Another Fender Twin Black Face Question

David Mullis · From: Rock Hill, SC

When I got my twin back in January, I had the local "tube amp guy" modify the tone stack to make it more suitable for steel. While he was doing it, I asked him about black facing it and he said it probably wouldn't sound as clean if he blackfaced it. Any opinions on this?

Thanks
David

Gino Iorfida · From: Pittsburgh, Pennsylvania, USA

In a word. Yes, he is correct. When Fender went to the 'silverface' specs, they did a coule of thigs 1) tried to eliminate distortion, and 2) keep the amp stable to allow for less skilled labor in the mfging. and 3) be able to use 'nonmatched tubes', and 4) get more volume.

Now to dissect in reverse order

4) increased voltage a bit. also gave a bit more clean headroom. This is almost NEVER changed when blackfacing
3) Bias circuit changed to a 'balance' as opposed to bias... ran tubes colder than they should,b ut since they were increasing the voltage, they figured this was fine. I recommend blackfacing the bias supply to get better control fo the bias. wont affect the clean headoroom (in fact it can increas it if set right)
2) The suprssion caps on the output tubes, also knwon for suckng some of the sparkle etc from the amps THIS part of blackfacing I do recommend-- will give a mre traditional tone, and more 'life' to the tone -- I have done this and in many cases had to clean up the lead dress inside quite a bit to keep the amp from oscillating at this point.
1) They changed the phase inverter section to give more clean headroom. Changing this to blackface specs is great for 6 stringers who want the amp on the edge of breakup and into overdrive... for playing sttel, I'd recommend keeping this 'silverfaced' for obvious reasons.

I have done the partial blackfacing on a number of amps and was pleased (rumour has it, this is EXACTLY what David Funk did in his 'thunderfunk' mods to amps-- blackface circuit w/ silverface phase inverter)
1)

Tony Prior · From: Charlotte NC

Gino is right on the button. One of the main reasons that fender made changes was due to component quality of life for all the amps used in the earlier series. Keep this in mind, Leo's amp builders were basically using design and components from a decade earlier and many of the items were failing with age and heat. The Silverface era brought about an upgrade of components to correct issues that the Fender engineering staff had been hearing about from the working muscicians. Yes, tone changed a tad , but the component quality was getting better.

A lot of this gets back to the earlier discussion of tubes hanging upside down. The heat generated from those 6L6's was a whole lot for the chassis components and sockets to absorb. In addition, as Gino mentions, the way the tubes were biased caused many a resistor to burn out..you know..go black , then dissolve.

Although many folks claim they are blackfacing an amp today, they really are not because the components they are using are leagues better in tolerance and quality than the ones available and used in the 50's and early 60's. And keep this in mind, the tubes used back then were pretty raw in quality compared to the ones we are all used to today and that is a huge factor in the overall sound of those amps. Todays manufacturers discard the tubes that back then were thought to be of high quality. So you could blackface an amp but if you don't use those same raggady tubes built in the 50's late 60's you didn't really perform the full mod. In many cases, todays tubes will not perform at peak performance with circuit specs from yester-year.

It's kinda like rebuilding a stock Corvette 327/350 HP motor using todays components to '67 specs. . When you're all done it's probably got 2x the power of the original motor. The car will outperform the original hands down.( if re-built correctly that is ).

When I was servicing Fender amps up until about mid 70's or so. I was getting regular updates for component changes from Fender engeering. It really was to much to keep track of. The manuals and schematics were a mess and when you opened an amp you were real lucky if any of the 7 or 8 schematic versions actually matched the amp in question so you had to take good notes before you took anything apart. Even transformer numbers were being
cross referenced . You could order one and get a cross referenced replacement.

It was always fun servicing Fender amps,cause you could actually get parts and fix them. It was not fun servicing the early VOX amps...open up one of those early Beatle heads and you'll see what I mean..An unraveled ball of twine glued back together comes to mind right about now. But when they worked well..boy..we used to say..first three rows get out of the way !!

Oh yes, I sold all my manuals at a guitar show many years ago...and thats a good thing...

I would also just recommend this, if you modify an amp that you have, keep the notes of what the components were before the mod so if need be in the future the amp can be returned to where it came from and the next repair guy will be able to see what changes were made which probably caused the current falure . A soldering iron in the hands of a
stump grinder can be a dangerous thing !

TP

[This message was edited by Tony Prior on 01 April 2003 at 03:35 AM.]

David Mullis · From: Rock Hill, SC

Thanks guys, that's just what I wanted to know. I think I'll leave it as is right now. With the tone stack mod that Gino suggested and a JBL k-130 4ohm, the amp sounds pretty schweet! I wouldn't mind getting more into modifying my own amps. The only thing I've really worked on has been solid state stuff. A Lemay or Peavey mod here and there, replacing all of the transistors in the first stage of the preamp in my old Christmas Tree amp etc. If I have a schematic and a set of instructions on what do to, I'm good to go. If there's any heavey duty troubleshooting thats needs to be done, I'd better stick with PC's and Network stuff

Tony Prior · From: Charlotte NC

Hey David..I'll say to you what I say to Joe each time we talk..Stop buying new amps and looking for a new tone..just play your Steel cause the tone you've got right now is pretty darn good !

A good friend of mine ( keyboard dude) said to me once not all that long ago " If I would have spent half the time practicing that I spent trying to find new sounds on the synth I would have been a pretty good player by now " !!

He isn't even a philospher...he's a musician/ tech-head like many of us....

Knowing the Steels you have ( JCH and PP ) along with the Twin with the JBL..I would be be willing to bet you've got awsome tone right now.

see ya soon..

tp

David Mullis · From: Rock Hill, SC

Thanks Tony!

Yeah I can't complain much in the tone dept. I was just curious more than anything to find out if the guy here in town was right. I wish I could have made it up to Kannapolis last weekend, but things have been really busy here, and I had a gig that night. As far as practicing, you know it's time to learn some new stuff when you get tired of hearing yourself play the same old worn out stuff all the time.

Back to practicing!

Take Care
David

Lawrence Lupkin · From: Brooklyn, New York, USA

Pardon my ignorance, but what is "blackfacing"

Gino Iorfida · From: Pittsburgh, Pennsylvania, USA

No 'ignorance' there.

Simply put. In the late 1960's, Fender was bought out by CBS inc. At the time of this buy out, Fender changed the cosmetic appearance of thier amplifiers, going from a black control panel with white lettering, to a silver panel with dark lettering. Amps with the black face plate are called 'blackface' and with the silver face plate 'silverface'.
At the same time as the changeover of cosmetics, engineers at Fender finally got their way (which Leo Fender objected to the following changes, so finally under CBS they could have more say), and implemented a few changes to the circuit that would 1) eliminate distortion, 2) increase output power, 3) allow the use of unmatched tubes, and 4) save assembly time by allowing more margin for error in how the wires were routed from component to component (called lead dress) by the use of 'oscillation supression circuitry'

Many rock, blues and country players didnt like the changes due to the tone being more 'sterile' sounding, less sparkle, and you coulnt get that good grungy blues/rock tone, so techs have been reverting fender circuitry back to 'blackface' specs for some time, however, it's only really been super popular over say the last 10 years give or take.

Jon Light · From: Saugerties, NY

The term derives from the cosmetics of the control panel of Fender amps of the early-mid 60's. Blackface as opposed to silverface for instance. But the reference is to the circuit design of the blackface amp. Blackfacing a silver face amp is the process of undoing the circuit changes that Fender did to the silverface amps of the late 60's into the 70's. You can browse here---
http://www.ampwares.com/ffg/index.html

to see the cosmetics.

Jon Light · From: Saugerties, NY

So what sort of tone stack modifications are we talking about here? I might be interested in looking into this for my BF Showman with my steel.

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