Variac

inspiredsports

OK, along with the new year about to unfold, so too is a new part of my audio addiction/sickness.

I'm venturing more heavily into tube gear and am bidding on old crappy tube preamps that I will either blow up or get working, while learning and having fun doing it (I'm having visions of Ben intentionally vaporizing various MW's by applying 220VAC) .

I understand the concept of a "Variac", but don't specifically know precisely where to connect it in circuit.

I'm assuming the original transformer leads are disconnected and the Variac leads substituted, then the power very slowly dialed up to whatever the output of the original was if nothing starts popping or smoking ???

I see cheap and expensive Variacs offered here and there. Suggestions?

As always, Thanks In Advance guys.

hearingimpared

You simply plug the device you are slowly trying to wake up into the outlet of the variac. Those suckers are very heavy.

megasat16

hearingimpared wrote: »

You simply plug the device you are slowly trying to wake up into the outlet of the variac. Those suckers are very heavy.

+1 to what he said.:D

CoolJazz

Like with a transformer, you need to pick one that will handle the current load that your concerned with!

If you find your highest output power amp and see what it draws at maximum, first you'll never find one that will run it and even if you do, it'll cost a huge amount to ship and it'd be a huge pain to move around.

So write off getting huge, full draw ever needed right now! You normally just need enough to power up stuff. Harder to know what rating to buy as a result.

Knowing what current is being drawn and where the voltage is set to is a useful part of bring something up slowly...keep that desire in mind too... So metering built in or outboard is something you'll wind up having or wanting!

CoolJazz

ShinAce

hearingimpared wrote: »

You simply plug the device you are slowly trying to wake up into the outlet of the variac. Those suckers are very heavy.

+1 . Plug variac into wall, then plug device into variac. They decided to put plugs on it instead of having you take your gear apart. Those crazy engineering types!

My suggestion, get a 10 amp variac.

inspiredsports

Super. I'm just playing with an old (but fully working) Dyna PAS-3 preamp I inherited for now, but will eventually move up the food chain.

I'm starting to hunt through flea markets and garage sales and I want to be sure I have a way to properly test when I get a component that has not been fired up for a few years.

I'm guessing any smoke or strange noises from the components means to dial it off quickly!

I am astounded by what my single 6DJ8/6922/ECC88 Yaqin does after I re-capped it with Mundorf Supreme's and placed it between my current SS pre and SS amp. I'm now going to focus on learning about tubed preamps.

dudeinaroom

I've got an autofromer that is rated at 15A 0-140 volts with a circuit breaker and on off switch. I planned on doing the same thing your doing. I might be able to part with it for $20 + shipping.

inspiredsports

dudeinaroom wrote: »

I've got an autofromer that is rated at 15A 0-140 volts with a circuit breaker and on off switch. I planned on doing the same thing your doing. I might be able to part with it for $20 + shipping.

Thanks. PM with questions sent.

ShinAce

inspiredsports wrote: »

Super. I'm just playing with an old (but fully working) Dyna PAS-3 preamp I inherited for now, but will eventually move up the food chain.

I'm starting to hunt through flea markets and garage sales and I want to be sure I have a way to properly test when I get a component that has not been fired up for a few years.

I'm guessing any smoke or strange noises from the components means to dial it off quickly!

I am astounded by what my single 6DJ8/6922/ECC88 Yaqin does after I re-capped it with Mundorf Supreme's and placed it between my current SS pre and SS amp. I'm now going to focus on learning about tubed preamps.

A classic test when powering up suspect equipment is to hook up a light bulb in series with the power cord. If it doesn't light, then the device is probably not going to smoke. If it lights up as you apply power, there's either a short or an extremely power hungry device on the table.

You can test with known good equipment to get a feel for the 'light'.

unc2701

Good description of the light bulb variac here:
http://www.antiqueradio.org/dimbulb.htm

dudeinaroom

PM sent back.

inspiredsports

Ted, I mailed out a check earlier this week and am looking forward to receiving the auto-former!

Now on to the next problem; I'm looking for a good working tube tester ("dynamic" or "mutual conductance", not the simple emissions type). I'll be starting a new thread soon.

dudeinaroom

Sorry, can't help you on that one. I'll keep an eye on the local craigslist for you, all kinds of crazy stuff come up around here.

inspiredsports

dudeinaroom wrote: »

Sorry, can't help you on that one. I'll keep an eye on the local craigslist for you, all kinds of crazy stuff come up around here.

Thanks, also, I just pulled the trigger on a nice Eico 667 and have posted a new thread at http://www.polkaudio.com/forums/showthread.php?t=93698

halo71

Ok, new guy, dumb question. Is a variac used in home audio tube amps mainly for testing equipment?

Cause I have used a variac/power soak in guitar tube amps before. The main purpose being to overdrive the tubes without making ears bleed.

mhardy6647

Yes, basically for slowly bringing up an old/unused piece of equipment and (with luck) giving elderly power supply electrolytic capacitors a chance to reform rather than to be blasted by full line voltage on their first power-up after a long rest.

A Variac can be used to lower/control line voltage, althoulgh there are other ways to do this (not necessarily cheaper ways, but probably a bit more elegant).

For the OPs benefit... if you don't have one, also get yourself a Kill-a-Watt. These are really handy to have for restoring/repairing old equipment (e.g., real-time current draw measurement and line voltage readout are available).

inspiredsports

mhardy6647 wrote: »

Yes, basically for slowly bringing up an old/unused piece of equipment and (with luck) giving elderly power supply electrolytic capacitors a chance to reform rather than to be blasted by full line voltage on their first power-up after a long rest.

A Variac can be used to lower/control line voltage, althoulgh there are other ways to do this (not necessarily cheaper ways, but probably a bit more elegant).

For the OPs benefit... if you don't have one, also get yourself a Kill-a-Watt. These are really handy to have for restoring/repairing old equipment (e.g., real-time current draw measurement and line voltage readout are available).

Like one of these? . . . http://www.p3international.com/products/special/P4400/P4400-CE.html

You guys are killing me!

--- everyone says you need a tubed preamp (and I agree!)
--- then you need a Variac to power up old unused gear
--- then you need new tubes
--- then you need a tube tester to make sure tubes old and/or new are good
--- then you need to recalibrate or perhaps rebuild the tube tester
--- then you need a Kill-a-Watt just to be sure the equipment's power supply isn't frying itself

inspiredsports

mhardy6647 wrote: »

Yes, basically for slowly bringing up an old/unused piece of equipment and (with luck) giving elderly power supply electrolytic capacitors a chance to reform rather than to be blasted by full line voltage on their first power-up after a long rest.

A Variac can be used to lower/control line voltage, althoulgh there are other ways to do this (not necessarily cheaper ways, but probably a bit more elegant).

For the OPs benefit... if you don't have one, also get yourself a Kill-a-Watt. These are really handy to have for restoring/repairing old equipment (e.g., real-time current draw measurement and line voltage readout are available).

Like one of these? . . .

http://www.p3international.com/products/special/P4400/P4400-CE.html

You guys are killing me!

--- everyone says you need a tubed preamp
--- then you need a Variac to power up old unused gear
--- then you need new tubes
--- then you need a tube tester to make sure tubes old and/or new are good
--- then you need to recalibrate or perhaps rebuild the tube tester
--- then you need a Kill-a-Watt just to be sure the equipment's power supply isn't frying itself



I guess now I'm in this for the LONG HAUL!

halo71

Guess I should read up on it. But I am assuming some/many/all stereo tube amps are self biasing?

inspiredsports

mhardy6647 wrote: »

Yes, basically for slowly bringing up an old/unused piece of equipment and (with luck) giving elderly power supply electrolytic capacitors a chance to reform rather than to be blasted by full line voltage on their first power-up after a long rest.

A Variac can be used to lower/control line voltage, althoulgh there are other ways to do this (not necessarily cheaper ways, but probably a bit more elegant).

For the OPs benefit... if you don't have one, also get yourself a Kill-a-Watt. These are really handy to have for restoring/repairing old equipment (e.g., real-time current draw measurement and line voltage readout are available).

I received my Kill-A-Watt yesterday and am having a blast going through the house figuring what all of my computers and electronics gear burns up in a month.

The best news I've found is that my dedicated 20A circuit for my 2 channel system with a PS Audio Power Port Premier displays a very consistent range of from 119.4 to 119.8 VAC every time I look at it.

I haven't had a chance to test on the component side of my APC power conditioner yet, but am sure with that good input, everything is golden on the output end.

Thanks for the tip! I will probably purchase a couple more of these to keep on various components around the house.

dudeinaroom

Sorry for the short delay. Was sent out around 9:00 this morning. Let me know how the packing material fared, tried some thing new.

inspiredsports

dudeinaroom wrote: »

Sorry for the short delay. Was sent out around 9:00 this morning. Let me know how the packing material fared, tried some thing new.

NO WORRIES.

Dang, dude . . . this thing is NICE and EXACTLY what I was looking for!

I plugged it in and let it warm up for a few minutes and then put the Kill-A-Watt on it per mhardy's post (and THANKS, that was a great suggestion!).

The voltage output dial on the Variac matches the readout on the Kill-A-Watt perfectly. In this case, I guess I really don't even need the Kill-A-Watt to check up on the Variac as it is so accurate, but being a control freak I like the precision digital readout.

Now I am ready to bring old tube gear back to life without fear.




PS,: Packaging was good, maybe a couple of sheet of crumpled newspaper in addition to the air bags, but it made it just fine.

dudeinaroom

Good to hear. Glad it found a good home. Wife says she is sorry it went out late.

Later,
dude

hearingimpared

inspiredsports wrote: »

NO WORRIES.

Dang, dude . . . this thing is NICE and EXACTLY what I was looking for!

I plugged it in and let it warm up for a few minutes and then put the Kill-A-Watt on it per mhardy's post (and THANKS, that was a great suggestion!).

The voltage output dial on the Variac matches the readout on the Kill-A-Watt perfectly. In this case, I guess I really don't even need the Kill-A-Watt to check up on the Variac as it is so accurate, but being a control freak I like the precision digital readout.

Now I am ready to bring old tube gear back to life without fear.




PS,: Packaging was good, maybe a couple of sheet of crumpled newspaper in addition to the air bags, but it made it just fine.

I had my Spectral DMC 10G, which is all solid state, in storage for 20 years. Before powering it up again, I called Spectral to see if there was anything special that needed to be done and spoke to their design engineer. Besides checking for any moisture inside, he strongly recommended waking the it up slowly over a 24 hour period with a variac. He gave me the exact voltage and time periods I should increase the voltage. I borrowed one from Billy (LibertyC) and did just that. So I guess if you get some vintage solid state devices that have been powered down for some years they should be awaken slowly with a variac too. If for nothing else to slowly reform the caps inside.

inspiredsports

hearingimpared wrote: »

I had my Spectral DMC 10G, which is all solid state, in storage for 20 years. Before powering it up again, I called Spectral to see if there was anything special that needed to be done and spoke to their design engineer. Besides checking for any moisture inside, he strongly recommended waking the it up slowly over a 24 hour period with a variac. He gave me the exact voltage and time periods I should increase the voltage. I borrowed one from Billy (LibertyC) and did just that. So I guess if you get some vintage solid state devices that have been powered down for some years they should be awaken slowly with a variac too. If for nothing else to slowly reform the caps inside.

I was wondering about solid state gear. For some reason I always thought that under-voltage was bad, but I guess maybe that's more for computer gear.

inspiredsports

I don't think companies build stuff like this any more.

It measures just 6-1/2" High X 5" Wide X 4-1/2" Deep, yet weighs over 8 lbs without its power cord.

With its dial set at 120 VAC, the external Kill-A-Watt digital meter slowly fluctuates from 119.9 to 120.1 (and it's set up to only measure .1, .3, .5, .7, .9 increments) so it's spot on perfect.

I opened it up and it was shiny and bright like an Intel clean room.

I used it set on 120 to feed my Eico tube tester for calibration, so I now know that is spot on.

Now, just for kicks, I'm placing it between by power conditioner and turntables for precise 33-1/3 and auditioning to see if I cn detect any added AC noise.

inspiredsports

hearingimpared wrote: »

I had my Spectral DMC 10G, which is all solid state, in storage for 20 years. Before powering it up again, I called Spectral to see if there was anything special that needed to be done and spoke to their design engineer. Besides checking for any moisture inside, he strongly recommended waking the it up slowly over a 24 hour period with a variac. He gave me the exact voltage and time periods I should increase the voltage. I borrowed one from Billy (LibertyC) and did just that. So I guess if you get some vintage solid state devices that have been powered down for some years they should be awaken slowly with a variac too. If for nothing else to slowly reform the caps inside.

Hey Joe, (and others)

Would you mind posting the time/voltage instructions that Spectral engineering gave you? I think it would be helpful to have that info posted here. I'm going to post any info like this that I am able to collect for both my SS and tube gear.

I think it will be helpful and easy to find then as this thread shows up when you search for "Variac" which is easy to remember.

Greg

hearingimpared

inspiredsports wrote: »

Hey Joe, (and others)

Would you mind posting the time/voltage instructions that Spectral engineering gave you? I think it would be helpful to have that info posted here. I'm going to post any info like this that I am able to collect for both my SS and tube gear.

I think it will be helpful and easy to find then as this thread shows up when you search for "Variac" which is easy to remember.

Greg

I know I have stuffed somewhere in a box. I'll see if I can dig it up. I can tell you it wasn't very complicated.

inspiredsports

Thanks. If you find happen to find it, post it up.

dudeinaroom

Did I say I wanted 20 for that, I meant 40. lol

inspiredsports

dudeinaroom wrote: »

Did I say I wanted 20 for that, I meant 40. lol

The hilarious thing is, as you can see from my post #1, that I didn't have a clue of what these were or how they worked. I really had no idea what I was looking for until a few more people posted details.

Then when you posted that you had an autoformer, I didn't know it was the "Variac" brand, but I had enough in my PayPal account to cover what you were asking so I figured I would give it a try.

You know what they say, "Sometimes even a blind squirrel finds an acorn."