The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all Tubes4hifi.com products and all Dynakitparts.com products


    Question about VARIAC

    Share

    bluemeanies

    Posts : 134
    Join date : 2015-02-09
    Age : 66
    Location : Folsom Pa.

    Question about VARIAC

    Post by bluemeanies on Tue Oct 25, 2016 10:30 am

    '
    i have a Staco Energy Variac that I purchased almost one year ago.
    Last night I had a loud hum coming from it and the kil-O -Watt that was connected to it did not work.
    I called a local electronic store that I have dealt with for years and is reliable in addition to giving good advice.
    He told me it was not worth the repair...once they go...that's it. He did explain what he thought the problem would be but said I could probably invest in a new one rather than repairing my currant Variac.
    He also thought that in my area a Variac is NOT needed. I told him I did notice fluctuations from morning, afternoon and evening but he said that those fluctuations would be nothing dangerous to my system. 
    None of my HT equipment was every connected to a VARIAC and I never had a problem.

    So besides spreading the news...what are people's opinions?
    If a Variac is necessary in you opinion what do your recommend....nothing expense.

    thanks everyone,
    blue

    Peter W.

    Posts : 235
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: Question about VARIAC

    Post by Peter W. on Tue Oct 25, 2016 11:42 am

    bluemeanies wrote:'
    >>MUCH SNIPPAGE<

    So besides spreading the news...what are people's opinions?
    If a Variac is necessary in you opinion what do your recommend....nothing expense.

    thanks everyone,
    blue

    BIT OF A RANT WARNING!

    I will assume that you have verified the line voltage coming into your dwelling as being within tariff, and within the safe operating parameters of your equipment. Generally that is somewhere between 110 and 120 VAC. Note that typical tariffs call off some percentage above/below some fixed voltage, these days usually 120 VAC.

    With that in mind, a Variac is a dangerously useless addition to your system, especially if operated anywhere near its capacity. Keep in mind that these devices were originally designed to dim incandescent light loads in theater applications, not as a buck/boost device. How they inveigled themselves into this application is a mystery to me. Perhaps as a (very) temporary expedient to determine the range of a problem and how much correction - temporary or permanent - is needed. But, certainly, no more.

    If you do have a permanent/ongoing or constant high/low voltage problem, or unacceptable voltage sags for extended periods, then a solution outside of a Variac is necessary. There are specific devices for the purpose that do an adequate job and are one helluvalot safer than a Variac.

    http://accessories.us.dell.com/sna/productdetail.aspx?c=us&l=en&s=bsd&cs=04&sku=A0429419&ST=pla&dgc=ST&cid=302824&lid=5758064&acd=12309152537461010&ven1=A0429419:112781467989:901pdb6671:c&ven2=:

    Is one such device from one such source. 2,400 watts (20A) should be enough for about any audio system, even one that is tube-based. But there are many such devices from any number of sources. BUT - In terms of capacity, allow for at least 2 X the anticipated load for the stabilizer/conditioner.

    Variacs have no place in the electronics hobby whatsoever unless they are metered for both voltage and output. Otherwise, not at all, ever, full stop.

    I keep a Heathkit IP5220 which also serves as an isolation transformer - and an immensely useful diagnostic device. Similar devices are made by VIZ, RCA, TEMA, B&K and many others.

    http://vacuumtubeaudio.info/artwork/projects/IP5220-3.jpg

    Best of luck with it - but lose the Variac as a buck/boost device!

    Bob Latino
    Admin

    Posts : 2454
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Question about VARIAC

    Post by Bob Latino on Tue Oct 25, 2016 9:37 pm

    I disagree with Peter W. ... There are many places in the USA that have line voltages well above 120 VAC. Over the years I have found that line voltages above 122 VAC can lead to shorter tube life at least in the VTA amps. The VTA amps are designed to look at 120 VAC and will work fine with anything up to about 122 VAC. I had someone in Texas tell me that his incoming line voltage was 126.7. The B+ voltage on his VTA ST-120 amp was way high (about 550 VDC) and his filament voltages which should have been 6.3 VAC were about 8 VAC. Modern tubes won't last long with much higher than normal filament voltages.

    Variacs do work well to reduce higher than normal line voltages to levels that tube amps are designed to work in. I think that bluemeanies loss of his Staco variac is an issue that rarely crops up with variacs. A variac is like a giant volume control (rheostat) for voltage. I have had a Staco here for 30 + years and have never had a problem with it.

    I would be careful of using a tube amp with a "line conditioner" such as the one in Peter W.'s link. Many "line conditioners" do not output a true sine wave. They "condition" the incoming AC but the output may (or may not) be a true sine wave. A tube amp will "choke" big time on anything other than a true sine wave. The only way you can be sure of a true sine wave is to plug your amp into a wall outlet or the output AC outlet on a variac. A variac will always give you a true sine wave. My recommendation is to use a variac only if your incoming line voltage is above 122 VAC for much of the day. If the output on your variac has an analog meter to show the voltage - don't trust it. Use your digital multimeter and plug it into the variac's outlet and turn the dial until you are at about 118 VAC. Your amp will be a lot happier and your tube life will increase.

    Bob

    10-E-C

    Posts : 94
    Join date : 2014-02-12
    Age : 63
    Location : upper east tn

    Re: Question about VARIAC

    Post by 10-E-C on Wed Oct 26, 2016 7:36 am

    This is from my experience with my M125's tube life. I knew my voltage was a tad high, in the 123 to 124 VAC range. I just ran my amps at that voltage and I run them hard a lot. In the first year of operation I lost 7 signal tubes, 12au7, 5814,12bh7 and 5963s and also one kt120.  After I lost my favorite 5963 tube I invested in a 15A variac to run my M125's, I set the output voltage via my fluke at 119 VAC and been running my amps for 10 months now without any tube lost and bias stays rock steady. I found some phillips 5963s which sound nicely in my system and very happy with the performance of my system now.

    TM

    Peter W.

    Posts : 235
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: Question about VARIAC

    Post by Peter W. on Wed Oct 26, 2016 7:53 am

    I suggested Tripp-Lite specifically as it generates "Hospital Grade" conditioned voltage, and does not use a ferroresonant transformer. Agreed that ferroresonant transformers are quite dirty and cause all sorts of noise downline if not very carefully managed.  

    http://www.tripplite.com/2400w-120v-power-conditioner-automatic-voltage-regulation-avr-ac-surge-protection-6-outlets~LC2400/  

    For specifications - note the EM & RF filtering, not typical of the cheaper models.

    This unit also meets ANSI Standard C84.1-1995 (R2005):  http://docslide.us/documents/ansi-c841-1995-r2005.html    Which, essentially, is the standard that power companies are also required to meet.

    Now, the issue with variacs. They are fixed devices inasmuch as varying input means varying output. Which means constant fiddling if you are in a typical residential situation where voltage may vary from as low as 108V during the heat of the day - not quite a full brownout, but not 120V either - to as high as what I measured once of 131V at our summer house. That is a 23V variance, admittedly in two different locations, but both where good audio equipment is in regular use, including considerable stuff from Dynaco.

    So, my preference is to use a device that manages a constant, filtered voltage, also with surge protection at a reasonable cost and with neither objectionable noise (audible), high cost or taking up too much real estate. I run equipment from Revox, Harman-Kardon (Citation), Scott, Dynaco, AR and more through my LC, without any discernible noise or distortion resulting.

    De gustibus et coloribus non est dispustandum.

    One more thing: Variable Auto-Transformers make heat. Accordingly, the rating of the Variac *must* be at least twice the anticipated load if the unit is to be left in place at all times. These devices were designed to dim lights, not manage wonky power. Just keep that in mind when using them "Off Label".

    Lastly: Analog vs. digital meters: This is very much a matter of taste, assuming that both meters are both accurate and properly calibrated. An analog meter shows 'dither' better than a digital meter - the needle bounce is far more noticeable than a shifting last digit, and the timing of the variance is much more easily discerned. Where I am watching for those variances, a mirrored analog meter is my preference. When I am measuring to/for a specific volt/amp/capacitance/resonance/whatever, I do very much prefer a digital meter.

    bluemeanies

    Posts : 134
    Join date : 2015-02-09
    Age : 66
    Location : Folsom Pa.

    Re: Question about VARIAC

    Post by bluemeanies on Wed Oct 26, 2016 11:19 am

    Ł
    I decided after speaking to STACO ENERGY the makers of this particular Variac to have it repaired. I purchased it online for $100.00 with shipping. The same unit today is valued at $450-$500. 
    Speaking to the STACO technician he feels after a couple of short tests with my FLUKE 115 and describing the issue it is a good possibility of a short even though the fuse did not blow but it keeps tripping the 20amp circuit breaker. Possible the brushes need to be updated. 
    I explained to him my exact use for the VARIAC and he mentioned they are used by many audiophiles although I do not label myself as such.
    My voltage line into my system ranges from a low 115 to a high of 125. At one reading it was 129. 
    I feel the VARIAC is worth the money spent but that is my opinion.
    I bought this unit used without a mark on it. The coils looked new.

    I delivered it to my electronics store this morning, which is local and whom I have dealt with over the years.
    I am expecting a good outcome especially since the owner told me before he started his business he worked for STACO and built VARIACS.
    I feel confident about making the right move.
    As far as the m125's and a line conditioner my experience was not that good. I have a FURMAN ELITE PF15 and having the m125's plugged into the FURMAN caused a hum/hiss in both my B&W804S & now my 803Diamonds.

    Thanks for all the comments!

    Peter W.

    Posts : 235
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: Question about VARIAC

    Post by Peter W. on Wed Oct 26, 2016 12:30 pm

    Staco is a good company and still manufacturing in the US - and if the unit can be repaired (much better than landfill), and you are satisfied with the process, then you are making the right decision for you.

    Enjoy!

    bluemeanies

    Posts : 134
    Join date : 2015-02-09
    Age : 66
    Location : Folsom Pa.

    Re: Question about VARIAC

    Post by bluemeanies on Wed Oct 26, 2016 8:17 pm

    Ok LISTEN UP.
    Nothing was wrong with the VARIAC except a lose wire. 
    It was put thru the test and operated fine.
    The brushes I was told looked like new and the STACO is built like a tank.

    I took her home yet I am still having problems. What bugs me is it worked fine with the killO watt for eight months now I don't know what the hell is going on. I change nothing in my system.
    The kill O Watt works fine by itself but plugging it into the the STACO it does not turn on and the VARIAC trips a 20amp breaker. The VARIAC is rated at 22amps and has a 30amp fuse.

    ANY THOUGHTS?

    Guest
    Guest

    Re: Question about VARIAC

    Post by Guest on Wed Oct 26, 2016 8:28 pm

    bluemeanies wrote:Ok LISTEN UP.
    Nothing was wrong with the VARIAC except a lose wire. 
    It was put thru the test and operated fine.
    The brushes I was told looked like new and the STACO is built like a tank.

    I took her home yet I am still having problems. What bugs me is it worked fine with the killO watt for eight months now I don't know what the hell is going on. I change nothing in my system.
    The kill O Watt works fine by itself but plugging it into the the STACO it does not turn on and the VARIAC trips a 20amp breaker. The VARIAC is rated at 22amps and has a 30amp fuse.

    ANY THOUGHTS?

    I wonder of they reversed phases?....that is...hot/active and neutral.
    I use a step up transformer to test builds for 220-240VAC. When I first got the step up transformer, they wired hot/active and neutral the wrong way, kept tripping the circuit breaker on the transformer unit when I plugged in an amp or preamp to test.

    Peter W.

    Posts : 235
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: Question about VARIAC

    Post by Peter W. on Thu Oct 27, 2016 9:24 am

    I wonder of they reversed phases?....that is...hot/active and neutral.
    I use a step up transformer to test builds for 220-240VAC. When I first got the step up transformer, they wired hot/active and neutral the wrong way, kept tripping the circuit breaker on the transformer unit when I plugged in an amp or preamp to test.[/quote


    Good thought!

    I keep a circuit tester for just this purpose. Cheap, simple, useful, and prevents unhappiness.

    https://s-media-cache-ak0.pinimg.com/originals/e7/3c/6e/e73c6e5042375e0cf44b08c7b7dddf42.jpg Less than US$10 at your local hardware or big-box store.

    Use it on the Variac output as well as at the wallplate.

    bluemeanies

    Posts : 134
    Join date : 2015-02-09
    Age : 66
    Location : Folsom Pa.

    Re: Question about VARIAC

    Post by bluemeanies on Thu Oct 27, 2016 10:32 am

    Ok all is good..."Thanks to AUDIOBILL"
    This guy is certifiable... "GENIUS"
    Figured out the problem or Bill did, but I did help...haha. I am replacing a 30amp fuse that I did not realize the VARIAC was using and I am replacing it with a 10amp fuse.
    I contacted STACO explained the situation and they agreed 30amps was to much for my application especially that the VARIAC is connected to a 20amp circuit.
    The lose wire was the reason the circuit breaker shut down which I had fixed.
    I ordered a 10amp slo-blo fuse and I may receive it as early as tomorrow or Saturday.

    Total cost for fuse and repair $52.00

    Thanks for the input.
    Good people here.

    bluemeanies

    Posts : 134
    Join date : 2015-02-09
    Age : 66
    Location : Folsom Pa.

    Re: Question about VARIAC

    Post by bluemeanies on Thu Oct 27, 2016 1:39 pm

    The latest is that HD had the fuses..2for $10.00...10amp.
    Everything is back to normal

    Peter W.

    Posts : 235
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Re: Question about VARIAC

    Post by Peter W. on Thu Oct 27, 2016 1:50 pm

    bluemeanies wrote:The latest is that HD had the fuses..2for $10.00...10amp.
    Everything is back to normal

    YIKES! $5/fuse?

    Didja look on Amazon? Mouser? I am seeing conventional AGC slow-blow fuses in the $1.65 range. MDL in the $1.40 range. MDQ fuses do get up into the $6.60 range, if that is where you are going.

    There is shipping, of course - and why I buy my fuses only when part of another order.

    bluemeanies

    Posts : 134
    Join date : 2015-02-09
    Age : 66
    Location : Folsom Pa.

    Re: Question about VARIAC

    Post by bluemeanies on Thu Oct 27, 2016 7:49 pm

    $10.00 did not break the bank and I did not have to wait.
    $1.40-$1.65 plus tax and shipping cost.
    Amazon and e-bay have the biggest scam going on shipping. It's a contractual agreement. Especially e-bay where the seller sets the cost of packing and shipping.

    wildiowa

    Posts : 140
    Join date : 2012-03-19

    Re: Question about VARIAC

    Post by wildiowa on Fri Oct 28, 2016 9:07 am

    I have joined in before on voltage issues and can only relate my experiences. After three strange and unexplained blowups on my Citation II I decided to send it back to Don Sachs for a going-through and repair. I also knew my voltage was consistently about 126 VAC so I inserted an ancient Variac a friend had and since then, not one problem. Whether the last tune up found and fixed something or bringing the voltages back in line (I do 119 VAC) solved the problem, I don't know. But I feel better knowing it's more in line for the original design rather than seeing these newer hotter voltages. Being in rock and roll combos I also have run across a lot of power conditioners but they do not seem to have the same design concept and physical heft so I went for the Variac.

    bluemeanies

    Posts : 134
    Join date : 2015-02-09
    Age : 66
    Location : Folsom Pa.

    VARIAC

    Post by bluemeanies on Fri Oct 28, 2016 12:26 pm

    wildiowa wrote:I have joined in before on voltage issues and can only relate my experiences. After three strange and unexplained blowups on my Citation II I decided to send it back to Don Sachs for a going-through and repair. I also knew my voltage was consistently about 126 VAC so I inserted an ancient Variac a friend had and since then, not one problem. Whether the last tune up found and fixed something or bringing the voltages back in line (I do 119 VAC) solved the problem, I don't know. But I feel better knowing it's more in line for the original design rather than seeing these newer hotter voltages. Being in rock and roll combos I also have run across a lot of power conditioners but they do not seem to have the same design concept and physical heft so I went for the Variac.

    wildiowa....IMHO I think a VARIAC is money well spent. I purchased my unit on e-bay for $100.00 with shipping. I thought the unit was valued at $400-$500 as was stated on the sellers ad. After this recent problem speaking to STACO ENERGY my specific model sells for a little over a $1000.00. It looked brand new not a scratch on it. Having it in repair shop there was a lose wire that had to be soldered...that was the main issue with it blowing the circuit. 
    Also a learning lesson from audiobill and I confirmed this with BILLOWS ELECTRICAL it had a 30 amp fuse which was way to much fuse for my application and house.
    I am now using a 10amp BUSSMANN fuse.
    The VARIAC is working perfectly. 
    Repair cost was $40.00 in addition to spending $10.00 for two 10amp fuses.
    Total cost for VARIAC, repair and fuses $150.00
    My in line house voltage was measured as low as 115 to as high as 125.
    I am glad to have the Variac.
    To be honest I think my VARIAC fell off a truck!
    Just wanted to share my store.

    Sponsored content

    Re: Question about VARIAC

    Post by Sponsored content


      Current date/time is Mon Feb 20, 2017 4:45 am