Vox AC15C1X

Grocer_Jack

Folks - any users of this amp out there? I'd be very interested on your views on the reliability of these amps. Also are you happy with the sound, especially with the Blue speaker? How does it sound with drive pedals? Also are there any problems in jumpering the normal and top boost channels?  Cheers and have a rockin' Friday.  

ICBM

Grocer_Jack said:

I'd be very interested on your views on the reliability of these amps.  

Hmmm... just a few weeks ago I had to repair one which had been left on overnight. It had cooked a valve, two caps and a large resistor. Not a huge job to repair, but bad enough since the PCB had to come out. It should be possible to leave an amp on indefinitely without it doing that, if it's properly designed. The valve failure and the caps/resistor were unrelated faults too - neither could have caused the other, although one of the shorted caps was certainly the cause of the resistor failing.

Not sure I would trust one now. A shame, since they sound very good, especially with the Blue speaker.

Grocer_Jack

ICBM said:

Grocer_Jack said:

I'd be very interested on your views on the reliability of these amps.  

Hmmm... just a few weeks ago I had to repair one which had been left on overnight. It had cooked a valve, two caps and a large resistor. Not a huge job to repair, but bad enough since the PCB had to come out. It should be possible to leave an amp on indefinitely without it doing that, if it's properly designed. The valve failure and the caps/resistor were unrelated faults too - neither could have caused the other, although one of the shorted caps was certainly the cause of the resistor failing.

Not sure I would trust one now. A shame, since they sound very good, especially with the Blue speaker.

Thanks - sounds a bit grim. Voxes traditionally get pretty hot over time - do you think all the failures were heat related? 

ICBM

Grocer_Jack said:

Thanks - sounds a bit grim. Voxes traditionally get pretty hot over time - do you think all the failures were heat related? 

The caps were - it was the two small-value HF suppressor caps in parallel with the main filters. The second of these shorted, causing the 'choke' resistor to burn out. Annoyingly, after replacing both these and putting the board back in, the *first* one then failed - it must also have been ready to, but was protected by the other short until the full voltage was then re-applied. So board out again... luckily I tend not to fully re-assemble an amp beyond what I need to test it the first time.

The valve was the V1 preamp valve and was unrelated, I suspect caused by the too-high DC filament voltage supply. (Over 7V, should be 6.3V). DC filament supplies are a common cause of trouble.

Grocer_Jack

Cheers. DC filament supplies are a cause of trouble in general, or just in Voxes?

dazzajl

I had one that had been upgraded to a Blue speaker and had been fitted with some highfalootinfancypants cryogenic treated valves. No idea what, if any, difference the valves made but it sounded glorious. 

Used to get bumped up and down stone stairs and thrown in the car every week and never caused me a spot of bother. 

I foolishly sold it to @TheMarlin who if I remember right sold it to a guy in Queen tribute that said it was the best sounding of the few he had.

Not sure whether that means it wasn’t typical of the amp or not and I’ve never tried another. 

ICBM

Grocer_Jack said:

DC filament supplies are a cause of trouble in general, or just in Voxes?

In general. Often they either shorten the valve life, or the rectifier overheats and fails or desolders itself, or both. They add unnecessary complication and in a well-designed amp they should not be necessary - although some modern valves do seem to have more of a noise problem with AC supplies than old ones.

uncledick

I've never had any issues with my C1X.  I do think it's fussy about overdrives in the front end.  I tend to use an original Dallas Rangemaster (lush) or an OCD for the rockier stuff.  Great for Indie stuff.  People have said it's pretty 'beamy' with sound projection which makes me think it might be better miced up for anything bigger than a small pub gig.

Grocer_Jack

Thanks folks - keep the info coming

ICBM

I should say I've never seen another dead one for any reason other than valves by the way! I just wasn't impressed by an amp that dies just from being left on for a few hours longer than normal.

susbemol

They're super reliable, one of the reasons they're used all over the biggest stages all over the place - as well as their great sound, obviously. 

Grocer_Jack

Thanks all. Anyone know whether jumpering channels is a possibility - some sort of A/B lead should work, yes? 

ICBM

Grocer_Jack said:

Thanks all. Anyone know whether jumpering channels is a possibility - some sort of A/B lead should work, yes? 

Yes, or any pedal with two outputs.