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Post subject: Replacing power tubes on a 1979 Pro Reverb
Posted: Wed Apr 14, 2010 11:54 am
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6L6GC replacement recommendations brand wise? Anything I should look out for?

The amp is "breaking up" at a lower level than it once did and these tubes look original so I am assuming this is the issue... the current ones in there are only labeled with Fender Special Design.

Correct me if I am wrong since I am not a tube amp expert! Thanks.


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Posted: Wed Apr 14, 2010 5:23 pm
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I'm not shure to understant very well your question:(....than it once did.....)?

Some of those amp( 74 until 79...) are desing to break earlier . Somes resistor in the phase inverter do that.

But different tubes can make little difference, but not sure.


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Posted: Wed Apr 14, 2010 6:02 pm
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Try the (TUBE AMP DOCTOR) TAD 6L6GC STR

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Posted: Wed Apr 14, 2010 7:09 pm
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The '79 Pro Reverb is no Pro Reverb at all, being more akin to an "ultra-linear" Twin Reverb with half the power (70 watts). Fender's engineers really pushed both the components and output tubes to the edge of the envelop in these designs, with plate voltages approaching 500 VDC (which is why the amp uses a silicon diode rectifer instead of the traditional 5U4GB tube). The original Fender-branded 6L6s were probably made by Westinghouse-USA and if you expect your replacement tubes to provide any worthwhile service life, I'd recommend that you buy the hardiest tubes you can afford. However, none of the currently-available 6L6s will last as long as the original bottles that Fender equipped these amps with. If you push the amp hard and regularly you'll get four or five years out of a set of JJ's, SovTeks, or TAD's -- probably less with Red Rubys or Groove Tubes.

HTH

Arjay


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Posted: Wed Apr 14, 2010 8:11 pm
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Hey Skate, if the budget is up to it, the late '70s - early '80s Sylvania 6L6GC STR tubes are up to the task. Most of these were bought up by Fender and Mesa Boogie and rebranded for their amps. Every once in awhile, these will come up from reputable NOS tube dealers. Another tube I would recommend, for this application, is the Phillips ECG 7581 of the same years. Oh yeah, Peavey also scooped up a lot of those Sylvanias. Art

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Posted: Wed Apr 14, 2010 8:41 pm
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Shame on the redesign, as the original Pro Reverb was one of the hidden treasures in Fender's amp line. I'm guessing blackfacing it would be too much, given the ultralinear design would probably mean new OT and PT transformers, etc...

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Posted: Wed Apr 14, 2010 9:28 pm
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They don't necessarily sound bad, but you can forget about any semblance of the legendary BF tone. And -- as you alluded to -- it's nigh impossible to mod this chassis "backwards". Better to set the amp for "flat" tonal response and clean volume, then let stompboxes do the work for you. That's what I do with my '78 UL SF Twin Reverb.

HTH

Arjay


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Posted: Wed Apr 14, 2010 9:44 pm
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Both Super and Pro Reverbs got the Twin Reverb chassis in 1977/78, but they were less powerful (70W RMS) than the Twin (135W RMS).

The Vibrosonic Reverb fall in the same territory as the Super Reverb and the Pro Reverb, but had the same output power as the Twin Reverb.

The Vibrosonic Reverb was essentially a Vibrosonic with the Twin Reverb chassis and a JBL D-130-F 15" speaker. It was available with 100 watts RMS of power with a '60s "tailed" Fender logo before its change to a 135 watts RMS combo featuring a "tailless" Fender decal in 1977. The Vibrosonic Reverb was introduced in 1972 and discontinued ten years later.

Fender switched back to the blackface era cosmetics some time in 1980. Vibrosonic Reverbs produced between late 1980 and 1981 have a black control panel and silver sparkle grille cloth.

A Line Out jack, hum balance pot, and a pull boost switch were added near the end of the models run.


The Vibrosonic Reverb shown below was made circa 1977/78. This amp is not mine.

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Source: http://www.rocknrollvintage.com/


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Posted: Wed Apr 14, 2010 10:22 pm
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Nothing says "I have absolutely nothing useful to contribute to the discussion at hand" better than a post like this.

Arjay


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Post subject:
Posted: Wed Apr 14, 2010 10:48 pm
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I totally agree with you, Arjay.

BTW, I think you've a Vibrosonic Reverb in your arsenal. You'll notice that this baby has your favourite JBL speaker under the hood.

Glad to see a pic of yours, dear!


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Post subject:
Posted: Thu Apr 15, 2010 8:49 pm
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Chromeface -

Maybe it's a country thing, but here in the US we don't just post pictures or text taken directly from other websites without making it clear it's not your own. We call it plagiarism, although others have other names for it.

Your text on the Vibrosonic Reverb of

"Fender switched back to the blackface era cosmetics some time in 1980. Vibrosonic Reverbs produced between late 1980 and 1981 have a black control panel and silver sparkle grille cloth.

A Line Out jack, hum balance pot, and a pull boost switch were added near the end of the models run."

is word for word what's on the Fender Field Guide page.
http://www.ampwares.com/amp.asp?id=120

Instead of passing it off as your own info, just post the link and let people know there's information. It's great information, but it's dishonest when you portray it as your own. :?

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Posted: Thu Apr 15, 2010 10:20 pm
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Ned, your take on this is interesting and your approach is very tactful. I'm not really affected by the amp texts, most of us have heard it or read it a 100 times. How many times have I posted: " replace with a known good tube"? That is flat out plagiarism. If you were standing here I'd say," try it with a good tested tube, not one you think is good, and don't give me that old trusted GE, it may be good, but we just don't know. We've got to get this right." Guess I'm too tolerant of some of these details. It's the folks here that concerns me. We have more in common with each other, than not. Art

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Post subject:
Posted: Fri Apr 16, 2010 7:23 am
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Art - I have no problem with a short phrase like the one you've shown, but when someone lifts 2-3 sentences from another website that has great information and pass it off as their own, that's different to me.

Opinions and first-hand knowledge are fine; the "I've heard that" is fine as well and I have no issue with them. It's just that this is the latest in a pattern from some users of posting material (text, images) that isn't theirs without clarifying.

Keeping people honest IMHO will keep these forums a great place for people to come, learn, contribute and discuss.

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Post subject:
Posted: Fri Apr 16, 2010 8:59 am
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nedorama wrote:
Opinions and first-hand knowledge are fine; the "I've heard that" is fine as well and I have no issue with them. It's just that this is the latest in a pattern from some users of posting material (text, images) that isn't theirs without clarifying.


I usually respond to a post only if I actually have something useful to contribute. And I always differentiate between that which I know and that which I think (fact vs opinion). But I never get involved in a topic for which I have absolutely no knowledge or interest.

I've owned, played, repaired, rebuilt, and restored Fender amps since 1966 so I figure something I have to say on a given topic may be of use to someone. And with some 2200+ professional gigs logged since 1967, I "walk the walk" just as much as I "talk the talk".

Arjay


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Post subject:
Posted: Fri Apr 16, 2010 10:31 am
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I have some Philips JAN 6L6s in a BF Pro reverb that sound really good.


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