Variac Owners....Amp rating for a 100 watt amplifier?

[Springfield Scooter]

Im considering a variac.
Its sole purpose would be for guitar amplifiers of 100 watts or less.
What would the minimum amp rating need to be, for this purpose?
Would a inexpensive Ebay variac, with a LED readout be suitable for my purpose?
Thoughts on something like this:

110V 500VA Variable Transformer With Digital Display LCD 60Hz 0-130V AC Voltage | eBay

(Capacity 500VA 0.5KVA 1KVA 1000VA 3000VA 3KVA. Just Different Color) Other Color 500VA / / / / /. A grounding port designed onto the device for much more stable and secure protections. Built-in Copper Coil.

www.ebay.com

 

[fitz]

Im considering a variac.
Its sole purpose would be for guitar amplifiers of 100 watts or less.
What would the minimum amp rating need to be, for this purpose?
Would a inexpensive Ebay variac, with a LED readout be suitable for my purpose?
Thoughts on something like this:

110V 500VA Variable Transformer With Digital Display LCD 60Hz 0-130V AC Voltage | eBay

(Capacity 500VA 0.5KVA 1KVA 1000VA 3000VA 3KVA. Just Different Color) Other Color 500VA / / / / /. A grounding port designed onto the device for much more stable and secure protections. Built-in Copper Coil.

www.ebay.com

I asked a similar question recently - and was looking at the same variac on Ambazon.
Common answer was check the mains fuse rating on the amp and go a little higher for the variac rating.
I have yet to buy one, but I'm looking at 10A versions.

 

[Springfield Scooter]

I asked a similar question recently - and was looking at the same variac on Ambazon.
Common answer was check the mains fuse rating on the amp and go a little higher for the variac rating.
I have yet to buy one, but I'm looking at 10A versions.

Thats good to know Fitz.
I dont want to spend any more than I have to, as its something I wont use very often...I dont think.
More for experimental purposes than anything.

 

[fitz]

I dont want to spend any more than I have to, as its something I wont use very often...I dont think.
More for experimental purposes than anything.

I was thinking the same thing.
Experiment with some lower voltage tone like EVH, and I've been contemplating an eventual amp kit build.
One of the recommended tools for the bench.

 

[playloud]

500VA is asking for trouble, in my opinion. If your wall voltage rises to 125V (not uncommon), then your variac is only rated to handle 4A.

Meanwhile, a 100W Marshall typically has a 4A slow-blow fuse (in the US). So the variac might go first!

I would stretch the budget to 10A/1000VA. Then you're less likely to buy twice...

 

[Chris-in-LA]

I’ve been told 10A others say 15A. eBay is full of used ones. I was able to find a base Staco 10A model in perfect shape for $110 plus $15 for shipping. There were ones cheaper than that as well that were more worn, in the $75 to $100 range. A perfect addition to any bench. These are $400 to $500 new.

 

[JohnH]

I've never tried a variac. But if I did I'd reckon the VA rating on the variac is basically Watts supplied. On the amp back panel the max Watts consumed is listed. Id suggest at least 2x that if running he amp from a variac.

 

[Chris-in-LA]

@JohnH, did you fall asleep at the keyboard?

 

[mallcorn]

Im considering a variac.
Its sole purpose would be for guitar amplifiers of 100 watts or less.
What would the minimum amp rating need to be, for this purpose?
Would a inexpensive Ebay variac, with a LED readout be suitable for my purpose?
Thoughts on something like this:

110V 500VA Variable Transformer With Digital Display LCD 60Hz 0-130V AC Voltage | eBay

(Capacity 500VA 0.5KVA 1KVA 1000VA 3000VA 3KVA. Just Different Color) Other Color 500VA / / / / /. A grounding port designed onto the device for much more stable and secure protections. Built-in Copper Coil.

www.ebay.com

Let me get this straight - you want to "cheap out" on an attenuator and risk damaging an expensive 100watt amp. Sounds like that might work.

If your amps have a master volume, you do not need an attenuator. If they are non-master volume amps, you need to spend the money on a quality product. My advice is don't buy an attenuator as they are not the best choice. Installing a Master Volume is a solid option also using a Power Station II is even a better choice. The MV will cost you about $100-$200 installed and the PSII will cost you around $750.

If you are not willing to spend the money maybe you should just sell the 100watt amp and get a 20watt amp.

 

[NotSure]

listed.

Couldn't have said it better myself.

 

[fitz]

Let me get this straight - you want to "cheap out" on an attenuator and risk damaging an expensive 100watt amp. Sounds like that might work.

If your amps have a master volume, you do not need an attenuator. If they are non-master volume amps, you need to spend the money on a quality product. My advice is don't buy an attenuator as they are not the best choice. Installing a Master Volume is a solid option also using a Power Station II is even a better choice. The MV will cost you about $100-$200 installed and the PSII will cost you around $750.

If you are not willing to spend the money maybe you should just sell the 100watt amp and get a 20watt amp.

A variac is not the same thing as an attenuator.
Master volume mods and amp wattage have nothing to do with lowering the mains input voltage.

 

[fitz]

.

 

[Rotorcraft230]

Im considering a variac.
Its sole purpose would be for guitar amplifiers of 100 watts or less.
What would the minimum amp rating need to be, for this purpose?
Would a inexpensive Ebay variac, with a LED readout be suitable for my purpose?
Thoughts on something like this:

110V 500VA Variable Transformer With Digital Display LCD 60Hz 0-130V AC Voltage | eBay

(Capacity 500VA 0.5KVA 1KVA 1000VA 3000VA 3KVA. Just Different Color) Other Color 500VA / / / / /. A grounding port designed onto the device for much more stable and secure protections. Built-in Copper Coil.

www.ebay.com

I’ve got several, don’t know why I jus bought them for a great price. My house voltage is122, you can experiment with different voltages 90vac all the way to your wall voltage. My son has found 90vac to be a good setting. He uses it more for attenuation.

These Superior Electric Variacs can be had for 75 for a good one. They are made from the 50s to the 80s. They are VERY stout and well built. Plus they look cool.

 

[Rotorcraft230]

@JohnH, did you fall asleep at the keyboard?

No shit!!

 

[Rotorcraft230]

I bought a volt gage on eBay and made this meter so I can easily see where the voltage is at for the amp.

 

[South Park]

Got this one For five bucks at the county dump . great for testing new amp builds . rustic equipment is real kool

 

[Rotorcraft230]

Got this one For five bucks at the county dump . great for testing new amp builds . rustic equipment is real kool View attachment 103805

That’s a good one, I want one!!!
Oh wait My wife says I already have enough.
LOL

 

[Mastershon]

Im considering a variac.
Its sole purpose would be for guitar amplifiers of 100 watts or less.
What would the minimum amp rating need to be, for this purpose?
Would a inexpensive Ebay variac, with a LED readout be suitable for my purpose?
Thoughts on something like this:

110V 500VA Variable Transformer With Digital Display LCD 60Hz 0-130V AC Voltage | eBay

(Capacity 500VA 0.5KVA 1KVA 1000VA 3000VA 3KVA. Just Different Color) Other Color 500VA / / / / /. A grounding port designed onto the device for much more stable and secure protections. Built-in Copper Coil.

www.ebay.com

Im considering a variac.
Its sole purpose would be for guitar amplifiers of 100 watts or less.
What would the minimum amp rating need to be, for this purpose?
Would a inexpensive Ebay variac, with a LED readout be suitable for my purpose?
Thoughts on something like this:

110V 500VA Variable Transformer With Digital Display LCD 60Hz 0-130V AC Voltage | eBay

(Capacity 500VA 0.5KVA 1KVA 1000VA 3000VA 3KVA. Just Different Color) Other Color 500VA / / / / /. A grounding port designed onto the device for much more stable and secure protections. Built-in Copper Coil.

www.ebay.com

I’ve been using that exact same 500VA unit on my EVH spec 1959 (and many other amps) for years without issue. It’s very accurate on its digital voltage display (cross checked with 3 multimeters) and never breaks a sweat.

 

[South Park]

The amp rating is not a factor hear. When you use a variac you pull all the tubes and test for shorts on the power transformer and test the plates for voltage . You can do this on low AC voltage if You do have a short the low voltage will not burn anything up

 

[Springfield Scooter]

I’ve been using that exact same 500VA unit on my EVH spec 1959 (and many other amps) for years without issue. It’s very accurate on its digital voltage display (cross checked with 3 multimeters) and never breaks a sweat.

I like that it has a digital readout, and the price too!