Starting a thread to discuss these high-end processor twins. Our own @Kal Rubinson was even impressed and several of us are owners. I have had one for several months but only set it up a couple of days ago (busy, intimidated...)
There's the earning it , spending it and having the time to enjoy what you spent ..Somewhat off-topic, I finally got my SDP-75 set up yesterday.
You can always try your best not toAin't shipping to Amir, don't want to know...
That's what I thought, but the JBL version disables/hides PEQ. I do not understand why, but there it is... Ironically, it allows you to load speaker-specific AEQ curves, so it is using PEQ in the background, just does not give the users access. Maybe as a group (consumers at large) we're too stupid so screw it up and thus it is a support nightmare for them? Dunno'...You don‘t need the Mini DSP. If you have 4 channels available, you can create sort of a MiniDSP within the Trinnov:
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The issue with these h/w devices is the number of filter taps available that limits the the effectiveness of their low frequency correction.
As a maths example, the miniDSP 2x4 HD product datasheet talks about 4096 taps. But this is the total number. For 4 channels you have 1024 taps each channel available. The frequency resolution of a 1024 taps filter @ 48 kHz samplerate is 48000/1024 = 46.875 Hz. So e.g. below 100 Hz there are just 2 frequency bins at 46.875 and 93.75 Hz. This seriously limits the control over the lower frequency range, and especially right where you need it.
If I remember, the Trinnov has 4096 taps (better than miniDSP 2x4) with a maximum filter length of 100ms. I believe the JBL SDP-75 is similar...
Whereas Acourate or Audiolense has 65,536 or even 131,072 filter taps and 500ms to 700ms of low frequency control at 10 Hz (user can set). The difference is both measurable and audible...
There also is an issue relative to Dirac Live, which uses IIR filters in the low end, which means no excessphase correction capabilities. i.e. it has no way to control standing waves at low frequencies. This is why we see similar graphs where the low frequency still has a lot of peaks and dips in the (measured) corrected response.
Don't get me wrong, not being critical of these devices. When it comes to room eq/correction, there are technical limitations one should be aware of so expectations can be realistically set.
The issue with these h/w devices is the number of filter taps available that limits the the effectiveness of their low frequency correction.
As a maths example, the miniDSP 2x4 HD product datasheet talks about 4096 taps. But this is the total number. For 4 channels you have 1024 taps each channel available. The frequency resolution of a 1024 taps filter @ 48 kHz samplerate is 48000/1024 = 46.875 Hz. So e.g. below 100 Hz there are just 2 frequency bins at 46.875 and 93.75 Hz. This seriously limits the control over the lower frequency range, and especially right where you need it.
If I remember, the Trinnov has 4096 taps (better than miniDSP 2x4) with a maximum filter length of 100ms. I believe the JBL SDP-75 is similar...
Whereas Acourate or Audiolense has 65,536 or even 131,072 filter taps and 500ms to 700ms of low frequency control at 10 Hz (user can set). The difference is both measurable and audible...
There also is an issue relative to Dirac Live, which uses IIR filters in the low end, which means no excessphase correction capabilities. i.e. it has no way to control standing waves at low frequencies. This is why we see similar graphs where the low frequency still has a lot of peaks and dips in the (measured) corrected response.
Don't get me wrong, not being critical of these devices. When it comes to room eq/correction, there are technical limitations one should be aware of so expectations can be realistically set.
You can always try your best not to peak
Sure, and make all us poor folk green with envy.Starting a thread to discuss these high-end processor twins.
I'd really love to see some measurements and if either beats the mid-fi stuff by a large margin.
That is some good info, Mitch, thank you! I had not thought about the tap lengths -- what little real-world IIR/FIR filter design I have done has not been DSP-based and at such high frequencies that many taps wasn't practical to implement. And my few graduate DSP courses were long, long ago (but in this galaxy). But your comments resonate (see what I did there?) as MCCAC had phase adjustment I could tweak, along with the phase adjustment on my subs, that made it a lot easier (not easy, mind) to dial them in than with Dirac Live.
Need to dig out your book and look again, pick up Acourate or something... Of course, now I'd fear wasting a bunch of moola on this new toy. I may hate you yet, Mitch, despite you being such a nice guy and all...
How important are the very long lengths (and correspondingly long times) in smaller rooms? Though Trinnov is coming from mostly large spaces so you'd think they want even more...
Haha I would suggest the smaller the room, the more low frequency excessphase correction is required to smooth out the low frequency reflections. i.e. typically the smaller the room worsens the peaks and dips so you get +20 dB or more SPL variation at low frequencies below Schroeder. Of course, room ratio plays a major role as well as size.
As far as the h/w devices are concerned, the filter tap limitation can't be overcome as it is fixed by the DSP devices being used.
The other issue is IIR versus FIR. Unfortunately, IIR filters (PEQ's Biquad's, whatever) don't have any excessphase correction capabilities at low frequencies and therefore are not the best design for "room eq/correction." So it is a double whammy in the low end, not enough filters taps and of the wrong filter type...
Got it. Trinnov/SDP-75 use an Intel processor inside, not a standard DSP chip. So they could do more... But I may be misremembering or misreading the literature I have seen.
Understand on the IIR/FIR issue. Trinnov has both, as they are mentioned and seen in the GUI and you can tweak their parameters, but I am not sure exactly where/how they are implemented in the system. Have to dig some more, but it is likely there are no real details provided to consumers. I do know they use PEQ to smooth the bass, and that is almost certainly using IIR bi-quads or similar (FIR's would be tremendously long as you said), so I think you are spot-on.
With the larger number of taps and using FIRs at LF delay would increase and that would make lipsync hard to get correctly.
With the larger number of taps and using FIRs at LF delay would increase and that would make lipsync hard to get correctly.
Understood, your rig over there is my dream system also, your my hero man.The past few years a combination of fantastic deals, mainly blems and B-stock units, some good bonuses, and a very understanding wife ("just get it before we retire") has netted me a system an order of magnitude beyond anything I ever dreamed. The thing I lack is any time to enjoy it...
Moving some stuff from the initial thread and adding some waterfalls to illustrate the effectiveness of long filters in small rooms (mine is 4 x 5 x 3 m):
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Trinnov Basic
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Trinnov + MSO
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Audiolense
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