Acoustic Image Focus 2R clipping problems

[bassix67]

Hey guys, I'm having problems with my acoustic image power amp.
The amp basically overheats and shuts down after about an hour set. I mainly play jazz, funk and top 40. The amp has been upgraded from 800w to 900w and serviced for this problem thanks to Rick at acoustic image. I'm powering a 2/12 DR Bass cab rated at 1000w. Could I be under driving the cab? Causing the amp to work to hard trying to to drive it. Thinking about switching speakers to neo's at less watts.
Let me know what u think.

[B String]

I've run my Focus like a race horse without it getting hot at all. Is the box 4 or 8 ohms? Either way, those amps don't run hot. I'd give Rick another call. Best customer service around.

[bassix67]

The box is 4 ohm and i run it full out with a sans amp pre controling it. It's been back to Rick 3x's already.

[bassix67]

B String, Do u run yours full volume? Had a showcase and it shut down during the set. Next set I set it at 2 o'clock and put more of me in the mix and it didn't clip out. That's all good but I don't always have PA to fall back on.

[KJung]

Originally Posted by bassix67

Hey guys, I'm having problems with my acoustic image power amp.
The amp basically overheats and shuts down after about an hour set. I mainly play jazz, funk and top 40. The amp has been upgraded from 800w to 900w and serviced for this problem thanks to Rick at acoustic image. I'm powering a 2/12 DR Bass cab rated at 1000w. Could I be under driving the cab? Causing the amp to work to hard trying to to drive it. Thinking about switching speakers to neo's at less watts.
Let me know what u think.

The wattage rating of a cab has little to do with anything. That is just a loose recommendation of the maximum power the amp can handle and is relatively useless info. There is no such thing as underpowering a cab. The 'cabinet power rating' has nothing to do with how much power the cab 'needs', nor how loud it will get at a given power level.

However, if you are pushing an amp VERY hard to try to make either a low SPL cab (a cab that takes a lot of watts to get up to full power) or too small of a cab for the job loud enough in an extreme volume situation (especially if you are cranking some additional low end into your tone), then an amp like the AI can definitely run hot and go into safety protection mode.

To give you an example, my TecAmp Puma (similar class D/SMPS design) runs totally cool and just slams at any volume with my big 4ohm 410 cabs. However, I was able to shut it down into safety protect mode at the end of one VERY loud gig (after 4 hours of wumpin') with a small 4ohm 212 cab that I had driven (like an idiot) into 'power compression' (i.e., that 'quashing' low end tone when you are driving a small cab beyond its limits and reaching that 'power compression' stage of the drivers).

My feeling is, a larger cab cab would solve all your issues.

Finally, cabs like Dr. Bass and Avatar and on occasion LDS that are kind of 'off the shelf component/crossover' designs can sometimes have some very strange impedance issues (i.e., a 4ohm rated cab having nominal impedance significantly below 4ohms). While the newer AI amps can run without a problem below 4ohms, the older models could be a bit fussy about that when really pushed.

IMO and IME.

[bassix67]

kjung, So I need more speakers to push more air so the amp doesnt work as hard?
Thanks for your input.
B.

[KJung]

Originally Posted by bassix67

kjung, So I need more speakers to push more air so the amp doesnt work as hard?
Thanks for your input.
B.

IMO and IME, yes, assuming there is nothing wrong with your amp. My Focus did get quite warm on occasion when I was REALLY pushing it, but never shut down with my big, high SPL 410's.

[bassix67]

Rick has seen the amp 3x's and they've upped the wattage rebuilt certain stages and put it thru harder test at the factory and can't get it to shut down. So, I'm starting to think it's my set-up thats causing it to go thermal. Maybe a simple 4x10 is the anwser or dump it all and start over LOL!!!!

[bassix67]

Sorry guys its a Focus SA class D 900W that keeps going thermal on me not Focus 2R

[KJung]

Originally Posted by bassix67

Sorry guys its a Focus SA class D 900W that keeps going thermal on me not Focus 2R

SA should be identical to the Focus Series I with a preamp driving the power amp through the effects return, I believe.

The original (older) AI cabs were a bit fussy with impedance. I wonder if that Dr. Bass cab dips below 4ohms in a meaningful way. Someone was just having trouble with an Avatar 4ohm cab and the Markbass LMII. Sometimes these companies that use kind of 'off the shelf stuff' cobbled together can have funny things happen to nominal impedance. The newer AI heads are safe to 2ohms I believe.

I less than 4ohm nominal impedance combined with a cab a bit too small for the gig (i.e., really having to push the amp) can easily cause a thermal shutdown.

K

[bassix67]

Hmmm Rick(AI)suggested that I borrow a 4x10 to see what happens. If it still goes thermal we'll work something out.