Those test results seem to indicate that the inukes are power factor corrected. If that's the case, they're an even better value than anyone realizes. In that price range it's unheard of. The whole reason I wasn't replacing my iron horses on the bass is that non-PFC switch modes usually perform worse on 100' #10's. (And labgruppen and powersoft were just out of the question..)
I originally purchased one NU4-6000 with the idea that it had to have way more power than the Rane MA6 amp (only 150 watts per channel) I was using for monitors, but after testing it against the Crest CA-9, a QSC PLX3600 I was amazed that it was so efficient and also could do serious continuous LF output, even with all four channels driven at 30Hz. I bought another two, never had an amp rack with 18,000 watts of power I could lift before.
My only complaint is the fans are loud, but I expect Behringer to release a Midas version of the amps that will correct that problem (for 50 cents of parts) and charge double.
Art
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Stole this from a bench test of the NU6000.
NU6000 at 4 Ohms both channels driven
1.80kW/channel @ 31hz
The lower trace is the AC mains current draw
Peak mains current is at 80A
The iNukes, as you can see, don't draw power cleanly. Ideally it would purely sinusoidal at 60hz and in phase with the mains voltage.
From what I understand, it's not ideal because resistance losses increase with the square of current, so short choppy peaks of high current waste more power than a more constant low amperage draw. This is in addition to the power factor losses.
So no, no PFC in iNukes. I've kindof wondered if you could buy an external power factor corrector and how much it would cost. But that's kindof at the limit of what I know about electronics.
NU6000 at 4 Ohms both channels driven
1.80kW/channel @ 31hz
The lower trace is the AC mains current draw
Peak mains current is at 80A
The iNukes, as you can see, don't draw power cleanly. Ideally it would purely sinusoidal at 60hz and in phase with the mains voltage.
From what I understand, it's not ideal because resistance losses increase with the square of current, so short choppy peaks of high current waste more power than a more constant low amperage draw. This is in addition to the power factor losses.
So no, no PFC in iNukes. I've kindof wondered if you could buy an external power factor corrector and how much it would cost. But that's kindof at the limit of what I know about electronics.
That would mean an RMS current of about 55A (or more) which is more in line with what I would expect. Art, how did you measure that 31A? Is that just the value of the 60 Hz fundamental? If so, that's also about right.
My PLX's don't like soft lines either, that's why they drive the mids/highs.
Still good to hear reports that those amps will perform in the field without going pffffft! Hell, it's only a $350 experiment one way or the other.
My cousin has been using a 6000DSP in his club to power his bass speakers for several months now. A 3000DSP is running the tops. He also has a spare of each available to be swapped in if necessary.
The AC draw of 31 amperes was measured using an ampmeter in series with the 60 Hz mains power cord. The 10.9 volt drop at that level was measured with a voltmeter on the same circuit. The slight difference in output voltage (85.5 volts at 60 Hz 84.6 volts at 30 Hz may be due to voltmeter inaccuracy.
Using pink noise (12 dB crest factor), four channels driven to clip with a 2 ohm speaker load, the NU-4 6000 only drew about 9 amps. Of interest, using 2 ohm resistor loads, the amp would cycle off every 5 seconds with pink noise, but does not cycle off with a nominal 2 ohm speaker load. Surprising that with sine waves (3 dB crest factor) it could draw more than three times the current without tripping.
Art
It seems Lowes is only stocking garbage lumber now. Still calling it "Top Choice", but its pretty crappy stuff. I am checking Home Depot now.
Is the theme in lumber now to take formaldehyde and sawdust and glue on some birch paper thin veneer and call it wood?
Any good alternatives to the Birch? As in stronger/better not cheaper.
Is the theme in lumber now to take formaldehyde and sawdust and glue on some birch paper thin veneer and call it wood?
Any good alternatives to the Birch? As in stronger/better not cheaper.
There is no wood product better or stronger than 13 ply 3/4" real Baltic Birch. Unfortunately, it generally comes in 60" x 60", not ideal for the Keystone layout.
You may have to go to a real lumberyard, as you have found much of the big box store plywood product is garbage. Just used a piece of 1/2" "Birch" (can't remember if it was Lowes or Home Depot), some of the pieces delaminated as soon as they went through the saw.
An AC ammeter calibrated for RMS with a sine wave is not perfectly accurate for a high crest factor waveform. But I would have expected it to read higher - soemwhere between that 31A and the real RMS value, if the peaks are hitting 80. Chalk it up to anotherone of the mysteries of life....
Not surprising with class D. Speakers are reactive and only dip down to that impedance minimum over a narrow band (or two). Elsewhere, the imedance is higher and partially reactive. And with ordinary amps (even low heat class H) ALL of the reactive power drawn by the speaker is dumped into the output transistors. That results in more heat and more power draw from the supply. With class D, all of the reactive power is returned to the power supply thru the output filter and flywheel diodes (less the reverse recovery losses which should be small). That means less overall current drawn from the supply.
"sandeply" at home depot is the rebranded name for "aracuo", a radianta pine product from Chile. it doesnt have as many plies as true birch, but they are even, and mostly void free. its also about 30 percent lighter than birch. Its a fairly "wet wood", and does warp a bit after th initial cut, but still useable.
The "sandeply" they're selling around here bears very little resemblence to Arauco. And "wet wood" doesn't even begin to describe the moisture content. Super-fast-growth cr@p.
One of the HDs around here had the poplar core Purebond back in stock again. Plywood run! Now that RAGBRAI is over I can go back to my projects again....
One of the HDs around here had the poplar core Purebond back in stock again. Plywood run! Now that RAGBRAI is over I can go back to my projects again....
So last night at our meeting we had some new people join and bring some of their resources. I know have available 2 Mackie FR2500 amps. Thoughts on running 1 bridged 4 ohm mono on each cab?
http://www.mackie.com/pdf/FRSeries_OM.pdf
It has a built in 30hz HPF, but I see it only states it -9db.
All input greatly appreciated. With all my back and forth just to confirm I am using the TBW100 - 4
I cannot wait to get started on this build. Hopefully tonight.
http://www.mackie.com/pdf/FRSeries_OM.pdf
It has a built in 30hz HPF, but I see it only states it -9db.
All input greatly appreciated. With all my back and forth just to confirm I am using the TBW100 - 4
I cannot wait to get started on this build. Hopefully tonight.
Those amps should do OK.
The HPF may lower the level up higher than 30 Hz a fair amount, the manual does not indicate the slope, but says "leave this off if you are powering a subwoofer".
wg_ski
I'm curious about your bridged mono input on these. I can tell you have some experience I certainly do not
Those are Yet Still Another QSC RMX Amplifier Clone. The 2500 should be ok, as the QSC RMX2450 is ok to bridge at 4 ohms. They run MUCH cooler than my old USA1310's (which are similar to the CE2000). I have had some problems with the EP2500 "clone", but I think it was an isolated incident and just Behringer being Behringer. Interesetingly enough, the smaller fully class AB version (of the original QSC) had more reports of overheating when pushed hard so stick with the 2500.
Awesome, knew you could deliver.
We are going to be running off of a generator (20kw diesel) I can only imagine the nastiness of the ac current. In my head I have a feeling everything is going to be more dialed back than pushed forward. If something goes down on the playa...that's it. I think we would all rather have a system -3db from what it can do, so that it makes it through 8 days 24/7 EDM in the desert.
From here on out, I am going to move my posts/questions over to Art's main KS thread so that another build can be referenced. If there is anything anyone would like to know during the build or have any requests for input, I owe you guys that for sure.
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