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Revel F208?

DNM

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(I don't get out much)

You're not alone :) I haven't seen it discussed with regards to crossovers hence an interesting post by you.

I've used MiniDSP 4x10HD for a few years and currently use the SHD for sub integration, but my interest in this was piqued reading some comments below:

ROON Knowledge Base:
https://kb.roonlabs.com/DSP_Engine:_Headroom_Management

Because of the phase shift associated with minimum phase processing, it's possible for DSP that doesn't make things louder to nonetheless cause individual samples to clip.

Roon's equalizer features are all minimum phase, and its sample rate converters can be configured to be minimum phase. Convolution filters may be minimum phase depending on how they were constructed."

ARCHIMAGO:
http://archimago.blogspot.com/2018/01/musings-more-fun-with-digital-filters.html

"Something I've noticed when playing with filters is that for minimum phase settings, because there's no pre-ring "release" of energy, the post-ringing amplitude tends to be more intense. In the 3kHz waveforms above, I only used -2dB attenuation with SoX and notice that there were a few clipped samples with the minimum phase filter setting, whereas this was not the case with linear and intermediate phase. I think this is a good reminder that DACs that use minimum phase filtering need to be a bit more careful to provide overhead for intersample overload (like MQA where the filters indeed overload!)."

I read somewhere on the MiniDSP forum that they have some unspecified headroom built into their processors to arrive at a notional 0dBFS but cant find it. I personally find the recordings that clip sound shite whether clipping or not clipping so don't loose any sleep over it.
 

DonH56

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Is there a link to this IEEE standard?

LIke Amir said, not a free one. I got a copy of the transient recorder and ADC standards as I helped author them, but I have to pay if I want it now, even though I am still a member. You may be able to download with Explore if you are an IEEE member (I did not try).

ADC: IEEE Standard 1241 https://www.techstreet.com/ieee/sta...y_code=ieee&vendor_id=4743&product_id=1772626
DAC: IEEE Standard 1658 https://www.techstreet.com/ieee/standards/ieee-1658-2011?product_id=1825326

Most product websites have white papers using the same or similar schemes (e.g. Analog Devices, e2v, Maxim, TI, etc.) Essentially you want to choose frequencies that are relatively prime and "touch" all codes possible in the record length you have. For design I always had a long-enough record that I could hit all codes.

HTH - Don
 

DonH56

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Minimum-phase filters have been discussed a couple of times -- a quick search just on my username turned up half a dozen. But others have more and more recent knowledge; you'll have to take my word for it that I knew filter theory pretty durn well at one time, long ago... Minimum-phase filters in DACs have no pre-ringing in response to an impulse (all ringing is after the impulse); linear-phase filters are symmetric so an impulse has equal rings on either side. Most of my life I've been concerned with time domain and pulse response so linear-phase filters were virtually always used. Linear phase means constant group delay which is a sneaky way of saying all frequencies are delayed equally; a pulse going into the filter looks identical coming out but with amplitude modified according to the filter's transfer function. But linear-phase is not minimum-phase... A number of audio folk claim to be able to hear the impact of pre-ringing and so prefer minimum-phase filters. Me, meh, ears of clay...
 
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phoenixdogfan

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Apparently so... though, I don't remember it being discussed (I don't get out much), or recommended. I just see "Throw a crossover in there and relieve your mains of some strain of producing lows." No memory of "But watch out! You might end up with clipping".





Only if you set some. I have a miniDSP OpenDRC-DI, which could be used as a one in -> two out digital crossover. The control software allows you to set attenuation on the input.

Also a miniDSP 2x4HD, same situation.

On the other hand, you could probably ask a roomful of people that aren't DSP Engineers whether their filters (or any other part of their system or environment is "minimum phase" and not get a knowledgeable answer.

I fit into that sub-species.

"Minimum phase. In control theory and signal processing, a linear, time-invariant system is said to be minimum-phase if the system and its inverse are causal and stable. The most general causal LTI transfer function can be uniquely factored into a series of an all-pass and a minimum phase system."

Uh, let me ask my brother.
You should probably set 1-2db atenuation on the input with the miniDSP 2 x 4 HD to avoid digital clipping?
 

RayDunzl

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You should probably set 1-2db atenuation on the input with the miniDSP 2 x 4 HD to avoid digital clipping?

Could be a good idea.

-2dB reduces the signal swing by about 1/5th.
 

hollis

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@stunta perhaps one more old school approach are tuned Helmholtz panel resonators, mounted in your alcove. http://www.mh-audio.nl/acalculators.asp#showcalc Click on the Helmholtz panel resonator. Try the calculator to see if you can come up with something that would fit your alcove and still be tuned to the big resonance frequency your are getting in there.
Sadly that link died, but here is where the calculator moved to:
http://www.mh-audio.nl/Acoustics/HelmholzPanelResonator.html

As someone with 370lbs of subs in a 12x20 bedroom, I will need to embark on a building project in this domain :)
 
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