Local I/O A to D, 96K or 48K

[Engineer]

As the title.
Hi all Just a quick question.
I know the internal processing is done at 96K, and there is plenty of SRC going on around the console, but what about the local I/O?

I’ve searched the forum and looked in the manual and can’t seem to find any spec on the local ADC and DAC on the SQ. (Maybe I am not looking hard enough)
We are given all kinds of specs on the stage boxes with the different sample rates of the DX GX GigaACE and so on, but I see nothing on the Fs of the local I/O.
If I had a 48K stage box would I gain ADC sample rate by using local I/O on the monitor desk or am I wasting my time?

It would be VERY important info for me if I am selling recording services. If I say to a customer I am doing a full 96K recording through the SQ I would be committing fraud if I was using local I/O on the console (Rather than through a 96K stage box) and the console ADC was only 48K. This is essential info.

Thanks in advance.

[Brian]

The simple answer to your question is that the preamps built into the SQ for the local I/O are running at 96k. However the console always runs at 96k. Even if you plug a 48k stage box into the desk, or send it 48k digital audio over an I/O expansion card slot, that audio would go through a conversion to 96k. The bigger question is what are you running your recordings at. Just because the console runs at 96k doesn’t mean you are recording at 96k.

[Engineer]

Hi.
Many thanks for the reply.
I would appreciate very much if you could point me to anything that specifies that the internal console ADC is running at 96K.
I have had many occasions before where items have implied various properties only to be something else.
Further to that I would have to end up running Smaart through the desk to find out for myself.
It seems odd that it is not specified in the user manual after all, and that always makes me suspicious.

Thanks

[SQuser]

I actually wanted to add the following, but I expected it would have been taken care of by now.
In the manual you will find in the specifications on page 113 under System: “Sampling Rate 96kHz” (see also picture).

> Further to that I would have to end up running Smaart through the desk to find out for myself.
Of course, it would be even safer to do that.

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[Engineer]

Hi There.
Yes, Thanks I have seen that, that is the core processing sample rate (or “The desk sample rate” ) not the I/O converter sample rate.

I am looking for the input “analogue to digital converter” sample rate for the local inputs which CAN be different from the console sample rate as the console uses Sample Rate Conversion on inputs which allows it to run stage boxes at 48K or 96K while running the core at 96K

All I need to see is “Local Mic Input sample rate 96K” somewhere on a spec sheet or direct from A&H or alternatively I need to get an analyser through the console flat to 40KHz or so.

I cant get my SMAART to display to 40KHz so I am waiting for my SysTune laptop to come back as that will measure to 96KHz (with a 192 interface)

[Brian]

Funny that you so are concerned about sample rates and yet don’t seem to care at all about bit rates. Bit rates have just as much, if not more of an impact on the quality of the sound as sample rates. It’s why the 32bit “Prime I/O” that A&H offers is so beneficial in recording environments.

It seems the best option is for you to measure it yourself so you don’t have to trust anyone else’s word for it.

[Engineer]

Well it really wasn’t supposed to be a difficult question.

I apologise if some find my persistence with getting confirmation of a simple specification problematic.

It’s not just a case of taking “somebody’s” word for it (Unless of course you have documentation, have done a test, or work for A&H) in which case it would have been helpful to mention it.

If just taking someone’s word for it was how I worked in this business I really wouldn’t have got very far.
As it is I have been a system tech for some of the world’s biggest sound companies, built over a hundred recording studio rooms, installed over 500 entertainment venues, been UK tech support engineer for a major US manufacturer, and I have been a tech committee chair for the AES.

All I want to know is what is the Fs of the ADC on the back of the console. (Not the Fs of the core processor) That is all.

As there is SRC in the console (which there is) it does not mean because it is a 96K processor that it has 96K ADC on the console rear mic pre.

If I connect an AR 2412 or an AB168 stage box to the SQ I only have 48KHz ADC at that end even though the desk core is running at 96K, and if I buy the 96K GX4816 to make sure I have 96K I/O it costs more than the whole SQ just for the 96K ADC box. So it stands to reason that I wonder if the ADC that is on the console is 96K or only 48K. If it is 48K and I need 96K then I have to buy a GX4816 if a client requires 96K recording.

As A&H do not mention the Fs of the ADC on the console in their local mic input specs it is also confusing, especially as some noise specs on the local mic input specify 20Hz to 20KHz range rather than 20Hz to 40KHz it would if tested at 96KHz (although this could just be because the world does all testing 20 to 20K)

Again. Thanks for your comments.

[SQuser]

> if I buy the 96K GX4816 to make sure I have 96K I/O
How do you know this for sure with this device?

> especially as some noise specs on the local mic input specify 20Hz to 20KHz range
Not just noise specs – you’ve probably also noticed on page 113 the frequency response specification of 20Hz to 20kHz.

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[Tobi]

Just to be sure… we all know, that no one can hear more than “44.1k” — right?

[Engineer]

Hi All again.

I have my answer.

After a load of messing about with USB Soundcards that claim to be 96K and came back with 48K measurements (Scarlet) I dug out the old Lynx Aurora, a beautiful device that is ruler flat at 192K (96K audio)

The SQ does indeed use 96K ADC on the local surface, so I can record at 96K just not through any of the D-Snake stage boxes.

One oddity though. I got a round trip latency figure from the SQ of 0.56 ms

Odd then that A&H don’t state the Fs of the ADC in the input specs and quote things in 20Hz to 20KHz ranges.

Anyway… Thanks all.

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[tourtelot]

Engineer, what app is that please?

D.

[Brian]

As far as your latency measurement goes, that is normal. The advertised latency of the systems (0.7ms) is the maximum latency (with a little wiggle room built in too I suspect). Using built in I/O will definitely be shorter than this. Even if you use a stage box (which adds some additional latency), it will still measure under 0.7ms.

[Engineer]

The analyser app is just Smaart Suite V9. I use that and AFMG SysTune. For many things I prefer SysTune, but Smaart is a good “point and shoot” analyser. SysTune has a really awesome delay finding plug-in that has never let me down.

Brian,
Yeah I suspect that difference in latency is the “wiggle room”

[Author]

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