Variac / voltage regulation question

[skoora]

So I get 120, minimum, out of my wall and I was told by a tech and a few other amp "dudes" that I may want to look into a Variac to lower it to 110-117, more so for older amps or older circuit repro's. Depending, of course on however they spec'd their transformers, I suppose. Anyway, without spending a ton off money what am I looking for in a variac. Is there a minimum Current draw rating I want to go with like a 10 A model like this( 10A Variac ) or can I use something like a Furman AR-1215 to get it down any lower than 117 as I've thinking of a voltage reulator/strip for a while anyway.

 

[rgorke]

10A is probably overkill. Mine is 5A and works great. I keep mine at around 80 v but I a one of those VH junkies. Never after 5 years have I had ANY tubes issues.

 

[Anonymous]

My Tenma Variac is a 10A one.

Steve

 

[TrueTone500]

I don't know if the Furman is going to keep the voltage at 117VAC... Aren't those a +/- 5VAC auto variable?

Go with a 10 amp Tenma, and set the voltage at 110VAC -117VAC max. REMOVE the dial so you don't accidentally bump the input voltage too high. When I worked in the field, it wasn't uncommon to see 15 and 20 amp circuits exceeding 126VAC! This is fine for general appliances - not so good for your vintage spec gear.

English made iron was traditionally designed to accept 220/230VAC which converts to 110/115VAC. By example, Transformer Equipment LTD (Cornford) specs dictate 115/230VAC. This means that 115VAC (USA) is the MAXIMUM input for optimal tone and functionality. Cornford and VOX amplifiers actually begin to sound 'odd' when 116VAC is exceeded.

Todays Marshall (and most other) amplifiers are designed to handle 120/240VAC selectable. If the specs on your vintage or vintage spec amplifier read 220/230VAC (UK) - run it at 115VAC max. I'm no expert, but I think you'll find the tone and feel to be more pleasing when the amp is operating as it was intended to.

 

[blackba]

I run my vintage amps at full wall voltage. They have all been recapped and handle the voltage fine. I used to have a weber browner and really didn't notice much tone change. I do have a 10A variac, but rarely use it....

 

[londaxe]

I run my vintage amps at full wall voltage. They have all been recapped and handle the voltage fine. I used to have a weber browner and really didn't notice much tone change. I do have a 10A variac, but rarely use it....

Same. I've done this, and haven't noticed a tone change. I only ever had it suggested to me (for this purpose ) as my 70's Orange heads both have a really high plate voltage

I've managed to kill two variacs somehow, so I'm not using them anymore.

 

[Shandog]

I've used as low as a 5amp ohmite. My variplex is a 3amp, but that's a bit different setup. Been using them for years no issues. Lot of guys can drop them as low as 70-75v range with no issues. Use caution though. Make sure you check the actual output with a tester. The meters on those are usually off by 5 volts. Especially the cheap Chinese.

 

[Shandog]

I run my vintage amps at full wall voltage. They have all been recapped and handle the voltage fine. I used to have a weber browner and really didn't notice much tone change. I do have a 10A variac, but rarely use it....

Same. I've done this, and haven't noticed a tone change. I only ever had it suggested to me (for this purpose ) as my 70's Orange heads both have a really high plate voltage

I've managed to kill two variacs somehow, so I'm not using them anymore.

Were they cheap versions? The rotary contacts on most of them are made very cheap. Plastic inside.

 

[londaxe]

Both of them were the tenma 10A variacs. One pretty much exploded the first time I plugged it in (damaged in shipping?), blowing both its own fuse and the 200A circuit breaker for the entire basement.

second one worked fine for a long time, but then just died one day. I gave up after that