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I am using a Behringer Inuke Nu6000 amp to power two BFM cabinets that are loaded with dual Eminence 3015lfs. I am using these with a 3 way cab and I have found that to get the cleanest sounding bass out of these I have to EQ them down to a pretty narrow range of 38-58 hz. I have a high pass set there and from 58-150 goes to the subs in the 3 way cabs I am using for tops (Carvin 1588a). In this configuration my setup sounds amazing. Although I do wish I got some lower bass.

Anyway... in that configuration my amp went into protect after about 8 hours of usage and started cutting out. I ended up turning the gain down to get it to stay on. So clearly I overheated it but why would that happen after 8 hours? What can I do to keep things humming along? My events usually go 10-14 hours... I do have limiters set using a DBX PA2 as well just to be clear.

First: for clarity, this amp only powers two subs, each sub is loaded with two 3015s. Am I correct?
Second: are the 3015s wired as series or parallel?
Third: in one line you said that the subs run from 38-58 hz, and in another line you said the subs run from 58-150 hz. I don't follow.

Odds are the BFM subs are much more efficient than the Carvin tops (I don't see a response chart in the manual for the Carvins) so you could take some load off the amp by letting your BFM subs take over the range they normally cover--up to 100hz or so.

This assumes you're using the same amp for both.

The amp powers two sub boxes for a total of 4 drivers. One box hooked up to each channel on the amp.

The tops are Carvin 1588a which are a powered 3 way cabinet with 15" drivers along with mids and tweeters. I have 38-58hz going to the sub boxes and 58hz - 20khz going to the tops.

I have the sub crossed over at 58hz because I noticed that as I dropped that crossover frequency between the sub and the top cab that the sound got progressively cleaner and the bass tightened up considerably.
Everything just sounded better.

But, even with the sub boxes getting a very narrow range of signal the amp still cut out after hours of heavy use.

tuna wrote:The amp powers two sub boxes for a total of 4 drivers. One box hooked up to each channel on the amp.

The tops are Carvin 1588a which are a powered 3 way cabinet with 15" drivers along with mids and tweeters. I have 38-58hz going to the sub boxes and 58hz - 20khz going to the tops.

I have the sub crossed over at 58hz because I noticed that as I dropped that crossover frequency between the sub and the top cab that the sound got progressively cleaner and the bass tightened up considerably.
Everything just sounded better.

But, even with the sub boxes getting a very narrow range of signal the amp still cut out after hours of heavy use.

Is the amp in a rack? Is the airflow the same for all amps in the rack? Is the rack shoved up against a wall, restricting airflow?

That amp draws air from the back, so you can always put a fan back there helping to keep a better flow of air.

Amp is in a rack along with a voltage regulator supplying power to the DBX PA2, Wifi Router, mixer and decks.

Rack was sitting under the DJ table with nothing obstructing the airflow but the DJ standing in front of it. Although you do have a good point that maybe I just need to put a fan in front of it.

They are wired parallel.

tuna wrote:I am using a Behringer Inuke Nu6000 amp to power two BFM cabinets that are loaded with dual Eminence 3015lfs. I am using these with a 3 way cab and I have found that to get the cleanest sounding bass out of these I have to EQ them down to a pretty narrow range of 38-58 hz. I have a high pass set there and from 58-150 goes to the subs in the 3 way cabs I am using for tops (Carvin 1588a). In this configuration my setup sounds amazing. Although I do wish I got some lower bass.

Anyway... in that configuration my amp went into protect after about 8 hours of usage and started cutting out. I ended up turning the gain down to get it to stay on. So clearly I overheated it but why would that happen after 8 hours? What can I do to keep things humming along? My events usually go 10-14 hours... I do have limiters set using a DBX PA2 as well just to be clear.

It was 8 hours this time. Another day it might be 6 hours, or 4, or 2.
If you drive an amp hard, at lower output impedances, it gets hot.
If it gets hot enough, it will stop (thermal protection circuitry).

How do you fix that?
Add more cabs (and amps).
This is because you can run all those cabs not as hard, for the same output.

IIRC you have "modified" T36's. I guess 38Hz is ok for a pair of them as a high pass, Bill would need to chime in on that (or someone with T36 plans).
The most excursion in drivers is at the lowest frequencies. That places the greatest demand on amplifier outputs as well.


I'm kinda wondering why you're bothering with subs though.
It seems almost pointless to run subs to 57Hz.
Most kick drum thump is between 50 and 80Hz, so it seems it's probably your Carvins that are covering that.

The whole idea of running subs is to take those frequencies away from other cabs that don't do that well. Which is why we often go for a crossover point of say 100Hz...

I brought the subs in simply to get a lot more volume of bass at lower frequencies. While the Carvins are full range and sound great just on their own... on their own the mid and hi frequencies get muddy. When I add the sub and cut out the bottom end of output on the carvin tops the sound cleans up significantly.

The 57 hz value as a crossover point between the sub cabinets and the top cabinet was just a number I arrived at in playing around with the crossover points. It seems that when I lowered the crossover there again the bass sounds being produced become a lot more clean sounding at volume.

What slopes are you using for the high/low pass?

BW48 on the high pass, LR48 on the low pass.

tuna wrote:maybe I just need to put a fan in front of it.

Nope, in back of it. Those pull air from the back to the front.

I still think Crown does it better with airflow front to back. The front of amps are almost always in a cleaner environment than the back....who wants to pull all that crap up against the wall through your amp, right?

Grant Bunter wrote:

IIRC you have "modified" T36's. I guess 38Hz is ok for a pair of them as a high pass, Bill would need to chime in on that (or someone with T36 plans).
The most excursion in drivers is at the lowest frequencies. That places the greatest demand on amplifier outputs as well.

Sorry grant but this is actally not true. Amplifiers work harder at lower impedance. Impedance minima align with excursion minima in the cabinets. Thr amp is actually working hardest where the driver moves the least in passband.

With an inuke 6000 and 2 3015lfs per channel you could thermal thr amp in the duration of a single song, if the bassline is centered at thr impedance minima and has a high duty cycle.

sine143 wrote: Sorry grant but this is actally not true. Amplifiers work harder at lower impedance. Impedance minima align with excursion minima in the cabinets. Thr amp is actually working hardest where the driver moves the least in passband.

With an inuke 6000 and 2 3015lfs per channel you could thermal thr amp in the duration of a single song, if the bassline is centered at thr impedance minima and has a high duty cycle.

Cheers S

Grant Bunter wrote:With an inuke 6000 and 2 3015lfs per channel you could thermal thr amp in the duration of a single song, if the bassline is centered at thr impedance minima and has a high duty cycle.

So how would I go remedying that? Bigger amp? Better settings on the EQ/crossover/limiter?