Variacs-Anyone Use Them?

[Aristocat]

I was thinking about getting an external variac as I've really liked amps that I jammed on before that had them (Mesa Mark).

Only issue is that I don't a thing about them not where to get one.

I'm using a 100W amp. Would I need to know where my amp was biased at in order to use it? Obviously, I'm going for the EVH 90V thing.

What are the pros/cons?

Thanks!

 

[TrueTone500]

I use one with both my Cornford and VOX AC30. Both the VOX and Cornford amps are designed to handle 110/220VAC (maximum voltage of 115/230VAC), not 120/240VAC. The voltage in my area can get as high as 128VAC! If you're going to run your amp at 90VAC, you should consider having it mod'd with a dedicated transformer to supply the heaters. When you drop the voltage, current increases proportionate to demand... This of-course results in increased heat. I would personally not run one with a PCB built amplifier. Some of the Bogner 100B amps were experiencing burned power connections when ran too hard in 'variac' mode. The connectors were blamed, but the issue was the increased current = increased heat. The 'fix' for this was to solder the wires directly to the terminals. I run my amps at 110 to 115VAC... No lower, no higher. Sounds best around 113VAC.

Bias within range low to high, and let your ear decide what sounds best.

 

[Aristocat]

I use one with both my Cornford and VOX AC30. Both the VOX and Cornford amps are designed to handle a maximum voltage of 115/230VAC, not 120/240VAC. The voltage in my area can get as high as 128VAC! If you're going to run your amp at 90VAC, you should consider having it mod'd with a dedicated transformer to supply the heaters. When you drop the voltage, current increases proportionate to demand... This of-course results in increased heat. I would personally not run one with a PCB built amplifier. Some of the Bogner 100B amps were experiencing burned power connections when ran too hard in 'variac' mode. The connectors were blamed, but the real issue was the increased current = increased heat. The fix for this was to solder the wires directly to the terminals. I run my amps at 110 to 115, but no higher. Sounds best around 113VAC.

Thanks for the thought out response!

I say 90 as EVH is the only guy that I can think of that used a variac. I just want to experimental tone wise.

I like doing little things such as strings/tubes etc for different tones.

Could I just drop it ten volts and be safe? What do you use for a variac?

Is there any real benefit aside from 'feel' or is this just snake oil?

 

[TrueTone500]

I use one with both my Cornford and VOX AC30. Both the VOX and Cornford amps are designed to handle a maximum voltage of 115/230VAC, not 120/240VAC. The voltage in my area can get as high as 128VAC! If you're going to run your amp at 90VAC, you should consider having it mod'd with a dedicated transformer to supply the heaters. When you drop the voltage, current increases proportionate to demand... This of-course results in increased heat. I would personally not run one with a PCB built amplifier. Some of the Bogner 100B amps were experiencing burned power connections when ran too hard in 'variac' mode. The connectors were blamed, but the real issue was the increased current = increased heat. The fix for this was to solder the wires directly to the terminals. I run my amps at 110 to 115, but no higher. Sounds best around 113VAC.

Thanks for the thought out response!

I say 90 as EVH is the only guy that I can think of that used a variac. I just want to experimental tone wise.

I like doing little things such as strings/tubes etc for different tones.

Could I just drop it ten volts and be safe? What do you use for a variac?

Is there any real benefit aside from 'feel' or is this just snake oil?

It's not 'snake-oil'. Varied voltage is one of the most effective means of changing how your amp reacts. The lower the voltage, the more 'gated' your attack becomes. It does not change the tone per se... It effects the way in which your amp responds to picking and the way in which the notes sustain. Sort-of induces a more 'vintage' feel. Bias contributes also. You can actuate the bias via an external modification if you want to go all-out. I owned a Mojave 'Dirty Boy' for a short while, so I was able to get good feel for variac w/varied bias. The DB uses Fender topology, so I would have had to make major changes to get a "Marshall" thing happening.

A 10 volt drop is fine. You can run as low as 110VAC without stripping the tubes, but no lower. I use a Tenma 10A/130VAC variac. I would look for a rebuilt Staco 3PN1010 if you don't mind spending $200.00 to $300.00 USD. The Staco's use % on the dial, so make sure you don't mistake the 100% mark as 100VAC. Always take a reading with a volt meter, set it where you want it, then remove the dial on the top so it does not get moved by accident.

 

[Aristocat]

I use one with both my Cornford and VOX AC30. Both the VOX and Cornford amps are designed to handle a maximum voltage of 115/230VAC, not 120/240VAC. The voltage in my area can get as high as 128VAC! If you're going to run your amp at 90VAC, you should consider having it mod'd with a dedicated transformer to supply the heaters. When you drop the voltage, current increases proportionate to demand... This of-course results in increased heat. I would personally not run one with a PCB built amplifier. Some of the Bogner 100B amps were experiencing burned power connections when ran too hard in 'variac' mode. The connectors were blamed, but the real issue was the increased current = increased heat. The fix for this was to solder the wires directly to the terminals. I run my amps at 110 to 115, but no higher. Sounds best around 113VAC.

Thanks for the thought out response!

I say 90 as EVH is the only guy that I can think of that used a variac. I just want to experimental tone wise.

I like doing little things such as strings/tubes etc for different tones.

Could I just drop it ten volts and be safe? What do you use for a variac?

Is there any real benefit aside from 'feel' or is this just snake oil?

It's not 'snake-oil'. Varied voltage is one of the most effective means of changing how your amp reacts. The lower the voltage, the more 'gated' your attack becomes. It does not change the tone per se... It effects the way in which your amp responds to picking and the way in which the notes sustain. Sort-of induces a more 'vintage' feel. Bias contributes also. You can actuate the bias via an external modification if you want to go all-out. I owned a Mojave 'Dirty Boy' for a short while, so I was able to get good feel for variac w/varied bias. The DB uses Fender topology, so I would have had to make major changes to get a "Marshall" thing happening.

A 10 volt drop is fine. You can run as low as 110VAC without stripping the tubes, but no lower. I use a Tenma 10A/130VAC variac. I would look for a rebuilt Staco 3PN1010 if you don't mind spending $200.00 to $300.00 USD. The Staco's use % on the dial, so make sure you don't mistake the 100% mark as 100VAC. Always take a reading with a volt meter, set it where you want it, then remove the dial on the top so it does not get moved by accident.

Damn, I thought this was going to be a $50 endeavor.

If I were to spend upwards of 200-300, It'd behove me to go ahead and get the new transformer making it a proprietary mod.

 

[TrueTone500]

There are cheaper variacs out there for players on a budget... You're obviously looking to experiment. I use a variac to keep the input from exceeding the factory spec. 115VAC maximum, not to change the way my amp responds. The Mojave DB sounded best at 117VAC, so the variac aspect was IMO more of a novelty.

Proprietary mod?

 

[Charvel_King]

I was thinking about getting an external variac as I've really liked amps that I jammed on before that had them (Mesa Mark).

Only issue is that I don't a thing about them not where to get one.

I'm using a 100W amp. Would I need to know where my amp was biased at in order to use it? Obviously, I'm going for the EVH 90V thing.

What are the pros/cons?

Thanks!

What Mark did you play with an internal variac?

 

[Chubtone]

If you had a '71 SLP that was stock, I could see thinking about a variac.. Your amp is modded so you don't need a variac and/or EQ/boost pedal in order to get that lowered to 90 volts sound. IMO

 

[blackba]

I was thinking about getting an external variac as I've really liked amps that I jammed on before that had them (Mesa Mark).

Only issue is that I don't a thing about them not where to get one.

I'm using a 100W amp. Would I need to know where my amp was biased at in order to use it? Obviously, I'm going for the EVH 90V thing.

What are the pros/cons?

Thanks!

What Mark did you play with an internal variac?

The Mesa mark IV tweed setting lowers the internal voltages inside the amp.

 

[Aristocat]

If you had a '71 SLP that was stock, I could see thinking about a variac.. Your amp is modded so you don't need a variac and/or EQ/boost pedal in order to get that lowered to 90 volts sound. IMO

I was more so interested in trying it. I've never taken an external variac and old Plexi and gave it a go. And you're right, if my amp were still stock it'd have more of an effect.

I dig the response when amp is variaced. At least that was what I thought with the Mesa I played.

 

[Greazygeo]

I bought an old one just says variac on it. Spent $40 for it. You dont need anything fancy. For my old vintage amps I use it set on 110. Sounds a little less hyped up.