Audiophile quality variacs to decrease voltage?
Bigshutterbug...Assuming that they acknowledge that 124 volts is too high, they CAN definitely solve the problem. Distribution transformers (the ones up on poles that feed into houses) have taps that can be selected so as to output the proper voltage. This is necessary because the voltage input to these transformers drops as you go further away from the substation (which has larger transformers). While I don't think your amp would suffer at 124 volts, the lifetime of incandescent light bulbs is strongly dependent on voltage. A five percent voltage reduction will double the life, with 20 percent less light output. |
It appears that my neighbors also have the same high voltage in the subdivision. I will take your advice and try to find someone there who knows something about it. I doubt they can solve the problem, but maybe I can find out why. Spending money without good reason is not one of the things I am know for.... I know all the cashiers at our local Goodwill by name! |
Thanks Microstrip and Magnumpi205. I looked into the one on the Jon Risch website, and it looks like it would be a great choice if I were able to make the time for such a project. I like the idea of also being able to run it as a balanced power device to reduce noise as well. What kind of switch are you using in yours Microstrip? Any thoughts on a good quality fuse for it? Thanks for your help! |
The performance of any power conditioner depends on the quality of the device and mains quality. Most of the time people wisely complain about Variac performance being poor because they are referring to the usual low quality high power types used for tools or other electrical appliances. I have used a custom made variac having several taps with a high quality very low resistance switch with excellent results, but the big cheap variac I use to power-up slowly dubious apparatus kills the sound of any amplifier! Manufacturer Joule Electra uses a variac in their power supplies and no one says they sound poor because of it! As usually, mots of time you get what you pay for. |
Bigshutterbug, I used my Hammond isolation transformer to power my Japan voltage Technics SP10 MK3. I have no experience with it on an amp. I will say that Variacs are notorious for sounding terrible and the Hammond transformer I suggested is an Isolation design, meaning it strips most of the noise off your line but delivers up to 1500 Va. I had problems finding one, and after contacting Hammond, Digikey, Radio Daze, Mouser and several other vendors that were supposed to stock, I hit a brick wall. I finally found mine at a tiny shop in GA that not only had it, but at considerable discount from the others. Heres a link, I suggest you shop some other spots for price and see how they compare: http://www.electronicdepotinc.com/index.html If you have a chance, post back here and tell us how you did. |
Thank you everyone for all of your helpful suggestions. I will double check my meter as Eldartford said for starters. If my voltage is still high, then I will consider the Hammond Step-down transformer at $360. The Tice Titan/Powerblock would be nice, but well beyond my budget for this system. The idea of purchasing a much more affordable transformer like the ones mentioned by Microstrip and Ngjockey sound even more appealing, but by the time I added the necessary parts to it to make it safe, useable and semi-attractive, it may be close to the price of the finished Hammond Albert talked about. Albert, does yours sound close to what you get straight from the socket? Thanks again everyone, for your ideas! |
Albertporter...Of course I understood his question. He measured 124 volts but it makes sense to be a bit skeptical of such a measurement. If it were my measurement I would double check my reading, (even I have been known to make a wrong reading)and if it still looked like 124 volts I would somehow check the meter (or try a different meter). By the way, the two sides of my power measure 115.6 and 114.5, which I believe is typical. My suggestion to measure the other leg of his power was related to troubleshooting the reason for a 124 volt reading. I never suggested running another line. If he absolutely must drop his voltage your transformer suggestion is clearly the best way to do it. Patching in a nine volt 3 amp booster transformer scares me. My main point was that I think his amp will do fine on 8 percent high voltage, and he really doesn't need to do anything. To repeat my question...what voltage regulation is the power company supposed to supply? Maybe you can get the power company to fix your "problem". |
Excellent suggestion by Microstrip. Just to make sure it's clear to everyone, the primary would be connected across the ac line, in addition to the secondary being connected in series between the hot side of the ac line and the hot side of the outlet on the box into which the amplifier's power cord would plug. The neutral side of the ac line would be wired straight through the box to the outlet for the amplifier (in addition to going to one side of the primary). Safety ground would also be connected straight through, as well as being connected to the metal box. It would also be prudent to put a fuse in the box, at the input, perhaps 4 or 5 amps slow blow. Regards, -- Al |
You do not need an autotransformer. Just buy a 115 - 9V transformer (I think 3A, 30W will be enough for your power amplifier) and wire the secondary in series with the mains feeding your amplifier. If you connect it the proper way you get 124-9 = 115V. If you get 133V just reverse either the primary or secondary winding terminals - not both at the same time! After checking you should put everything in a nice box. |
Eldartford, did you understand the posters question? He's obviously measured 124 volts at his place and stated: I have an older 30 w.p.c. tube amp that should be run with 110-115 Volts coming into the unit. I take this to mean the design is from the 1950's or 60's when USA voltage was lower. As for measuring the other leg of his 220, that's not a bad idea but running another line to access that side of the transformer would cost more than the transformer I provided a link to. Also, I doubt the two sides of his 220 are that far apart, the other side could be higher or lower. Even if lower, probably nowhere near 110 volts he's shooting for. Too late to advise him to not spend money, he's already purchased a Variac in hope of protecting his investment. Unfortunately Variacs are famous for turning good sound into BAD. If I misunderstood the question I hope Bigshutterbug will post back and clarify, but that's the meaning I derived from his question. |
How sure are you about the 124 volts? I would doublecheck this before buying anything. Also check the other leg of the 220 volt input to your house. Maybe the other leg is 8 percent low which means you have a neutral grounding problem. It is not unusual to see a volt difference, but 18 volts (+9 to -9) would be bad. (Does anyone know what spec the power company is obligated to maintain?) If the 124 volts is correct that's just less than 8 percent high. Don't worry about filiaments. (Has anyone ever had a filiament burn out?) Your plate voltages will be 8 percent high but different amps run the same tubes at different plate voltages so I doubt this will be a problem. Look at the bright side. You have a 32.4 watt amp :-) |
Perhaps a step down transformer, designed to operate Japan electronics within the USA? I have one made by Hammond, if you input 121 volts it delivers 105 volts at the plug. With your voltage near 125, you might hit a perfect 110-112 volts. http://www.hammondmfg.com/179.htm I suggest the one rated for 1500 Va to insure headroom. |
