Weird problem with my Artisan 15

[joeobrien]

I have written to Blackstar about this but no reply yet. Anyone have any idea what this could be?

When I turn on the A15 I usually have it set on 5 watts output and after it warms up a bit I flick over the 15 watts. However, within about 30 seconds or so the amp "dies" and the signal just drops off to zero with a slight nasty distortion sound on the way out. I then flick back to 5 watts and its fine - plays like normal. After about 5 mins of playing I flick back to 15 watts and its working again and for some weird reason stays working for the rest of the playing session 2-4 hours no problem. But almost every time I power down completely and come back a day or so later there is this strange effect when I switch to 15 watts output.

Another thing is that the amp on 5 or 15 watts makes far too much hissing noise even at say 9 o'clock on the volume dial. With my Strat it's almost unplayable (I have to quickly roll the volume off every time in between songs) and this is without overdrive pedals then its much worse. When I played the demo amp in the shop there was no background noise at all.

I like the tone of the amp when all is well and I like the difference between EF86 and ECC83 channels but these little niggles in performance are getting me down and may make me sell the amp which would be a great shame having paid so much (its still very new). My other Peavey Valve King amp has no such problems and is totally reliable. I need to be able to totally trust my Artisan for gigs etc. but I'm not there yet and I keep expecting something to go wrong every time I turn it on. Not a good feeling. I'll of course take it back to the shop but here in Dubai its not like UK. They won't exchange unless the amp is absolutely broken - that's why I need some idea what it could be to convince them there is something wrong.

Any thoughts? Otherwise I'll sell it and buy a Marshall 1974X or Bluesbreaker RI and be done with it.

Thanks.

[ezietsman]

It sounds like you have valves on their way out. This happens. Take it to your amp tech if you don't want to change the valves yourself. He should be able to determine which are going faulty. I believe the Artisan 15 is a plug and go type of amp so you can just get new valves and put them in, no biasing required as it is a cathode biased amp. Make sure about that.

[joeobrien]

It sounds like you have valves on their way out. This happens. Take it to your amp tech if you don't want to change the valves yourself. He should be able to determine which are going faulty. I believe the Artisan 15 is a plug and go type of amp so you can just get new valves and put them in, no biasing required as it is a cathode biased amp. Make sure about that.

Yes I think you're right. If its true that the 5/15 watt switching uses the triode/pentode aspect of the power tubes then it hints at a problem with a failing power tube. The hiss/noise level could be anything so I'll go with changing the preamp tubes too. It makes me smile because I did exactly the same with my Peavey amp soon after buying it. But then I knew it was a cheap amp - I didn't expect that on an Artisan somehow.

I can probably fit them myself and order them from UK or US. Thanks for your advice. Doesn't endear me to Blackstar though - so much for the high quality components bs... Might also add Swart to my list of possible replacements.

Cheers

[ezietsman]

I don't think anyone can say the Artisans are anything but high quality. Valves can get damaged in shipping and sometimes they just go. Like lightbulbs. Fit some quality valves in there and take good care of the amp, make sure you use the standby switch (not really necessary with the valve rectifier) and they should last ages. I would go miles to get an A15 Combo. Damn those things just OOZE blues.

[joeobrien]

Yeah you're right. The tone out of the amp is absolutely wonderful at times. It doesn't need any pedal to sound good and for SRV or Bonamassa style blues (depending on which guitar I pick up) it can be really awesome. Anyway, I'll change the tubes and take it from there.

Cheers again.

[joeobrien]

Quick update for the record:

Took amp back to shop and they changed the tubes (all I think - but see below).

Amp came back fixed but had new problem. A kind of faint swishing noise even with guitar volume turned down. I've heard this noise before and it was a valve/tube problem.

Received my delivery of tubes from the Tube Depot in USA. New Sensor Mullards (EL84s, 12AX7s) and JJs (EF803S, EZ rectifier).

Fitted the tubes myself (very easy) but noticed it had an EH 12AU7 in V1 of channel 1. I was surprised and have a feeling the shop put the wrong tube in. Nowhere does it say 12AU7s in the circuit...

Anyhow, now plays perfectly. No funny noises.

Growing to like the amp - actually plays very beautifully at low volumes on clean and if you use an OD it still sounds great at low volumes.