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Variac and a Marshall Reissue?

2/19/2000 11:06 PM
BIG Dave
Variac and a Marshall Reissue?
With all the talk about using a variac set to 90 VAC to bring a vintage Marshall into sonic nirvana, what about using a reissue with a variac? If a vintage Marshall was designed to run on 110 VAC, then running it at 90 VAC would be 82% of the "correct" voltage. If the reissues are designed to run on 120 VAC, then should the variac also be set to 82% (98/99 VAC) of the intended voltage to get a similar effect? (Yes, I know I'll need to rebias after stepping the voltage down.)
2/20/2000 12:23 AM

Hey, been wondering the same thing myself. I was planning on taking a JCM 800 (model 2204), putting a hoffman board into it, putting it on a variac @ 90 vac and letting the tone flow. Lemme know how yours turns out.  
2/20/2000 2:20 AM

If you're looking for an under-powered amp sound  
(which some call a "brown" sound), why don't you  
just swap the power transformer for one that  
delivers less B+. It has the same effect as  
putting a variac before the amp without reducing  
the heater supply and leading to cathode-  
stripping. Saves tubes and gets you the sound  
you want for the same if not less money.  
P.S. My experience with amps that have been  
"variac'd" is that they don't sound as great  
as you'd like to believe. The preamp stages  
and tone controls don't work the same, often  
for the worse. It does give you distortion at  
a lower volume, but the distortion you get is  
NOT the same as the distortion the same amp  
would put out if cranked and is not as sweet  
or warm in my opinion (but I suppose the  
volume might be a little easier on the ears).  
Try it and report your findings.  
2/20/2000 8:01 AM
email'd better be careful with that Variac. There is a concern about the AC voltage fluctuations going INTO the variac. You set that thing low...the brown out happens...what kinda strain is going to happen to your amp. Too low power can freak things out almost as too much. The components were designed for a specific range.And when you consider 5% or 10% tolerences throughout...that can add up. If you do that, it would seem to me that you would need an Ultra-clean power in an expensive high power regulator to be safe. The question becomes......"Do I really wanna spend that much to get a tone that 99% of the people aint'a gonna give a shit about, anyway?" I already asked this question, and that's the response I got. And when I thought about made sense. If you can't get the tone you are looking's probably you. (Here come the flames...but think before you do) A great guitar player can plug a MexiStrat into a Crate practice amp...and make it sound killer. (Not including myself forte is knowing good sound and how to get it on tape....99.99% of the time , it's the player...not the equipment.)Everyone seems to be looking for that elusive (or downright...I Wanna Nail THAT tone)...that they seem to overlook the fact that........maybe people are looking for YOUR NEW TONE.  
THERE'S a concept.  
C'mon ain't gonna nail ANYBODY...and why would you want to. YOU can't do what Stevie or Jimi did better than they did. Take some lessons from their tremendously gifted talents that they decided to share with us....and move forward. One of US may be the next thing....but only if it's special, and only if it's different.  
O.K....enough of this diatribe...I apologize if I offended anybody.....but....  
(Flame Retartant Suit On)  
2/20/2000 1:40 PM
Variacs are bad ideas in general
There are two problems with variacs  
- they starve the heater voltage, which means that the tubes may wear out faster  
- the variac has a range all the way to zero; someone can twiddle the knobs much further down than you intended. Imagine a bass player or a drummer with his hand on the variac knob.  
If you're after the browning sound of lowered B+, you really oughta try reducing the B+ with a zener or amplified Zener that can be simply switched in and out. It weighs a lot less than a variac, too.
2/20/2000 3:06 PM
BIG Dave
I'll respect anyones opinion, however...
Reducing the B+ with a Zener sounds like a good idea. Are there any papers published on this?  
As far as the comments above from Brad, first let me say that I respect your opinion, however, are any of us truly satisfied with our sound? There are nights when I think I've got the best sound on the planet, then there are nights when I feel otherwise. Let's think about Brad's comment, "A great guitar player can plug a MexiStrat into a Crate practice amp...and make it sound killer." When I plug into my '63 Princeton, I play and sound different than when I plug into any of my Marshall's. I believe that the sound and gain structure of an amp affects the way we play as well as what we play. If the reference to cheap Strat's and Crate amps is truly accurate, then why do we spend all this money on vintage Les Paul's and plexi Marshall's? Why do we tinker with the equipment we have to improve it? Why don't we all buy solid state amps and just say to ourselves, "If it sounds like poop, then it must be me?". I believe the answer lies with a combination of talent as well as good sounding equipment. I may be talented enough to play in wedding bands, rock bands, and bar mitzvah bands and get paid for it yet I may never have passed the audition if I was playing through an amp that sounds like a dying animal or a guitar with strings 3 inches off the neck! I guess I'm done. Please don't be mad at me, this is just my opinion.
2/20/2000 7:46 PM
So will I
"Reducing the B+ with a Zener sounds like a good idea. Are there any papers published on this?"
Published papers? Not that I know of. Just postings here. You take a high power and high voltage zener or a high voltage lower power zener and a power transistor to do the heavy hauling and just wipe 50-100 V off your B+. The tube filaments stay at the right heat, just the B+ goes down. I put one schematic in my "MOSFET Follies" section at GEO, Randall has some more at his site.  
"however, are any of us truly satisfied with our sound?"
Only for fleeting moments if you're like me.  
"I believe that the sound and gain structure of an amp affects the way we play as well as what we play."
It should - if we're listening to what we play, the sound should affect us.  
"Please don't be mad at me, this is just my opinion."
Who said anything about mad?  
I just wanted you to know that it's not all that good for your tubes. Beyond that, it's your amp, and you can do anything you like with it, no matter what I say, and go with God doing it.  
The problem with tolerating the recent spate of flame mongers at ampage is that everyone starts expecting to be flamed. It cuts the technical content down to a trickle.  
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