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Post subject: Re: 64 reverb unit
Posted: Sat Jun 02, 2012 6:14 pm
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Yeah, get what you're sayin', Beemer. Only tried a RI once, at practice. It seemed to have too much gain and was kind of brittle sounding to my ears. So I opted to build the Weber unit, just a fullwave rectified, knock-off of the 6G15. Art

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Post subject: Re: 64 reverb unit
Posted: Sun Jun 03, 2012 1:09 am
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aclempoppi wrote:
Yeah, get what you're sayin', Beemer. Only tried a RI once, at practice. It seemed to have too much gain and was kind of brittle sounding to my ears. So I opted to build the Weber unit, just a fullwave rectified, knock-off of the 6G15. Art


Another big issue with the re-issue 6G15 is the imported tank itself. An original made-in-USA Accutronics spring assembly or even better an original Gibbs/Hammond unit, combined with Steve's mods, brings the tone and versatility much closer to the original model.

Arjay

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Post subject: Re: 64 reverb unit
Posted: Sun Jun 03, 2012 3:33 pm
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Is this the type of tank you are talking about? Its a 1970 Hammond tank. I assume the standard tank for this unit is the 17 inch long model with 2 pairs of springs?

http://www.ebay.com/itm/1970-Reverb-Tan ... 500wt_1009


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Post subject: Re: 64 reverb unit
Posted: Sun Jun 03, 2012 3:38 pm
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+1 on both counts.

Arjay

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Post subject: Re: 64 reverb unit
Posted: Sun Jun 03, 2012 3:47 pm
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Do these things come with standardized impedances and such, or do I have to make sure they would match my reverb unit? (Noob question!)


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Post subject: Re: 64 reverb unit
Posted: Sun Jun 03, 2012 6:26 pm
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There are a number of different configurations. As an example, the tanks that Fender used with vintage reverb-equipped amps typically measured 0.8 ohms at the input and roughly 82 ohms at the output. I'm not sure what the values were for the stand-alone unit but BMW2002ti will doubtless know more about this issue. AFAIK, the tube-buffered circuit like the 6G15 affords some latitude in impedance-matching.

HTH

Arjay

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Post subject: Re: 64 reverb unit
Posted: Tue Jun 05, 2012 12:34 am
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Thanks Arjay. I'll have to research this a little more.

BMW, earlier you said the RI tank needs a strong 6V6. Any particular recommendations for an original unit as far as tubes go? My tube guy has RCA, Sylvania and Tung Sol 6K6's.


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Post subject: Re: 64 reverb unit
Posted: Tue Jun 05, 2012 2:53 am
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If you wanna go NOS... the brown micanol based 6V6GTY (Raytheon, Sylvania, GE) or the 6V6GTA (original US made TungSol or RCA). If you go new production... a selected (for strength & no shorts) JJ 6V6S.

As for the reverb tank, I used an OEM Accutronics (Cary, IL) from a SF era Princeton Reverb I redid. Model number is: 4AB3C1B with about 8 ohms input and 2K ohm output nominal impedances. Worked a lot better than the stock Korean made tank which comes in the '63 RI Reverb Unit.


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Post subject: Re: 64 reverb unit
Posted: Tue Jun 05, 2012 1:58 pm
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Beemer, so you're recommending a 6V6 in a vintage unit as well? Is that what your running in yours?


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Post subject: Re: 64 reverb unit
Posted: Tue Jun 05, 2012 2:14 pm
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s3mamill, No... run a good black plate 6K6GT in the original 6G15 Reverb Units. They are shifted more towards a midrange and higher tone than a typical 6V6GT. Which is where you want the reverb to work. I like either Sylvania (for a brighter tone) or RCA (for a more midrange tone), NOS BP 6K6GT. The NOS are still relatively cheap. So, you can get one of both and try them in the unit.

I believe that the iron used in the original Reverb Unit is much stouter than used in the RI's. This helps push the 6K6GT (which has less output than a 6V6GT) better. The tone of the 6K6GT (a true Pentode) is better for reverb work than the more potent 6V6GT (beam Pentode)--- at least in these vintage Fender units.

The TungSol 6K6GT is also a very good tube.

http://www.ebay.com/itm/Pair-6k6gt-Tung ... 0720481376

Also, if you are going to re-do the power and bypass caps and certain resistors... I found a good (I used a Mills WW) 820 ohm resistor in the cathode-to-ground position of the 6K6GT sets the bias a bit better than the OEM 1K-ohm one. (see the photo of my 6G15, as reference).


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Post subject: Re: 64 reverb unit
Posted: Thu Jun 07, 2012 6:41 am
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I got the unit yesterday. Here are some photos. The innards look legit. The transformer has a 606 code though, which makes me think this a replacement. I thought these 606 coded transformers were used after CBS bought Fender. (edit: Looks like the other code on the transformer is 125P24A, I guess that makes it a match) Any thoughts you guys have would be appreciated. Also, whats that metal arm that reaches to the reverb tank. A brace or something? This is my first experience with one of these things. Also, I'm wondering about the tolex. I know fender went from a rough white tolex to a smooth white tolex between 61-64. DId they do the same with the brown. I did some googling, but didn't find any examples of brown combos with smooth brown tolex, though there seems to be a few reverb units in this smooth brown tolex. I know that was a transitional time and there were lots of variations with regard to inner and outer specs.
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Post subject: Re: 64 reverb unit
Posted: Thu Jun 07, 2012 10:47 am
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s3mamill. Very nice looking unit. Everything seems stock/OEM in it.

"606" is the manufacturer code for Schumacher. A common transformer company used by Fender, in those days.

The angled-bracket slides on two screws--the bracket is used to support the tank in travel mode (bracket pushed all the way into the tank). Then, in play mode--- you pull the bracket back off the tank and allow it to float on the spring-tied posts suspension. It has a l-shaped hole, that keep the bracket pulled away from the tank--- so that so you can set it to the PLAY mode.

I believe a lot of brownface era Fenders were in a transition period. You see different tolex, grilles, even control knobs in brownies.


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Post subject: Re: 64 reverb unit
Posted: Thu Jun 07, 2012 2:01 pm
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The "125P24A" P/N for the power tranny is consistent for a Fender Electric Instrument Company" component. It's likely original to the unit and entirely appropriate for a pre-CBS part. CBS-era P/N's are formatted as "022XXX".

HTH

Arjay

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Post subject: Re: 64 reverb unit
Posted: Thu Jun 07, 2012 8:58 pm
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Here's a couple pics of my '63....
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Post subject: Re: 64 reverb unit
Posted: Thu Jun 07, 2012 9:02 pm
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a shot of the board
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