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Old 12th February 2013, 06:32 PM   #21
abcdmku is offline abcdmku  United States
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I'm powering 2 dual 10" folded horns at 2ohms, only 600w though. I'm yet to try max power, though. No heat at all, I've never felt heat out of the iNuke3000DSP. I've powered both 8 ohm channels to the max it will let me; One 4 ohm max and 8 ohm max, Right now I'm doing 2ohm at 600, and 8ohm at max. Next weekend I will be bridging and testing 8 ohm at max it will let me, from 10hz to 200hz.

Oh, and I wasn't able to get around to testing the power output :c
 
Old 12th February 2013, 06:46 PM   #22
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Now we're getting into DIY territory
One could get one of these amps and change the feedback to post filter.

That would also adjust the DF.

This thread is about the iNuke12000 which is stable at 2 ohms.
The current models don't say they are stable at 2, but maybe DIY modding could lower the power supply voltage for better stability at 2 ohms for the other models.

Change a few caps, And come up with some DIY ways to heatsink quietly.

These could be good DIY project amps! They are at the price point.
 
Old 12th February 2013, 09:05 PM   #23
abcdmku is offline abcdmku  United States
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Originally Posted by raintalk View Post
Now we're getting into DIY territory
One could get one of these amps and change the feedback to post filter.

That would also adjust the DF.

This thread is about the iNuke12000 which is stable at 2 ohms.
The current models don't say they are stable at 2, but maybe DIY modding could lower the power supply voltage for better stability at 2 ohms for the other models.

Change a few caps, And come up with some DIY ways to heatsink quietly.

These could be good DIY project amps! They are at the price point.
Agreed!

The iNuke3000, and iNuke1000 are 2 ohm stable. For the 3000, I know the channel will shut off if too low of an impedance is detected. I don't know how low the impedance needs to be for this to happen. Being that the 6000 is only 4 Ohm stable It might cut the channel before you can get 2 Ohms. A easy way to mod the 6000, would be to take a look at the iNuke12000's power supply. (when it comes out that is) I'm sure the 6000 and the 12000 will be a similar setup. but for 399 you could get a 10kW amp.

For the cooling, perhaps it's possible to slap some liquid cooling meant for high performance CPU's being over clocked. These start as low as $50. Obviously it wont be easy being that the connection is meant for a CPU, but I'm sure its doable.

"One could get one of these amps and change the feedback to post filter.

That would also adjust the DF."

I'm still learning about DIY amps. What would this do? And what is DF?
 
Old 12th February 2013, 10:01 PM   #24
tomi is offline tomi  Wales
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Regarding the feedback tapoff point, I have a feeling that some other extremely well-regarded PA amplifiers also do the same (not seen any schematics, just something I suspect from having chatted to their guys).
Granted, it sounded like an odd idea. I assumed the problem was that it was difficult to get global stability with a multiple-pole output filter. Taking the negative feedback tapoff before the filter you can use an integrator and have a single dominant pole as in a conventional amp.
At that point the best you can do is to estimate what the actual output, post filter, is at the top of the audio spectrum and compensate for it with some "hidden" (from the user) DSP.

But then I might be wrong.
===

Regarding power ratings, does anyone know of a simple resource or article explaining the current standards for rating amplifier power output (I had a quick look on the web a while back, but found nothing useful). It's easy to find amps with output ratings exceeding their rated power draw by a factor of 2 to 4. I'd not accuse any reputable manufacturer of fudging the numbers, but they're obviously using ratings other than a the "all day" continuous sine wave power that the unsuspecting DIYer might expect.
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Old 12th February 2013, 10:51 PM   #25
abcdmku is offline abcdmku  United States
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Tomi, for the power ratings, are you talking about when it says:
Power consumption @ 4 ohms 620W
Because that's 1/8 Power. Or are you talking about:
"USA / Canada 120V~, 60Hz (25A)
UK / Australia / Europe 220-240 V~, 50/60 Hz, (12A)
Korea / China 220-240 V~, 50/60 Hz,(12A)
Japan 100 V~, 50/60 Hz, (25A) "
 
Old 13th February 2013, 02:28 AM   #26
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The fellow testing noted the difference between the low duty cycle and relatively high peaks of music vs. continuous sine wave. The PS will draw less current on music even though it is peaking at "full power". He also noted that the amps reduce output when confronting a low duty cycle signal within I think he said 6dB of full power (rail voltage essentially).

DF = damping factor.
A measure of the ratio of the output impedance of the amp vs an 8 ohm load. A DF = 1 would be an output impedance of 8 ohms. That would be a zero feedback tube amp.

Moving the feedback point to after an output network would try to make the output look like the input, ie. flatten freq response and reduce distortion introduced by the output filter. But there is the issue of phase shift, delay and related issues that make stability a potential issue.

I suspect this is why they did it the way that they did.

It should have nil effect on at least 5kHz and down. Above that the response is load dependent.

What the tester in the nice article apparently did not try was reactive loads at any frequency. That's where we separate the good, the bad and the ugly.
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Old 14th February 2013, 11:06 PM   #27
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Quote:
And come up with some DIY ways to heatsink quietly.
One poster here who runs subs with iNUKE fanless.

The biggest concern I ever had with my 3000DSP is the fact that no matter what I do to it, it never gets warm.

A million ways to slice, dissect, ponder over specs, and thats cool, but somebody show me a better value than iNUKE DSP.

WRT the OP, if I ever had need for a 12K watt amp I would not hesitate for a second.

Bear, you would like this amp, guaranteed.
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Old 15th February 2013, 12:59 AM   #28
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If you want it to get warm, put it on a low Z dummy load, stiff AC mains, and run it up near or at clipping. It ought to get quite hot.

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Old 15th February 2013, 03:04 PM   #29
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I am [one of] those who run the NU3000 (two stacked, currently) fanless. The top will get warm to the touch but not too hot. I have four cats, and i really should find a way so that they can enjoy a warm spot to sleep on
 
Old 16th February 2013, 02:49 PM   #30
abcdmku is offline abcdmku  United States
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Originally Posted by Soldermizer View Post
I am [one of] those who run the NU3000 (two stacked, currently) fanless. The top will get warm to the touch but not too hot. I have four cats, and i really should find a way so that they can enjoy a warm spot to sleep on
Soldermizer, I thought about removing the fan, but it doesn't bother me. So I decided it would be safer to keep it. Just out of curiosity, would you have bought the NU4-6000 instead if it was out?

On aside note, MCM pushed back the date the NU4-6000s are backordered till. The new arrival date is "March 3rd". It probably will be pushed back again.

Behringer Rack Mount Digital Amplifier - iNuke Series - 1100W RMS x 4CH | NU4-6000 (NU46000) | Behringer
 

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