Behringer iNuke NU3000 w/o any fan...?

[ashok]

Maybe I was hasty about the sound of 'vocals'. On some albums it sounds hard compared to what I was used to . This certainly will take time to evaluate !

[compressit]

I use a 3000 DSP for my bass guitar rig @8 ohm. It is almost disturbing how cool this amp runs. Even after long hours at substantial volume.
Also, to all the iNUKE naysayers and name callers. You really need to look and listen to this package. It is one of the best values in pro audio.

[ashok]

Listened to the nu3000 for three hours last night . As I said the bass and other percussion instruments seem to have more bite which seems to be the trademark of most classD amps I have heard. Voice is good but I think it differs from my usual ss/AB amp. HF is certainly different on my other amps. They sound more 'airy' depending on the signal. But I could be wrong. Can't make a final conclusion unless I compare them side by side.
However I am happy I bought it. It's a good amp!
The fan IS terribly noisy. Not noticeable when the volume is up but very audible in between tracks and VERY obviously noisy when you go near the amp. Not acceptable at all . This surely needs to be fixed. Even my PC's fan is less noisy !

[Soldermizer]

Thus my original inspiration to remove the fan entirely

[JonasKarud]

Originally Posted by Soldermizer

Thus my original inspiration to remove the fan entirely

Or use very quiet Nexus fans: Nexus Quiet Fan | The World's Quietest Fans | 80MM Real Silent Case Fan | Ideal for a Quiet PC

[Soldermizer]

Other than putting on some easy adhesive heat sinks, how complex would it be to put the heat producing MOSFETS (HEXFETs actually) onto a large heatsink? This is probably beyond my competence. I have seen tutorials for peope who did this with PC power supplies (link).

Fanless Power Supply: Marko's Homebrew | silentpcreview.com

In the case of the Behringer NU3000, the 4 "factory" heat sinks are "live" so I guess one just cannot bolt them to the case or a large heatsink. Isn't this what mica plates are for? I am not brave (foolhardy) enough to dismount the working MOSFETS. Anyone else here want to meet that challenge?

[ashok]

I guessed the current 'heat sinks' were live so each one will have to be independent of the others. Since there is such a huge space above the transistors , one should design a heat sink that fits in 'vertically' and painted matt black. Rough idea is to attach it to the vertical section using heat sink compound and a screw setup to clamp it tight and extend upwards as fins to cool it. Maybe I should run it without the fan and see what else runs hot. Looks like the smps also has two transistors with heat sinks. A very quiet low speed fan might still be essential ?

Can anyone run this amp without the fan and some reasonable high load ( 100 watts per channel ? ) and take an IR picture of the whole board ?

[Soldermizer]

You ask much.

My test equipment is limited, but I guess this could be a valid test: put a VOM across one speaker terminal, set to AC volts, and play a sine wave and try at increasing volume, noting the voltages, until the amp goes into protect mode.

I will be glad to do this, but have a girlfriend visiting and also will have to move the pets out of the room so they don't go nuts.

I would be surprised if fanless will allow as much as 100 watts RMS/channel but who knows?

[Soldermizer]

For those interested, I did a photo tutorial of modding my 2nd NU3000. It is a Word Doc, available here:

Index of /shared/Behringer NU3000 fanless

[Soldermizer]

OK, screw the girlfriend (So to speak), and the pets, I did a quick test. My fanless NU3000 will put 13.2 VAC (50 Hz tone) into 4 ohms load (assumed, two Bose 901 II per channel), for a minute or two before one channel goes "red." Using the Power = V^2/R formula, that would be about 43 Watt/channel. Room temp was about 72 deg. F. I may do more runs to see what the max. I can do without protect coming on.