Schu Posted January 9, 2017 Share Posted January 9, 2017 Simple question... Can a Veriac be useful in a modern tube based system? Quote Link to comment Share on other sites More sharing options...
mike stehr Posted January 9, 2017 Share Posted January 9, 2017 Wall voltage too high? Quote Link to comment Share on other sites More sharing options...
Schu Posted January 10, 2017 Author Share Posted January 10, 2017 Well... not that I am aware of. I read something somewhere by where you slowly raise the voltage to operating conditions it can help with wear and tear. I was just curious. Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted January 10, 2017 Share Posted January 10, 2017 I've seen people use one on old tube amp that have not functioned in a long time. It will be interesting to see more post on the topic for us newbies to tubes. Quote Link to comment Share on other sites More sharing options...
tom b. 57 Posted January 10, 2017 Share Posted January 10, 2017 I think that a variac is an essential tool for any vintage audio collector, tube or solid state. Not being certain of the history of vintage gear that one has acquired, it is good to apply voltage at a regulated pace instead of hitting it with 110/120 all at once. I may be wrong with this train of thought but I choose to slowly ramp up the voltage. Tom Quote Link to comment Share on other sites More sharing options...
Don Richard Posted January 10, 2017 Share Posted January 10, 2017 12 hours ago, Schu said: Well... not that I am aware of. I read something somewhere by where you slowly raise the voltage to operating conditions it can help with wear and tear. I was just curious. A variac can be useful for powering older equipment for the first time, to reform the dielectric in the electrolytic caps primarily. A standby switch used to be a standard feature on tube equipment. This let the filaments get up to temperature before applying B+. This is a simple mod, requiring a switch and some wire. Quote Link to comment Share on other sites More sharing options...
Schu Posted January 10, 2017 Author Share Posted January 10, 2017 So this type of "ramping" of voltage is no longer critical with modern electronics? Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted January 10, 2017 Share Posted January 10, 2017 35 minutes ago, Don Richard said: A variac can be useful for powering older equipment for the first time, to reform the dielectric in the electrolytic caps primarily. This is it. No real reason to ramp up new or modern equipment that's in use regularly. Equipment with integrated circuits should NOT be ramped up with a variac in my opinion. Quote Link to comment Share on other sites More sharing options...
Schu Posted January 10, 2017 Author Share Posted January 10, 2017 Point to point is my main concern though everything I own was made within the last few years. Quote Link to comment Share on other sites More sharing options...
EMRR Posted January 12, 2017 Share Posted January 12, 2017 The danger side would be that many Variacs go to 130VAC, so you can over-voltage a device accidentally. Likewise if you left something sitting at 60VAC for a long time accidentally you might cause tube problems from inappropriate operating points. If you need permanent or regular voltage adjustment, I kinda like the idea of the stepped devices that switch in 5V increments, much harder for the dog kid or monkey to run by and change. And no, no reason for daily variac use. Quote Link to comment Share on other sites More sharing options...
avguytx Posted February 20, 2017 Share Posted February 20, 2017 I'm going over this part, myself, as Bob Latino says the VTA ST-70's (and others) need to see around 117-120v optimally. My wall voltage is pretty consistent around 125v +/- a volt. So I either use something like this... https://www.circuitspecialists.com/variac-variable-ac-ps05kva.html Or something like this... https://www.amazon.com/Tripp-Lite-LC1200-Conditioner-Outlet/dp/B0000512LA/ref=sr_1_2?ie=UTF8&qid=1487609371&sr=8-2&keywords=tripplite+line+conditioner We use these in a couple locations here at the school as there are some old lines and voltage is erratic in some older buildings. I had one building that had a swing from 110v up to 130v. You can imagine how that affected lights, computers, printers, etc. They (our crew and the city) finally found loose connections outside on the main feed and fixed it. Do the variacs (like top choice) work off a percentage of line voltage or a set voltage output based on the adjustment? Quote Link to comment Share on other sites More sharing options...
EMRR Posted February 22, 2017 Share Posted February 22, 2017 A Variac is a continuously adjustable power potentiometer. Meant for temporary use. Here's a wider range version of what I was speaking of, though not the one you'd want, just as example. There are others with 5 volt steps that top out at 120V, where this example has some step-up capability and larger steps. All lack a ground connection, so you'd need to wire ground path around the unit. This is fixed power taps on an isolation transformer. http://www.ebay.com/itm/Stancor-Line-Adjuster-Transformer-/332115872246 Quote Link to comment Share on other sites More sharing options...
mike stehr Posted February 23, 2017 Share Posted February 23, 2017 https://www.bkprecision.com/products/discontinued/TR110-isolation-transformer.html You can find used older versions for a lot less. I bought a pair last summer off CL for 35 bucks or some such. The old Stancor is cool looking, however... 1 Quote Link to comment Share on other sites More sharing options...
avguytx Posted February 23, 2017 Share Posted February 23, 2017 So what's the best thing to use on a continual basis to keep a tube amp around 117 volts continually? Apparently not a variable? Quote Link to comment Share on other sites More sharing options...
Marvel Posted February 24, 2017 Share Posted February 24, 2017 I have a huge wirewound resistor/variac, used to control stage lighting. I used it to drop the voltage on my Dynaco ST70. The power transformer used to run really hot, and TVA gives us rather high a/c voltage at the outlets. Bruce Quote Link to comment Share on other sites More sharing options...
muel Posted February 24, 2017 Share Posted February 24, 2017 I use an APC Smart UPS 1500. It is pure sine wave output and will boost low input voltage up to 30% and cut high voltage up to 12% without using the batteries. I've been told it could affect my sound but I haven't experienced anything negative. I can keep listening even when the power goes out... for a little while anyway. Quote Link to comment Share on other sites More sharing options...
SiliconTi Posted February 24, 2017 Share Posted February 24, 2017 8 hours ago, muel said: I use an APC Smart UPS 1500. It is pure sine wave output and will boost low input voltage up to 30% and cut high voltage up to 12% without using the batteries. I've been told it could affect my sound but I haven't experienced anything negative. I can keep listening even when the power goes out... for a little while anyway. I use the same model - seems to do a good job and I like the my equipment is safe from electric weirdness. Quote Link to comment Share on other sites More sharing options...
avguytx Posted February 24, 2017 Share Posted February 24, 2017 We use those, and larger versions, here at the school on my servers (one per) but I'm not sure I'm ready to spend $400+ just to bring the voltage down 5 to 7v. We also use these at the school localized in some of the older buildings where we have erratic voltage swings; lights dimming in room, voltage ranging from 114 to 130v, etc. They work wonders in there which saves me computers, printers, switches, etc. https://www.amazon.com/Tripp-Lite-LC1200-Conditioner-Outlet/dp/B0000512LA/ref=sr_1_1?s=electronics&ie=UTF8&qid=1487945152&sr=1-1&keywords=tripp+lite+line+conditioner Quote Link to comment Share on other sites More sharing options...
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