Acoustic Image: over-sensetive protection?

[Roscoe East]

So I had a somewhat disasterous gig this past weekend.

My Acoustic Image Focus 1 (Series II) head, which has worked flawlessly for the past 5 or 6 years, decided it was time to get all intermittant: It was muting for several seconds at a time any time I played a big loud transient. Power light stayed on the entire time, it definitely wasn't an intermittant patchcord or speaker cable because the mute period was always the same length, about 3 or 4 seconds every time.

It certainly seemed to me as though the amp's protection circuit was kicking in; iow, it was probably working as intended, protecting itself by muting the output (although I'm only guessing that the AI Series II heads even have a protection circuit, suppose I should check the manual to confirm).

And there are two issues with Saturday's gig that I suspect might have contributed to the amp going into protection:
1) my amp plus two guitar amps and a small PA system were all plugged into the same single 20 amp AC circuit, by way of a 100' extension cord (!!)
2) my amp was turned up just slightly louder than I've ever had it before. In all the time I've owned this head I've never had the Input and Master Gain controls up higher than 12:00, but this weekend I had them both at 1:00.

So my question is: Are either of those scenarios likely candidates for triggering the AI's protection circuit? Or does neither explain my situation, and I may have a defective amp with an overly-sensetive protection circuit?

Any insight would be greatly appreciated. Thanks.

[evilgabe]

I would just call them up. Their customer service is excellent. They should be able to help you figure out the issue.

Acoustic Image

[Bluesy Soul]

Originally Posted by evilgabe

I would just call them up. Their customer service is excellent. They should be able to help you figure out the issue.

Acoustic Image

+1.

Was the Focus well-ventilated?

[Roscoe East]

Originally Posted by evilgabe

I would just call them up. Their customer service is excellent. They should be able to help you figure out the issue.

Yeah, that goes without saying. Was just wondering if there were any similar experiences from end-users.

Originally Posted by Bluesy Soul

Was the Focus well-ventilated?

Yes, just sitting on top of my speaker cabinets in a gigantic warehouse that, while not getting direct flow-through ventilation, was open to the outside via a huge garage door. I checked several times throught our two sets to see if it was overheating, and it never felt abnormally warm.

[T-Bird]

Hi.

+1 for calling them.

They went farther than most companies I know of with me, and I bought only the front and back panel (the pre and the power modules) from a private seller.

Given the crappy electricity on site, my vote would go for normal operation in a low voltage situation where the current rises above the protection treshold.

Regards
Sam

[Roscoe East]

Originally Posted by T-Bird

Given the crappy electricity on site, my vote would go for normal operation in a low voltage situation where the current rises above the protection treshold.

Just got an answer from Acoustic Image and they concur:

"The 100 foot extension cord was probably the source of the problem. There is a circuit in the amp that turns off the output when the low voltage power supply drops to a certain voltage. The extension brought the ac line voltage down quite a bit so when you hit a transient, the internal voltage dropped enough to cause the temporary shutdown. Try using the high pass filter to reduce the power demand on the low frequency transients. That should help get rid of the problem."


And the amp worked just fine at Wednesday's show, so I'm glad it was a one-off problem!

[wcriley]

Is plugging into a 100 ft extension cord any different than plugging into 100 ft of in-wall wiring? (Assuming the wire is the same guage.)

[T-Bird]

Hi.

Glad to hear the problem was just a temporary one.

Originally Posted by wcriley

Is plugging into a 100 ft extension cord any different than plugging into 100 ft of in-wall wiring? (Assuming the wire is the same guage.)

No.

The voltage drop is the same if all the conditions are the same.

IMHO the only thing that a "power conditioner" is good for is that one can monitor the voltage. If it has a voltage meter that is, obviously.

Regards
Sam