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Post subject: Re: Fender Twin hum
Posted: Fri Sep 30, 2011 8:11 am
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Hello Arjay
Can you recomend a supplier that I could get a complete set of replacement tubes for my amp. When I hand it in for service, I do not want to be at the mercy of the techs stock availablity. The amp is the Fender Twin 70's model.

Thanks
John


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Post subject: Re: Fender Twin hum
Posted: Fri Sep 30, 2011 9:32 am
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Not a "complete set", per se. I've looked a few of these so-called "Fender-optimized" ensembles and virtually every one contained one or more marginal tubes IMO.

What you need is this: a nice matched quartet of 6L6GC's. Red Ruby's, JJ's, Sov-Tek, and EHX make some good ones that are also reasonably priced. Ignore all the hype about "gold-plated pins" and such.

You need four 7025's (or 12AX7A commercial equivalents). These need to be quality bottles, with low noise and smooth saturation characteristics. JJ has some good ones or you can still find some NOS milspec versions.

A pair of 12AT7's complete the array. Tung-Sol or Mullard re-issues seem to be the preferred brands. One of them should be certified for balanced transconductance (this tube will be used in position "V6", the phase-inverter stage).

HTH

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Fender Twin hum
Posted: Fri Sep 30, 2011 10:08 am
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Hello Arjay
Thanks for the information, I just contacted the Tube Depot regarding the J.J. tubes, I am awaiting an answer for my price quote. The site did mention that the 6L6s were sold as a matched pair, would the come as a matched quartet. ?

John


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Post subject: Re: Fender Twin hum
Posted: Fri Sep 30, 2011 11:04 am
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Sorry to butt in... but some ppl I know have really like the TAD 6L6GC-STR tubes. I would get a matched quad of power tubes first. Get them biased.

There are a variety of good 12AX7 and 12AT7 tubes. I like the Tungsol or Mullard reissued 12AX7. And JAN Philips 12ATWC. All of these tube can be bought from the Tube Store, amongst other sites.

http://thetubestore.com/tad6l6gc.html


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Post subject: Re: Fender Twin hum
Posted: Fri Sep 30, 2011 11:13 am
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Nothing to be "sorry" for -- The Tube Store offers some great glass. And your recommendations would likely perform just as well as mine.

Rawk on!

8)

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Fender Twin hum
Posted: Sat Oct 01, 2011 10:17 am
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Hello Arjay
How do you tell which Model / Circuit number of an amp. I am constanly seeing articles refering to this # example AB763, AA1069 etc. Is it printed somewhere on the amp.

John


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Post subject: Re: Fender Twin hum
Posted: Sat Oct 01, 2011 12:57 pm
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You have to determine when the amp was made.

Arjay

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Post subject: Re: Fender Twin hum
Posted: Sat Oct 01, 2011 2:47 pm
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Hello Arjay
The amps serial # A767106 says that it was made in 1974, according to some information I have previously downloaded.

John


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Post subject: Re: Fender Twin hum
Posted: Sat Oct 01, 2011 2:58 pm
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This is likely the schematic for your amp......

http://web.archive.org/web/200710170523 ... _schem.pdf

Circuit revisions subsequent to 1970 never received an alpha-numberic designation as with Leo's original designs.

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Fender Twin hum
Posted: Thu Jan 24, 2013 1:16 pm
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hi there i just got a silverface twin reverb probably from the late 70, whit hum balace pot in the rear panel adn bias pot to, i want to restore the amp but i'm having a hard time finding the shematics or the layout plans, any one knows or where to find it.

thank's


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Post subject: Re: Fender Twin hum
Posted: Thu Jan 24, 2013 2:47 pm
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You'll likely find the schematic for your amp here......

http://web.archive.org/web/200807170341 ... fender.htm

Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: Fender Twin hum
Posted: Thu Jan 24, 2013 3:40 pm
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Retroverbial wrote:
You'll likely find the schematic for your amp here......

http://web.archive.org/web/200807170341 ... fender.htm

Arjay


And then start a new thread.

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