The clearest and true wisdom I've ever been able to find at all on the use of Variacs and transformers! I made an oops and got an ENGL 840/50 power amp from Europe and I had no idea the voltage differs and wouldn't be able to use the power amp outright! It seems like a step up transformer is the safest bet in using it here in America, though I'll probably save and go the way of the Variac when I've got enough for something nice and can monitor the voltage.
Hi Peter. If you want to get as accurate as you can set the power to where you have 6.3 volts ac on your tube filaments. That's the most important voltage to respect on the tubes.
Don't understand how 4 morons can click on thumbs down while listening to a Master Builder who shares his knowledge !??.............Thanks for this video Sir !................Lou........Quebec
I just purchased a new 2000 watt, 20 Amp variac instead of the 1000 or 500 volt items based upon your recommendation to get the 20 Amp version. I'm fining that I really like 105 vac power with certain tube amps.
Mine is a Technopower brand, it's a good one. I like it cause it has two analog meters one for voltage, one for current. It also has switch for two current ranges, one fused at two amps, the other at ten amps. I always keep it on the two amp setting for testing and when you're dialing the voltage up slowly on something you can tell immediately if you have a problem by watching the current meter. They're a good investment for the player, an absolute necessity for anyone doing electrical/electronics.
What a great video. I have been looking for something like this for about a year now, because I have moved all my American Tube Amps to Europe and definitely can't be directly plugged in the wall without the correct voltage and plug adapter . What a shame though you pay so much for a Fender, Mesa Boogie, and Peavey and they don't even have the voltage selector on the back like on my Marshall Amp. Had I know that it was going to be this difficult I would have sold them back in the US first and bought new ones in the EU. Either way this would be the best alternative for my situation cost wise. None of the American Manufacturers have gotten back to me either with an answer of what to do. I was very disappointed. Needless to say I will be searching for a Variac online soon. Thank you Bob
Thanks - glad you enjoyed it - to answer your question - your amp will sound very weak and anemic and the heaters will not be properly lit on your tubes.
Thanks Bob, great info. Quick question; Im in australia with 240v I have a evh 5150 iii guitar amp (modern all tube amp) I bought a variac and i plugged my amp in, all good. However i decreases the volts down to as low as 150v and still the volume of my amp was loud... although i did notice some drop for sure. How low on the variac can i turn it down to?
Excellent presentation, thanks for this. I have a couple Furman power conditioners (P-1800 PFR plugged into a P-1800 AR). They often do not output exactly 120v. Sould I use a manual variac plugged into the P-1800 PFR to make up the slight difference (+/- 4v) from 120v? Or is it generally a bad idea to plug a manual variac into a power conditioner?
Hello Bob, great info....can we use a voltage converters instead of a Stepdown Tr. Cause the Tr are way too much heavier than the voltage converters to carry around.
Great video Bob! I live in Japan where the voltage is 100. I have an amp on the way from England with a variable voltage selector: 100, 115, 230, 240. I would like to run the amp at 240 if possible. Years ago I was at Ken Fischer's and we ran a Hiwatt through a through its different voltage options through a Variac, and it it sounded way better at 245, max voltage, through the Variac than it did at 105 or anything in-between. Since I don't trust myself to use a Variac, as I'm bound to f*#k it up, please recommend a step UP transformer option. Thank you!
What kind of variac would you recommend for a US only player? And do I have to worry about buying a poorly made variac that creates electrical noise which then is heard on the amp or does that not happen?
I'd recommend buying a good quality Staco. 0-120/140V with enough amperage to power the amount of equipment you plan on running. A 10 amp unit will usually be a very good quality one. A cheap variac will not introduce noise but it will not work for long.
Hi Bob, great video, very informative! I have a quick question I was hoping you could help with. I have a Mesa Boogie big block bass amp,750 watt@2 ohms (or 550@4ohms etc) USA version that I want to use in Europe. Would a step-down transformer of 1500 watt/va be enough for that kind of high wattage? Much appreciated! (Ps I have that same Fender opb 51 reissue bass in the background of your video!)
The wattage that goes to your speaker is not the one to be concerned with. It's the wattage that your amp uses from the power supply that is your concern. That wattage is usually printed on the back of the amp near the power cord. 1500 should be plenty.... They did a good job on that bass, I wish they made the neck bigger like the original was.
@@BobGjika Thanks for taking the time to reply. On the back of the amp it only says 120 volts and 15 amps, would this equal 1800 watts of power consumption? If so I'm guessing I might need to get a higher power stepDwn...Also after further investigation it seems a lot of the Step-down boxes only give 70% of there rating when used for longer periods. Thanks again for your time and help!
@@MN-kb2nx you should e mail the manufacturer and ask them. That label is just telling you to plug that into a 120 volt supply with a minimum of 15 available amps. Your average outlet if not in a kitchen would be connected to a 15 amp breaker.
Hi Bob Thanks for all your infos.. maybe you could help me?.. I live in France and have an original 1969 twin reverb with the lower voltage transfo transition at 315v. (Ac768 schematics). The blackface pt on schematic give 340v. It is a export model in 240v. So, to have the 340v that I want i baught an original 1965 pt twin reverb , the 125p34a pt... it is in 110v us original version, so I use a transfo converter 240-110v. But I have only 317v in power supplies of the pt, and only 400-410v b+, schematics give me 340v and 460v. My heater is only 6.19v. I check my converter transfo and I have 110-112v output . do you think it is too low to give me the 340v for blackface Tone?.. there is the tad converter transfo with 117v output ... it will be better with 7vac more? or a variac to find the good voltage to have the 340v in my amp and 6.3v heater. But which variac to use with 240v here in France?... All résistances and caps are checked in my amps.. my plate voltage on my 6l6 are only 400-405v.. thanks for your help! Jérémy
set the line voltage to where you have 6.3 volts on the heaters. at that point all other voltages in the amp will be correct to the transformers windings
Man I wish I had seen this years ago. I read an article with EVH where he said he was running his Marshall at 140 volts. So I tried it expecting instant greatness. Don't do this lol it sounded like shattered dreams and electrical smoke
I seem to recall hearing that EVH's first Marshall was one that someone had brought over from the UK or Europe. That would explain the 140v setting, because it had the 200+v transformers in it. So it would have been like dialing down a 110v Marshall to around 80-ish volts.
Very informative and excellent presentation....... On the subject of a variac, I want to slowly power up the filter caps in a Fender pro Reverb, the variac in question is 220 v has a power rating of APS 500 watts with a 2 amp current rating. Would this be a suitable variac? Many thanks for any advice. Greetings from the UK
Start at around 20 volts and every ten or so minutes bring it up 20 more volts. Do not bring it up to more than around 3/4 of the total voltage. At this point shut it down and put all the tubes back in the amp, make sure the speaker is attached and just bring the dial on the variac up like a slow sweep until you reach the proper operating voltage.
Hello, Does a step down transformer can affect the original sound of a vintage amp even if I’ll use the right voltage or somewhere close to the right voltage?
Very concise and intelligent presentation Bob. I have some questions for you, if you don't mind. Do power tubes last longer at a slightly reduced voltage? I'm running a new for American market Marshall 2245/JTM45. I measured the wall outlets in my house and the are all 120VAC. The Marshall JTM45 say's to use 117VAC 60 Hurtz 175 Watts (on the rear panel) under the power supply input. Both the H.T. and Mains fuses say 100-120V, T500mME 250V and 230T500mVA. I measured the output voltage of my (surge protector) voltage regulator/ over current protection device at 120VAC when plugged into my 120VAC wall outlets . It has an option to run 10%up or 10% down. I then plugged it into my 120VAC outlets and at 10% step down it measured 108VAC/110VAC. I am experimenting with reduces voltage. It has changed the sound of all 6 of my tube amps in a way that I like. After the other amps had no problems I got brave and lowered the input voltage to my Marshall JTM45 to 108VAC, it did not change the sound as much as it did the other amps, but I still think it sounds good. I am ready to purchase a heavy duty as you pointed out 1500/2000W Variac @20 Amps to set the voltage above or slightly less than 108VAC. But NEVER above the designed 120VAC of the Marshall JTN45. How low do you think I could go? I hear 90VAC is about the lowest, but I would not push my luck. I'm thinking of 100 to 104VAC as the lowest. Do you think I'm on the right track? The Marshall uses two 5881 power tubes and three 12AX7's and as it is it is the best sounding amp I ever played through. In a way I question myself and say, if it's that good why am I fussing around with voltage? I am planning on playing out so both a Variac and my Multi-meter is a requirement as far as I am concerned even it I run at 120VAC. I'm in Alabama, U.S.A. -Peter P.S. If your interested the whole 110VAV/90VAC started in America up at Niagra Falls power plant. The conveyed the electricity of great distances to NY City and because the population was great and the power consumption high they decided to use lower voltage transmission lines. Also the 110VAC could not always be maintained under times of peak load so they designed the system to go as low as 90VAC. So in that manner, and for many many years all American products that used electricity were designed to operate normally at voltages from 90 to 110 VAC. In today's world with many more power generators on line they can get 120 VAC to every household so that is the standard. The higher the voltage in the transmission lines the more efficient the system and perhaps that is why Europe uses 230/25VAC as standard. My prior house in Tennessee was 117VAC and my new house in Alabama is a solid 120VAC.
I only use 20~30 watts small amps. If I wanna buy the step down/up box. Do I still have to buy the 1500 watts capacity ones? they are really heavy... I don't care that much about the output accuracy.
Hey man, hope you can help me I have an old matchless that only takes 110v (I live in the uk) and I don’t want to change the internal transformers. What do you recon I should do?
hi Luke. most step downs will cut your voltage by half but you probably need more than that because you probably have around 240 where you are. you could use a step down box and then plug a variac into the 120 out from the step down and adjust to whatever voltage you want.
Hi Bob, I am sorry to bother you with another question, but I have seen variacs that look like yours on eBay. The one that I was looking at is a Superior Electric 3PN116B rated at 10amps. Don't if this one in particular would be suitable for my amps. My amps are a mesa BOOGIE Tremoverb amp combo, Fender blackface Bandmaster 1965, JTM45, Ceriatone 50 watt HRM amp. Any advice on an American brand like Staco or something else that would be suitable and how many amp rating on the variac that I would need. There are so many model variacs on the market. To buy a new Staco is like $750.00 USD. Perhaps something on eBay? Thanks Michael Newell from Niagara Falls, Ontario
michael newell : Are you still into getting a variac? There’s some red Chinese ones on Ebay for around $60. There’s also a video of a guy using one on a Marshall (sounded great).
IS it that critical , never built a guitar amp, made some audio amps , didnt notice that big of a sound issue , i think bigger difference would come from a choice of transform then 10-20% voltage oscillation , off course if not constant, if constant that would be audible
