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MOTU 1248, 8M, 16A Thunderbolt interface Audio Interfaces
Old 16th March 2019
  #3871
Gear Maniac
 

I am almost certain that is TB1 , that is why I bought a Aorus pro, and will buy an alpine ridge card
Old 17th March 2019
  #3872
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jlaws's Avatar
I have the alpine ridge plus apple adapter. It works ok except hotplugging doesn't work. Might be better to get the startec adapter.
Old 4 weeks ago
  #3873
Gear Maniac
so, after lots of thinking and trying to find information on the web, I finally settled on an purchase of MOTU 8pre-es.

I want to build a rehearsal recording studio, so the bands can produce themselves. I was having lots of trouble in trying to find out cost / effective devices so I ended choosing the 8 pre-es with my Motu 1248. just to take out 10 meters of cable / infrastructure will hopefully save me a bunch, that I will be able to spend on other stuff.

so my questions, to those familiar with motu avb:

1) how stable is ur AVB system?

2) have u added additional preamps through ADAT? do u note significant latency?

3) if u have added additional preamps through adat, have u tried cheap ones like Behringer AD or others? how do they compare to MOTU's? I originally planned to have 2 motu 8 pre es, but I will not have the budget for it in the begging

4) are u using MOTU's app to control ur units? are they running smooth? I have an old iPad 4 and an iPhone 6. in both of them, the Motu's app feel sluggish.

Next week, I will also be able to provide replies or test data to those interested. so if u have a question, please let me know, and I will do my best in answering them when I'm testing it with my 1248.

thank u!!!
Old 4 weeks ago
  #3874
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In #3704 Ponzi asked about the technology behind volume controls of "monitor out". Was there ever ar reply to this?
I would also like to know if "main out" and mon out" is controlled by analog means or by the DAC chip? Or is it controlled by some bit-reducing chip before the DAC or maybe a chip after the DAC?
Old 4 weeks ago
  #3875
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ponzi's Avatar
Quote:
Originally Posted by skjenzen View Post
In #3704 Ponzi asked about the technology behind volume controls of "monitor out". Was there ever ar reply to this?
I would also like to know if "main out" and mon out" is controlled by analog means or by the DAC chip? Or is it controlled by some bit-reducing chip before the DAC or maybe a chip after the DAC?
I think there was some educated guessing, but I don't know the exact nature of the mechanism. As I observed, if there is not an analogue gain control, turning down the volume reduces the bit resolution.
Old 4 weeks ago
  #3876
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emrr's Avatar
Quote:
Originally Posted by skjenzen View Post
In #3704 Ponzi asked about the technology behind volume controls of "monitor out". Was there ever ar reply to this?
I would also like to know if "main out" and mon out" is controlled by analog means or by the DAC chip? Or is it controlled by some bit-reducing chip before the DAC or maybe a chip after the DAC?
The chip data sheets and MOTU both say digital control of output, analog control of input. Digital gain control is built into the DA chip.
Old 4 weeks ago
  #3877
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ponzi's Avatar
Quote:
Originally Posted by emrr View Post
The chip data sheets and MOTU both say digital control of output, analog control of input. Digital gain control is built into the DA chip.
Please refer me to the specific documentation on this. Your answer begs the question. Sure, the chip has digital gain control--put a number in and that is the attenuation in decibels--question again is whether the chip implements it with an array of resistors or simply does arithmetic on the bits so that at low volumes its essentially 8 bit resolution like an 80s video game.
Old 4 weeks ago
  #3878
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Lady Gaia's Avatar
Quote:
Originally Posted by ponzi View Post
Please refer me to the specific documentation on this. Your answer begs the question. Sure, the chip has digital gain control--put a number in and that is the attenuation in decibels--question again is whether the chip implements it with an array of resistors or simply does arithmetic on the bits so that at low volumes its essentially 8 bit resolution like an 80s video game.
There's no reason it would have to have a dramatic impact. 32-bit floating point DACs are common enough that if that's what they're using then digital control would be more than sufficient to allow for a full 24-bit range even at low output levels.
Old 4 weeks ago
  #3879
Here for the gear
 

Quote:
Originally Posted by Lady Gaia View Post
There's no reason it would have to have a dramatic impact. 32-bit floating point DACs are common enough that if that's what they're using then digital control would be more than sufficient to allow for a full 24-bit range even at low output levels.
According to block diagrams of the ES9016 chip it performs volume control in a filter section before the DA conversion. For that reason the effective bit-depth at low volume levels must be lowered compared with source.

Smart interpolation etc. can probably help a lot on perceived effect of reduced volume. I have read somewhere in a presentation by ESS, that they consider s/n in the chip internal volume control to be almost as good as absolute top level analog controls at thousands of dollars. For that reason it is very interesting to know if the chip volume control is used for the outputs of main/mon and phones.
Old 3 weeks ago
  #3880
Using a hardware monitor controller in the control room is such a joy... all analog, no worries about bit-depth reduction, plus you can get multi-speaker switching, robust headphone amps and a quality fader to control volume. Winner!
Old 3 weeks ago
  #3881
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ponzi's Avatar
Quote:
Originally Posted by HCMarkus View Post
Using a hardware monitor controller in the control room is such a joy... all analog, no worries about bit-depth reduction, plus you can get multi-speaker switching, robust headphone amps and a quality fader to control volume. Winner!
I can't disagree. I use a mackie big knob passive for my 1248. the two channels do not track togther at lower volumes.

The 828es I just got has a more useable volume control. What I did was turn the gain of my bryston amp way down so that I dont need to worry so much about losing resolution at low volumes.
Old 2 weeks ago
  #3882
Here for the gear
 

I finally asked Motu support about volume control for the analog outputs in my Motu 1248. They replied quickly - good service:

"The ES DAC on the 1248 covers all Analog Outputs on the BACK of the 1248. This means the Main, Monitor, and eight Analog Outputs. The only outputs that the ES DAC does not cover are the Phones outputs on the front.

As for the volume control, everything is being handled by the DAC, regardless of if you use the front panel knobs or the web app control."

By the way, I really love my Motu 1248
Old 2 weeks ago
  #3883
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ponzi's Avatar
We sort of knew that, the question remains, how the dac handles it.
Old 2 weeks ago
  #3884
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Quote:
Originally Posted by ponzi View Post
We sort of knew that, the question remains, how the dac handles it.
I think, at this category of devices it's pretty much common thing and one can't really ask for feature set (eg. something akin to digitally controlled relay attenuators) like at some 2 channel converters with similar or higher price point than full blown multi-channel interface.

Not that I specifically tested MOTU interfaces in this regard, but I've played with and measured few other Sabre based DACs. And it's behaving very well (like without truncation artifacts), I believe, they were first on market to introduce DAC chips with 32 bit path and internal processing. And they tried to make as good as possible for features like integrated volume control.
There is even their presentation about that..
http://www.esstech.com/files/3014/40...me-control.pdf

Of course it also depends on execution of analog circuitry around that at particular device, they mention application with highest Sabre model and summed 8 available outputs at chip to stereo for best possible dynamic range. Which doesn't seem to be case for MOTU interfaces, but it anyway reach very respectable 123dB according to specs of 1248 for example.

Naturally digital controls can work very well, when you don't need to apply some excessively high attenuation to reach your working level. So it makes sense to optimize sensitivity of downstream device (like with analog trims at normal active monitors) and be in range of say 20-30dB for quietest listening.

In that regard, I kinda like approach of RME (and lot of others), where they have three fixed presets for output sensitivity, so first coarse level adjustment is at analog domain and from there you can use digital control to adjust your working volume. Such "hybrid" kind of volume control can work very well, because at the analog stage you can establish some basic level to make downstream devices happy you can get other advantages od fine adjustment in digital domain (like you're free of problems with pot L/R tracking, you can be very precise with adjustments by small steps and there is perfect recall etc.).

Michal
Old 1 week ago
  #3885
Gear Maniac
 
Dan O's Avatar
 

Can someone please write a summary on this thread...

I don't know if it's mentioned somewhere but does anyone know which converter chips 16a is using? The sabre is only on the outs right?

and

Anyone who knows if Motu is planning any updates or MK2 soon?
Old 1 week ago
  #3886
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ponzi's Avatar
Thanks all for the contributions to the discussion. My take-away at this point is that I am disappointed that I was correct in assuming that the volume of the analog outputs is performed by mathematical operations such that lower volumes have less digital resolution. Because of this, it is of sonic benefit to have some sort of attenuation in the analog domain to avoid turning down the digital volume quite a bit. In other words, those wonderful noise and distortion specs apply to full volume, and use of the digitally based volume control will diminish the sonic quality--though I am sure there is room to debate how much diminution is involved.

I think the most prudent suggestion was that one provide the necessary analog attenuation to ensure that one is only using the top range of the digital volume control. My mackie big knob, consisting of a solid and ergonomic case and knob, houses a poorly performing potentiometer, and I will be looking into finding an audiophile pot to replace it with. I am investigating whether the big knob product uses some sort of t-pad in its attenuation, or is simply a straight pot.

I am very pleased with my 1248 and 828es overall, but I do want to maximize my listening experience, and the full-scale output of these devices is far more than needed to drive my monitors to a sensible volume. I also note that in my shopping experience, in-line fixed db attenuators are ridiculously expensive.
Old 1 week ago
  #3887
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loopy's Avatar
 

Quote:
Originally Posted by ponzi View Post
Thanks all for the contributions to the discussion. My take-away at this point is that I am disappointed that I was correct in assuming that the volume of the analog outputs is performed by mathematical operations such that lower volumes have less digital resolution. Because of this, it is of sonic benefit to have some sort of attenuation in the analog domain to avoid turning down the digital volume quite a bit. In other words, those wonderful noise and distortion specs apply to full volume, and use of the digitally based volume control will diminish the sonic quality--though I am sure there is room to debate how much diminution is involved.

I think the most prudent suggestion was that one provide the necessary analog attenuation to ensure that one is only using the top range of the digital volume control. My mackie big knob, consisting of a solid and ergonomic case and knob, houses a poorly performing potentiometer, and I will be looking into finding an audiophile pot to replace it with. I am investigating whether the big knob product uses some sort of t-pad in its attenuation, or is simply a straight pot.

I am very pleased with my 1248 and 828es overall, but I do want to maximize my listening experience, and the full-scale output of these devices is far more than needed to drive my monitors to a sensible volume. I also note that in my shopping experience, in-line fixed db attenuators are ridiculously expensive.
I had the same problem with my Mackie Big Knob Passive. Being a bit OCD, it drove me up the walls and lasted 2 days before I sent it back.
Old 1 week ago
  #3888
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Quote:
Originally Posted by ponzi View Post
I was correct in assuming that the volume of the analog outputs is performed by mathematical operations such that lower volumes have less digital resolution. .
Did you derive this by the absence of evidence to the contrary?

The Sabre (AFAIK) is a 32-bit DAC with an on-board DSP. To me this suggests that it could handle digital volume control with ample extra resolution beyond the 24-bit stream coming from the host.

I admit I’m no expert here, but it seems to me that you shouldn’t experience bit reduction until you adjust the level to less than 1% of maximum.
Old 1 week ago
  #3889
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Quote:
Originally Posted by ponzi View Post
Thanks all for the contributions to the discussion. My take-away at this point is that I am disappointed that I was correct in assuming that the volume of the analog outputs is performed by mathematical operations such that lower volumes have less digital resolution.
These MOTU's use the ESS Sabre volume control, which is actually quite good.

MOTU 1248, 8M, 16A Thunderbolt interface

http://www.esstech.com/files/3014/40...me-control.pdf
Old 1 week ago
  #3890
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ponzi's Avatar
Quote:
Originally Posted by infindebula View Post
Did you derive this by the absence of evidence to the contrary?

The Sabre (AFAIK) is a 32-bit DAC with an on-board DSP. To me this suggests that it could handle digital volume control with ample extra resolution beyond the 24-bit stream coming from the host.

I admit I’m no expert here, but it seems to me that you shouldn’t experience bit reduction until you adjust the level to less than 1% of maximum.
Yes, absence of evidence to the contrary. We have had a lot of discussion and we know its in the sabre chip. We don't know how the sabre chip handles the dac. It has 32 bit internal bus for all its fancy calculations, but we don't know how many bits go into the analog part out. I don't know what technology it uses. I recall at the dawn of digital sound in the 1980s, the analog conversion was done as if you had 16 resistors increasing ohms in powers of two, and they were switched in and out based on the 16 bit number going in to it. In this case, if the volume is such that the peak signal is 4 bits, then the sonic quality will degrade to a 4 bit device.

But maybe there are other technologies since then--maybe some sort of pulse width modulation as is done in class D amps.

I believe the volume has 128 steps, so that is binary, what 7 bits? So it could be implemented with 7 resistors being switched in and out.

Thanks for showing that powerpoint on the subject of analog versus digital--someone else posted it a couple of days ago. It reinforces that I understand the big picture, technology wise, but the exact implementation on the sabre chip is still a black box. I admit I am a bit lazy here as I may be able to download the spec sheet or investigate the chip, but at this point, I have the information presented thus far and a willingness to learn more.

The powerpoint discusses this in terms of the noise floor, but I am not sure that is the same as a 4 bit musical signal having only 16 discrete output voltages and hence is not very true to the original signal, noise floor or not.

Obviously, a digital only process is least expensive. If its 24 or 32 bit in nature, then the low volumes could still be seen as having 16 bit resolution and this would not be a problem at all, perhaps. But...do we know as a fact that the output dac process is 32 bit just because the internal bus is?
Old 1 week ago
  #3891
Lives for gear
@ponzi your point is well-stated. But while your concerns are founded in doubt, MOTU though it good enough to include on their interfaces, and you can always use your ears, or ask someone here to do some null tests on the digitally attenuated output.
Old 1 week ago
  #3892
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ponzi's Avatar
Quote:
Originally Posted by infindebula View Post
@ponzi your point is well-stated. But while your concerns are founded in doubt, MOTU though it good enough to include on their interfaces, and you can always use your ears, or ask someone here to do some null tests on the digitally attenuated output.
Sure, but I also note that when asked the question, according to a poster here, motu did not directly answer it, but rather noted that the chip was handling volume control without specifying the mechanism it uses in doing so--though I am sure they are aware of the information. I am simply awaiting exact information which thus far has eluded us.
Old 1 week ago
  #3893
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@ponzi

MR Miller is a lead developer at MOTU so I expect he knows what he’s talking about.

Quote:
Originally Posted by mrmiller View Post
Yes, we do use the DAC's 32-bit volume control, which is quite good.
The presentation I linked above says that the 32 bit Sabre DAC volume control is better than most analog volume controls:

Quote:
• The -135dB of the ESS Sabre DAC would need an exceptionally low noise analog volume control to beat its internal digital one
For comparison a Cranesong Avocet 2 monitor controller has a noise floor of -115dB.

It also confirms that attenuation is performed in the digital domain in 32bit, which is extremely high resolution.

More on this here:
http://www.esstech.com/files/4314/4095/4318/sabrewp.pdf

Quote:
Clickless, Very High Resolution Volume control
The firmware presents a 0.5dB volume control register to the user allowing setting of volume to 0.5dB accuracy. However, internally the volume control operates to less than 1/64 of a dB and smoothly moves from one requested volume to the next. This results in a perfectly click-less volume step.
Apogee use Sabre DAC volume controls too:

ESS Sabre32 DAC - Apogee Electronics
Quote:
While developing Symphony I/O’s standard-setting DAC stage, it became evident that the components used to provide digitally-controlled analog attenuation were limiting the DAC’s performance, so another design had to be found. The 32-bit digital attenuation offered by the ESS Sabre32 DAC is the perfect solution – digital resolution is maintained far beyond the circuit noise floor while noise and distortion performance remains un-compromised.
It sounds good to me.
Old 1 week ago
  #3894
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Dan O's Avatar
 

Anyone who knows if MOTU is planning any updates on the avb interfaces such as 16a?

Wouldn’t it be time for a mk2?
Old 1 week ago
  #3895
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locojohn's Avatar
Quote:
Originally Posted by Dan O View Post
Anyone who knows if MOTU is planning any updates on the avb interfaces such as 16a?

Wouldn’t it be time for a mk2?
What is it that you do not like in the original version? They better improve their drivers indeed – their last updates are from fall 2018.

Andrejs
Old 1 week ago
  #3896
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Monkey Man's Avatar
 

Echo that.

With all the ridiculous delays I've had in purchasing, including being ripped off by the previous wholesaler, I've been holding out hope that an update will appear.

I'm hoping for coloured metering, something I asked about 3 years ago, and DHP (direct hardware playthrough) when using Digital Performer.
Old 1 week ago
  #3897
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Dan O's Avatar
 

Quote:
Originally Posted by locojohn View Post
What is it that you do not like in the original version? They better improve their drivers indeed – their last updates are from fall 2018.

Andrejs
I’m comparing with orion32 gen3 . Maybe motu could upgrade the AD as well. Maybe add color display instead as on some of the other interfaces.
Old 1 week ago
  #3898
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Quote:
Originally Posted by locojohn View Post
What is it that you do not like in the original version? They better improve their drivers indeed – their last updates are from fall 2018.

Andrejs
Colour OLED displays and TB/USB connectivity on a USB-C connector would be on my wish list
Old 1 week ago
  #3899
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Quote:
Originally Posted by infindebula View Post
Colour OLED displays and TB/USB connectivity on a USB-C connector would be on my wish list
I am hoping for a TB3 interface on their next interface.

Just wanted to built a new PC with a Gigabyte Designare motherboard and it seems that the Gigabyte TB 3 port (Titan Ridge) on this motherboard does not support the actual MOTU TB1 interfaces.
Old 6 days ago
  #3900
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arthur_br's Avatar
Quote:
Just wanted to built a new PC with a Gigabyte Designare motherboard and it seems that the Gigabyte TB 3 port (Titan Ridge) on this motherboard does not support the actual MOTU TB1 interfaces.
Is that true? Because I have an 8M and I was thinking of doing the exact same movement of buying the Designare and a TB 3 to 2 adapter. Anyone knows if this could work, please?
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