Digital Audio Interface

[James Jack]

I'm using Qlab in a theatre that has a Mackie 24-4 analog mixer with 6 aux sends. I would like to send certain ques to various parts of the set using Qlab's router. An example would be an old tube radio prop in the corner.

Is there a favorite rack mounted digital audio interface that can go between the laptop computer and the mixer to allow me to separate the ques in this way?

There are so many on the market. Need 48P on inputs, 8-12 inputs would probably be enough.

I would appreciate any suggestions from the group.

[Angus Turner]

It really depends on your budget - there's any number of great interfaces out there, but there's no point recommending one that's $2000 if your budget is $500.

Thanks
Angus Turner
angus...@gmail.com

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[James Jack]

I think the $500 range might suffice. Any brands that come to mind that I should focus on?

[Vinny Osborne]

You can't go wrong with either Focusrite or Maudio.

[Sam Kusnetz]

James Jack wrote:
> I think the $500 range might suffice. Any brands that come to mind
> that I should focus on?

Vinny Osborne wrote:
> You can't go wrong with either Focusrite or Maudio.

With the utmost respect, I believe you absolutely can go wrong with M-Audio.

While we've seen failures in almost every interface under the sun with
the notable exception of the Metric Halo boxes, some fail more than others.

Historically, the most problematic interfaces (including hardware and
software/driver problems) have been made by Echo, M-Audio, Digi/Avid,
and MOTU. That's not to say that those problems haven't or cannot be
resolved, only that we have seen enough problems to know they're not flukes.

In the range of $500 or thereabouts, I recommend the Roland Octacapture
or the Focusrite Saffire Pro 40. I'm told the Focusrite Scarlett series
are good, but I don't have much data on that one.

Cheerio
Sam

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[Daniel Perelstein]

James,

An important question is what do you need in terms of outputs. You say you need 8-12 inputs, but nothing in your message describes what you need inputs for. Do you have separate recording needs in addition to the playback needs you describe in your message? Have you gotten "inputs" and "outputs" mixed up (in which case, the need for 48V is confusing)? Everything in your message points to the fact that you need multiple outputs so you can route QLab playback to different speakers, but then when you're talking about your specific needs, you don't mention outputs at all.

How many outputs do you need? You say you've got 6 aux sends on the Mackie. So, are you looking for 6 outputs? Or something that can expand beyond what the board can provide? (You won't, if you don't need control of gain, EQ, or mixing with other sources, need to go through your Mackie at all if you don't want. You can go directly from your audio interface to your amps. Although, again, depending on your needs, you might choose to route some or all of your channels through the Mackie).

Just something to think about as, when looking for an audio interface for playback, the number of outputs is often a really big driving factor, and often times the number of inputs is just an accessory.
Dan

Daniel Perelstein                 

Full-service music and sound for the theater

Musical Direction | Sound Design | Composition | Multi-Instrumentalist
Conducting, Arranging & Orchestrations, Vocal Coaching, Accompanying
www . danielperelstein . com

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[James Jack]

Hi Daniel

Thanks for your response.

Basically, I want to playback certain audio cues to specific areas of the set, rather than having all the audio run through the main house speakers.

My thinking is to use the interface as a front end to feed the Mackie and use the mixers 6 aux sends to drive the specific set speakers.

The more I/Os the merrier, but I doubt I would ever need the full 24 inputs that the mixer has. Also, the theatre doesn't have a huge budget for elaborate audio set ups.

I just want to give the audience a more realistic audio experience by having the sound of a phone booth ringing coming from a phone booth rather than the house speakers, as an example.

The other aux sends can be used for the greenroom and lobby feeds.

Is that a little bit clearer?

[Steven Devino]

Why do you think you need the mixer in between? Most of these interfaces will drive an active speaker directly. I mixer can be handy if you are worried about volume emergencies but skipping the mixer reduced one more possible place where things could go wrong.

At $500 I would not bother with anything more than 2 outputs.

Steve

[Daniel Perelstein]

James,

Your example is perfectly reasonable. This is common in the theater, and exciting.

It also clarifies that what you are looking for is OUTPUTS on an interface, not INPUTS. Your interface will connect to your computer, and deliver outputs from your computer to the Mackie (or, if you prefer, directly to your amplifiers or powered speakers). Inputs on an interface are used to take audio from an external device (microphone, instrument, etc) and get that audio into your computer (for instance, for recording purposes). It doesn't look like you need any inputs at all in the setup you describe (although most interfaces are designed for recording, so they tend to have more inputs than outputs, but it is the outputs that you are interested in).

Hope this clears things up as you do your research. Count the number of outputs available to you on the interface (and since your mixer is an analog Mackie, you can only really make use of the analog I/O); this will be the number of discrete channels of audio you can address from QLab.

Also, unless you have other goals beyond what you've explained here, it doesn't sound like you need to continue searching for a device that provides 48 V phantom power. Many devices certainly will, but it seems irrelevant to what you are trying to set up here.

Dan

On Saturday, October 5, 2013, James Jack wrote:

Hi Daniel

Thanks for your response.

Basically, I want to playback certain audio cues to specific areas of the set, rather than having all the audio run through the main house speakers.

My thinking is to use the interface as a front end to feed the Mackie and use the mixers 6 aux sends to drive the specific set speakers.

The more I/Os the merrier, but I doubt I would ever need the full 24 inputs that the mixer has. Also, the theatre doesn't have a huge budget for elaborate audio set ups.

I just want to give the audience a more realistic audio experience by having the sound of a phone booth ringing coming from a phone booth rather than the house speakers, as an example.

The other aux sends can be used for the greenroom and lobby feeds.

Is that a little bit clearer?

[micpool]

On Saturday, October 5, 2013 7:13:50 PM UTC+1, Steve Devino wrote:

At $500 I would not bother with anything more than 2 outputs.

I think this  needlessly  limits  the creativity of the OP for no good reason. Although it is not a unit I would normally spec I have a show running on an installed system with a focusrite saffire Pro40 which is running 10 Analog out +8ADAT in and out with some very heavy sequences of 4 ch wavs perfectly well, and there are probably several other units around this price point in regular use as 8 output systems in pro theatres.

There is one annoyance with the focusrite. It frequently doesn't boot with the correct sync source. Once set manually it remains stable. If you are using it with the internal clock this shouldn't be a problem.

Mic

[Daniel Perelstein]

On the topic of individual recommendations, at the risk of being beheaded on this list, I've owned a MOTU ultralite for the last five years, which retails for about $550 and has 10 analog outputs. I've had it in use over and over again without fail (a few years ago, certain computers had difficulty recognizing it, but customer support provided me with a way to force it through the terminal, which worked. In any case, it must've been an issue with driver or OS or something, as it hasn't been an issue in years. In any case, once recognized, I've never had any failure).

It has been great for me, and I'd highly recommend it based on my experiences. 

That said, I know that others on this list have experienced issues both with the device and with MOTU more broadly (although I also have never had an issue with my recording interface, which is also a MOTU device).

Not sure exactly what the discrepancy is that explains this. 

Dan

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[James Jack]

Hi Daniel

Exactly. That really helps.

Thank you

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[micpool]

I was just checking some US pricing in connection with my previous post and stumbled across a 10 out job for 199USD 

Of course it is made by the company beginning with 'B' or more accurately 'b' in the new logotype styling, but it is  plastered with MIDAS logos.

It's a Behringer FCA610. Is anyone [secretly] trying it out. 

30 outputs for  600dollars???

Mic

[Sam Kusnetz]

Daniel Perelstein wrote:
> On the topic of individual recommendations, at the risk of being
> beheaded on this list, I've owned a MOTU ultralite for the last five

> years, which retails for about $550 and has 10 analog outputs. \

>
> It has been great for me, and I'd highly recommend it based on my
> experiences.
>
> That said, I know that others on this list have experienced issues
> both with the device and with MOTU more broadly (although I also have
> never had an issue with my recording interface, which is also a MOTU
> device).
>
> Not sure exactly what the discrepancy is that explains this.

Dan

First of all, I hope neither you nor anybody else ever feels they will
be "beheaded" on this list. We want this list to be useful and
comfortable for everybody, and I personally frown upon any commentary
that feels too aggressive to anybody.

Now, I'd like to try to answer your question about the discrepancy
between your experience with your MOTU Ultralite, and the seemingly
prevailing attitude towards MOTU devices in general.

My knowledge of MOTU device failures comes from about a decade of
personal experience with about a dozen 828mk3s, half a dozen Ultralites,
and one 828mk1, plus a survey I conducted on this email list which gave
me data points on perhaps another dozen, plus my conversations with my
Figure 53 teammate Andy Lang (nee Leviss) whose experience involves
direct access so several dozen more.

There were, without doubt or question, issues in MOTU's drivers up until
the latest version that rendered the 828mk3's unpredictable with QLab on
Mac OS 10.7 and newer. For many folks, myself included, this was enough
of a problem to render them useless.

Separately from that, there appears to have been a period of time in
which there were manufacturing problems that led to unrecoverable
hardware failures in both the 828s and the Ultralites, but only some
units had this problem. Others were fine.

You've had good experiences with your Ultralight, and that's terrific.
But statistically speaking, MOTU devices have a higher failure rate
overall. I'm not trying to say they're all duds, as I would say about,
for example, the old Echo Layla interface which had a *design* defect
rendering the device horribly susceptible to EMI interference if you
connected both the inputs and the outputs at the same time. That's a
situation where *anybody* using one of those boxes could set up a
situation in which they encountered noise. The thing about the MOTUs is
that some units have problems and others do not. Their design appears to
be robust, but their manufacturing is not consistent.

That said, I've been told that these manufacturing problems have been
solved, and the driver issue has been solved, and if those two things
are both true then I'll be very pleased.

Hopefully this helps to explain why I recommend against MOTU even though
plenty of people have had no problems with theirs.

[Daniel Perelstein]

Sorry, Sam, I should've included a wink or something with my comment. Folks around here are knowledgeable, helpful, and opinionated. Just how I like 'em. 

In any case, your details on the motu story are helpful, and I hope they are to the OP as well. Guess I've been lucky with my devices, as it sounds like it's just a crapshoot. 

Dam

[Sam Kusnetz]

Daniel Perelstein wrote:
> Sorry, Sam, I should've included a wink or something with my comment.
> Folks around here are knowledgeable, helpful, and opinionated. Just
> how I like 'em.

I'm very glad to hear that. No problem at all, then.

> In any case, your details on the motu story are helpful, and I hope
> they are to the OP as well. Guess I've been lucky with my devices, as
> it sounds like it's just a crapshoot.

It's a difficult thing, because really all those interfaces are built
for a recording environment and not for live theater. For that reason, I
believe, we're seeing people move more and more towards solutions like
the UB-MADI and Dante, which are audio distribution devices rather than
recording interfaces with a lot of outputs.

It's an exciting time to be in our line of work.

[Steven Devino]

Not much headroom on the Saffire Pro40 and 108dB of dynamic range. Not bad for fooling around at home or doing low volume surround mixes for a home video post setup, but 15.7dBu max output means your speakers have to have lots more headroom or a really exceptional SNR or you will  tend to result generate a lot of incidental distortion on dynamic peaks. 

I care A LOT about the sound quality I deliver to my audience even if I am just doing community theatre. 

Why not rent or borrow first to see if you are happy with the results.  Try a sharp clap of thunder to all speakers at the same time to see if you really do.

• Maximum level (A-weighted): 15.7dBu at 0.883%

Steve

[Lee, Jeremy (lee4jm)]

Focusrite- maybe OK.  M-Audio I stay away from if at all possible.

On Oct 5, 2013, at 1:04 PM, Vinny Osborne <the...@eircom.net> wrote:

You can't go wrong with either Focusrite or Maudio.

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[Bruce Ellman]

I have the FCA1616 (8 analog + 8 ADAT). Seems solid, sounds decent with some features firmly rooted in the 20th century (unbalanced inserts?). I haven't tried it yet with QLab, but it has one maddening feature, which I'm sure the FCA610 shares, in that there is an un-bypassable hardware output volume control. I just want unity gain out of the darn thing and not have a measure of unpredictably in its playback.

 

However, at $250 for 16 x 16 ($500 for 32 outputs!) can be attractive for those on a serious budget.

 

Bruce

[micpool]

I think you are shifting the goalposts around this discussion.

You seemed to be suggesting that the OP would be better off spending his money on a 2 channel interface than pursuing his intention of experimenting with the multiple loudspeaker arrangements which are at the heart of all good sound designs.

I disagreed, and now this seems to be about who cares more about sound quality. Ok so he'll only have 108dB of dynamic range (12dB more than a CD). So stick this on top of a noise floor of 30dB and with a carefully set up gain structure he'll be banging out thunderclaps and gunshots at 138dB without a problem. 

I normally spec RME interfaces, but if a theatre owns a focusrite that they have had working reliably in their rack for a long time, then it is perfectly possible to produce a superb sounding show. To dismiss this sort of quality, although short of the maximum achievable technical spec as only adequate for fooling around on low level mixes at home is frankly ridiculous.

Mic

[Steven Devino]

Not really that ridiculous. The maximum output spec is +15dBu. That is 7 dB lower than the Mackie mixer he is using and 9 dB lower than the expensive stuff in most cases. 

Most music modern mastered music has 14-18dB of dynamic range variation and impulse type sounds like kicks and thunder can be much more dynamic than that. But just keeping to the music example, to get a reasonable gain structure, the OP will have to run average level to the interface from the computer at 7-10 dB lower than normal to avoid clipping. 

In theatre it might be challenging to get the rain to a loud enough level to be clearly understood and still have headroom for thunder (just an example). OR what is more likely is if you hit the loud percussive cues on all channels at once which is a really effective technique for making a point without volume, you might find the $500 interface can't keep up and artificially compresses all the the outputs due to lack of power supply capacity. 

Then you get to make that up with the speaker or speaker processor gain, so you give that up in terms of SNR. It can work but it can't get loud and it takes some crafty gain management.

And I am not suggesting he abandon his goal, rather I am suggesting renting something better and get to know the gear before purchase. Owning an 8 channel $500 I/O for live sound reproduction with its significant dynamic range and headroom requirements and tradeoffs could be throwing good money after bad. 

Its just advice not direction. 

Steven Devino

sde...@gmail.com

[Jeremy Lee]

I wouldn't worry about it that much.  I generally set my QLab input gains by running a 1k tone at -20 in the QLab mixer, and setting the input gains on the console so that it reaches whatever the console sees as "nominal"- usually 20 or more dB below 0dBFS.  In QLab, I use -20 on my master fader on cues with the output faders generally at 0 or below if I'm doing complex routing.  A REALLY loud cue might hit -7 or -5 in the QLab mixer's master fader.  That still gives me plenty of headroom before I hit 0dBFS on any piece of gear.

With 24 bit converters reaching -100dB or below on the noise floor, adding a couple of dB of gain to a device at the console doesn't really make a difference.  Add a single moving light or scroller, and the noise floor of the theatre goes up quite a lot more.

I don't have the ability to test converters, but with my ears, I do notice the difference in dynamic and frequency range between something like an RME and something like a MOTU/ M-Audio box.  I say just drop the sound card altogether and get a Dante card for your mixer and go virtual ;-)

Jeremy

-- 

Jeremy Lee

    Sound Designer, NYC - USA 829

        http://www.jjlee.com

[James Jack]

Thanks, everyone for all the sage advice. I'm not too worried about the noise floor. Our venue is hardly in the Carnegie Hall class.

I think I'm pointed in the right direction, now.

This group is a great resource.

Cheers,

J.E. Jack

[Steven Devino]

100% agree with Jeremy. You just have to make sure you understand what it is he is suggesting and implement it.

Steve

[micpool]

On Sunday, October 6, 2013 3:21:21 AM UTC+1, Steve Devino wrote:
> to get a reasonable gain structure, the OP will have to run average level to the interface from the computer at 7-10 dB lower than normal to avoid clipping. 

All that goes between the computer and the interface is data. Regardless of the performance of the DA converters the data any interface sends for 0dBFS at any given rate and sample size will be identical.

If an interface produces an analog level of 15dBu for a data input of 0dBFS then it will need 9dB more gain on the console than an interface that produces 24dBu for 0dBFS. Everything will then be the same except the noise floor will have been brought up 9dB, with 108dB of dynamic range this isn't really an issue.

By your logic, if you were miking up a marimba and had 2 microphones, one of which was 9dB less sensitive, then would the less sensitive microphone only be suitable for low level mixes at home because it would need a higher gain on the console? Probably not.

Would you tell,someone that they have to run their sound check CD off a player with XLR outputs at +4dB because a CD player with phono outs at -10 would be unusable in a professional situation.

I am not trying to argue that there are not audible differences between different DA converters. All I am saying is if you only have 500 dollars,for,an interface then you are still in the game and can produce excellent work using multiple outputs that will thrill audiences.


Mic

[micpool]

On Sunday, October 6, 2013 11:49:20 PM UTC+1, micpool wrote:

>
> All that goes between the computer and the interface is data. Regardless of the performance of the DA converters the data any interface sends for 0dBFS at any given rate and sample size will be identical.
>
>

Sorry, that should have been interface receives (or computer sends)

[Steven Devino]

Missed my point. a device with -15dBu maximum output requires careful gain structure to avoid overdriving its own output. If you know how to set it up then fine. If you can live with the sound quality then fine too. That doesn't mean there aren't better tools for the job. 

A device with max output of -15dBu is clearly meant for small post work largely in a home studio since it is so miss matched to the rest of the live gain structure. Even a $75 Behringer mixer will have higher maximum output. 

And yes, I will not use a CD player with -10dBV for playback. That is why I was one of the original QLAB users way back in its early beta days. It solved that problem first.

 

Steven Devino

sde...@gmail.com

[mackerr]

Huh? A device with a maximum output of +15dBu requires exactly the same gain structure to avoid over driving its output since the data is the same. What it requires from the console input or power amp is 9dB more gain than a device with a maximum output of +24dBu, to reach the same level out of the speaker, a gain difference that as Mic points out, is no big deal. Just as it is no big deal with microphones, and no big deal with CD players unless the unbalanced output of the CD player causes an increase in induced noise. It is the unbalance characteristic that speaks against the RCA out not the level.

Mac

[micpool]

Missed my point as well....Last try!

A DA  with 15dBu max output cannot overdrive its own output. (Nor can a CD with a DA with -10 nominal outputs) because it cannot receive a digital datastream which exceeds 0dBFS. What it receives at the input as a digital data stream it will output as an analogue signal (just a bit quieter than a DA with a 24dBu for 0dBFS output.)

No-one is disputing that a 2000 dollar interface is likely to have  better sound quality than a 500 dollar interface, but this has almost nothing to do with the  analogue level a device outputs when receiving an 0dBFS digital input. The PrismSound Orpheus a beautiful DA and yours for only 6000 dollars will only let you have Switchable '+4dBu' (0dBFS = +18dBu) or '-10dBV (0dBFS = +6dBu), so you won't be wanting to live with the sound quality of that then!

On consoles high headroom is desirable to avoid clipping from single analogue sources on channels or high combined  levels on summing busses. A DA converter has a known maximum digital input and the output it produces for this maximum level is not particularly relevant to the sound quality of the unit 

Many very high end DA converters have switches on the back to select output levels.

And finally and comprehensively for completeness here are the dBFS standards from around the world. I don't think manufacturers supplying European broadcasters with EBU R68 kit are thinking, "damn, those US installation engineers are getting so much better sound quality with their swanky 24dBu outputs while we're just having to live with our inadequate tools '

• EBU R68 is used in most European countries, specifying +18 dBu at 0 dBFS
• In Europe, the EBU recommend that -18 dBFS equates to the Alignment Level
• European & UK calibration for Post & Film is −18 dBFS = 0 VU
• UK broadcasters, Alignment Level is taken as 0 dBu (PPM4 or -4VU)
• US installations use +24 dBu for 0 dBFS
• American and Australian Post: −20 dBFS = 0 VU = +4 dBu
• The American SMPTE standard defines -20 dBFS as the Alignment Level
• In Japan, France and some other countries, converters may be calibrated for +22 dBu at 0 dBFS.
• BBC spec: −18 dBFS = PPM "4" = 0 dBu
• German ARD & studio PPM +6 dBu = −10 (−9) dBFS. +16 (+15)dBu = 0 dBFS. No VU.
• Belgium VRT: 0dB (VRT Ref.) = +6dBu ; -9dBFS = 0dB (VRT Ref.) ; 0dBFS = +15dBu.

Best Summarised as Analog Audio Levels (with Respect to Full Scale Digital)

+24dBu (SMPTE RP155), +18dBu (EBU R68), +15dBu (Germany), +10dBV (consumer +12.2 dBu).

Mic

[Steven Devino]

Ok I give. My point was the user has to be aware of the short comings and compensate in the correct place.

And by the way You can absolutely overdrive the output of a DA depending on how much head room the reconstruction stage has. Maximum peak after reconstruction can be higher ( or try to go higher) than 0dbFS.  An example: a sign wave that is exactly 1/4 the sample freq. sampled at exactly the half power points. The resulting samples will be .7, .7, -.7, -.7.  If that is normalized to 1, 1, -1, -1 then run through the same converter it will attempt to make a sine with a peak value of 1.4 but will clip instead.  That is purely hypothetical and the absolute worst case but it represents the means by which someone trying to add gain in the digital realm might generate a distorted output. 

Much more of a lesson about why one should not normalize to 1 in a willy nilly fashion than not buying cheap interfaces. 

And I am still not going to use a CD player as long as I can use QLAB. 

Either way 

Steve Devino

Mobile

--

[mackerr]

Yes, the analog output can be driven past the rated analog output for 0dBfs, be it +18dBu or +24dBu or whatever. It is up to the manufacturer to include this headroom in their design. Maybe some crappy gear doesn't have it, but I'd bet most good gear does. A recent thread at PSW about measuring the output at 0dBfs has shown exactly that result with a Yamaha 01v96 (not a real high end console). A sine wave at 0dBfs is actually 40Vpp (14.14Vrms) which equates to a level of +25.2dBu. Since standard operating level for professional audio has been +4dBu for ages, and that equates to something between -14dBfs and -20dBfs depending on the convertors, this becomes a real case of hair splitting. 

There are plenty of reason to not use a CD player in a production environment, the audio level isn't really one of them.

Mac