Fender Twin Reverb 1971

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Fender Twin Reverb 1971

Postby supershifter2 on Wed Aug 03, 2016 9:51 am

Does anyone know which circuit design a 1971 Fender Twin Reverb has ? I find 3 different silver face circuits on the web but no years.
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Re: Fender Twin Reverb 1971

Postby pdf64 on Thu Aug 04, 2016 11:29 am

The AA270 is from Feb 1970, so may be a contender http://bmamps.com/Schematics/fender/70_(AA270)_Twin_Reverb_Schematic.pdf
The MV was introduced in 72 I think http://bmamps.com/Schematics/fender/twi ... _schem.pdf
Bear in mind that all designs tend to undergo change over time, so even at the factory gate, it may not have precisely matched any of the easily available schematics such as those above; of course since then repairs and mods may have been effected.
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Re: Fender Twin Reverb 1971

Postby stratele52 on Sat Aug 06, 2016 11:27 am

For '70 area, I, sometimes, see a mix of few schematics on same amp, just small things.
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Re: Fender Twin Reverb 1971

Postby JJman on Thu Aug 11, 2016 1:31 am

1970 AA270
1971 MV but no boost
1972 MV with Boost

My guesstimation. The faceplate tells you which of the 3 it is. Never go by tube charts on SF amps.
-If it says "Vintage" on it, it isn't.
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Re: Fender Twin Reverb 1971

Postby OldSchoolDave on Thu Aug 11, 2016 11:06 pm

JJman wrote:1970 AA270
1971 MV but no boost
1972 MV with Boost


I thought the pull boost came along later ('73 or '74). FWIW, my '72 Twin doesn't have it.

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Re: Fender Twin Reverb 1971

Postby supershifter2 on Mon Aug 15, 2016 4:20 am

After looking at schematics and comparing them to my amp circuit I have found that my 71 has the AA270 circuit but doesnt have the 2000pf caps after the 1500 ohm resistors on pin 5 of the 6L6's. After much research I found that the AA270 circuit was used from 1970 to the first part of 1972. During the later part of 72 the MV without boost was added and those 72's got it. In 1973 boost(push-pull) was added and that circuit design continued through 1975. 1969 was a bad year for the Twin and other amps that got the AC568 circuit with all the extra circuit junk that was added that ruined the tone. I have downloaded the schematics for the AA568, AA270, late 1972 MV NO boost , 73-75 MV with boost, AA769 but the forum will not let me upload them. Also mine has the Paktron "blue blob" tone caps.
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