Why I Bought A Brown Box To Protect My Vintage Tube Amps - Ask Zac 127 

A lot of good comments and a lot of knowledge being shared here. One thing about a variac is that if the wall voltage changes over the courses of the evening, what comes out of the variac is going to go up and down; and a Brown Box would do that as well. On my stage rig, (I play through a pair of Vibroverb clones-those being '69 Bandmaster Reverbs in single 15" cabinets), I take the house voltage into a Furman AR which takes the voltage to a filtered, consistent 120v and from there into a Brown Box and then to the amps. My ears aren't as good as they used to be, but from night to night my house sound is predictable (Which makes the soundman's job SO much easier), I play better because I'm comfortable with how I sound, AND I haven't had a single amp failure since I started running this rig. Thanks for the post Zac!

Recommend biasing your amps at the lower voltage you like. I recently built a 6G6-B Bassman clone.. out ot the wall the plate voltages on the power tubes was 493 volts DC being fed with 120 VAC wall power. Dropping to 108 VAC using a variac or Brown Box brings the plates down to 446 volts DC. Rebiased at the lower level and it's working great. Same thing on a JTM 45 clone. One thing to keep in mind, if you do rebias at the lower level, make sure to use your Brownbox or Variac afterwards.. plugging into the wall voltage will drive the grid current pretty high.

I've had mine for quite a few years and wouldn't light up my Fender '67 Super Reverb without it. It also brings out the best in my Dr Z amps and my Carr amps which are , of course, hardwired and that is where the Brown Box really shines.

Not everybody has been playing guitar since they, were 8 yrs old so some of us may not know about the Brown Box. And any # of other pedals and gear. I That's why it's good to talk about older devices, gear & pedals, etc... Some of us are new and don't know about this stuff.

I built a adjustable lock system on my old variac so you can't exceed more than 120 volts and also bought a cheap voltage meter so you get a constant readout of voltage, wattage, amps and etc. It was more affordable for me and that's just a suggestion if you can't afford a Brown Box, they aren't cheap! The Brown Box is very cool and sleek as you said, nice video and good info.

Zac. Even if the brown box did not make an obvious tone difference, It is about preserving your vintage amps, and tubes.

First time I ever saw one of these was at my buddy Phil Keaggy’s house. We were talking about how heavy his AC30 was & he showed it to me & explained it to me. I’m a tweed amp guy so when I get back out I think this is a must! Good video!

Mid 90's I giged with an early 70"s 100w Marshall SL. It was so inconsistent it was a nightmare. Being an electrician started measuring the voltage at each venue. My favorite local venue was downtown Ft Wayne, IN and it would usually be 127-129v. The old venue also had crazy grounding issues. During the day when all the big buildings were full of people and the grid was sagging just a bit, it would be 121-124v.

EXCELLENT TOPIC - I've been teetering on this for a year, but am ordering one now for my 63 Bassman and 64 Super Reverb - thanks Zac.

I’d argue the brown box is good for any hand wired point to point tube amp! I use a brown box with a 5e3 and a Maz 18nr for years! A little sag is good! Little more breathy, can get under your fingers more, it’s lovely!

WOW!! No one, anywhere, has or attempted to educate or demonstrate how voltage impacts both the sound and longevity of equipment. I sincerely miss reading you monthly “Ask Zac” in Vintage Guitar Magazine. It was also refreshing to hear your honesty regarding the integrity of this magazine. Thank you for all you have done and continue to contribute to the guitar community.

This is a nice multi-tap buck. The wonderful part is that it only needs to handle the wattage of the voltage drop X current, so for instance if you only need to drop 12 volts this transformer only needs to be 1/10 the size that would be required for a full-load transformer instead of just the "buck". I made one for $30 using two filament transformers, cheap case, jacks, switches and voltage display. That let me select -6, -12, -18, -24

At 112 the amp cleaned up really nice. Thank you for sharing. Stay safe and be blessed

Nice paisley picking - more please! Digging the box - I’m on a quest now to find one. Why not? Parts are scarce and expensive. My old amps are precious to me. Thanks Zac!

I bought a brown box a few years ago!! Really helps and makes a difference in the tone as well!! My friend borrowed mine for a show or two then he bought himself one 😀 If you've invested money on a nice vintage amp or amps or even new vox or fender style amps its worth the money to get one!! I like running my tone King imperial on it which is newer amp but sounds the best around 117/118 instead of 120 to 122 to me so that's where I run it whether at the house or out somewhere else. Some places the voltage as Zac says can run as high as 125/126 so you definitely want to reduce that down going even into a newer tube amp.

What an eye opener! For us non electricians and electronics people! Thank you!

Been using a variac but not only is it kind of dangerous because if the knob gets knocked it may spit out high voltage, but it's super heavy and ridiculous to carry around. So I just pulled the trigger on a Brown Box after watching this video, thank you Zac.

Great idea; and you guys are right; these things were designed for a certain voltage. EVH was experimenting with that also for sounds back in the day.

I love mine and use it for all my amps, even my new ones. Our wall voltage often exceeds 120V.

I always knew about EVH playing with voltage levels back in the day. I learned about the brown box a couple years ago from a rig rundown video with Dave Cobb and got one for my '66 Princeton. As always great video Zac.

I bought one from the first batch from Pat. It is still running great. Does the job. My '68 champ sounds much happier with it.

I've been thinking about picking one of these up for my 65 AC30 for quite a while, I think you pushed me over the edge!

Pat Geraghty is a genius and gift to ALL us twangers with “priceless” transformers!

I bought a brownbox about 5 years ago after picking up a 62 AC30 TB/6. It really does make a difference. I haven’t ran it as low as 112 yet but I will try that next time for sure. Usually I just dial it in to 115 or so. Sometimes I’m getting 125v out of my outlet so it’s nice to tame that before juicing a high dollar vintage amp. I also have a 65 TR and 65 Princeton and I use the brownbox with all of them.

Really love your videos. Just went out to your store and bought the amp schematic shirt to go along with my Ask Zac mug and It's a sickness shirt. Keep making more videos.

Alternative product is now being made by a small company called Nocturnal Amplification . Same as the little box thing you have there. 115v and 108v inputs iirc.

I love my Brown Box! All of my amps, vintage and modern, just sound right with correct voltage. Tweed actually sounds like tweed. You are the FDR of tone, and I enjoy your Fireside Chats...

Very informative! I've always wondered about voltage adjustments on amps. Long time Vintage guitar reader, miss your column!

Just bought mine. Thank you Zac for the great info and discount.

Thanks for the awesome video Zak. We really appreciate it and what awesome information!

Awesome video Zac! I had no idea and will definitely be picking one up. Im fortunate enough to have my grandfathers ‘58 Harvard and appreciate that I will get better tone and protect the components. Love your channel.

I use the "tone Preserver " Same idea at a lower cost. Keeps my 6v6gt's happy P.s. my wall voltage at its highest was 128 volts on a Saturday near Chicago.

Good for all tube amps. I use the Brown Box for my 66 Vibrolux as well as my boutique Retro King JTM45. Chuck the builder advised to use it. Said the amp would run best at around 110 - 115 volts. Even though it can run at much higher voltages unlike vintage Fenders that are meant to run no more than 117.

Of all the variables vintage amp players obsess over, this seems like the best use of time and energy. Voltage is what your amp runs on, like gas for your car or food for your body! That said, there's a chance that your vintage amp was modified to fix the over-voltage problem during a re-cap long ago, and the brown box/variac won't help, since the B+ may have been adjusted with a resistor change. Great stuff, Zac!

Regarding the 230/240 volts market, They have the Eurovolt unit which I happen to have and it works the same way 😉👌 Zac, one thing you should have been told and that my tech warned me about... You should not change the voltage on the brown box with the amp turned on or even in standbye mode. Ideally you should connect the unit, choose the voltage that you want and only after that you should turn the amp on or in standbye. That's the way it should be done and not changing voltage up and down while the amp is already on... My trustworthy tech explained to me that by changing voltage with the amp on or in standbye is a huge blow for the tubes on the amp and it's not good to do so.... Don't know if the new owners explained that or if Pat the original designer of it can be reached still on this, but it's something supported by the way the amps were designed and how they handle voltage.. so I follow that rule of thumb religiously and ever since I'm advising others to do it as well .. set the desired voltage and only after that turn the amp on or in standbye 😉 Thanks for the video and yes, brown box and Eurovolt box are absolutely marvelous pieces of equipment 😎👌💪💪

You can buy variacs with digital readouts that will show the incoming voltage & also the voltage you set the variac to. That said, if you are gigging it is probably in your best interest to buy a brown box. I have an old variac in my home studio that I have set to around 112V for use with my 50's/60's Gibson & Fender amps. Great video Zac!

Thanks Zac! I too have a vintage 1965 Vox tube amp that I mentioned a few months ago when you first talked about your gigging setup. I went in search and found the AmpRx Brown Box about 4 months ago. You should mention that the BB has multiple outlets.

Wow I do hear the difference, its definitely smoother and not spikey with the brown box at lower voltage , Im sold!

I have 2 Brown Boxes , actually One Brown Box and One Brownie . I use then all the time with my vintage amps which I use at every gig and my sound is more consistent . I went to a club here a while back and the voltage coming out of the wall was 133 , Thank goodness I had the Brown Box with me (I always do ) To save the old 64 Deluxe Reverb from over voltage .....

Thanks Zac I've been looking for something like this. I hadn't heard of this company.

Thanks for the tip, Zac. I can tell the difference even over the internet. 👍🎸

Great video Zac!! I would also recommend to bias the amp with the voltage that your are going to use.

I really like this idea. I think its worth the money to have both some say in the voltage to the amp in order to provide consistency and because you could actually run an amp at a lower voltage all the time and chip away at the wear problem at least a little bit. It might extend out the life of the components enough to really have an impact over time, especially in a frequent usage situation.

Yeah I have a 61 Princeton and a bunch of combo's from the mid 60''s as well so probably a good idea Thanks Zac

Was a fan of "Vintaage Guitar," which I picked up each month at the great newsstand at the bookstore attached to the very first Tower Records in Sacramento, Calif. (Btw. Ted "Unabomber" Kacsynski reportedly used to browse magazines at the same store.)

Thanks for the incredible video!

Never heard of this pedal before. Thanks for the heads-up. First time viewer, new subscriber. Keep up the nice work.

Need to check one of these out for my old amps

I bought one. It is the real deal. Makes all my vintage amps (fender/gibson/marshall) sound killer!

Great stuff man.. Ton of excellent knowledge!

Derek Underdown was Dick Denny's boss at Vox. He came over to L.A. about 2008 for the launch party of my friend Jim Elyea's Book: "Vox Amps: The JMI Years". Derek told me never to run a`60's JMI era amp over 110v. The other voltage taps are fine, it's just the 120v tap that's off..

Interesting.Thanx 4 the info!!

⚓️ Thanks Zac 😎 yep … the tech bag should include a good (Fluke) multimeter. Power- particularly at festivals…. Old ass venues like the converted movie houses where the electrical systems have not been maintained, is suspect.… the ten year wire terminal tighten up is really important, voltage losses from loose terminals is significant. Higher voltage is from utilities keeping a safety factor from the brown out… where the utilities may be liable for low voltage damage. 😎

Awesome Zac🎸《☆》I had to look😁on the back of my VOX AD50VT Valvetronix amp is a power level knob. It's calibrated in Watts up to 50W. I generally keep it wfo but I'll mess around with it next session. Thanks for the info Brother👍😎☮

My oh my. My dream amp. I have a few that would be top tier/top 4 or 5, but the super'verb tops the list. The best 3 amps ive ever played thru and heard in person were a '72 silver face twin that had been modded some and among those mods were a jbl and a celestion that i cant remember exactly which. The headroom was unbelievable, the tone was beyond description, the dynamics in that wide clean tone were like nothing ive ever known. a tiny guitar volume change/ picking style/technique/etc would thicken or soften, sing like angel or honk and growl like a demon. However, it weighed a metric ton, and it was LOUD.there was no friendly volume. It was pristine clean up to like 6 but its zero-one setting on the volume dial was spinal tap-esque. My buddy, whom i readily admit bearing a covetous grudge against, was given an exquisitely mint, 110% original, gen-u-ine 1964 princeton. Its tone is best described as imagine the best intercourse of you life, now convert that to aural form. A rivera twin would fall in there as a dream does everything well acquisition too. Nobody realizes or talks about how many country icons played thru super verbs in the late 60s and the 70s on a ton of BIG recordings. Roy Nichols and James Burton come to mind in that regard. Waylon, however, might not be considered a virtuoso on the fretboard but his style was his unmistakable own and his tone, phaser,no phaser,dirty,clean, dont matter, it was PHENOMENAL!!!

Although I risked damaging my Blackface Super, I would sometimes run the veric at 90 volts. I was able to get the "brown sound" at a lower volume.

Huge difference even through my phone on yt … to bad I don’t have a sweet vintage tube amp but this is good to know my friend 👍😎

I have a black and gold one, which was a limited edition that I bought new and I personally find it works on all of my amps, not just vintage. One thing that I haven’t done yet but want to is to compare the tone of the lowered voltage but by keeping the bias the same, so for example use 70% max recommended plate dissipation at both voltages, that way I’ll better understand if the tone shaping is more of a result of the lower plate dissipation or if it’s truly just a voltage thing, that’s something I have not yet seen anyone do or even discuss.

Thanks for the video. I have a 61 Bassman, 71 Bandmaster and a 81 jmp . Took your advice and ordered one.

I wonder if that was some of the reason why my old Black Face Bass Man amp sounded so much better in this one old Church than any of the newer ones I played in. I figured it was just the acoustics of the 75 year old building vs. the 15 to 20 year old newer ones. Maybe the old wiring didn't transmit as much voltage as the newer ones. This was back in the 70's when we (or at least I) wasn't thinking about the wiring and we were still using the old 2 wire plugs. I would love to go back in time to test out that theory. as well as play my old Telecaster that I sold in the 1980s.

Vox being a UK company works very well at 220V

I bought the BB 1 from Sweetwater and it blew out in a couple of months. I called Pat and he said he had some bad transformers get a BB 2 which I did but Sweetwater did not make it easy or very nice for me. And I had spent over 5 figures there .But BB 2 works fine. I like it a lot. Some SW folks are ok to work with some are not.

Jumping in to add one other thing I learned with old Fenders. They rarely indicated what the line voltage was that they then derived all the other voltages specified on the schematics. 5F6-A Bassman was an exception, showing 117vac. With my amps I learned that the sweetest voltage setting was the one that put close to the indicated 6.3vac on the heaters. Buck transformers work extremely well with the early solid state rectified Brown Fender amps, which I learned could have over 500v on the power tube plates if run at modern line voltages. Using a buck transformer to drop the voltage to around 110vac will bring the plate voltages down into the 440-450v range.

How many ask zac-ers are planning on digging out there multimeters to check voltages in their music rooms & studios tonight?

Eye-opening, to say the least. I've been wondering why my newly-acquired '70s Vibro Champ has been running hotter than hell at times. An amp tech tried to explain to me the reason behind, but I didn't quite get it. I do now!

I own a Ho’s Electronics attenuator/reamper, it has a built in variac. I also own a load box he made for me, it also has a built in variac with 90, 110 and 120 settings. These were made in the early 90’s.

Oh wow its got a NAME now* ;) I built a few of these as I was in a LOW voltage area, where I was previously had a pretty full 250+volts meant I needed to step DOWN (Note - Angus from ACDC is VERY fussy about what volts he gives his Marshalls) Theyre quite easy to make (DISCLAIMER:- ONLY if you know your stuff working with high line voltage - if youre not an engineer type, ASK YOUR TECH) Take a tapped low voltage transformer, connect the live in to the center tap.. A 9-0-9 volt type gives around +10 +(bypass) or -10 volts, multiple taps gives you more control... Remember a 100w amp, only needs a 15-20 watt drop transformer, due to to the voltage ratio Come to think of it I never tried it on my old AC30 (which I kinda wish I still had) I used pretty tough russian EL84s and I LIKED the sound of it 'hot' - I cant recall if I ever TRIED the variac on it tho:) Tubes suffer from both too high OR too low (cathode stripping) voltage.. AC30's and Traynors run tubes WAY= hot, and dont last long if over cooked ;)

I have a 6G6B Bassman and its filter capacitors used to periodically explode due to excessive incoming grid voltage. Not a nice surprise. Living out in a rural area, at times I've had to deal with household wall socket voltages in excess of 130. Yikes. Takes the fun out of playing an old amp. The Brown Box lets me see what the local grid voltage happens to be and adjust this before it hits an old amp. I bought it mainly as a safety item, but I'm also interested in exploring the difference in sound and feel that results when those circuits are provided with the voltages they were designed to use.

Wow! A noticeable difference for sure! You can hear it with headphones

Jeez Louise! I was subscribed to VG for years....even before I owned anything vintage. I used to read your columns. I'm just now realizing you are the same Zac. I feel stupid. lol

love your channel Zak!

I built my own “brown box” buck transformer using a 12 amp Hammond 6.3v filament transformer. It’s in a large cast aluminum Hammond enclosure with a digital display. The display has current, voltage, watts, line capacitance and power factor all measuring the output. It’s fused with an IEC jack on the input and an amp style fuse holder on the output. I get 112vac and 116vac @120vac line on the outputs, which are switchable. You can get different voltage transformers to drop to a specific number, higher or lower. Whatever you do, build or buy, you do need a way to reduce the voltage going into amps designed for 110/115/117vac.

Wow, that's very cool. I've got a 1957 Gretsch, I might need one of those. Thanks man!

By pass was a noticeable harsh , piercing difference , where as the reduced voltage seems more than adequate to project tone - with out the “ pushy” response of the “over voltage” sound !

Few other added benefits: • It reduces any added noise and amp runs quieter• It also takes down the volume a hair which always helps. Great video-love my Brown box.

I’ve been meaning to get a couple of these for the longest time

Thanks Zac, I think I may pull the trigger on one of these...

How do slight changes of say +/- up to 10% or so in line voltage affect the reliability and sound of the amp ?

Great explanation and demonstration, Zac -- I only have one vintage amp. The rest are somewhat newer (25 years old or less). But when I was living in an older house about 15 years ago, I noticed my amplifiers sounding noticeably different depending on each outlet I was using. I assumed this might be due to varying voltages, but I was never quite sure, as I didn't test the voltages coming out of each outlet (the wiring in the house was definitely sketchy!). I assume a BrownBox would have helped. Great info!

A high quality line conditioner really is the ticket.

Truth is ...Most of the big name touring bands using vintage amps ... they all use very expensive voltage regulation devices. ( they would not do so if this was not a real concern ) Therefore, this is a tried and trusted, and real thing ... and the Brown Box is great value for money. (if you are not in the financial league of bands such as AC/DC, who use very expensive voltage correction technology on their vintage amps then, the Brown Box is for you ... vintage amp owners !

Sounds better when you kick it in. 👍

I’ve found the Brown Box great for any tube amp!

Hello, Zac! I hope you're having a great day!

We've all become Eric Johnson ... EVERY possible little thing! Kidding. I WISH I became within 100 light years of being as good as Eric. Lots of good discussion here. I want one. I have an old Premier and a BF Piggyback Bassman, but lots of other reasons. My wall voltage varies 117 to 124. Doesn't almost anyplace do that at different times? It would be good to find a sweet spot. I'm betting most amps - modern or vintage - have one. You could bias to a specific voltage and then always have it or be close to it. Audible? Yeah. My ears are around 7 decades old and I could hear it here. I listened to Zac play the higher voltage, then the lower, and then I stopped the video before Zac's final comments and asked myself: You think you hear a difference? What difference did you hear? I didn't want to glom on to "strident" - which he had already used. And I didn't really think the higher voltage was really strident. But definitely warmer and sweeter. No doubt about it.

I cant read what it says on the back plexi panel of my 1968 50w matshall plxi amp but i guess it would be 110volts? It is bone stock and real clean and has the original transformers im going to check this brown box and talk to my long time amp tech thanks good show !

When I noticed a problem was getting new power tubes in my JTM45 and I could not turn the bias pot low enough to get the tubes down to 70% plate dissipation. My outlet read 123.3vac. You should not have to modify the resistors in the bias circuit of your amp.

This is a great idea. There is a potential issue if you are not careful though. When you lower the input voltage you are also increasing the Bias current. Just like overvoltage is not good for an amp, overcurrent (Biased too hot) is going to reduce the life of your power tubes. If your amp was biased medium to Hot with normal wall voltage, you should check that the amp is not biased too hot when you find your sweet spot voltage. Power tubes have gotten very expensive in the last year, there is no need wear them out unnecessarily. I wouldn't want my amp to be the test subject, but using a variac, I believe you could lower the voltage so much that you could watch your power tubes die in seconds?

What about modem reissues? I have a 65 deluxe reissue is it designed to run on the modern higher wall voltage?

With a ‘61 Bandmaster, ‘63 & ‘64 Ampeg, and two ‘50s Gibsons, I think I need to check out a Brown Box! 😂

I use the blue european version of the Brown Box....The EuroVolt....infact I have two of them....one of the best things Ive ever bought....it was the answer to all my problems....I tend to get 246volts out of the wall and it just makes everything that wants 230v or 220v hard and stiff....it was a nightmare.

Although my work amps are much more recent, I have several early '60's Fenders, so there's a Brown Box in my future!

Awesome episode love the show the only thing I would add is if you know the sweet spot at the end you should buy us the tubes to match that voltage so if they like 110 or 111 or 113 if it really matters if you buy us the tubes to match the Barry egg numbers

There is definitely a different sound Zac, less strident is spot on 👍👍

At what point did amp design for "vintage" AC voltage change over to being designed to handle "modern" voltage? Would there be an improvement, or any change, in the sound of a 1960 Brown-face, Cream Tolex, Fender Showman top? It was designed to play very clean. Could lower voltage make it even cleaner? ( Or, would it depend on the speaker load? )

That Paisley Tele is just gorgeous !

Truetone didn't they used to be Visual sound effect? Best service ever, sent them my old angry fuzz. Don't know what they did, it came back improved vs what it was before?!?? People always judge craftsmen boutique stuff but these guys are passionate about what they do and the service after warranty is always there, free of charge. Including Baratza for coffee aficionados. Dave F is the only one who never sent my amp back in 13 years

I use a different make of buck transformer that accomplishes much the same thing. Worth every cent if you have vintage amps.

I bought one recently for the pair of combos I use onstage and neither is a vintage model (Dr. Z Stang Ray and Mahalo Katy 66). If it will increase tube life, it will pay for itself in that aspect alone.

Wonder if I should get one of these to protect my 1960 Gibson Skylark GA-5T. I don’t move it around, but it sometimes crackles… and the tremolo circuit has blown up once before.