Vox AC50 Head

My amp is a circa 1965 grey panel "big box" solid state-rectified AC50, manufactured by the original JMI company. It has very little features - just Brilliant and Normal channels, each with high and low output jacks and each with volume, treble and bass knobs. This amp has TWO XLR outputs for driving a pair of cabinets, if desired. This is not the most versatile of amps, I suppose, but what it does, it does EXTREMELY well.

I have this amp hooked up to an open-backed 2 x 12 Vox "Washington DC" AC50 reproduction cabinet, manufactured by North Coast Music (http://www.voxshowroom.com/northcoast/vox/index.html). (NCM is a company all Vox fans should be aware of us - they make superb handmade repos of all of the classic 1960s Vox cabs, trolleys, hardware, logo plates, etc., and have a license from Vox in the UK to produce these items.) My cab is fitted with Rola Celestion G12M's, although I plan on replacing these with either WeberVST Blue Pups or Vox/Celestion Blue Bulldogs in the near future, for a more authentic '60s tone. For guitars, I use a Rickenbacker 330 and 360/12 (with scatterwound toaster pickups) and a 1962 Silvertone 1446, which is a Harmony-made semi-hollow archtop with Gibson mini-humbuckers). As you probably guessed, I play mostly mid-'60s garage and British Invasion-type pop stuff, and this is the amp to use for that! It is an extremely loud amp, and is excellent for the clear, clean ringing tones that this kind of music requires. The Beatles used these amps in the first part of 1964, and if you've ever seen the footage of their first US concert (Washington, DC - Feb. '64), you can see that they were able to maintain a clean guitar tone even at volume levels meant to compete with the screaming fans. If you are looking for a crunchy distortion, this is not the amp for you. Tone-wise, I don't care much for the brilliant channel - too thin sounding for my taste. The normal channel offers ringing highs and rich, deep, warm, resonant bass response. Excellent full spectrum of tones. Like all of the classic JMI-manufactured Vox amps, it has that wonderful compressed, punchy tone that so many of us love. These amps are often favored by bassists, and I can see why. Unlike a lot of powerful amps, the AC50 sounds superb even at lower volumes, so it is suitable for small clubs as well as bigger halls. At about half-way on the volume knob it starts to get into overdrive, and it reminded me of the classic Paul Weller tone of the Jam (he favored AC30's). By that point, the amp is pretty loud.

I've only had it a short while, but it seems to be solidly manufactured. Heck, it's lasted 36 years!

The warranty expired long ago!

I've been playing guitar since 1977. For the past 13 years I've mainly used a 1985 Vox AC30, which has quite different from the original JMI models and the current AC30 reissues. I'd been hankering for a "real" Vox, but the JMI models are waaaaay out of my price range ($2000-$3000), and for several hundred dollars less than the cost of a new AC30 reissue, I was able to get a genuine JMI Vox with a sound comparable to the classic AC30's. For some reason, these amps are not as sought after as their little brothers, and are a great bargain.

made in 1969 it has the standard treble bass pots and two chanels brilian and normal it is perfect so i would never mod it and i dont wish it had any thing my boss and ibanez stompbox collection do the rest

Ive used both of my guitars alnico humbuckers deliver a very crunchy sound while single coils give it a twangy jimi style

no trouble except i had to replace the on off light

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This is an update to my original posting on the Vox AC50. I originally was using a reissue AC30 as a speaker cab (Celestion greenbacks, G12M reissues). Those speakers are very good. I wasn't thrilled with the sound, though, to rate it a full 10, but read on...
I had a feeling that the speaker combo (and cabinet) that I was jerry-rigging might be at fault. To make a long story short, I recently came upon a real, unmodified, 1966 Vox 2 x 12 cab with silver Vox Celestions (JMI) rated at 16 ohms each, 25 watts.
Needless to say, the old AC30 "reissue" and its speakers are HISTORY. I couldn't through the damn thing out fast enough. The 2 x 12 Vox cab (closed back) with the silver Vox speakers, paired up with the AC50, are like god. No shit. The compression that cab generates and the speaker combo generate so much grind, natural reverb, and pure tone that I have to change my original ratings on the AC50: TEN in EVERY FRIGGIN CATEGORY. It holds its own with any JTM45, Marshall 50 watt, Hiwatt -- you name ANY UK amp from that period and it can stand head and shoulders. You get wonderful, powerful overdrive at the 6 position on volume that it brings tears to my eyes (and has damaged my hearing permanently, but WELL WORTH the damage, you understand?)
Note that if you intend to go the vintage VOX route, you gotta pair these amp heads up with a vintage cab (with speakers) or at the very least, a modern, birch or other solid wood cabinet (no particleboard, PLEASE) and alnico or top-rated Celestion, Fane, Jensen, etc., speakers, preferrably in a closed-back configuration. Then, and only then, will you know ROCK as it was meant to be heard and played.

Probably a '64 version of the AC50 amp head; it has 2 x EL34 power tubes and a set of ECC83's in the preamp stage with silicon rectifier and input/output transformers. It's a JMI product with 4 inputs; 2 are "Normal" channel with low and high sensitivity, the other 2 are "Brilliant" with low and high sensitivity (I believe the brilliant channel is similar to the "bright" on a Fender). Each channel has 1 vol/1 treble/1 bass pot. There's a voltage selector. The speaker outputs are 2 XLR/switchcraft (like a mic cable) with 8/16 ohm selector plug; you can power two cabs off of this head. The basketweave cloth is black with white/red/green thread trim, with black plastic handle/"Vox" logo.
Really a simple amp, not unlike an AC30 without the top boost and vibra-trem circuits. No frills. The output is supposedly 50 watts, but its more like 60-70 watt rms. Is this enough power? Hell, yes, it can shake a house.
The versatility of this amp is on the same level as a '60's Vox or Fender product -- you get great tone which you can shape with the treble/bass and also use "cascading" (patching one channel into another -- read below).
This head weighs a ton! The transformers are massive (bigger than any thing I've seen on a tube Fender) and the chassis is steel, plus the birch cabinet is rather heavy on its own.

I've used Gibson/Fender/Rickenbacker with this amp and each guitar comes out sounding primo. The musical style that the amp is best suited for is similar to what you would get if you crossed a Marshall JTM45 crossed with a Vox AC30 without the top boost -- you can get a bright sounding tone on the brilliant channel and a more dark sounding tone on the normal. The EL34 pair produce a lot of "ommph". Usually, the normal channel on a AC30 is useless since you can't change the treble or bass (there aren't any pots!) but here on the AC50 you can. Hence, the sound you can get out of this channel is much better. Overall, the amp channels are not extremely "bass" oriented, so you can't get the deep dark sound that a Marshall can deliver, but then again, if that's what you want, then a Marshall is what you need.
The amp runs really quiet for something that is 35 years old. The channels are really clean up to 7 or above, so this amp is perfect if you want tone and can deliver the effects with pedals (which is what I do).
The overdrive on this amp starts at about "5-7" on the volume pot, but by that time you'll be deaf with this amp. Better to use a overdrive pedal than have your ears bleed.
I mentioned the "cascading" -- you plug your guitar into one of the output channels, and then use 1/4" jack cables to connect the "empty" inputs together -- for example, run "normal", "high sensitive" into the "brilliant", "low sensitive" input, and then plug your guitar into the "brilliant", "high sensitive" input. Then, using the volume/treble/bass pots on the normal channel, start pumping that channel into the "brilliant" by adjusting the "normal" volume up until you start to hear a change in the "brilliant" sound. Obviously, you can switch the inputs around any way you like and shape the sound accordingly. I've been able to get a pretty good vintage JTM45 sound this way by turning the treble down on the normal, pulling the bass up on the normal, and them "pumping" the normal into the brilliant channel. Likewise, I can get a "treble boost" sound by turning the "normal" channel treble to "10", bass to "1" and pump that in to the "brilliant" channel.
It's really like an old Fender amp -- you futz with the tone using the treble/bass pots, and once you've got the tone, you hook up the effects. By itself, it sound rather unique, cool, and POWERFUL.

It's really rugged in construction, but with its advanced age, I'd leave it in the studio or home. It has original electronics and has been taken care of very well over the years. Possibly this is due to the silicon rectifier; the tube rectifier version (GZ34) was a dangerous beast that could blow up if you cranked the amp too hard.
I would be careful using older amps with this much power; especially since the amp head is cooled by just a large vent at the top of the head. Use a fan to keep the EL34's happy. Also take care when doing things like "cascading"; don't overdo the "pumping".

There's no such thing -- best bet is to get the schematics for the circuit (go see http://www.voxshowroom.com) and then find someone who can deal with its innards.

The AC50 was JMI's answer to a loud amp that could be heard above the screams. Yeah, it does that very well -- I can't hear my neighbors scream at me at all when I'm past "5" on the volume setting. If you are looking for an interesting, offbeat British tube amp that will deafen your audience, get this amp. It is a great amp to play through, even at low volumes, and if you need the power, it's THERE.
I don't know much about what sort of "voice" JMI was trying to deliver on this amp -- seems that the choice of EL34's may have been influenced by Jim Marshall, maybe? The JTM bluesbreaker amp was released in '62 and I have a feeling that the bluesbreaker amp may have influenced JMI to develop their circuit to support the EL34. No matter -- the volume is there, and, there's still the "Vox" sound coming out of the speakers. The treble/bass pots on each channel really makes the amp more versatile than the standard AC30, although a treble boost would have been nice to add. But I doubt that the treble boost would have been heard above the screaming fans back in '64. Anyway, as I said earlier, a Vox is a Vox...
The bigger brother of the AC50 was the AC100, Mark I and Mark II models. Go see the voxshowroom page on info on these -- these were real mutha's with KT88 output tubes that were made in small numbers and were literally "bombs" in amp's head clothing waiting to go off -- I mean, UNSTABLE, man. I've never heard a AC100 personally but after playing through the AC50 I don't think I want to go deaf at this stage in my life.
How did I come across the AC50? Why did I choose it? I got fed up with AC30 reissues! Currently, I am playing this head through a reissue Korg/Marshall-produced Vox AC30 combo cab with Celestion G12m 8 ohm speakers. I used to play through the AC30 reissue itself but the amp circuit has been trouble since I got it back in '93 (volume jumping up and down, static, you name it -- a real piece of &*#&!, I've changed tubes, did every friggin' thing that I could) and I finally could stand it no more and just pulled the tubes from the AC30 and use it now as an "extension speaker" for the AC50. Wise move, in my opinion -- the printed circuit board on the reissue AC30 is a bitch to service and no amp person that I've talked to will touch it. Bad news.
At that point, I decided to go out and get the real thing -- the AC30's are WAY too overpriced, but the AC50 is decent money and many of them were used briefly and then put away in favor of more powerful amps (AC100, solid-state Vox, Marshalls, etc.) So a lot of AC50's have survived in really excellent condition, inside and out. I really don't use the vibrato or tremolo on an AC30, anyway, and the AC30 "normal" channel is a joke (I've read numerous posts on Harmony where nobody uses that channel at all) so the AC30 circuit doesn't really suit my needs, outside of the nifty treble boost.
Anyway, you can find these heads from time to time -- I'd demo one and see if it suits your needs, soundwise.