TOPIC:

I don’t think you read that quite right.  I’m using SHD for mains and Subs, I use the DAC analogue out (Channels 3 and 4) for subs and I use the digital out of the SHD (channels 1 and 2) to feed an external DAC.  The only latency issues I should have is the timing differences between the internal and external DACs but I’ll have timing issues to correct with the sub placement anyway.  There’s no latency data available for either DAC that I’ve been able to find so I can’t assess this until I do the MSO process.  At this stage I haven’t finished with the placement of subs anyway and until I do I won’t be doing optimisation.

I don’t think I’ve got any entrenched ideas, I’m just seeking information.  If anything I’m ignorant of some of the technical details around MiniDSPs and sub integration, which is why I’m here.  I’ve only had the unit a week and I only just finished making the last XLR balanced cable for the subs, the soldering iron is still hot.  One temp long cable to make so I can move the subs around while connected.

Understood.
Without testing the MSB DAC, you don't know its latency.  Latency is one of those specifications all DAC manufacturers should make available.  Sadly, most don't.
But, I suspect you'll get perfectly equivalent performance setting aside you expensive DAC and using the SHD DAC outputs for both sub/main duties.  That removes numerous variables that could complicate your setup. 

Dave.

Is the latency of the internal DAC to the SHD known?  The MSB delay is about 0.5Sec, MSB advised me that’s about the figure.

dreite wrote:

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But, I suspect you'll get perfectly equivalent performance setting aside you expensive DAC and using the SHD DAC outputs for both sub/main duties.  

Dave.

Well, I gave that a try since I’d never actually listened to the DAC on the mains, it wasn’t the reason I purchased the SHD but I’m always willing to give things a try.  I’m afraid the MSB sounds a lot better than the SHD but it may also be that the SHD is still running in, who knows.  I’ll give it another try in a week or so when it’s been used a while.

I can always redeploy the MSB to the other system, I have Watt Puppy 8s there, they don’t need subs.  

I’ll leave everything running for the next 4 days and things should be well burned in by then, I’ll make the comparison again.  The MSB is well used.

rortmanns wrote:

Is the latency of the internal DAC to the SHD known?  The MSB delay is about 0.5Sec, MSB advised me that’s about the figure.

The latency of the SHD is 25mS
www.minidsp.com/forum/minidsp-for-newbies/19531-processing-time

0.5 seconds is a huge amount of latency.  I suspect that might be incorrect information.  However, some DAC's with ASRC can have significant amounts.  (And possibly sampling-rate dependent.)
Regardless, you can't compensate that relative amount with the SHD since the maximum setting is 30mS.

Dave.

I wish it was incorrect, it came direct from the guy at MSB.  The unit has a video mode just to compensate for that if you want to use it with a home theatre etc but that mode is at the cost of performance. 

I’ll let things settle and then decide the path forward.  I have room treatment to do in the interim.  

if things don’t work out I’ll see if any of the other devices offer more delay to compensate.

Well, this is a story I've heard previously.
Audiophiles purchase these miniDSP units even though they don't check some of the audiophile boxes that need to be checked.  And then some sort of a hybrid rationalization scheme emerges.
I still don't understand it.  

Dave.

dreite wrote:

Well, this is a story I've heard previously.
Audiophiles purchase these miniDSP units even though they don't check some of the audiophile boxes that need to be checked.  And then some sort of a hybrid rationalization scheme emerges.
I still don't understand it.  

Dave.

I’m not sure what ‘audiophile boxes’ there are to check.  The unit does everything I expected.  I bought it with the intent to use my external DAC, I just had no idea the MSB had such a long delay, that’s not the fault of the SHD and the information on delay is not readily available for the MSB.  I only found out because I was talking to MSB about some other things and mentioned my integration plan, they jumped right in and told me the likely issue.  The SHD has digital and analogue outputs concurrently, what I’m doing is hardly esoteric, if you only wanted one or the other you’d buy the unit that only does that.

MiniDSP is similar with its information, their technical information leaves a lot to be desired. Eg publish the max delays for each product etc, a simple function matrix would do the trick.

rortmanns wrote:

Is the latency of the internal DAC to the SHD known?  The MSB delay is about 0.5Sec, MSB advised me that’s about the figure.

In answer to the first question - no, I don't believe it is. There are figures for the combined latency of the whole input-output signal path (the 25 ms mentioned above) but the vast majority of that will be from the DSP section that would apply to the signal sent to your MSB DAC just the same as via the SHD's DAC and onto your sub. The latency of just the SHD's DAC will be much less than this total and won't pose any issue at all though, and would just get included in any acoustic measurements.

What would be a HUGE problem though is if your MSB really does have a 0.5 s (500 ms) latency. That would basically make it impossible to properly integrate your subwoofers, since the maximum conpensatory delay you could apply to your subs on your SHD is 30 ms, and I'd be stunned if your subs gave you the capability of setting an additional 470 ms delay. Relative positions of main speakers and sub in your room will affect time delay requirements but would be utterly dwarfed by the 500 ms of your DAC.

Your number one priority should be to make a measurement to confirm that the latency difference between the DACs really is as much as ballpark 500 ms, because if it is you need to totally rethink what you're doing. To do this I would use REW to make the following measurement:

• Set your microphone up at a point equidistant from your two speakers*.
• Set up cabling and signal routing in your SHD so that the SHD DAC is used for, say, the left speaker and your MSB DAC for the right speaker.
• Do not include your subwoofers for this test.
• In the measurement window, select to use an acoustic timing reference and set this to be your left speaker (the one using the SHD DAC). 
• Make a measurements for your left speaker on its own, and for your right speaker on its own (sweep up to 20 kHz).
• Once you have the measurement, choose the overlays option, and then impulse response. The signal for each speaker will have a sharp initial spike (the first arriving direct signal from the speaker) followed by a sequence of smaller spikes (which are reflected signals from room boundaries and things in your room). You'll need to zoom out A LOT to see the signal for your right speaker if there really is a 500 ms delay. The difference in latency between the MSB and SHD dacs will be the time delay between the initial spike from your left speaker (will be at 0 ms on the graph) to the initial signal from your right speaker (which will be at about 500 ms if your info. is correct, but hopefully it's rather sooner!)

*To check that the delay truly is ballpark 500 ms just setting up with a tape-measure will be fine, and you main listening position should be equidistant so I'd just use there. For a more accurate measurement of latency above you could check this acoustically using the SHD DAC for both channels first, and even compensating for the difference on the main measurement. What matters here is an order of magnitude check though. 500 ms is unusable, whereas say 5 ms would be.

No, no, no.  An acoustic measurement scenario is waaaaaaay too complicated to determine this latency.
My goodness.  This can easily be determined with an electronic measurement....and far more accurately.

It matters not anyway, because his relative latency is far too much to be able to compensate for electrically in the SHD.
The simple solution here is to not use the MSB DAC.

Dave.

dreite wrote:

No, no, no.  An acoustic measurement scenario is waaaaaaay too complicated to determine this latency.
My goodness.  This can easily be determined with an electronic measurement....and far more accurately.

It matters not anyway, because his relative latency is far too much to be able to compensate for electrically in the SHD.
The simple solution here is to not use the MSB DAC.

Dave.

I disagree. The OP probably doesn't have a means to measure it electrically, and an acoustic measurement is 100% accurate enough here.

(Yes a more accurate measurement could be made electrically but the uncertainties on the acoustic measurement are likely at the inaudible level.)

Actually, note the point of my measurement was to measure the difference in latency between the two DACs, not the latency of either.

Hey, I don't need any lectures on making basic measurements.
The process I use IS actually a differential measurement, and very easy to implement.
And the equipment required is very basic and he probably already has it.  Easily done with a typical dual-channel soundcard scheme.

Dave.

dreite wrote:

Hey, I don't need any lectures on making basic measurements.
The process I use IS actually a differential measurement, and very easy to implement.
And the equipment required is very basic and he probably already has it.  Easily done with a typical dual-channel soundcard scheme.

Dave.

There was nothing remotely 'lecturing' in my post. If you wish to share details of how you'd rather the OP measured the difference in latency then please do but as it stands I've shared a totally reasonable way to do so. Which for what it's worth is what I'd do myself in their position as I wouldn't have an electrical alternative.

You probably do have the necessary electrical alternative.  (You just don't realize it.)
A basic two-channel soundcard, with the right software and setup, is an extremely powerful measurment tool.
Recommending/outlining a convoluted acoustic measurement scheme to perform a measurement like this is problematic, at best.  When measuring 'just' electronic characteristics of device(s) you should never introduce acoustic measurements into the mix.

I will make a separate post when I get a chance.  This thread has been jacked sufficiently now.
The OP has contacted MSB directly, so he already has the info he was interested in.

Dave.