have to be more specific, supplying the right voltage, and right amperage, you'd have to find a service manual or schematic (with voltages noted ) first, before you can find a PT matching these specs - maybe mail Fender customer service, they might have the right info?

[zook]

I'd go with a Weber PT and OT for a Twin Reverb. The OT will be correct for 4 6L6s and the PT has the necessary current for the same. Iyt also has sufficient amperage for the 6.3 Volt heaters.

They are also reasonably priced

Winnie

[Cleeve]

Is the red knob the '94 Twin Amp?
if so it has some solid state stuff in it too- and a separate winding for the bias and solid state trinkets-
http://www.fender.com/support/amp_sc..._Schematic.pdf

Also note there is a special extra winding on the secondary of the OT for a line out XLR.

The part numbers are on there if that schematic matches your reality.

I think you already told us, but what's the story with this amp- how did both transformers manage to be bad? Usually it's only ever one or the other, as the amp won't work with one bad transformer, so it can't be on to blow the other one...

[backline]

Originally Posted by Cleeve

Is the red knob the '94 Twin Amp?
if so it has some solid state stuff in it too- and a separate winding for the bias and solid state trinkets-
http://www.fender.com/support/amp_sc..._Schematic.pdf

Also note there is a special extra winding on the secondary of the OT for a line out XLR.

The part numbers are on there if that schematic matches your reality.

I think you already told us, but what's the story with this amp- how did both transformers manage to be bad? Usually it's only ever one or the other, as the amp won't work with one bad transformer, so it can't be on to blow the other one...

This is where it gets a bit confusing, 1994 was the transition year. To my knowledge the red knobs went by the name of "The Twin". After/during 1994, Fender released what was called a "Twin Amp" which were even more complex and less reliable than the red knobs were. It was these later amps that were to get the nickname of the "Evil Twin".
I just would not want one of these, but that is just my opinion. If you put the time and effort into the red knob Twins of 1988-1994, you can have a pretty good sounding amp. The problem is/was that there are a lot of amps that basically do what these amps do; without the added reliability, heat, and complexity of build issues. It was a very sophisticated amp, unnecessarily so IMO. But anyway....
You got yours for a great price. It is kind of a unique amp that not many players have. Robben Ford likes them, I like them (whoopee), and you like yours. So I just want to wish you the best of luck with restoring this piece of Fender history. It was a period in the company's history that was "new". CBS had just recently sold the firm (Thank God) a few years prior; and the new owners were trying hard to get this once proud name back on top. It took a while, but the Fender we see today has come a long way since Leo sold out. As far as mass produced amps are concerned, I think Fender has a lot more to offer than Marshall. But that is just MHO.
Good Luck with your amp.

[jimmynumber9]

Well, the mercury magnetics are not stock. They just have the specs that can work... (it's not a sure thing is what I was told) Fender has nothing but a simple owners manual on this amp and the only schematic I can find on the web is very vague at best.


http://docs.google.com/gview?a=v&pid...on%2Fpdf&pli=1

It has some power requirements though.

[Cleeve]

Is the schematic you found the one also from schematic heaven as on this thread?
http://music-electronics-forum.com/t6949/

[jimmynumber9]

That schematic is for a supertwin. The red knob twin has a lot more to it. and a lot less information at the same time. At least the one I have.

[jimmynumber9]

It's an 89 twin the twin amp. one went bad before I got it and he got the wrong one replaced how the story goes with a nonstock part. The power is stock, but the output does not seem to be so. 94 is the year the records got back up to where they should be.

[Wally]

Jimmy, if the PT is stock and working, you need not bother with replacing that one. The OT is less of a problem.....the physical dimensions might be harder to match than would the electronic aspects. There are many OT's that will electronically fit your needs.
I agree with ROman that a 4/8/16 ohm multi-tap OT might be preferred. For my purposes, I would rather be able to run parallel wiring in that cab, so the 4 or 8 ohm taps would be useful. THat was an odd amp for FEnder in that they ran the two speakers in series. ???Who knows why??? Some folks liek the use of as many windings as possible.
IN a parallel scheme, if one speaker fails, you still have one speaker fucntioning. IN that series scheme, one failure puts the amp out of commission.

[jimmynumber9]

The power is actually rusted. I don't want any problems to come from it.

[Cleeve]

A little rust wont hurt a thing, mask everything, and spray paint it with automotive engine paint.
Or better, take the tranny off, abrade it with a green 3m scuff pad, then automotive engine paint.
Plus now with musical instrument related things, the term in 'relic' not 'rust'.. ha. uhh oh.. nevermind..