Playing with a variac......

[Greazygeo]

Having a few vintage amps around that were made when line voltages were lower than modern times, it has interested me to know what they sounded like with lower voltages. Finally had the opportunity to pick up a Variac and give it a whirl....so far I've only tried a 68 plexi 100 Super tremolo (not had a chance to open it up and check voltages to see what exactly changes). Ive tried it as low as 100v and as high as 120 so far. Down around 100 its more spongy feeling and around 115 is where I like it.

Running the amp on 10 used to pop the mains fuse, while on 7 the amp was fine. With the lower line voltage, the amp will run on 10 now no problem.

My OR120 will only run on 5 before popping the fuse, it is intended to run on 240v so the mains fuse is too small, I need to get to the shop and grab a bigger fuse one of these days. It's plate voltage is up over 600V! Interesting to see what the variac does with it.

Geo

 

[Digital Jams]

You talking about blowing fuses on vintage marshalls is getting me all hot and bothered

I still can only think of how many marshalls were blown up after Eddie and his interview stating 140vac

 

[JTyson]

Was it 140? I thought he dropped it to around 98? Hmmmm.....

 

[Digital Jams]

Was it 140? I thought he dropped it to around 98? Hmmmm.....

I have the mag at home, he clearly stated 140vac and then the disclaimer was there from the mag stating that they are not responsible for your melted plexi

 

[thegame]

Only a matter of time before you succumb to the brown sound

 

[Greazygeo]

Only a matter of time before you succumb to the brown sound

No brown sound for me....but if you heard my 69 plexi...it would be game over. I was playing that today, it's just awesome.

 

[Greazygeo]

You talking about blowing fuses on vintage marshalls is getting me all hot and bothered

I still can only think of how many marshalls were blown up after Eddie and his interview stating 140vac

Don't be breaking that thong out now!

 

[Cornfordcrunch]

Was it 140? I thought he dropped it to around 98? Hmmmm.....

He ran it at around 90 volts but told people for years that he increased it to 140....just to throw people off....kind of a dickish move.

 

[glpg80]

Was it 140? I thought he dropped it to around 98? Hmmmm.....

He ran it at around 90 volts but told people for years that he increased it to 140....just to throw people off....kind of a dickish move.

+1111

he told people the wrong way.

even the design of 5150's shows that the voltages of 5150 transformers are WAY lower than soldano SLO's actual voltages.

he variaced his SLO, and his marshall.

enough to turn the plates from around ~300V to ~170V, give or take manufacturing tollerance.

a signature amplifier he designed copying his SLO at the time in early 1991-1993 would not be running at such low voltages if he variaced in the opposite direction.

eddie lied.

 

[degenaro]

Having a few vintage amps around that were made when line voltages were lower than modern times, it has interested me to know what they sounded like with lower voltages. Finally had the opportunity to pick up a Variac and give it a whirl....so far I've only tried a 68 plexi 100 Super tremolo (not had a chance to open it up and check voltages to see what exactly changes). Ive tried it as low as 100v and as high as 120 so far. Down around 100 its more spongy feeling and around 115 is where I like it.

Running the amp on 10 used to pop the mains fuse, while on 7 the amp was fine. With the lower line voltage, the amp will run on 10 now no problem.

My OR120 will only run on 5 before popping the fuse, it is intended to run on 240v so the mains fuse is too small, I need to get to the shop and grab a bigger fuse one of these days. It's plate voltage is up over 600V! Interesting to see what the variac does with it.

Geo

Popping the mains means the amp is biased to hot for running it full tilt.

 

[Greazygeo]

Having a few vintage amps around that were made when line voltages were lower than modern times, it has interested me to know what they sounded like with lower voltages. Finally had the opportunity to pick up a Variac and give it a whirl....so far I've only tried a 68 plexi 100 Super tremolo (not had a chance to open it up and check voltages to see what exactly changes). Ive tried it as low as 100v and as high as 120 so far. Down around 100 its more spongy feeling and around 115 is where I like it.

Running the amp on 10 used to pop the mains fuse, while on 7 the amp was fine. With the lower line voltage, the amp will run on 10 now no problem.

My OR120 will only run on 5 before popping the fuse, it is intended to run on 240v so the mains fuse is too small, I need to get to the shop and grab a bigger fuse one of these days. It's plate voltage is up over 600V! Interesting to see what the variac does with it.

Geo

Popping the mains means the amp is biased to hot for running it full tilt.

Not sure where the Orange is, been quite awhile since that one was open. I know the fuse is too low a rating for 110-120v ( I think it is a 2 amp).

The Marshall is at 60% give or take unless it went whacky (it's a 68 Super Trem 100). If I remember, it's a 3 amp mains fuse. It's normally on 7.

 

[70strathead]

i was using one for my 74' 50w jmp for a long time at around 90-95V...loved it and actually want to buy a new one since mine crapped out on me a while ago.

 

[jessexxx]

Randy rhodes did the same thing ...i believe he had a voltage converter to vary the incoming voltage the amp saw...dropping the voltage is usually where you hear the difference because although your dropping the voltage the amp will draw more amperage (thats why your blowing fuses)

usually 10% voltage difference will yield little to no effect,..there designed for such..it's when you drop it below that 10% that your amp will be working harder and sucking more amperage...check out your tubes when ya do it!...they should get alot brighter!...and alot hotter!!

try it at 90/85 volts and rebias at that voltage and see how it is.

warning!!..it's real easy to fry stuff when you start dropping voltage/increasing amperage!!...blowing fuses is a red flag..

 

[maiden_fan]

This thread is useless without clips!

 

[blackba]

I have been using a Weber browner with my Vox AC50. I run it around 115VAC. Compared to regular line voltage it sounds a bit smoother and more pleasant. Lowering the line voltage helped bring down the plate voltage a bit. I did rebias when I changed the input voltage.

I was going to go with a Variac, but the Weber browner is nice cause its light and clicks into place with the settings. It uses a bunch of high power diodes to drop the voltage.....

 

[70strathead]

This thread is useless without clips!

I recorded this little diddy years ago using a dimed 50w JMP with Variac at 90v using a slight level boost with a grey DOD overdrive and strat of course...the tubes were melting!


https://www.soundclick.com/bands/page_so ... ID=3187337

 

[Greazygeo]

Randy rhodes did the same thing ...i believe he had a voltage converter to vary the incoming voltage the amp saw...dropping the voltage is usually where you hear the difference because although your dropping the voltage the amp will draw more amperage (thats why your blowing fuses)

usually 10% voltage difference will yield little to no effect,..there designed for such..it's when you drop it below that 10% that your amp will be working harder and sucking more amperage...check out your tubes when ya do it!...they should get alot brighter!...and alot hotter!!

try it at 90/85 volts and rebias at that voltage and see how it is.

warning!!..it's real easy to fry stuff when you start dropping voltage/increasing amperage!!...blowing fuses is a red flag..

Mine blows the fuses when not using the variac. Using it and dropping the line voltage down to 115v is when it doesn't. I'm not looking to do the EVH thing, just get the voltage down alittle bit.

The tone doesn't really change, but the feel sure does.

 

[JTyson]

This thread is useless without clips!

I recorded this little diddy years ago using a dimed 50w JMP with Variac at 90v using a slight level boost with a grey DOD overdrive and strat of course...the tubes were melting!


https://www.soundclick.com/bands/page_so ... ID=3187337

Wow Ant, that tone is awesome. So are you doing any re-biasing to run it at 90V, or anything besides stepping down the voltage? I have a variac, but have been afraid to use it because of conflicting info. I love your playing

 

[jessexxx]

Randy rhodes did the same thing ...i believe he had a voltage converter to vary the incoming voltage the amp saw...dropping the voltage is usually where you hear the difference because although your dropping the voltage the amp will draw more amperage (thats why your blowing fuses)

usually 10% voltage difference will yield little to no effect,..there designed for such..it's when you drop it below that 10% that your amp will be working harder and sucking more amperage...check out your tubes when ya do it!...they should get alot brighter!...and alot hotter!!

try it at 90/85 volts and rebias at that voltage and see how it is.

warning!!..it's real easy to fry stuff when you start dropping voltage/increasing amperage!!...blowing fuses is a red flag..

Mine blows the fuses when not using the variac. Using it and dropping the line voltage down to 115v is when it doesn't. I'm not looking to do the EVH thing, just get the voltage down alittle bit.

The tone doesn't really change, but the feel sure does.

gotcha!

u in england?

what is your incoming voltage before the variac?

 

[Greazygeo]

Randy rhodes did the same thing ...i believe he had a voltage converter to vary the incoming voltage the amp saw...dropping the voltage is usually where you hear the difference because although your dropping the voltage the amp will draw more amperage (thats why your blowing fuses)

usually 10% voltage difference will yield little to no effect,..there designed for such..it's when you drop it below that 10% that your amp will be working harder and sucking more amperage...check out your tubes when ya do it!...they should get alot brighter!...and alot hotter!!

try it at 90/85 volts and rebias at that voltage and see how it is.

warning!!..it's real easy to fry stuff when you start dropping voltage/increasing amperage!!...blowing fuses is a red flag..

Mine blows the fuses when not using the variac. Using it and dropping the line voltage down to 115v is when it doesn't. I'm not looking to do the EVH thing, just get the voltage down alittle bit.

The tone doesn't really change, but the feel sure does.

gotcha!

u in england?

what is your incoming voltage before the variac?

England....nope, just wonderful Ohio!

It varies alittle but generally 123V