Twin Reverb: Whats the scoop about "Black Faced

JB Arnold · Post by **JB Arnold** » 21 Jun 2003 5:35 am

You're going to have to mod the reissue as well. same deal, a little harder to work on from what I'm told. Also, the stock speakers that come from Fender eventually have to go. The Eminence speakers aren't bad, just not top of the line-I'm thinking of checking out their new Neodymium speakers-7 oz. magnets dudes-easy on the back, and neodymiuim really makes a difference.

JB

------------------
Fulawka D-10 9&5
Fessenden D-10 8&8
Mullen Royal Precision D-10 8 & 5
"All in all, looking back, I'd have to say the best advice anyone ever gave me was 'Hands Up, Don't Move!"
www.johnbarnold.com/pedalsteel
www.buddycage.net

http://www.nrpsmusic.com/index.html

Donny Hinson · Post by **Donny Hinson** » 21 Jun 2003 9:47 am

The bass control has the least distortion when set around three which is also the best balance point for low end punch...

"Low end punch"??? Somebody's kidding, right?

I've never heard any amp that had "low end punch" with the bass set at 3. "Twang", maybe, but certainly no "punch"!

"Punch" is what Chalker had, and he never ran the bass at "3"!

Jeff Watson · Post by **Jeff Watson** » 21 Jun 2003 10:24 am

I can't really add anything to this discussion from a technical standpoint but.... I have spent the last couple of years trying to duplicate the sound I was getting from my '64 Twin (its MINT and I can't justify dragging it to bars & rehearsals). I do a fair amount of trading on eBay so everytime I came across a decent deal on a blackface or early 70's Twin or a Showman head I would buy it and test drive it looking for THE ONE. I went thru a dozen or so before deciding that the first one I had tried (and kept) was the closest to my original. Its a silverface '72 Dual Showman Reverb head. I really couldn't believe how much difference there was between individual amps of basically the same design. Of course without having gone thru them all looking for maintenance issues one can't know how much of a role that might play. I did find that each amp would tend to be (to my ears anyway) either big & ballsy and darker sounding or a thinner and cleaner sound. Ultimately it didn't seem to matter whether it was a blackface or silverface, it was the individual amp. I did blackface my Dual Showman and am happy with the mods, but most of that big beautiful sound was there originally. The Dual Showman Reverb head (same circuit as a Twin) is a hot tip for those of us becoming to decrepit to be schleping a Twin around town.

Brad Sarno · Post by **Brad Sarno** » 21 Jun 2003 1:56 pm

Hey JB, I just did some of the Dan Healy mod on my '69 Twin Reverb (with a Black Widow 1501 instead of 2-12"). It's already recapped with some nice film and foil caps. It even has audiophile paper in oil caps on the input section. The mod I just did today was to change the 22uF/25v cathode bypass caps. They had already been upgraded to Sprague Atoms, but I went ahead and put in some Tantalum caps of the same value. It very clearly cleaned up the top end. Highs are smoothly and cleanly extended. It's a bit too sparkly or glassy on my Strat but for steel it's very cool.

I found these caps here in town but you can get them from Mouser on line.

Next is Healy Mod part two. Changing the plate resistors to non-inductive metal film types.

Healy's been my audio hero for about 15 years. He's truly one of the most significant players in the development of modern (since the 60's) live sound production and live recording. The man has the very best "low-end theory" in the bizness.

------------------
Brad Sarno
Blue Jade Audio Mastering
St. Louis

Chick Donner · Post by **Chick Donner** » 21 Jun 2003 2:16 pm

The biggest differences was referenced in part above . . . BOTH the power AND output transformers are different, along with some coupling caps and other minor components.

THe Blackface twins have the cathodes of the 6L6's run straight to ground, while the Silver twins had a cathode (negative feedback) resistor. Can't tell how many times I've seen folks attempt to "mod" the silver to black by just taking out those resistors and grounding the cathodes, then wonder why the transformers blew out. To do the job right requires new transformers. Big bucks. And why, for a >100 lb amp?

Got rid of my last twins in 1970 - - replaced with ShoBud single channels, which, along with my Webbs, I still use.

JB Arnold · Post by **JB Arnold** » 21 Jun 2003 9:32 pm

Hi Brad! Ive got my amp sitting down at the shop right now while the guy rounds up parts.

Healy has been touched by God when it comes to sound, and if he said to use turds instead of tubes I'd be in the back yard right now following the dog around with a shovel.

And if that's what he suggested, I bet it would sound better too.....

JB

------------------
Fulawka D-10 9&5
Fessenden D-10 8&8
Mullen Royal Precision D-10 8 & 5
"All in all, looking back, I'd have to say the best advice anyone ever gave me was 'Hands Up, Don't Move!"
www.johnbarnold.com/pedalsteel
www.buddycage.net

http://www.nrpsmusic.com/index.html

Brad Sarno · Post by **Brad Sarno** » 23 Jun 2003 4:35 pm

So I've got the tantalum cathode bypass caps in there and I just disconnected the tremolo circuit and also snipped the suppression caps (.002uF ceramic) leaving pins 8 grounded. The amp is yet cleaner but this time took a turn for the warmer, fuller direction. Ok by me!!

Mine is a '69 but is a AB763 circuit. The twins vary subtly around these transitional years. In fact, the schematic for the AB763 doesn't show the suppression caps but my amp did indeed have them installed.

------------------
Brad Sarno
Blue Jade Audio Mastering
St. Louis

Bill Terry · Post by **Bill Terry** » 24 Jun 2003 11:01 am

Brad, your '69 had the AB763 bias adjust circuit, phase inverter, power supply dropping resistors, etc., but also the 2000pF caps? Weird...

My '69 Twin had an AB763 tube chart, but was definitely not AB763, I think it was AC568 or whatever the one was with the big cathode resistors. I read on the FFG that Fender had a bunch of AB763 tube charts and just kept using them until they ran out.

However, the transformers on my Twin were exactly the same as AB763. I think a lot of the very early SF Twins had the same transformers. I've worked on three different SFs that did, one '68 and two '69s. That's the main reason I looked for an early non-master SF when I bought mine. I wanted the 85W version.

Plus that drip-edge on the grill from '68-'69 is cool...

Bruce Derr · Post by **Bruce Derr** » 24 Jun 2003 12:23 pm

One thing that affects the sound of these amps quite a bit is the biasing of the power tubes. This might account for some of the variances in sound that folks have been observing. Also, I have heard that Fender tends to bias the reissues on the cold side which makes them sound a bit thin (but lengthens tube life).

JB Arnold · Post by **JB Arnold** » 24 Jun 2003 1:29 pm

My amp is at Robbs now, and zimmerman says he'll have parts in afewdays and be done in one. I';ll let y'all know how it goes.

JB

------------------
Fulawka D-10 9&5
Fessenden D-10 8&8
"All in all, looking back, I'd have to say the best advice anyone ever gave me was 'Hands Up, Don't Move!"
www.johnbarnold.com/pedalsteel
www.buddycage.net

http://www.nrpsmusic.com/index.html

Mike Marchelya · Post by **Mike Marchelya** » 24 Jun 2003 8:01 pm

I'm told that the "lead dress" (wiring) of the silverface amps was progressively changed for the worse as the silverface years went on. Earlier silverface amps have little or no change, but some say to "do it right" the wiring on some of the later ones should be blackfaced as well. Anyway, that's what I've been told.

Now if anyone is interested, I have a very, very early Dual Showman Reverb head with the blue sparkle grill and aluminum trim for sale. All resistors, caps and pots look to be totally original. It's SOooo original it's even got the ratty (and I mean ratty) 2-prong power cord, so for safety's sake, please plan to change that IMMEDIATELY.

Since it is such an early SF, this one could be blackfaced relatively easily and cheaply. It's not perfect cosmetically but it is very nice. It's missing the Fender logo and the bottom brackets that allow it to be fastened to a speaker cabinet.

The chrome could use a little polishing, but it only has a couple of TINY snags in the grillcloth (no holes) and no major rips, dents or tears in the Tolex. Just the odd scuff here and there. The original knobs are all in great shape and the reverb pan is in there too, but no footswitch.

An aftermarket Twin Reverb cabinet and a 15" JBL should make this about perfect for steel for a LOT less $$$ than it would cost to buy a decent BF Twin. Even if you could find one, that Twin would likely need some tubes and a little TLC, too, so factor that into your comparison pricing.

If you're really on a budget, you could probably part out the original cabinet on ebay to help the cost of the project.

Forum members get first shot. First $475 + ship takes it. Not many of these around in solid, original condition, so all you procrastinators please don't blame me if you get sore from kicking yourself just north of your pac-seats if you let this one get away.

And no trades unless you've got a vintage L-5 or Charlie Christian laying around.

Note new e-mail MikeMarchelya@comcast.net

Brad Sarno · Post by **Brad Sarno** » 25 Jun 2003 8:54 am

Bill, you're right. It was the tube chart that gave me the AB 763 number. I'll have to poke around some more in the chassis to see what model it really is. The SN tells me it's a '69 but what circuit they used I'm not exactly sure yet.

------------------
Brad Sarno
Blue Jade Audio Mastering
St. Louis

Brad Sarno · Post by **Brad Sarno** » 2 Jul 2003 8:48 am

Gino, you're so right. Merely the removal of the suppression cap's is a huge improvement. The sound got clearer and tighter sounding. On mine they were the two .002 ceramic cap's on the two middle power tubes. I snipped the caps off leaving the legs still connected to the tube pins and ground.

And the change of the cathode bypass electrolytics from aluminum to tantalum was also very cool, cleaning up the high end noticably.

Last night I played my first loud gig with the modded Twin. It's a whole new beast. I recommend these mods to any twin user as long as it's for steel. Guitar no longer sounds that great thru it since it's so clean.

------------------
Brad Sarno
Blue Jade Audio Mastering
St. Louis