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Demystifying Interfaces
#3032942 03/12/20 04:31 PM
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A recent question over on Keyboard Corner prompted me to do some thinking about interfaces and what we can expect from them. Here are some initial thoughts, to be followed by more later.

In my opinion, the most important way to pick an interface is to go backwards -- look at your actual needs, make a comprehensive list, and then start investigating the hardware. This is very important, because it's in any manufacturer's best interest (in the short term) to convince its audience that its latest product is the best thing since the invention of sex, regardless of whether the match between user and gear is appropriate. Whenever you see hype that says "the product for just about anyone", take a step back... it may be a great thing for some people, but very few audio products are fabulous for everybody. (Except M-Tron Pro. M-Tron Pro is fabulous for everybody. Sorry, it just IS.)

I'll give some examples in a bit. Stay tuned!

mike


Dr. Mike Metlay (PhD in nuclear physics, whoop de doo)
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Re: Demystifying Interfaces
Dr Mike Metlay #3032946 03/12/20 04:46 PM
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Originally Posted by Dr Mike Metlay

In my opinion, the most important way to pick an interface is to go backwards -- look at your actual needs, make a comprehensive list, and then start investigating the hardware.


Nothing backwards about that - I always tell people to figure out what they need right now, what they might need a couple of years from now, and then see what will work for them for at least a few years. The thing that needs demystifying is what they need to know. For example, if you want to have more than one monitor mix, you need an interface with more output jacks than just one (or a pair) labeled "monitor" or "control room." And you need to understand that, unless there's more than a single stereo output stream, the headphone jack, while it might have its own volume control, caries the same signal as the monitor output. And you have to understand under what circumstances a hardware mixer or its built-in DSP near-equivalent for monitoring is important. Stuff like that.

Re: Demystifying Interfaces
Dr Mike Metlay #3032950 03/12/20 05:33 PM
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We learn as we go!!!! Apologies for the ramble, I do get to the point below if you want to skip to the end.

My first recording interface was the original MOTU 896. Functionally, it was fine for my needs at the time, learning how to get stuff done.
My first DAW was also MOTU - Digital Performer 3 or 4.

I reached a point where I just stopped being interested, partly distracted by buying a place to live in WA and moving from CA and partly once I got to WA I realized that I just didn't like my DAW or my interface.
The DAW interface was messy, overly cluttered and seemed to be an attempt to offer EVERYTHING all at once when I really wanted to only see all the options if/when I needed them.

The 896 sounded pretty OK but it just was not inspiring to me. I wasn't learning about Recording Studio World or reading Tape Op or getting the idea that I could add more interesting mic pres. I might still have it if I'd known that stuff then, so it goes.

Then I got a rack mount Mackie Onyx interface, which came with Tracktion (see my thread on Tracktion/Waveform). The mic pres did sound better plus 2 of them had inserts so I added an FMR RNC. All the XLR plugs remained on back, don't like that. Worse yet, Mackie never updated the firmware or supported the unit for long term use. Even more worser, all the mic pres had cheap pots soldered to a circuit board for adjusting the gain. They got scratchy, I HATE scratchy pots and especially ones that are difficult or impossible to service. It reached a point where I would record something and the track would be out of sync with the rest of the recording, probably a firmware update issue.

So thinking less is more and liking the digital controller idea I went with a MOTU Audio Express. There was a lot to like on that, it was small, simple, could be controlled from the computer. On the other hand, only two XLR mic inputs and two 1/4" line inputs. So I added an FMR RNP.

Then an opportunity came to buy a MOTU 896 Hybrid Mk III from a local rich kid who had moved up and didn't need it. I kept the Audio Express for a "spare" and switched. Both of them had incredibly LOUD monitor outputs, I had to turn my monitors way down to avoid having my face blown off.

While I liked that MOTU has kept firmware updates fairly current, used all digital controllers instead of pots and sounded good, I disliked the interfaces, the loud outputs and the lack of a simple 2 headphone set up (which the Mackie had). My 2008 Mac Pro started getting intermittently goofy, Firewire was becoming obselete and I thought it would be nice to at least have the potential to go mobile.

So I moved from one obselete system to another - 2014 MacBook Pro with Thunderbolt 2.

I'd learned that I wanted my recording interface to have the following.
8 inputs
Digital rotary controllers
A computer driven software controller in addition to manual controls
Support from the company for updates
More than one interface connection port so it could "hub" for a dedicated hard drive
2 simple headphone jacks with volume knobs ON THE FRONT
At least a couple of combo jack inputs ON THE FRONT
A complete set of outputs so I could use the live mics on location as recording mics and pass the signal along as needed.
Thunderbolt and/or USB 3.0/C

After considerable research, I got a Presonus Quantum, it ticked almost every box. I like it, the preamps sound great and so does playback.
While the Main Output control and Headphone jacks are adjusted with pots, I can live with that. Scratchy pots on the output side will not compromise the sound quality of the recording process.

Only took me many years and some $$$ to learn all this stuffs, education is never free!!!! Cheers, Kuru


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Re: Demystifying Interfaces
Dr Mike Metlay #3033019 03/13/20 12:37 AM
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Originally Posted by Dr Mike Metlay
very few audio products are fabulous for everybody. (Except M-Tron Pro. M-Tron Pro is fabulous for everybody. Sorry, it just IS.)


yeahthat keys


A reason why I collect old keyboards is that I feel partly responsible for doing it, responsible for preserving history and being a custodian for these things
Plus, old gear has a story. I like that.
Re: Demystifying Interfaces
davedoerfler #3033038 03/13/20 03:05 AM
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Originally Posted by davedoerfler
Originally Posted by Dr Mike Metlay
very few audio products are fabulous for everybody. (Except M-Tron Pro. M-Tron Pro is fabulous for everybody. Sorry, it just IS.)


yeahthat keys
Despite the fact that I've been gently perusing interfaces as my wife and I prepare to move into our new house with its dedicated studio space... this thread just left me wanting a better Mellotron VST. roll


Samuel B. Lupowitz
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Re: Demystifying Interfaces
samuelblupowitz #3033162 03/13/20 10:35 PM
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Originally Posted by samuelblupowitz
Originally Posted by davedoerfler
Originally Posted by Dr Mike Metlay
very few audio products are fabulous for everybody. (Except M-Tron Pro. M-Tron Pro is fabulous for everybody. Sorry, it just IS.)


yeahthat keys
Despite the fact that I've been gently perusing interfaces as my wife and I prepare to move into our new house with its dedicated studio space... this thread just left me wanting a better Mellotron VST. roll

There aren't many better than M-Tron Pro. Super easy to use, stupid-efficient on CPU load (it was invented for PowerPC processors, for heaven's sake), and a freaking gigantic library of sounds, covering nearly every tape rack ever made for the original. Omenie's Streetlytron Pro for iOS is the best for that platform and has a decent library, but nothing like M-Tron Pro's.

But I digress. Back to interfaces! grin


Dr. Mike Metlay (PhD in nuclear physics, whoop de doo)
Wordsmith - Musician - Tech Freak - Amiable Zany
Everyone on this forum is a friend I haven't met yet
-- except for Bryce, who's, well, YOU know.
Re: Demystifying Interfaces
Dr Mike Metlay #3033194 03/14/20 03:24 AM
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Mike R has pointed out a couple of places where folks trip themselves up. I want to go into detail about one or two of them right now.

The first thing you need to know (about any interface ever) is: how many channels of actual conversion does it have? Not how many inputs or how many outputs, although that information comes in handy later... how many actual CHIPS stand between the analog and digital realms. You can assume that most or all of them will be 2-channel and might operate in dual mono or stereo, but that's as far as you can assume anything.

It is quite common for interfaces, especially the moderately-priced ones with lots of connectivity, to boast about how many ins and outs they have. Here's the thing they don't tell you: often, even most of the time, some of those ins and outs share one conversion channel pair. That means you can't actually use all of them at once unless you sum them before sending them to conversion. If you only have four ADCs, you can't encode more than eight channels of audio at a time, no matter how much you squint and try to read the manual sideways.

On the other side of the divide, if an interface only has one DAC (and many do), then you will get a grand total of one stereo output from your DAW, no more. You might have multiple physical outputs, but they'll all be fed the exact same signal. This is not always a bad thing; for example, the Yamaha AG06, which is my sets-the-bar standard for a small desktop interface, has two stereo outputs, one for a fixed-level signal and one for a pair of control-room monitors, plus a stereo headphone jack. Each of these signals can be set independently, but they all pass the same two channels of audio. On Behringer minimixers and those who use a similar signal flow diagram, this is even more useless because the same analog audio line taps the mains and the headphones in order instead of feeding them separately. That means you can't control your main output level and your control room or headphone levels separately. Mess with one, you're messing with all of them.

So what do you look for to get at the truth? On the input side, look for phrases like "X channels of simultaneous recording" or "X analog inputs". That's an accurate number for how much conversion you can count on. On the output side, ignore phrases like "both monitor AND headphone outs" and focus on phrases like "independent headphone mix" or "independent cue mix". That indicates that you actually have two stereo DACs to work with, not just the one, and you can route two different signals to them.

Look for numbers of converted channels, not total I/O. For example, a USB-equipped mixer might say "stereo USB to your computer" or "main mix with loopback", or it might say "independent recording capability on the first 16 inputs". See the difference?

Another place where you can get tripped up is with interfaces that offer many different independent cue mixes. In most if not all cases, this is because the interface itself has a digital mixer built in that creates these mixes for you based on the channels available to it from the digital domain. Same audio out of the DAW, treated and mixed and rearranged differently in the DSP hardware on the interface before going to the outside world. Still useful, but not necessarily what you were expecting.

One place where you can maximize your I/O (at the cost of some extra hardware) is with digital ins and outs. When you see a tiny half-rack interface boasting 20 or more inputs, at least 8 of them and possibly 16 will be digital, with no conversion chips at all. An optical cable feeds the interface with eight channels of digital audio, or four at 88.2 or 96 kHz. If you have two cables, you can do 16 or eight channels. The same goes for outputs. To use these ports, you need to have something that provides a digital signal; this can be, for example, an 8-channel rack preamp with digital output, or an 8-channel distribution amp with digital input. Those are real independent channels, but you can't get to them in the analog domain without extra hardware to do your conversion.

More soon!


Dr. Mike Metlay (PhD in nuclear physics, whoop de doo)
Wordsmith - Musician - Tech Freak - Amiable Zany
Everyone on this forum is a friend I haven't met yet
-- except for Bryce, who's, well, YOU know.
Re: Demystifying Interfaces
Dr Mike Metlay #3033327 03/14/20 07:28 PM
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Great stuff Dr Mike!

I wanted 8 inputs more because I like to plug in a few essentials and have them ready to go than that I want to record 8 channels in simultaneously, although the Quantum can do that (probably 2 chips as stated above).
Always a work in prorgress, as I find my sounds I can dedicate inputs. I do have a stereo pair dedicated to my Roland Handsonic now, that is hit the On switch, arm the tracks and go.

Tangent Warning!

Some points in my workflow may always require fiddling about since I have to compromise "best possible convenience" with "Keep It Simple, Stupid".
For example, I really only have one "character" preamp and am not on the hunt for another one. That is both a mic-pre and a DI and I love the sound of both of them. It is possible to use them both at once, two seperate channels. But, I do use different mics (sometimes with an FMR RNC inserted, sometimes not), different basses/guitars etc. So I do have to tweak a bit anyway.

I am still considering getting a Neat Beecsster for mobility, that plus headphones and a laptop would be a convenient mobile "studio."
My main reasons for recording elsewhere would be a bigger, better sounding room and a live track of drums, bass and guitar.
Instead of putting mics on everything one could find the best sounding point in the room for drums and then adjust bass and guitar positions/volumes accordingly.
I am not super fussy about bleed as long as the performance is good, in fact I don't care much at all about it. Parallel processing can provide options to address most shortcomings in a mix like that.
I don't have to make everything sound "just so and no other way", I am very open to "this feels good and it sounds just like it sounds."

Back to interfaces!!!!
The software that is free for the MOTU 896 I had provided busses as you describe above. It also allowed adjustment of built-in effects and EQ that could be sent to Cue Mix only for making a singer happy with reverb among other things. Or you could record he track with the effects, something I prefer to avoid.

I found the GUI for that to be a bit cryptic and fussy. It's gone now anyway.


There is never enough time to be in a hurry...
Re: Demystifying Interfaces
Dr Mike Metlay #3033333 03/14/20 07:53 PM
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Originally Posted by Dr Mike Metlay


It is quite common for interfaces, especially the moderately-priced ones with lots of connectivity, to boast about how many ins and outs they have. Here's the thing they don't tell you: often, even most of the time, some of those ins and outs share one conversion channel pair. That means you can't actually use all of them at once unless you sum them before sending them to conversion. If you only have four ADCs, you can't encode more than eight channels of audio at a time, no matter how much you squint and try to read the manual sideways.


Seems like a long time since I've seen that, but what I warn people about when looking at the advertised number of inputs and outputs is that a lot of them don't go through A/D or D/A converters. An interface claiming 26 inputs is likely to have 8 analog inputs (usually with combo XLR connectors for mic, line, or instrument DI inputs) 2 8-channel ADAT optical inputs (which become 4 channels each at 2x sample rate) and an S/PDIF input, usually on an RCA phono jack. Those ADAT inputs can be really handy, but if you want to record the whole band and some room and audience mics, you'll need a couple of outboard mic preamps with ADAT output. And then, there are outputs. Sometimes they include the headphone jack(s) in the count even though they carry the same signal as the "main" or "monitor" outputs.

Quote
So what do you look for to get at the truth? On the input side, look for phrases like "X channels of simultaneous recording" or "X analog inputs".

You look at the box and count the holes in it. wink

Re: Demystifying Interfaces
Dr Mike Metlay #3033913 03/18/20 06:06 AM
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This is a solid thread. It is especially true once you need more than 8 channels. There are a LOT of 8ch over USB/Thunderbolt/whatever boxes. But if you need 24 or 32 or more channels, the field thins tremendously (and there are no budget solutions). The input/output list is critical, along with anything else you need done - monitor control, etc. You start getting into situations where there aren't "all-in-one" solutions and you have to plan outside of built in digital mixers, volume controls, etc. Running surround speakers is another example of a requirement that most interfaces can't solve without external help for volume offsets, volume control, etc.

I had worked up to an RME UFX, which had all the expected driver stability benefits. Over time, I used all its inputs, then all the inputs on an ADAT expansion, the AES inputs were in use, most of the outputs were in use, and I was noticing that the length of the USB2 cable mattered, and which one I pulled out of the drawer.

The upgrade took careful planning. I was done with USB. I wanted something that didn't have to live 6' from my DAW. I wanted something expandable that I could grow over time. I settled on a Focusrite Dante setup. I put the PCIe card in one of the motherboard slots that directly connects to the CPU - not even a trip through the motherboard bridge chips! 128ch of I/O at minuscule latency. My studio went from all kinds of analog snakes and cables to simple Ethernet runs. I could put any box anywhere. I can add boxes 8ch or 16ch at a time whenever I want. I finally got to where mic pre's hit converters and the signal is digital all the way to my Genelec speakers. The improvement in imaging was not subtle - my whole family noticed the clarity when all the analog stuff went out of the monitor chain. (And I had been using a high end Grace Design monitor control box). I went with a Midas M32 to run monitor mixes to Dante headphone amps (Focusrite AM2s), that was later upgraded to a Allen & Heath SQ-5 which lets me run the whole studio at 96Khz if desired. At any given point in time there are just shy of 40ch of audio routing into the DAW and it is rock solid.

But to your point, this is a "designed" system. It was carefully assembled, tested, and deployed. All the hardware is "off the shelf", but it didn't come "assembled" if you will. Dante has become a digital patch-bay for me, and I can put any signal in the studio anywhere, which is very cool. An analog patch bay would be faster and easier, but the digital one is more flexible. Until I can afford a real analog console, this has been a wonderful setup. I'm sold on Ethernet interfaces, the expansion and scale is fantastic. The latency of the transport itself is sub 1ms, so I've essentially got ProTools HDX kinds of latency, even in the monitor path. One AD and one DA - all through FPGA hardware and no software drivers. So drummers have been happy. It is possible, but it took thought, and there are definitely other ways..

Re: Demystifying Interfaces
Dr Mike Metlay #3035476 03/28/20 03:48 PM
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Nice posting, Nathanael. Sorry it took me so long to reply! You make a couple of important points here, one large and one deceptively small.

One is that we are now entering the era when even relatively small home studio setups can see the benefits of Dante and other networking protocols. You've pointed out how much tighter your timing is and how much more straightforward the wiring can be, and I think we'll see more people discovering these benefits even when they aren't doing as much I/O as you are.

Along with that, we'll be seeing more and more different network boxes for small setups to go alongside the big layouts that are built by companies like Focusrite Pro. We're already starting to see home-studio-oriented stuff from ESI, and MOTU has been working in this space for quite some time. This is a topic that will continue to expand rapidly in the entire recording space as well as in live and install sound...

My one gripe here, of course, is that the wonderful thing about standards is that there are so many of them. Dante is only one way to network gear over Ethernet cabling; there are at least two other standards out there, and each one has its proponents. The problem is that a lot of the terminology at that level tends to leave beginners in the dust; one guy claims Dante is superior while another supports AVB, but it's hard for a newbie to understand their positions. Probably a topic for a new thread.

The other point: USB cables come in all shapes and sizes and lengths and build qualities. If something that used to work stops working, or if something that usually works isn't working now, the first thing to do is to swap USB cables and see if that helps. grin

mike


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