Inuke power and clipping at -5MV? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 9 Old 06-29-2020, 10:14 PM - Thread Starter
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Inuke power and clipping at -5MV?

I fell down the rabbit hole deeper than expected (but with great return) and had to run three nu1000dsp amps to my DIY three way setup. Problem is that my AVR is said to run the same 150w out as my amps but seemed to be much cleaner and without clipping. What did I do wrong on my setup or is the amp really not sending the same power.

My AVR is a Yamaha rxa2060, My three amps are nu1000dsp in a two way setup for my three HTM12 top / pa460 bottoms (150w top / 150w bottom).

Issues are..... at -5db MV my amps start clipping, more like -4/-3 but I have my MV on lock a -5db and only on some program material the red lights will tickle. I am not clipping input at all into the inuke and I am only running rca out of my Yamaha straight into the inuke. I get that pro audio has different voltage as home audio so it doesn’t bother me so much but because I had my HTMs on my avr at much higher MV levels (but unknown same spl levels) I thought I would just ask if you all have a similar story like mine after adding pro amps.





FYI - everything runs fine at 111db spl without issues and at that level it seems very comfortable without sheetrock breaking or ears ringing so I am satisfied but curious. Yes, the room needs work.

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post #2 of 9 Old 06-29-2020, 10:21 PM
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I run a cleanbox pro between my AVR out and my iNuke inputs.

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post #3 of 9 Old 06-29-2020, 10:31 PM - Thread Starter
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I though the cleanbox was mostly meant for....
A: removing noise in the system
B: matching gain / input power

I don’t have a problem with noise and input will not clip (just before ~0db).
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post #4 of 9 Old 06-30-2020, 05:14 AM
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The level at 20 Hz is roughly 20 dB higher than at 1 kHz. That is a pretty big boost, and 20 dB in power is a factor of 100 (10^(20/10) = 10^2 = 100), so you are asking the amps to deliver ~100 times the power. You may be driving them much harder than you think.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #5 of 9 Old 06-30-2020, 07:54 AM - Thread Starter
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Quote:
Originally Posted by DonH50 View Post
The level at 20 Hz is roughly 20 dB higher than at 1 kHz. That is a pretty big boost, and 20 dB in power is a factor of 100 (10^(20/10) = 10^2 = 100), so you are asking the amps to deliver ~100 times the power. You may be driving them much harder than you think.

I run my mains with a 80hz xo in my avr, subs take over from there.
The top (350hz and up) / bottoms (80hz to 350hz) only play to 80hz and both channels clip at equal levels, highs clip just before mbm’s though.

I thought I was running things too hot but I am not boosting anything. If anything maybe I am just underpowered maybe, maybe?
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post #6 of 9 Old 06-30-2020, 06:51 PM
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Can't say I can find any reviews on your particular AVR but Gene Dellasalla (spelling?) at Audioholics has commented that some Yamaha receivers, and heck even prepros, have an unusually low preamp output before the onset of clipping, yes clipping of the preamp stage. [Say compared to Denon]. Even though we think of the clip lights in a power amp as being indicative of the unit itself (your inukes), it might be that in his odd case its circuit is instead accidentally keying on the distortion of the musical content coming in, pre-distorted from the Yamaha.



I'll see if I can find one of his reviews which speaks to this and will be back.
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post #7 of 9 Old 06-30-2020, 07:02 PM
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This unit also ends with "60" so I think it is the same series as yours. It probably shares the same Preamp circuit op amps.

"Yamaha RX-A860 Preamplifier Measurements

In the past some Yamaha AV receivers had weak output drivers in their preamp outputs where they didn't supply enough voltage to hit the magic 2Vrms, which is what most power amplifiers need to achieve full rated power. Sadly, it looks like Yamaha has taken a step backwards with the RX-A860. At 1.9Vrms output, the receiver shut down. When I checked at a slightly lower output (1.6Vrms), I noticed a pretty nasty FFT distortion profile. There simply is NO excuse for this in a day and age when opamps are cheap and supply voltage is plentiful.
Images:
Yamaha RX-A860 FFT @ 1.6Vrms.jpg

Yamaha RX-A860 Preamp Out FFT Distortion Analysis @ 1.6Vrms
Yamaha RX-A860 FFT @ 1Vrms.jpg

Yamaha RX-A860 Preamp Out FFT Distortion Analysis @ 1Vrms

At 1Vrms, the output looks much cleaner. If you're planning on using external amplification with the RX-A860, look for a power amplifier with a relatively high voltage gain (29dB or greater) so that it can achieve full rated power below where the preamp outputs of the RX-A860 starts clipping. For example, a 200-watt amplifier with a voltage gain of 29dB will reach its rated power at around 1.4Vrms."

Later, right before the conclusion:
"the preamp out section of this receiver is a bit weak, making it critical to match with a high gain amplifier to ensure the preamp itself doesn't clip while driving external amplification. "

Another possible work around would be to jack up the preamp level out puts with a device called a "line amp". It is sort of a "preamp post amp". AudioControl make nice ones I believe but by the time you get all your channels covered it may end up being better to just get a new, fundamentally beefier preout AVR or a prepro instead.

Last edited by m. zillch; 06-30-2020 at 07:07 PM.
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post #8 of 9 Old 07-02-2020, 04:20 PM
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Quote:
Originally Posted by Audiophile75 View Post
I run my mains with a 80hz xo in my avr, subs take over from there.
The top (350hz and up) / bottoms (80hz to 350hz) only play to 80hz and both channels clip at equal levels, highs clip just before mbm’s though.

I thought I was running things too hot but I am not boosting anything. If anything maybe I am just underpowered maybe, maybe?
Maybe... I see a couple of potential reasons after a brief look at the manuals for the AVR and amplifier.

The Behringer is rated at 160 W/ch, not much more than your AVR, so may not be that much of a power boost. I suspect a signal level mismatch. I could not find a gain or input sensitivity spec for the amp but it has balanced inputs and is fundamentally a pro amp so chances are it is expecting something like 4 V balanced. Your AVR is rated at 1 V output and is single-ended (so half the signal compared to a balanced output) so I suspect the AVR is simply not providing enough signal to meet the amplifier's input requirements. You could try adding a transformer or active gain stage between the AVR and amp to boost the signal level into the amplifier.

The catch is that, if the amplifiers are clipping, it is probably not sensing clipping on the input from the AVR but rather at the amplifier's output. It that case the amplifiers are simply not capable of providing the power you need (or want) and you need more powerful amplifiers. You must be listening pretty loudly and/or have speakers that are fairly low-sensitivity and/or hard to drive.

Note AVR's do not split frequency bands before the amps so unless you have an external crossover the amps may clip at the same level.

HTH - Don

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #9 of 9 Old 07-02-2020, 06:17 PM - Thread Starter
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I ordered two clean boxes yesterday. I think @markmon1 was on to something, I just find it weird that my pro amp inputs are pretty close to clipping already. Hopefully by upping the voltage it doesn’t up the input levels too much more, more of a level match rather than a level boost.

Mark, was it a easy setup? Pretty straight forward?
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