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OLDER MARSHALLS USE A VARIAC OR NOT USE VARIAC THAT IS THE QUESTION ???


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9/11/2000 3:30 PM
MICHAEL
OLDER MARSHALLS USE A VARIAC OR NOT USE VARIAC THAT IS THE QUESTION ???
Greetings Amp gods !!  
I have heard so much conflicting information. One professional viamatly opposes vatiacs for older marshalls and some say they are imperative. I have also heard that if they must run at 220-240 volts they run properly but if they are run at 110 or 120 they do not run to there true potential for that matter -- still others tell me this is bullshit - please does anyone know the truth to this mysterious question ???? HELP !!
 
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9/11/2000 6:21 PM
John
I THINK THIS IS A GOOD QUESTION I W...
I THINK THIS IS A GOOD QUESTION I WOULD LIKE TO KNOW ALSO GOOD QUESTION MIKE
 
9/11/2000 6:27 PM
Graywater
Re: OLDER MARSHALLS USE A VARIAC OR NOT USE VARIAC THAT IS THE QUESTION ???
Michael,  
 
If your amplifier was sold in a countly with a nominal 110-120 line voltage then use thia voltage. If it were designed for countries with 220-240 volts you need to use these voltages.  
 
It may be that present line voltages are a tad high for your model as they have crept up 15 volts in many parts of the US since the 1960s. If so, pleas refer to R.G.'s site as he has simple bucking transformer circuit that would meet your needs.  
 
GW
 
9/12/2000 12:03 AM
Peter S

Michael,  
Variacs are for technicians to use when working on your amp. It's really a bad idea to use a variac to run an amp unless you know exactly what you are doing. It would be just as cheap to buy a PT from Mercury as it would to buy a variac and step up transformer to run on 240. Chances are if you do this you'll end up buying a PT from Mercury anyway after you blow yours up. You can stick in a replacement PT and save your European transformer for when/if you decide to sell the amp.  
 
Peter S
 
9/12/2000 2:05 PM
Trace

Hey Michael!  
 
I know that there was a huge thread on this topic not all that long ago (maybe it's in the archives or Steve Ahola has it--he's good like that!! ha, ha) but I agree with Peter about it being a bad idea.  
 
The use of a variac came about as a way to get more gain out of an older Marshall at lower volumes. To be 100% honest with you I've tried it and I know Speedracers messed with it a lot and I don't hear all that much difference where it would make a player HAVE to have a variac. In my opinion it's not the "end all" for getting a killer tone from a plexi amp.  
 
A couple ways to get more gain from an older Marshall without having to mess around with a variac would be...  
 
1.) Give the Sovtek 6V6's a try since they are supposed to handle the voltage in older Marshalls (around 470V I believe but I'm sure someone here could tell us for sure). You could crank the amp up higher without it being so loud that you end up goign deaf! (ha,ha) I haven't tried the Sovtek 6V6's so I cannot comment on how they sound.  
 
2.) Install a Post Phase Inverter Master Volume so that you can crank up the volumes (both Bass & Treble Volumes) and get the preamp to work a bit more.  
 
Most people are VERY surprised just how much gain is in the preamp of a plexi. "Yes" power tube distortion is part of the magic of an older Marhall and I certainly cannot disagree with that but when you crank up a plexi you are also cranking the preamp up as well.  
 
The Post PI Master is a good way to get a killer tone and still be able to control the volume level. We have to remember that these amps were designed in a time when guitar amps were not miked adn these amps were meant to be played loud in huge arenas as opposed to smaller clubs.  
 
3.) You can buy a THD Hotplate or a Marshall Power Brake so that you can crank the amp and then still be able to control the volume to the speaker cabinet.  
 
There's good and bad with these babies. The good side is you can get all the power tube break up you want and still be a a reasonable volume and the bad news is that these are rough on amps. In all fairness I used a Powr Brake for over 2 years live on a 73 Marshall and it never caused any harm.  
 
Most people say "It doesn't sound the same when you turn the volume down on the Power Break / Hot Plate..." This is true but you have to keep in mind that the speakers are NOT workin as hard when the volume is turned down as opposed to not having an attenuator in the chain. When you drive an older Marshall hard the speakers are also getting pounded and naturally it effects the tone.  
 
OK, enough rambling (ha, ha) I need some coffee now!! :)  
 
Hope it helps  
Trace
 
9/12/2000 2:35 PM
Rebel420

in addition to what Trace said (cant aregue with any of it!), I think over at SpeedRacer's site, he mentions the plate voltage on the later 70's amrshalls were lower than the plexis and early 70's marshalls, so going with one of those amps would ive you that 'variac' sound without risking yoru filaments... I know some pl4exis and early 70s marshalls had palte ovltages way over 500v!
 
9/13/2000 6:19 PM
Michael

I was actually questioning this not to crank the amp ala Eddy Van Halen but to protect the amp from overloading or damaging the transformers, caps and resistors sorry bout the mis understanding but I appreciate all your responses muchly !! thanks ! I still get one guy saying yes and the other guy saying no so I am more confused than ever !!
 

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