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Input sensitivity match

laidick

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#1
hi,

i have hypex NC502MP, the input sensitivity says 2.35Vrms as below:

1569390705085.png


and the AVM60 XLR output has 8.4Vrms output
1569390762144.png


would that introduce any clipping if I turn the volume up to reference level?
how should I interpret this number to make sure they match on the same baseline?

Thanks!
 

SIY

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#2
The 8.4V is the max level with everything turned up all the way and a full scale signal. As the punchline of the old joke goes, "Don't do that."

IOW, this setup will work fine as is unless you choose to abuse it.
 

Krunok

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#3
The 8.4V is the max level with everything turned up all the way and a full scale signal. As the punchline of the old joke goes, "Don't do that."

IOW, this setup will work fine as is unless you choose to abuse it.
Can you please help me with similar question?

My amp has input sensitivity of 1V. Room EQ software attenuates input signal by 12dB before the DAC which efectively lowers DAC output, right?

Does this mean that DAC with 2V output will get it's max output lowered to 0.5V due to 12 dB of attenuation?
 

Krunok

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#5
Can you give some particulars? Especially about the EQ software.
Not sure why would you need that but here it is: BruteFIR convolution engine that runs on top of Volumio (which feeds the DAC via USB) attenuates input signal by 12dB to avoid clipping due to EQ filters gain. DAC has max output of 2V and amp has input sensitivity of 1V.

Does that mean that even when i crank DAC to the max it won't give more than 0.5V because of 12dB attenuation of the input signal before the DAC?
 

SIY

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#6
I asked because I wanted to see if it was EQ software I've used before. I haven't used BruteFIR, so anything I say will be highly speculative. I'm guessing that the 12dB is put on before EQ, so that the EQ has enough headroom- then that 0.5V you're talking about only applies to the parts of the frequency range where there isn't a boost.

Practical answer: can you crank the music loud enough? If so, have a beer.
 

DonH56

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#7
If it attenuates the input but then adds gain in the EQ after that then it is hard to say the final output level. If EQ adds 12 dB then there is no net change in peak output. I'd guess the attenuation is to allow the EQ to add up to 12 dB of gain (boost) at certain frequencies without changing the peak input level. Back when I was doing digital filters optimizing dynamic range through the filter was a multi-step process as you worked through the various stages to maximize the dynamic range of each without overload. In this case it sounds like they have simplified it by not allowing more than 12 dB of boost anywhere and then attenuating the input by 12 dB to ensure the output never exceeds the input. Hopefully they are monitoring the final signal levels and adjusting the net gain to preserve signal peaks such that a max of say 0 dB in results in 0 dB output.

Note that would be at the frequency with the most boost; other frequencies will be equal or lower.

HTH - Don

Edit: @SIY provide the same answer much more succinctly as I was typing, sorry.
 

Krunok

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#8
Ok, everything clear, thank you both! :)

So what will happen in my amp when DAC pushes 2V at it's inputs? Will the clipping occur? Does it depend on the amp design?
 

DonH56

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#9
Maybe, and yes. Depends on how much headroom has. With 1 V sensitivity and 2 V input that is 6 dB over its rating. Probably clip, at least a little, but some amps design in that much headroom, some don't. If it is too loud turn it down. ;) For noise it is usually better to have higher gain earlier in the chain so I really doubt you'll have problems.
 

Krunok

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#10
Maybe, and yes. Depends on how much headroom has. With 1 V sensitivity and 2 V input that is 6 dB over its rating. Probably clip, at least a little, but some amps design in that much headroom, some don't. If it is too loud turn it down. ;) For noise it is usually better to have higher gain earlier in the chain so I really doubt you'll have problems.
When I turn off BruteFIR to have full 2V output and crank the power to the max I can't really hear clipping. But maybe I simply can't notice it as the music is so loud I can't leave it on for more than a few seconds as it is quite unpleasant. In other words, I dont' have a real problem, just asking a theoretical question. Thank you both guys, I think I'll now have that beer @SIY mentioned. Cheers!
 

laidick

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#11
The 8.4V is the max level with everything turned up all the way and a full scale signal. As the punchline of the old joke goes, "Don't do that."

IOW, this setup will work fine as is unless you choose to abuse it.
I tested the anthem RCA output and XLR output the same time, when I enable ARC, the left channel has offset +4 to achieve reference 75dB @ -30dBFs with MV= -15.
When I play a pink noise @ 0dBFs, MV -15, the RCA output voltage become 2.6V and XLR has 5.2V. (is it always double ? I am not sure but observed this so far)

Then I have XLR output to nc502mp, where the input sensitivity is 2.35V , will this 5.2V from XLR introduce clipping on the nc502mp module ? How could I tell if I don't have any pro measurement kit?

Thanks!
 
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