AVS Forum | Home Theater Discussions And Reviews (https://www.avsforum.com/forum/)
-   DIY Speakers and Subs (https://www.avsforum.com/forum/155-diy-speakers-subs/)
-   -   NU6000DSP Amp Rundown... (https://www.avsforum.com/forum/155-diy-speakers-subs/2911854-nu6000dsp-amp-rundown.html)

Shreds 08-13-2017 02:49 PM

NU6000DSP Amp Rundown...
 
6 Attachment(s)
I think this data might help some of you DIY'ers on a budget in your system design.

Here is the guts of the DUT:
https://www.avsforum.com/forum/attac...1&d=1502656186
https://www.avsforum.com/forum/attac...1&d=1502656400
https://www.avsforum.com/forum/attac...1&d=1502656811

Based on what I've seen online over the years of this amp being looked at or tested, I think this is at least the 3rd version of the amp. The only major mod that I see that they did is to move the toroidal inductors and power resistors into the line of the fan (which in the stock amp blows back to front).
https://www.avsforum.com/forum/attac...1&d=1502660388
This was reported to significantly help with fan noise. The only heat sink is the bottom of the chassis for both the PSU and amp output silicon so my advice would be not to put this amp on top of something else that generates heat like an AVR. I also wouldn't recommend reversing fan direction simply because there are important components that generate the most heat in front of the fans and this is the most efficient way to cool them.

PSU rail voltage measured -83.8V/83.8V. Maximum clean input before clipping is 6.8Vpk - 4.72Vrms (unbalanced). Volume controls are detented with 20 clicks. A lot of AVR's sub outputs are rated at 1.2Vrms unbalanced and I tested to see if the amp could be driven to maximum output with this signal and it can with the volumes turned up 15 clicks.

The front signal LED's... from the 1st light to where the 2nd lights up is 12dB. From the 2nd to the 3rd is 5dB and from the 3rd to the clip light is 5dB. The clip lights are only accurate at 7.5Hz and below. Above that frequency, the amp goes into clip without the red light coming on. At 100Hz, the clip light is off by 1.5dB. By the time the clip light comes on the amp is already into about 5-10% THD depending on the frequency. This is with no limiter engaged.

I right away noticed that the noise floor of the amp was horrendous. When zooming in on the waveform, I realized that the amp's output was oscillating.
https://www.avsforum.com/forum/attac...1&d=1502657314

I thought there might be something wrong with the amp since the last thing before the output of a digital amp is a low pass filter to clean up the switching noise. I feared that if after the filter there was still ~7Vp-p on the output at such a high frequency, it might be a much worse problem up stream from that. The amp never kicked the fans up at idle though and there didn't seem to be any abnormal heat. The oscillation didn't change with different loads or at different volume levels.

I decided to contact Behringer about it. After a couple rounds of back and forth describing the issue to them and showing them scope shots, this was the tech's response:

"This is a class D amplifier, Any Class D amps will most likely have this same readings. No speaker could reproduce this, since it's 20 times higher then the highest frequency a human can hear.

rest assured, there's nothing wrong with it, Class D amps do this."

Well in my experience they don't but hey whatever. :p I figured I'd carry on with the testing and if it blew up, just send it back. To it's credit the amp survived the usual trauma that goes with max output sine wave testing and now that it's hooked up to a pair of HT-18's it's doing the job.

Another thing that I noticed in the testing was that the outputs of the amp are out of phase.
https://www.avsforum.com/forum/attac...1&d=1502658180

I remember reading a while back when I think Brian O. was testing the inuke12k, he mentioned the same thing with the polarity being reversed. He guessed they might have gotten the XLR hot and cold wrong if memory serves. I don't really know if that's the case or if it gets reversed further on down the stream but either way, it's a pretty big oversight on the design of the amp and points to a lack of detailed testing of the product.
*Edit*: -At least one owner of a nu6k non dsp version has reported that his amp was in phase when compared with his nu6kdsp which was out of phase when using the Polarity .wav test. See his post here.

At idle, the amp consumed 147.71W of power. Something that I found surprising was that when the power was off to the unit but it was still plugged in, it consumed 16.17W of power. I thought the power switch broke the main wire coming in but apparently it doesn't. I didn't have the time to track down exactly what was being fed the power but this might have something to do with why some report popping issues with a remote start setup.

I tested 30Hz on a 15A power line and the most that I could get out of the amp was 817.51W(average) – 1627.69W(peak) per channel using 5.2 ohm loads. Any more and the amp would power cycle. It would power cycle using a burst test at 30Hz as well at around 1923Wpk. All of the rest of the tests that I did were performed using a 30A 120V line and I had absolutely no issues with power cycling no matter how hard I pushed so anyone with problems with cycling out there, look at your house power.

I have a lot of interesting data that I'll post here including max power, burst power, limiter settings vs. power output, frequency response graphs and DSP tricks for getting less rolloff or cheating the high pass filters to go lower (all with graphs) so stay tuned. I'll try to get it all out there this week as time permits.

*Edit* Links to all data collected:
Latency measurement
Power measurements 5.2ohms both channels driven
Power measurements 10.43ohms 1 channel driven
Power measurement TIH hulk punch scene
DSP limiter measurements
Frequency response measurement
PEQ filters measurements
High pass filter frequency lowering cheat
Low end response extension curve/signal chain rolloff compensation curves
Polarity test .wav file
Wacky waveforms
NU6000 vs. NX6000 Internal pics

18Hurts 08-13-2017 03:06 PM

Thanks for the extensive info and screen shots of the 6K,

I don't have an iNuke as a Crown XTi is more my style but any testing of monster amps is always interesting. The high frequency noise bothers me, if it was hooked to a sub I guess it would not matter. Looking forward to all the information and load testing--maybe you'll luck out and blow it up. ;)

Are you planning on testing an iNuke 3000 DSP to see if the noise problem goes away when not bridged? Shame Behringer does not throw a heatsink on the output transistors, maybe they could of lowered the fan speed if they had. Thanks again for your efforts, don't blow any subs! :)

Shreds 08-13-2017 04:48 PM

Quote:

Originally Posted by 18Hurts (Post 54628206)
The high frequency noise bothers me, if it was hooked to a sub I guess it would not matter.

Honestly, kinda bugs me too. Wait until you see how it affects the high end. ;)

Quote:

Originally Posted by 18Hurts (Post 54628206)
Are you planning on testing an iNuke 3000 DSP to see if the noise problem goes away when not bridged? Shame Behringer does not throw a heatsink on the output transistors, maybe they could of lowered the fan speed if they had.

That's a good point about bridged outputs, if I come across one I'll have to check that. Or even another 6k... I still don't fully trust their explanation. Couldn't agree more about the sinks.

18Hurts 08-13-2017 08:00 PM

Quote:

Originally Posted by Shreds (Post 54628624)
Honestly, kinda bugs me too. Wait until you see how it affects the high end. ;)

That's a good point about bridged outputs, if I come across one I'll have to check that. Or even another 6k... I still don't fully trust their explanation. Couldn't agree more about the sinks.

I heard about the hash on the high end of the iNukes when I was in the market for a DSP amp back in 2014--I went with the Crown XTi series but still keep watch. Since then, Samsung bought Harmon (Crown) and Behringer bought out LABGruppen--wonder if anything will happen? This is audio so it takes years...and years...and years for anyone to roll out anything new. If the computer companies were run like the audio companies we'd be ooohing and aaahing over faster punch card readers.

I was hoping that Behringer after purchasing LABGruppen and knowing that the monster Samsung could crush them would pull their head out and roll out one grade higher on the Class D amp side. A very clean full range amp with heatsinks, quiet fans, outstanding efficiency and a bit of overengineering with accurate specs thrown in. Don't use the term "i" or "nuke" as it sounds like something for a thirteen year old. :rolleyes:

Behringer has had a home theater page up for a year or two, no products as of yet. I figure (and hope) they realize Samsung is in the mix so maybe delayed their launch to upgrade their performance/quality/specifications?

I was interested in getting another PA class D amp for my smaller sub but with no decent choices, I'm pondering a SpeakerPower plate amp which I'll run external. Buy once, cry once :cool:

biga6761 08-13-2017 08:57 PM

Thanks so very much for your time and valuable experience being applied to this Shreds. I wait desperate for all info to come.
Totally and humbly, we are not worthy.

LTD02 08-14-2017 03:14 AM

nice work paul.
interesting finding on the 15a line.
looking forward to the rest of it.
when referencing power, would it be possible to stick to the convention of referring to power as power and none of the other crazy stuff like peak instantaneous power or whatever, as that is going to confuse people even more than behringer's kooky specs?

Shreds 08-14-2017 06:40 AM

Thanks John. I calculated the peak and average power so I'll list both and be as detailed as I can be about the testing.

Ricci 08-14-2017 06:52 AM

Quote:

Originally Posted by Shreds (Post 54628154)
Another thing that I noticed in the testing was that the outputs of the amp are out of phase.
https://www.avsforum.com/forum/attach...1&d=1502658180

I remember reading a while back when I think Brian O. was testing the inuke12k, he mentioned the same thing with the polarity being reversed. He guessed they might have gotten the XLR hot and cold wrong if memory serves. I don't really know if that's the case or if it gets reversed further on down the stream but either way, it's a pretty big oversight on the design of the amp and points to a lack of detailed testing of the product.



It took me quite a while to figure this out when I got my 6K years ago. (The first one promptly blew up and was replaced under warranty.) I used it covering 80-650Hz for a while but I noticed that I had to flip the polarity of the signal going to it to get the XO transitions cleaned up better. I figured I'd jacked up my wiring somewhere and went through everything even to the point of the 9v battery test. Finally figured out it was the amp.

lukeamdman 08-14-2017 07:43 AM

I wonder if the power figures for the 6k non-DSP would be any different.

I do recall that when I briefly did some comparisons between single channel of a unbridged nu4-6k and a 3kDSP I though the clip limiter, even when set to max, was kicking in a little early on the 3kDSP.

notnyt 08-14-2017 09:07 AM

Were you floating your scope when you tested this or did you use a differential probe?

Also when I measured the NU4-6000, switching freq was around 430khz, wonder if they changed this as well. It was one of the older versions before they moved the parts around. Those are different amps, but they're more similar than different..

Scott Simonian 08-14-2017 09:57 AM

Thanks, Paul! Wow!

tuxedocivic 08-14-2017 10:03 AM

Great stuff.

Thats terrible about the polarity. I better check my 3000. Only ever used it a few times when polarity would matter and I recall having some issues.

OSUCowboy1389 08-14-2017 10:17 AM

Very interesting stuff. Noob question. On the gain knobs what is Zero? All the way clockwise or all the way counter clockwise?

Sent from my SM-G920V using Tapatalk

pnhayden 08-14-2017 11:05 AM

Shreds, Its this level of technical communication that I think makes this forum so popular. Thank you very much for your contributions to the community.

ZLTFUL 08-14-2017 11:26 AM

Quote:

Originally Posted by OSUCowboy1389 (Post 54631746)
Very interesting stuff. Noob question. On the gain knobs what is Zero? All the way clockwise or all the way counter clockwise?

Sent from my SM-G920V using Tapatalk

Full left (counter-clockwise) is "zero" on the gain knobs.

desertdome 08-14-2017 11:45 AM

Quote:

Originally Posted by ZLTFUL (Post 54632178)
Full left (counter-clockwise) is "zero" on the gain knobs.

I'll disagree - at least with the zero. :)

Full right is "zero" with attenuation of the input signal as you rotate counter-clockwise. Most amps show the numbers like this Crest amp:

http://www.hometheatershack.com/foru...9200-front.jpg

bscool 08-14-2017 11:45 AM

Does anyone know if other Behringer amps do this also, with reversing polarity? Maybe they are using the European pinout I found out this is fairly common with Marantz pre amps, that they flip the polarity when using the XLR vs the RCA. Something about a European standard vs American. You can read more about it if you google it https://www.google.com/search?q=xlr+...h=798&dpr=1.25


https://en.wikipedia.org/wiki/XLR_connector

"EIA Standard RS-297-A describes the use of the three-pin XLR - known as XLR3 - for balanced audio signal level applications:

Prior to the introduction of this standard, the wiring of pins 2 and 3 varied. The pin 2 "hot" and pin 3 "cold" convention was typically used by European and Japanese equipment manufacturers, but American companies used pin 3 "hot" and pin 2 "cold". This caused problems when interconnecting equipment with unbalanced connections. "

My thought is maybe Behringer uses the European pinout on their Pro Audio equipment.

Edit: I just used REW impulse response to verify XLR vs RCA on the Marantz. I had assumed it was the Marantz XLR that was reversed but it is my Sunfire amp also reversed using the European standard on the XLR input. The XLR is the reverse of the polarity that the RCA use on the Sunfire amp. So the Inuke is reverse and so is the Sunfire on XLR but the Sunfire is correct when using RCA. Talk about a mess and confusion.

Edit # 2 see post 25 looks like Marantz or my 7702 uses the European pinout according to the manual.:confused:


MKtheater 08-14-2017 12:02 PM

All my gear is in phase with the Marantz and inukes.

BassThatHz 08-14-2017 12:40 PM

When I tested my xti and itech they too do not turn off fully via the front power button. They don't pop when turned on via relays though as they have delayed startup.

bscool 08-14-2017 01:07 PM

Quote:

Originally Posted by MKtheater (Post 54632408)
All my gear is in phase with the Marantz and inukes.


Do you connect using both RCA and XLR? I only noticed it when using XLR and RCA together. If using all XLR or all RCA it shows no error in Audyessy.

Edit post 25 below shows my Marantz is European pinout on the XLRs (reverse from RCA and USA XLR pinout). If someone is using all Inukes and XLR connections in their system they wouldn't notice the reverse polarity unless mixing them with another amp/integrated amp that has the reverse polarity(USA/correct polarity) like my Sunfire amp when using RCA input. But using XLR the Inuke and Sunfire are both using the same European pinout so they are in phase. Lol that is not confusing or anything :rolleyes:

RoboAVS 08-14-2017 02:17 PM

Quote:

Originally Posted by Ricci (Post 54630644)
It took me quite a while to figure this out when I got my 6K years ago. (The first one promptly blew up and was replaced under warranty.) I used it covering 80-650Hz for a while but I noticed that I had to flip the polarity of the signal going to it to get the XO transitions cleaned up better. I figured I'd jacked up my wiring somewhere and went through everything even to the point of the 9v battery test. Finally figured out it was the amp.

I recently went to nu3000dsps for my htm12s and mbms i built.
Audyssey picked up the phase problem actually.

I reversed polarity on all 4 speakers and it is resolved.
i wondered about it but never discussed it. Now i know.

mains are 8ohm and mbms are dayton pa12s....also 8ohm

Subs using 6000dsp and 3000dsp and even on the 1000dsp no polarity issues.


Regarding high frequency performance inukes have been tested at 8ohms to have good response to 20khz.

at 2 and 4ohms there are major issues making the inukes only usable for full range at 8ohms

DocOrange88 08-14-2017 02:43 PM

I just picked up 3 NU4-6000 to run all my speakers and my subs are going to run off one NU3000DSP so we will see what I find. Onkyo RZ5100 as the preamp.

ZLTFUL 08-14-2017 03:53 PM

Quote:

Originally Posted by desertdome (Post 54632278)
I'll disagree - at least with the zero. :)

Full right is "zero" with attenuation of the input signal as you rotate counter-clockwise. Most amps show the numbers like this Crest amp:

http://www.hometheatershack.com/foru...9200-front.jpg

Which is why I used "zero"... instead of zero...or 0 or nil... I swear to God Michael... :D
Save

BassThatHz 08-14-2017 04:34 PM

Quote:

Originally Posted by ZLTFUL (Post 54633778)
Quote:

Originally Posted by desertdome (Post 54632278)
I'll disagree - at least with the zero. https://www.avsforum.com//forum/images/smilies/smile.gif

Full right is "zero" with attenuation of the input signal as you rotate counter-clockwise. Most amps show the numbers like this Crest amp:

http://www.hometheatershack.com/foru...9200-front.jpg

Which is why I used "zero"... instead of zero...or 0 or nil... I swear to God Michael... https://www.avsforum.com//forum/image...es/biggrin.gif
Save

Counter-clockwise?
Weird!
Must be a china thing...

bscool 08-14-2017 05:31 PM

3 Attachment(s)
So does anyone know which standard most pre pro use for the XLR European or US? Just found this in my 7702 manual.

AV7702mk g BALANCED XLR PRE OUT connector PIN

The PIN arrangement in this device uses the European method.
In the USA method, B is COLD, and C is HOT.
When connecting a device that utilizes the USA type of PIN arrangement,
replace the B and C plugs on one side of the balanced cable.

The attached pic shows a diagram from the manual.

Edit added XLR pinout from Inkue manual and Sunfire manual which shows the European pinout so they are the same as Marantz. Maybe the European pinout is more common even in the US?

So for people using the integrated amp in the AVR or connecting another amplifier via RCA, they will be out of polarity and you will want to set the Inuke to 180 in the settings from my experience so far. I also did some more looking and it looks like Denon and Onkyo also uses European XLR pinout.

michael hurd 08-14-2017 08:05 PM

Quote:

Originally Posted by Shreds (Post 54628154)
I think this data might help some of you DIY'ers on a budget in your system design.


Based on what I've seen online over the years of this amp being looked at or tested, I think this is at least the 3rd version of the amp.



Based on the printing on the board that states REV 03, I would say that is plain and obvious, needs no mention.




https://www.avsforum.com/forum/attach...1&d=1502657314

I thought there might be something wrong with the amp since the last thing before the output of a digital amp is a low pass filter to clean up the switching noise.

I decided to contact Behringer about it. After a couple rounds of back and forth describing the issue to them and showing them scope shots, this was the tech's response:

"This is a class D amplifier, Any Class D amps will most likely have this same readings. No speaker could reproduce this, since it's 20 times higher then the highest frequency a human can hear.

rest assured, there's nothing wrong with it, Class D amps do this."

Well in my experience they don't but hey whatever. :p

Might want to consult Hypex with their N-Core amplifier > check the FAQ here:

https://www.diyclassd.com/faq

Specifically FAQ #2....

2 Q: I hooked up my UcD to an oscilloscope and I see some HF sine wave at about 400 kHz. Is this normal?

A: Yes. The 400kHz signal you see at the output of the amplifier is the residue of the switching nature of class D amplifiers. This is completely normal and does no harm. For more information please refer to our EMI application note.


I remember reading a while back when I think Brian O. was testing the inuke12k, he mentioned the same thing with the polarity being reversed. He guessed they might have gotten the XLR hot and cold wrong if memory serves. I don't really know if that's the case or if it gets reversed further on down the stream but either way, it's a pretty big oversight on the design of the amp and points to a lack of detailed testing of the product.

European vs north american standards: https://www.avsforum.com/forum/155-di...l#post54634250

I have a lot of interesting data that I'll post here including max power, burst power, limiter settings vs. power output, frequency response graphs and DSP tricks for getting less rolloff or cheating the high pass filters to go lower (all with graphs) so stay tuned. I'll try to get it all out there this week as time permits.

All good information on idle draw, and the power cycling at full tilt on a 15 amp line.

Shreds 08-14-2017 09:39 PM

NU6000DSP Latency Measurement...
 
1 Attachment(s)
Good sleuthing @bscool . I'm sure this is what Brian O. was talking about in his post about the NU12000 test. A gigantic thumbs down to the responsible party of making a different standard of wiring pins 2 and 3 based on nationality. I don't know about you guys but I just want to kick engineers sometimes.

I've only been taught by the people that I respect in the pro sound industry that the conventional wiring of XLR was 1.X-ground 2.L-line 3.R-return(or reverse) and that's how I design my stuff.

Now that I think about it though, when I performed the following test I was using 1/4" unbalanced and I had to reverse the polarity on the output of the amp in this test as well to get the waveform to match. Still don't know if it's the input or somewhere in the output stage that's flipping the script but either way, just something to be aware of.

I do this test all the time when setting up a computer and soundcard/interface rig for recording to make sure that what the ASIO driver is reporting to the DAW in latency is correct so that my takes are exactly on time. It's basically just a loopback measurement of an impulse. The loopback of the interface used with nothing in the loop showed the source signal and input signal lined up exactly. So when the NU6000DSP was put in the loop, the delay was detected.
https://www.avsforum.com/forum/attach...1&d=1502767584

Note that the polarity of the output needed to be reversed for the above waveforms to match up even though it was done with an unbalanced input. I don't know if every amp and version of the model is like this but I can say for sure that this one was.

I set the delay in the DSP to 1ms for the bottom test and you can notice how much the waveform moved. I was able to verify in the program that was used for this test that the latency of the inuke's DSP is about .5ms. This was the case no matter how many filters or sections of the DSP were engaged. I also verified that the delay setting in the DSP are right on the money for the time that they claim to delay.

I have to give credit here to Behringer's software team. This is impressively low latency. When using this amp for sub channel, experiment with adding ~0.5foot of distance for the sub channel in the AVR when taking your measurements and look at the x-over area for best response to counter this latency.

I'll try and get the power data out tomorrow night if time permits.

beastaudio 08-15-2017 12:00 PM

Lookin' good dude. Can't wait for the rest of the results :)

OSUCowboy1389 08-15-2017 12:46 PM

Quote:

Originally Posted by BassThatHz (Post 54633986)
Counter-clockwise?
Weird!
Must be a china thing...

So in looking at the inuke remote connection interface 12 o'clock appears to be 0db gain. All the way clockwise is +12db and counter clockwise is -12db.

Sent from my SM-G920V using Tapatalk

LTD02 08-15-2017 01:16 PM

Quote:

Originally Posted by bscool (Post 54634250)
So does anyone know which standard most pre pro use for the XLR European or US? Just found this in my 7702 manual.

AV7702mk g BALANCED XLR PRE OUT connector PIN

The PIN arrangement in this device uses the European method.
In the USA method, B is COLD, and C is HOT.
When connecting a device that utilizes the USA type of PIN arrangement,
replace the B and C plugs on one side of the balanced cable.

The attached pic shows a diagram from the manual.

Edit added XLR pinout from Inkue manual and Sunfire manual which shows the European pinout so they are the same as Marantz. Maybe the European pinout is more common even in the US?

So for people using the integrated amp in the AVR or connecting another amplifier via RCA, they will be out of polarity and you will want to set the Inuke to 180 in the settings from my experience so far. I also did some more looking and it looks like Denon and Onkyo also uses European XLR pinout.


i never heard of pin 3 hot, pin 2 cold, so i checked when the standard was adopted.


it looks like EIA Standard RS-297-A was adopted in 1970, so there shouldn't be any current US gear running xlr pin 3 hot.


All times are GMT -7. The time now is 06:54 AM.

Powered by vBulletin® Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
vBulletin Security provided by vBSecurity (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
User Alert System provided by Advanced User Tagging (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.