Voltage Attenuators: Snake Oil? 

Would you buy one? Do you have one? What do you think?

Yeah, so, regardless of what your experts say, it IS about saving your tubes. Your PR is a perfect example. Those 6v6’s, if they’re vintage, won’t last long with plate voltages of over 415vdc. That’s what line voltage attenuators are all about. Experience tells me that.

The real benefit of these is getting reliable, consistent tone and over voltage protection, especially for vintage Vox’s that do not line 120 volts, much less 128 volts, which I periodically get at home.

Snake oil: $200 power cables that improve your tone.

I'm pretty sure that EVH used variac's not for extra saturation, but as an external volume control. By bringing the voltage down by even more than you did he'd get the sound of a cranked marshall but at lower more stage friendly volumes for the clubs they were playing at the time.

I use a Brown Box because one of the amps I play is a 1965 Vibrolux Reverb, and it was never designed to see 122-124 volts, so keep everything at about 113 volts. Just to protect my amps.

I’ve had a brownie since they came out (smaller version of brown box, same voltage correction) and it definitely makes a positive difference when your wall voltage is 120-122 like most houses are and the amp is vintage 60’s running 117. I can’t say I noticed on my modern amps, however I wouldn’t be without it on my vintage blackfaces or Ampeg.

I own a few old vintage amps that are designed for 110VAC (1959) and 117VAC (1963) and use a BrownBox to feed them the voltage these amps were designed for. For me it’s more about feeding all the amp components with the voltage they were designed for. I haven’t had a need to change out my caps on any of those amps yet either. BTW, the amps sound killer to my ears. Do what you want, enjoy your personal opinion, but it works for me. Peace.

Good timing for me on this video. I don’t own any vintage amps but am having a nice amp built and was wondering if a Brown Box might be a good investment to prevent high voltage from wearing things out. (My house is a bit old and the wiring isn’t up to current specs; is grounded but old wires throughout) As far as the difference in tone from the voltage selection can’t you do the same thing by adjusting gain on the amp, assuming there is gain and master volume, and if not adjust the volume on the guitar to get the tone you want

From my understanding voltage attenuators aren’t all about saturation. Back when the circuits of 60s and 70s amps were designed the standard voltage coming out of a wall was 115v. So the thought is, the circuits were dialed in to 115, to get the True Tone of the amp you should run it at 115v. I personally think it does open the amp up more. I think it’s more of a headroom thing but also balances out the harmonics(saturation) a bit. I’ve owned a ton of vintage Amos but never a brown box. I will say when I played my 66 super reverb with a brown box it did sound better but with or without it’s probably the best clean fender amp I’ve ever heard. This info is really just from research and talking to knowledgeable people.

Voltage fluctuated from the wall even in the 50’s and 60’s,just like it does now….if I was looking for a Variac,EVH type sound,and you adjusted the bias to compensate for the lower plate voltage,one of these might be cool….I don’t think they are necessary by any means….There are many vintage amps that have been and are plugged straight into the wall with no issues…..so for a sound/tone thing,I get it……for a “my amp was designed for X wall voltage “,not so much…..

For anyone that doesn’t hear the difference, this is still a valuable asset. Your amp and its components will run cooler and therefore be more reliable. You also get a dB drop which most players are doing by killing the input signal and getting less time from the power tubes!

Great analysis. I definitely heard some stuff going on there. Not sure if it was enough to warrant me buying a voltage attenuator, though. One thing that I do know, is that the Benson sounds incredible! Wow.

Idk if I would buy one of the voltage attenuators but now you’re making want to buy that Revstar.

Not snake oil at all. It means your vintage amps run at the voltage they were designed to. It also does help preserve your tubes (a little) in the sense that in some vintage amps where they were running the plate voltages so close to the design limits of the tubes, and with modern wall voltages being what they are actually puts them above the design parameters, thus saving your tubes and costly repair bills.

Is this closely related to a bias knob? Like on a 5 knob Butler Tube driver.

The original version of Leo Fender's Music Man amps (and they weren't the only ones) achieved the "LOW" setting (half power) by cutting the voltage to the whole amp (they did this through a tap on the power transformer's primary winding), which is a more drastic cut than the Brown Box can offer. You could achieve the same results as these Music Man do by using a Variac. Since with lower voltage, the power tubes operate at much less volts on the plates (by about a 1:4 ratio, line volts to high voltage on the plates of power tubes, meaning if you reduce the line voltage by 10 volts, you've reduced the high voltage to the power tubes by about 40 volts), they will not produce as many watts, so clipping at the power tubes, saturation, occurs at a lower loudness. Some functions on some amps will quit working at low voltage levels. It has been said that using a Variac will damage your amp, and it can since they also allow you to run the voltage higher. Running a lower voltage only harms the tubes, because at lower voltages, a tube will develop a build-up on the cathode which chokes the emissions of electrons. It takes many hours of operation at very low voltages for this to happen; a Brown Box does not allow low enough voltage drop to consider this. The build-up on the cathode of the tube can be mostly burned off by simply running the tube at regular voltage for a while, say between breaks, but NOT on Standby mode, if your Standby mode is like Fender's design (most are, but a few designs such as Silvertone 1484 and a few Gibsons, simply kill the signal through the amp), which turns off the high voltage (not the heater voltage) to the tubes. If you've read this far, then now let's also add that for longest tube life, only use your (Fender-type) Standby switch to warm up the tubes' heaters; do not leave amp in standby for extended periods, as this also eventually chokes the tubes, slowly, over time. It's all right there, the real deal; read it again.

I have a Fender Twin Reverb Reissue and a Tone King Sky King. The voltage attenuators do nothing I can’t do with the control knobs on either. Now if you are changing volume down on either to try and keep someone or neighbors happy in the middle of the night then an attenuator will allow to to lower the volume bit bring some breakup back into that reduced volume. So playing open at your favorite breakup volume they are snake oil, playing a big amp at bedroom volume they have their place in sculpting your sound. That’s what I have found with them.

Voltage attenuators are to protect British amps that were designed to run on 115V and will protect the circuitry of your amp from US standard 120V that often exceeds 124V the variance in tone is subjective but the protection it gives your British amp is objective.

I've got my own transformer sourced that is a 6 amp 115v 5amp CT transformer that I plan to use like the "Tone preserver" but better. My house line voltage swings from 105v to 130v but on average its in between 115v and 126v. So I'm building my own version of the tone preserver but it will also boost. So it can buck by -5 or -10 or boost by +5 or +10. I figured the wiring out and sourced the parts. I'll use a hammond 511-0900 enclosure. And I have a meter display already that reads volts, current amps and power (watts). So that will really help me stay closer to 120v and prolong tube life not to mention it will strain my power/output transformers less. So I was just about to buy everything for the project when thought about the fact that for the same cost -$2 I could just get a 500VA (5 amp) Variac that i could mod for use with the meter display for output voltage and current etc. I also thought about putting the display into a 1590BB that would go in between the variac and the amp. That way I could always monitor the power/current and more importantly I could add a couple Millivolt displays also that would show each power tube pairs bias voltage. I could accomplish this using a simple TRS cable coming from the amps bias test points. I'd just have to add a single trs jack to the back of the amp. I already modded my Marshall with a hammond 194G choke last year and made the front panel removable with cabinet magnets. So now getting to the bias test points and bias pots on my DSL100HR is as simple as popping off the front cover. I also made the choke switchable so I can use the choke or the stock resistor it replaced. The switch is right behind the output transformer on the top of the chassis so being able to easily remove the front panel to access that really helps. So rolling tubes, checking bias and changing it, selecting choke or no choke etc is all easier now that I can just remove the front panel. Taking all the screw out from the back just to check the bias is a pain in the ass and having access from the front of the amp means I dint have to move the amp to remove the back panel for all the stuff. Anyways this whole desire for voltage regulation comes from my quest to get my power tubes to last as long as possible while still sounding really great. Before I realized the power fluctuations were happening I was going through a quad of power tubes in about 7 or 8 months. Now with careful monitoring and a cheap automatic Chinese made boost/buck voltage stabilizer they last almost 3x as long or more and I hope to improve on that further. Anyways I know the tone preserver is for vintage equipment and modern amps can handle A BIT of voltage swing. But my house line voltage swing is much more than what is considered acceptable. And just cause modern amps can handle higher voltages doesn't mean the tubes like it. For those reasons (controlling excessively high or low voltage to extend tube amp transformer life) I think voltage regulation is worth it. For tonal reasons I think it's much more subjective.

I wonder if amps in the UK where I live sound different to the same US spec amp 240v vs 125v has anyone ever tried to test this ?

The Princeton was designed for 110VAC, the rest for 120VAC. USA changed to 120VAC as a standard in 1967. I could possibly see a reason for going with lower voltage if unit was designed for lower voltage,(plate voltage?) but otherwise, I would not see why it was needed. I run Amateur radio gear , some of which is 60 years old. THAT gear might require moving a tap on a power transformer as all voltages from transformer taps are above designed level. More heat, calibration issues, etc. In industrial service, I had to have older motors rewound for the newer voltages used (240 VS 220) (440 vs 460) if they came in for service issues. If Voltages were continuously LOW in certain areas of the city, I have had motors wound for the lower voltage as well (208 vs expected 220)

did make a difference....a little sweeter especially on the cleans....did van halen use this type of thing in the studio for recording??

Rivera's Venus Deux Recording 2x6v6 is advertised as a 25/5 watt amp. I asked them how they achieve the attenuation and they said voltage reduction, probably with some other fine tuning. It definitely lowers headroom.

I always thought that the varian provided a cleaner ac and thus less noise. We used and install iso power supplier in many NYC recording studios for that reason. Getting "clean" ac makes a difference, less noise, but improvement in sound? Not so sure. I hear a slight difference, but not an "improvement" . I am lucky now to live rural and my AC spot on 110 all day everyday and I am the only load on the huge line transformer on the pole. THAT make a difference. "

These really arent about tone. And you should be rebiasing after attenuating the voltage. Especially on the -12 setting. Depending on where your players dissipation was prior to dropping the voltage you might be fine not rebiasing. But dropping voltage without rebiasing is similar to swapping tubes without rebiasing. Again this isnt about tone but they dont make that point clear because it likely helps sell these things to people who dont understand them and likely dont need them. It's about not exceeding tube and transformers limits. This can be a good way of prolonging your power tubes and transformers. Plus when gigging somdmetimescyou can run into venues with seriously high or low voltage. That's why I would build a voltage stabilizer that can boost by swapping the secondary wires around to change phase. That way you could cut by -6 or -12 and boost by +6 or +12. But I'd also use a 5v CT transformer instead of a 6.3v CT transformer because I personally think -5, -10 and +5, +10 would be more practical. Most guys who build these likely go with 6.3v CT transformers cause they are more common and cheaper at around $17 (for example the hammond 166N6 4amp 115v 6.3vCT). But if you look around you can find a 6amp 115v 5vCT for the same price. I found one in mouser last week for $17. I forget the model number though. Anyways the way I see it is you either need one of these or you dont. And if you want to drop voltage for tonal or volume reasons then using a variac (dont forget to rebias after) would be better and cheaper AND more precise AND it can boost some not just buck.

Itsvnot snake oil ppl just dont understand the imprtance of correct wall voltage. Because we as players do t have the controll of the grid coming into our homes, and when we have old equipment from the 80s 70s 60s and 50s we need to MATCH the voltage the dear equipment to the wall. In eu, we have 240 volts. But depending on time and day, it can go lower to 234volts sometimes even 248 volts. Thats where products like these is needed. A marshall amp designed for 230 will run 240 volts from the wall no issues. But class A amps like laney vc30 designed for 230, running that at wall 240 will increase the overall voltage into the amp snd destroy the output tranny when play hard at 10. Something iv done twice before already.

I emailed Friedman, Matchless and other boutique manufacturers that I own about whether the Brown Box was a good idea. Everyone said categorically that if your wall voltage runs above 120v then it is a great idea. Matchless said my Lightning specifically would sound better at 115v. These are guys that have made a ton of amps and know what they are talking about. I sue these attenuators just to run at the exact voltage the amps were rated for.

Not enough of a difference.

So many famous guitarist have used Variacs for decades

I have the Amp Maniac from Vintage Sound Workbench two run my 2 Champs at a bit lower voltage, and while I do notice that it slows the response a bit (sag/compression) in a way that I like and thinks sounds good/is more fun to play, I'd say the main benefit is getting to switch more switches and having more lights 🤫

I can tell from the comments that most people don’t have a college level education in electronics and have no idea about how a tube amplifier works.

There not enough there to warrant my money. You want to reduce voltage? Buy some smaller extension cords until you get the voltage you want! I find the boxes that transfer to a dummy load works great. You can open up your amp and still control volume. Let’s see some of those on here.

EVH, nuff said.

Wouldn't a 50 dollar variac do the same thing? Great sound on the JCM BTW.

I couldn’t tell the difference.

It's definitely not snake oil. I can hear a tone change plus - 3 volts

Snake oil

The object is not a great sound difference. It is not a fuzz box

I have one. I use it with '50s and '60s amps. '70s and '80s amps don't need it. New boutique amps and reissues don't need it. So this demo features the wrong amps.

Snake Oil.

Magic beans for sale

If someone convinces you to pay $300 for something that saves a $100 pair of tubes for an extra month than you're the same type of customer that thinks a $500 set of 70 yr old mullards will make your mediocre playing sound better.

Not snake oil but an extremely overpriced solution. Pretty sure you can build one for 1/10th of what these sell for

Hey man, I want to keep my hearing! Bye.