Low power for amps?

billando

I was practicing at the local hall and 3 of my 100w amps had barely any volume but lower powered amps worked. I changed all the cables, cabs and guitars...Is this a power issue at the practice place? Can't imagine 3 of my amps being faulty at the same time?! 

Funkfingers

It is possible for several amplifiers to go sick at the same time.

It is possible that the venue has some restriction on how much mains electricity can be drawn. Current starvation could do some nasty things to your valves.

Physical characteristics of a venue can affect how sound travels from stage to audience.

Big amps turned down low can sound less powerful than a lower power ones, running in their sweet spot. In effect, the 100w amps may be too powerful to work well in the venue.

soma1975

Are  the 100w amps solid state?

billando

Jcm 900 head, marshall superlead and jcm 900combo. Took the combo home expecting it to work but same thing happened! Volume so low you can speak over it at full volume. 

ICBM

Test the amps somewhere else, and if all are working fine then it could have been a venue power issue. While it's just possible (though extremely unlikely) for three amps to develop faults at the same time, it's almost impossible for them to all develop exactly the same intermittent fault in one place and then recover at the same time in another.

If it's not the amps, it could be a wiring fault in the venue.

[long story]

A long time ago I was on holiday in France over Christmas, in a chalet complex which was only about a third full because it was partly closed for maintenance during the holiday. On Christmas day, everyone put their Christmas dinner in the ovens at about 10am, but as more and more were turned on the lights started slowly dimming and the ovens not reaching the proper temperature, and by around 11 it was obvious that something was badly wrong and that dinner would not be served! Me and my dad went to investigate, and found the site substation, which was making a loud crackling sound from inside the (locked) doors. We called the site manager, who sent an electrician over - who turned up about an hour later, visibly drunk and not at all happy to be there on Christmas day. Luckily when he opened the doors it was very obvious what the problem was - a large screw terminal was sparking. The electrician produced an enormous screwdriver, and somewhat unsteadily and slightly worryingly given his drunkenness, stuck it in the terminal screw and tightened it. Immediately the sparking stopped, and everything was back to normal.

It was the neutral connection for the whole section of the site that was in use - when there was only a light load it must have been making a good enough contact to work, but not when there were twenty ovens all running at the same time. Probably someone had disconnected the other two areas when they were working on them - which would have shared the neutral connection to the incoming power cable - then forgotten to re-tighten the screw.

The drunken electrician now seemed very happy that it was such a simple job, presumably knowing how much he could charge the site for the call-out .

[/long story]

TLDR - if you find nothing wrong with the amps, it may be worth contacting the venue and suggesting they have their electrics checked, since there is a potential fire risk if it was that.

billando

Thanks for the reply. The same issue happened at my house when I took the jcm900 combo home

ICBM

billando said:

Thanks for the reply. The same issue happened at my house when I took the jcm900 combo home

Not a power supply issue then, just very unlucky with three duff amps at the same time!

billando

Ok so noticed on the combo the LEDs for output valves failing were on. Closer inspection they both weren't properly in. Not sure if something caused them to pop slightly but I put them back in properly and now it's working!! Interesting tomoro to see if my other amps were the same. Surely looking like a power issue now would u say? Only happened with the 100w amps.  

ICBM

billando said:

Surely looking like a power issue now would u say?

No. There is no way a power issue of any kind could cause fuse holders to undo themselves.

billando

I'm not an expert with that kind of thing but it's strange it likely happened on 3 100w amps. No chance of sabotage.