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Double Bass Acoustic Image Focus heat issues???

james condino

james condino

Spruce dork
Commercial User
Sep 30, 2007
5,443
13,478
asheville, nc
www.condino.com
#1
I just got back from a gig with my jazz trio and ran into a new situation for me. Perfect weather, sunny afternoon, (packed house, beautiful girls and summer dresses everywhere!) but not hot by any standard. 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- fantastic thick deep bass with ample reserve. We took about a 15 minute break (power was turned off). 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. I switched out cables, preamps, everything; finally I pushed it into the shade and pulled the strings as hard as I could to keep up playing acoustic with a pair of Django style guitar players plugged in at moderate volume. I was able to hang and be heard on everything but the solos. 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. Is there a thermal overload on these? I felt like an inadequate high school kid with some cheap pawn shop amp- not someone with a couple of grand on the stage. Is this something I should have looked at or is it one of the AI glitches that I need to live with? Not a good time of the year to be without a reliable amp....
 
#3
The speaker load is the first thing I thought of. It sounds like a lot of current is flowing, which is causing your amp to run hot. Acme's are nice, but you pay a price for their low sensitivity. You could try turning the gain down a bit or set the high pass filter a little higher. Both of these things will tend to decrease the power demand on your amp. Playing outside (which can demand more power) and the amp sitting in the sun are considerations. You can exceed the ability of most amplifiers to dissipate heat.
 
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#4
james condino said:
I just got back from a gig with my jazz trio and ran into a new situation for me. Perfect weather, sunny afternoon, (packed house, beautiful girls and summer dresses everywhere!) but not hot by any standard. 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- fantastic thick deep bass with ample reserve. We took about a 15 minute break (power was turned off). 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. I switched out cables, preamps, everything; finally I pushed it into the shade and pulled the strings as hard as I could to keep up playing acoustic with a pair of Django style guitar players plugged in at moderate volume. I was able to hang and be heard on everything but the solos. 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. Is there a thermal overload on these? I felt like an inadequate high school kid with some cheap pawn shop amp- not someone with a couple of grand on the stage. Is this something I should have looked at or is it one of the AI glitches that I need to live with? Not a good time of the year to be without a reliable amp....
Click to expand...

Sorry to hear about your amp malfunction. I run a nearly identical rig so your issue is of particular interest. If I understood your post correctly, you switched the amp off during your 15-minute break and when you returned it would not power-up. Then 10 minutes later it came back to life and operated normally. I'm pretty sure that the Focus does have thermal protection but 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?).

AI amps aren't cheap and it's gotta be frustrating to have a problem like this at a gig. Fortunately they have a reputation for excellent customer service and support and if you haven't already done so, you might give them a call.

If you succeed in solving the issue please post a follow-up.

-bob
 
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#5
I never had a AI amp, but if they have a fan, switching off a hot amp might increase the temperature (assuming the fan stops and doesn't continue to cool the amp down) on the parts and sensors. It is possible that ten minutes later the parts and sensors are cooled down enough to enable the amp again.
Just an idea...

If this is the case, it might be a good idea to leg the amp switched on to let the fans do their work and only mute the input.
 
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#6
In many modern cars, the cooling fan(s) often stay on for a while AFTER the engine has been shut off to continue the removal of heat from the engine bay.
I, too, wonder if turning the amp OFF, led to a build-up of heat, which was only removed when the amp was turned on again.
I'm just spit ballin' here - WW and EI Doubler owner.
Thanks. Good Luck - nothing worse that "gear drama"...
 
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#9
ai focus series 3 owner here. we have lots of outdoor gigs. my amp cannot be used in sunlight. simply the way it is. it will consistently shut down if used in sunlight.

i built a homemade rack case so i can use it outdoors and have it in the shade.
 
#12
Running two ohms, with extended low end cabs like those Acmes, you are consuming a lot of current, generating a lot of heat. The digital power amp will blow before your cabs give anywarning, you won't hear it coming in most cases. POOOOOOOFF. :-)
 
#13
MR PC said:
Running two ohms, with extended low end cabs like those Acmes, you are consuming a lot of current, generating a lot of heat. The digital power amp will blow before your cabs give anywarning, you won't hear it coming in most cases. POOOOOOOFF. :)
Click to expand...

What you say is certainly true on several points, with other amps/cabinets, but not in James' situation - 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.

But yes, you're right -- the Acmes aren't very efficient (by design) and can draw a lot of power, generating a lot of heat.
 
#14
AHH I see, 8 ohm cabs...but the impedance deal is pretty mysterious. With those I think that some of those sub freq low notes might push the operation of the amp down past 2 ohms, at least temporarily. Maybe a tech could comment.
 
#15
james condino said:
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. No sunshine gigs is a bummer....
Click to expand...

i still play plenty of gigs in the sunshine; i must make sure my focus 3 amp is in the shade, however. hence the rack case. as an aside, i have run my amp on sunny days into three 8 ohm cabs (nominal 2.67 ohm load) with no issues.

as a further aside, 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. this incident was what prompted me to build the shade-providing rack case.
 
#16
Perplexing issue. I have a Focus series 3 and a Clarus series 2 and haven’t had a problem with overheating, often running at 2 ohms. But then, I can’t recall having played any gigs at which the amp was in direct sunlight.

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. If this is indeed the case, I guess you could call it an engineering oversight, and while there are several obvious workarounds that could prevent the problem from occurring, AI should be made aware of the issue (if they aren’t already).

FWIW, several replies seem to insist on pointing a finger at the Acme speakers. As the OP states, the Focus is designed to handle 2-Ohm loads and rated at 1000W into that load. I often run two 4-Ohm Acme cabinets and have never experienced an issue with either the Focus or Clarus. The OP is using a pair of 8-Ohm cabinets. It’s not the Acmes.

-bob
 
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#17
yodedude2 said:
i still play plenty of gigs in the sunshine; i must make sure my focus 3 amp is in the shade, however. hence the rack case. as an aside, i have run my amp on sunny days into three 8 ohm cabs (nominal 2.67 ohm load) with no issues.

as a further aside, 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. this incident was what prompted me to build the shade-providing rack case.
Click to expand...
Your posts shed a lot of sunlight (ahem) on the issue--thanks.

But more importantly, did you crossbreed an El Camino with a GTO?!

-bob
 
#20
cacophonic said:
Your father is my hero. Have you told him that a '70 Judge wagon would make an awesome bass hauler?
Click to expand...

he once planned to take a 70ish tempest/t-37 wagon and build it to gto specs with a ram air iv. he had quite the imagination. he passed in 2006. here are just a few of the projects he worked up: rdyoder virtual museum

thanks for allowing the derail, op.
 

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