Amps - PAT question

not_the_dj

Our band gear is being tested this week, and I’m wondering if I need to lug a cab along for when my amp head is tested. 

Do they actually need to turn it on, and if so will it begin on standby be ok....or does it need turning on fully (in which case i’d need a cab attached)?

maltingsaudio

Interesting but the person testing will have to make the decision.The only test which requires the amp to actually power up is the leakage or load test which applies full mains for a very short space of time. This test is not recommended for computers as they can’t boot up fully in the time that the test runs. I would argue this also applies to valve amps (and digital desks)and therefor the test can be skipped. Therefor the need to have the head seeing a load during PAT testing is not necessary and you can leave your cab at home.

I would add this is my opinion and how I would test your amp and either pass or fail it. Other people doing the same may disagree down to their interpretation of what is a PAT test and what should or shouldn’t be tested for, as the rules are subject to interpretation.

ICBM

I would always want to power the amp up. Strictly speaking you don't need to take it off standby since the PAT test doesn't cover the internal workings, it's a mains safety test.

Probably 99% of valve amps are safe to switch fully on with no load anyway, as long as there is no input signal and/or the volume controls are at zero.

So basically, you don't need the cab.

The only amps I can think of which are unstable with no load and no signal are the Vox AC50 and the Mesa Dual Rectifier in 'Modern High Gain' mode, so unless it's one of these I wouldn't be too worried.

not_the_dj

Thanks guys. It’s a Jet City Custom 22 and also a 20HV. 

DJH83004

With a Class 1 piece of equipment which your amp is, the mains cable is actually plugged into the tester, with a flying lead clipped to the chassis, the amp is actually switched on to test for continuity across the transformer primary but it is not subjected to mains voltage. The test is looking for insulation resistance and earth leakage. I do these as part of a service, so have always run the amp up anyway. But a commercial PAT tester would not normally do that. 

Gadget

Bear in mind that you will likely have the mains lead tested / charged as a separate piece of equipment, so best to take the one you are likley to actually use out and about, to ensure full compliance.

not_the_dj

Gadget said:

Bear in mind that you will likely have the mains lead tested / charged as a separate piece of equipment, so best to take the one you are likley to actually use out and about, to ensure full compliance.

I’ve got all my leads ready, I have a few spare ones so i’m making sure everything is covered.