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Post subject: Two part about a new '68 Custom Twin Reverb
Posted: Sat Feb 27, 2016 10:48 am
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I purchased a '68 Custom Twin Reverb: Which channel would be best to apply a Groove Tube SAG-FHG pre-amp set? Also, how can I date my amp?


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Post subject: Re: Two part about a new '68 Custom Twin Reverb
Posted: Sun Feb 28, 2016 3:07 am
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This set ?
Witch Channel ? Both; V1,V2 and V6, Read ;

http://www.musiciansfriend.com/preamp-t ... anging-kit

The Groove Tubes SAG-FHG Fender High Gain Kit includes two high gain preamp tubes and one matched 12AT7 phase inverter. All SAG kits are selected on a limited basis. The two selected high gain ECC83S tubes are optimized for the preamp stage of Fender amplifiers of all eras which use a 12AX7/7025 first gain stage.

Special Applications Group (SAG) provides further testing and grading for certain performance characteristics and these vacuum tubes are specially selected from premium Groove Tubes preamp tubes which have been tested to meet the GT standard.

This 3-tube set is optimized for Fender amps which use 12AX7 or 7025 tubes in V1 and V2. SAG-FHG includes two high gain preamp tubes to be used in the V1 and V2 positions, and one MPI (matched phase inverter) 12AT7 tube for the V6 position (in the case of blackface amps. The V1 and V2 tubes will increase the front end gain structure of the amplifier as much as 20% over typical stock tubes. The matched phase inverter tube will assure a balanced output section when used with matched power tubes (highly recommended) which will assure sustain across the entire range of your instrument.

The MPI (Matched Phase Inverter) is a SAG Selected 12AT7 as is standard Fender practice.

Each of the three kit tubes is marked as to it's specific rating. In the future if you wish to change your gain structure, it is a simple matter to request a higher or lower value as the actual characteristics of your amplifier's gain stage is now known.

Country of origin: Russia


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Post subject: Re: Two part about a new '68 Custom Twin Reverb
Posted: Sun Feb 28, 2016 11:37 am
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Thank you for your reply... the only problem with that though is the fact that the '68 Custom Twin Reverb is a two channel amp which uses two 12AX7 per channel and one 12AT7 each for reverb and vibrato. As far as I can tell from provided documentation and downloadable schematics, there is no PI tube.


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Post subject: Re: Two part about a new '68 Custom Twin Reverb
Posted: Sun Feb 28, 2016 12:07 pm
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cimejimmy wrote:
Thank you for your reply... the only problem with that though is the fact that the '68 Custom Twin Reverb is a two channel amp which uses two 12AX7 per channel and one 12AT7 each for reverb and vibrato. As far as I can tell from provided documentation and downloadable schematics, there is no PI tube.



All amps use a PI tube :lol:

Oups , sorry :oops:
It is the 12AT7 close to the Output tubes.
All Twin Reverb is a two channel amp and use many 12AX7 and 12AT7.
The kit is for the "most" important three 12XX7 tubes in the amp, not for all 12XX7

Did your amp layout look like this ? You can see V1,V2 and V6.

http://el34world.com/charts/Schematics/ ... _AA270.pdf


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Post subject: Re: Two part about a new '68 Custom Twin Reverb
Posted: Mon Feb 29, 2016 9:19 pm
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Thanks again! Yes, that's the closest schematic I've seen but not exact. It seems that, both, the V3 and V6 12AT7 triodes are used as dual function... one part to control reverb/vibrato and the other used as PI. I don't have a copy of the most current schematic to verify this, but it seems to make the most sense. You see, this new model has a standard '68 "Vintage" channel on channel 2. Channel 1, however, is the "Custom" channel which has a "Bassman tone stack" and shares both the Reverb/Vibrato.
:)


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Post subject: Re: Two part about a new '68 Custom Twin Reverb
Posted: Tue Mar 01, 2016 2:02 am
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Something here, no schematic :(

http://ampwares.com/amplifiers/fender-6 ... in-reverb/

I write to Fender consumer relation.


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Post subject: Re: Two part about a new '68 Custom Twin Reverb
Posted: Wed Mar 02, 2016 7:19 am
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Thank you, very much, again! Well... This all started because I had contacted Fender support and they would not release a schematic or tube layout diagram - and I'm still waiting on ANY answer from them. Now, I DID find these two web pages, should anyone else need this info. While this is not specific, official Fender information, it may answer a lot of questions.
Jimmy
:)


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Post subject: Re: Two part about a new '68 Custom Twin Reverb
Posted: Wed Mar 02, 2016 7:22 am
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:oops:
Ooops!
Here's those web pages:

http://ampwares.com/amplifiers/fender-6 ... in-reverb/

http://www.kcanostubes.com/content/fend ... mendations

Sorry!


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Post subject: Re: Two part about a new '68 Custom Twin Reverb
Posted: Wed Mar 02, 2016 2:58 pm
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I receive an answer about the schematic ; :(

Chase Miller (Fender)
Mar 2, 13:19

Hi Louis,

We currently do not have an available schematic for that amplifier. The techs have yet to make a "scrubbed" version of the schematic for this amplifier. I'm not sure if it will be available in the near future either.

Regards-

Chase Miller

Representative, Consumer Relations /U.S. Direct
Sales

Fender Musical Instruments Corp.
17600 N. Perimeter Drive, Suite 100

Scottsdale, AZ 85255

Telephone: 480-845-5131

Fax: 480-367-5262


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Post subject: Re: Two part about a new '68 Custom Twin Reverb
Posted: Wed Mar 02, 2016 3:48 pm
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That's the most ridiculous thing I've heard of all week!

How in the hell does FMIC expect their authorized service centers to repair these amps?

:roll:

Arjay

_________________
"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: Two part about a new '68 Custom Twin Reverb
Posted: Wed Mar 02, 2016 3:56 pm
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After I said thank's for the answer to Chase.
Chase Miller (Fender)
Mar 2, 15:21

You're very welcome. I apologize that we didn't have one to provide.

Regards-

Chase Miller

Representative, Consumer Relations /U.S. Direct
Sales

_________________________________
Repair of this amplifier will make the difference between professionals and amateurs :lol:


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Post subject: Re: Two part about a new '68 Custom Twin Reverb
Posted: Thu Mar 03, 2016 7:26 pm
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I’m surprised they have many schematics for download as it is. I mean the 68 Custom amps, why should Fender give out the slick channel voicing design. If you know your way around a regular Twin Reverb RI and a Bassman tone stack, I’m sure you can figure out the 68 Custom Twin Reverb, for repair purposes.

I just purchased a Michael Landau Deville. I’m only guessing they don’t have a schematic for that one either. It’s like its proprietary information. Take a regular HR Deville III (which the schematic is available for download) and take out all the drive channel, use a tube for the reverb drivers. Add upgraded spks. I'll ask anyway.

One thing for sure, the factory floor has a schematic. It wouldn’t be in production if they didn’t. I bet they try to keep it a secret, SSSSShhhhhh,,, it doesn’t exist.


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Post subject: Re: Two part about a new '68 Custom Twin Reverb
Posted: Fri Mar 04, 2016 2:17 am
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jackhammer wrote:
I’m surprised they have many schematics for download as it is. I mean the 68 Custom amps, why should Fender give out the slick channel voicing design. If you know your way around a regular Twin Reverb RI and a Bassman tone stack, I’m sure you can figure out the 68 Custom Twin Reverb, for repair purposes.

+1 , you need to have some electronic knowledge.

I just purchased a Michael Landau Deville. I’m only guessing they don’t have a schematic for that one either. It’s like its proprietary information. Take a regular HR Deville III (which the schematic is available for download) and take out all the drive channel, use a tube for the reverb drivers. Add upgraded spks. I'll ask anyway.

One thing for sure, the factory floor has a schematic. It wouldn’t be in production if they didn’t. I bet they try to keep it a secret, SSSSShhhhhh,,, it doesn’t exist.
+1, IMO it may not be the right "size"for the web and/or no people at Fender have time to put on web




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