Double Bass Acoustic Image Focus heat issues???

[Povl Carstensen]

Anyways, this was a 4 ohms load. Just to be a bit irritating.....

 

[richfirstbass]

Anyways, this was a 4 ohms load. Just to be a bit irritating.....

Not irritating at all, as it's a fact.

The operation of the amplifier was in it's published specification range. So, the options are (from an internet distance), operator related, environmental, the equipment, or a combination thereof.

 

[cacophonic]

I don't think it's necessary to send the OP's amp to the lab for analysis. There's enough information present in the thread to reasonably conclude that the issue is, in fact, due to heat absorbed from exposure to direct sunlight.

...I was running my Acoustic Image Focus 1 series iii with a pair of ACME low B1s at a mid level for the first two sets ... The rig was sitting in the sun and warm to the touch when I returned. I tried to power it back on...nothing...completely dead. ... After about ten minutes in the shade, I trided again and everything worked fine for the rest of the gig. In a couple of years hard regular use, this is the first time I've encountered this problem.

After reading that, I hypothesized:

... it seems extremely unlikely that merely sitting in the sun (with the power off) would create enough heat inside the box to trip the protection circuit. Some wild guesses include an intermittent faut with the power switch, the power-on delay circuit, or the protection circuit (possibly a bad relay?). ...

But then others posted the following:

ai focus series 3 owner here. we have lots of outdoor gigs. my amp cannot be used in sunlight. ... it will consistently shut down if used in sunlight

The two ACME cabs are 8 ohm each. The Focus is rated at 800 watts at 4 ohms and safe down to 2 ohms. The combination is usually very nice and there is plenty of reserve.

... the Focus is safe for extended use down to 2 ohms, and the OP mentioned that his B1s are 8ohm cabinets, which means he's pushing a load of 4ohms anyway. And, no POOOOF because the unit has a thermal protection circuit, which is what (we presume) caused the amp to shut down -- but as a result of direct sunlight, not amp load.

i still play plenty of gigs in the sunshine; i must make sure my focus 3 amp is in the shade, however. ... i have run my amp on sunny days into three 8 ohm cabs (nominal 2.67 ohm load) with no issues. ... at our regular outdoor gig i once set the amp up in the shade of my cabinets. sometime during the last set, i lost all volume. i turned toward my rig and noticed that the setting sun had moved the cabinets' shadow, and the amp was in direct sunlight. ...

Note: yodedude2 reports having had this problem several times. While he doesn't tell us what speaker system he was using when the problem occurred, there are no ACME products listed in the gear section of his profile information page.

I have a Focus series 3 and a Clarus series 2 and haven’t had a problem with overheating, often running at 2 ohms. ...

... I've used the same amp with a pair of B2s (2x10s each) and with ACME flatwounds, both much more power hungry, and run three of them combined with no issues in the past ...

After reading about the experiences of the OP, yodedude2, the input provided by Mark Golihur, and considering my own experiences as a long-time owner of AI amps and ACME cabinets (and punishing them mercilessly for years), I found myself in agreement with the theory that direct sunlight was the culprit:

... Perhaps the enclosure serves as a heat sink for the output devices, and lacks sufficient thermal dissipation to cope with the normal heat generated by the amp and the additional heat that the black-painted aluminum absorbs from exposure to sunlight. ...

Certainly, it seems obvious that the ACME speakers are neither the problem nor a significant contributing factor.

-bob

 

[yodedude2]

i've never had acmes. my amp (focus 1 series 3) shut off mid-gig three times. i mostly ran two cabinets (4 ohms paralleled) back then, but briefly used three 1x10s (eminence s2010s) for a while (2.67 ohms paralleled). the first time the amp shut off, i never quite figured out why. the second time, i moved the amp out of direct sunlight, and after our break the amp worked fine the rest of the gig. the last time, as i mentioned, the amp started out in the shade but shut off after the sunlight angle moved (see post #15).

the past few years we've have good f.o.h. support, so i mostly play through one fearful 12/6. i always keep the amp in the shade and never have issues any longer. i have years of service from my focus. i even use the focus as a subwoofer amp when i use my p.a. setup in other situations.

o.p., i gently suggest keeping the amp out of direct sunlight. if you do so, i suspect you will avoid this particular shutdown issue. best wishes from deep south texas!

 

[tyb507]

Paint it white?

 

[Don Kasper]

Paint it white?

How about "Chrome-Plating" the case?

 

[james condino]

I'd pay extra for a chrome plated version!

So I went back and played another gig at the same place today with a different band. Here is the real kicker- while I was gone this week, the owners built a very nice covered roof over the stage, so all sun related issues for the equipment and the musicians are gone.....

j.
www.condino.com
www.kaybassrepair.com