Vox AC4

Oh, well! The features of this AC4 (JMI Domino Series) are almost spartan, but this is why i like those amps!

- 4 watts
- 1 volume knob
- 1 tone knob and a coupled ON-OFF switch
- 1 speed knob for tremolo
- 1 footswich pedal for tremolo ON-OFF
- 2 channels
- single EF86 preamp
- class a EL84 poweramp
- power supply with EZ80
- simple tremolo circuit with ECC83

- 10inch speaker from Richard Allen
(note that VOX AC4 uses 8inch speakers)

The sound quality of the amp was quite bad when i bought it. I t sounded muffled even with a single single coil guitar!
This is due to a modification of a amateur! There where several additional capacitors in the amps. Especially on on the top of the output-transformer. After removing the parts, the sound quality was quite OK. But I noticed, that the speaker from Richard Allen was in a bad condition and replaced in with a Jensen AlNiCo speaker.

Now it sounded really brilliant!! For this i give it a 10

As soon as the volume knob it turned all the way up (quite loud now for only 4Watts since i replaced the speaker), the power-amp creates a warm, decent overdrive. I think it's sound is very sweet and I'm looking forward for the next recording session. Meanwhile I use i in my bedroom :-)

Additional remark: I almost forgot to tell about the tremolo. It modulates quite deep but it's sound is better than the tremolo of my AC30 from my point of view!

After this service, I think that it will be reliable for a long time again although I would not use it for a live session because the case is not built as rugged as the later VOX Amps.

I Never needed it but VOX provided the schematics of the AC4 on their support site for free. For this I give it a big 10!

All in all, it took me quite a while to service this amp and I guess that I'll never give it away. The tubes are still quite common and due to it's simplicity of the wiring it's sounding really good. Compared to the VOX VR30 (Valvetronics), the dynamics are much better and is sounding quite right without fiddling with the tone and bass knobs. Compared to my VOX AC30, the AC4 could be his little brother. For this I give it a 10 again!

Well I can only rough guess the year of mine as maybe 1963-64. Dont shoot me if I'm a year out. Well its a very cute tube amp, probably aimed at the bedroom muso, as are most of the tiny combos. It has one channel and two input jacks. One tone/one volume and one trem speed control (or should that be vibrato.. what do I know). The contols are about as basic as you can get, but all function well.
I've only used this at home as it is so small and have never tried to mic it.
It has always sounded good to me, and many others who have listened to it and is plenty loud enough for home use.

I've used this amp with all sorts.... strats,telecasters, elecrto-acoustics, and it has always given a satifying result.. and I am as picky as hell will sound.
Its fine for almost anything musical........ I dont know about anything heavy or too distorted........ but it overdrives gently and seems to be rich in harmonic content. (Bearing in mind the size and slight boxyness) but come on it's not an AC30 is it!!
It's even been on the end of a 4 way mixer with 2 guitars and 2 vocal mics.... and it worked brilliantly.. I kid you not.
Country/Rock/Beatles/ even the Shadows... and running through my old Watkins Copycat Echo with my jv strat.. LOOK OUT HANK ! and for that alone I'd give it a 9

I Don't have to rely on it and I probably wouldn't as it can get a bit crackly and hissy now and then and does need lots of care to keep it running quietly.
Footswitch is faulty but I dont use the trem so no problem.

Iv'e never dealt with vox so I have no idea.

Iv'e played guitar for 30 years using peavey amps and p/a.
Iv'e had this amp for about 18 years and to be honest, when my friend offered it to me for nothing / not working, I assumed it was just an old busted reissue or something. When he finally took it out of his attic my eyes lit up when I read Vox. He said it was just cluttering his place and he was glad to be rid. Within 2 hours it was running like new and remarkably clean too.
So I was more than happy although I had no idea about value. I was just glad to get a little amp that sounded good. Its just been a good little amp for me at home and I wouldnt part with it now.

Probably from the 1960's, mine bears a JMI lable. Bought used, had it for about 25 years.

All valve , single ended class A, single channel, 2 inputs, combined on / off volume control, tone control plus speed control for the built in tremolo.

Valve complement: is: EZ80 rectifier, ECC83 tremolo oscillator/buffer, EF86 pre-amp and EL84 output. Plywood cabinet.

1 x 8" Elac speaker, captive footwitch for the trem ... and that's it. Would be nice to have had reverb instead of tremolo IMO.

Have played just about everything through it at living room levels - Strat, Epiphone Joe Pass, precision bass, acoustic with soundhole pickup and tenor banjo fitted with a Schaller "bug", even miked up a nylon string and recorded vocals through it. All sound good at low to medium levels.

The amp records well and can be easily coaxed to give "natural" overdrive. Responds well to all sorts of pedals too. Quite boxy due to the 8" speaker.

The tremolo stopped working several years ago (possibly the valve) but as I don't like the effect, I've never investigated further. The on / off switch is temperamental so I leave it "on" and switch it on and off from the mains. The plastic air vents fell off.

However, it has NEVER broken down, I've never had it serviced and it is still running on the ORIGINAL valves, How reliable is that?

Never contacted them.

I have been playing for about 30 years and have changed equipment several times (have had Marshall, Laney, Impact (remeber those?) plus a couple of dodgy tranny amps) but have always held on to the little Vox.

Currently use Fender and Roland amps, Fender, Yamaha and Epiphone guitars and stil use the AC4 for practice.

I have gigged with this amp using an acoustic with a soundhole pickup as part of a trio with another guitar and a vocalist. We also fed a Tascam Porta 2 into it and mixed the two guitars with two vocal mics in small pub venues (without a back - up) and recorded the gig at the same time.... versatility is about imagination!

1962 or earlier copper panel era. At the time I had 2 ac-10s and a vibrochamp and I had this fantasy that maybe the AC-4 would be like an el84 version of a champ. Technically it is a single ended amp but the two are world's apart in good tone. AC-4 has no features hardly. A single volume and tone if I recall-and tremelo. I had the amp gone through and filter caps replaced, nos mullard tubes and a speaker recone by weber. Even if you played a humbucking pickup through the amp completely cranked you can barely hear it. It's useless. All tube.

This amp is no AC-10 or vibrochamp. I was hoping something that combined these two amps and quickly discovered why this has never been a very popular amp. The AC4 does NOT have the Vox sound or any sound worth recording period. It's a muffled, farty low volume amp you need a listening device to hear. It has the distinction of being the worst sounding amp I ever owned. I would take the cheapest solid state practice amp over the ac4. Worthless. The tremelo is the worst I've ever heard. It was like someone went out of there way to design the most poorly sounding tremelo of all time. This does not have that wonderful ac10 tremelo.

Cheap, rickety, ancient and unreliable. A museum piece. Not as rugged in construction as the other jmi models

none

Well, I paid $200 for it in working condition which was a steal. I put $80 in for a cap job and $50 for the speaker recone. I think I sold it for around $650. I saw one on ebay the other day for $1650 and had to laugh. This does not have the "beatles" or Vox sound. Get an ac10 instead of this. The best practice amp of all time is the vibrochamp. That's what I learned from the ac4