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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Audio Measurement and Testing => Topic started by: David Sturzenbecher on March 10, 2014, 01:32:07 pm

Title: Multiple Measurements with 2 USBPre2's
Post by: David Sturzenbecher on March 10, 2014, 01:32:07 pm

Hello,
I have two USBPre2ís and was interested to know if anyone had experience using more then one device to acquire measurement traces with Smaart 7.  I have used a Ocatacapture for more then one trace, but never two separate devices.  Any gotchas?

Thanks
Dave
Title: Re: Multiple Measurements with 2 USBPre2's
Post by: Timo Beckman on March 10, 2014, 02:03:27 pm
Up to now i do not have any problems and i'm using 5 Smaart i/o's at this time.
The only challenge i had was to find a USB hub multi TT here in the Netherlands. After trying about 25 different hubs i had to order 1 in America.
The problem i had with the first 3 i/o's was the USB protocol on my mac. Card 1 and 2 no problem but nm.3 got refused because apparently the usb protocol sees each i/o as a full bandwidth device and nm 3 is seen as to much for 1 port.
I tried to use a motu 4pre (firewire) along with the i/o's and that gave me problems. Since i was running out of time (and in my case patience) i figured out an other way to hook all up at that time so no idea what happened there sorry.
 https://www.facebook.com/photo.php?fbid=10202965183718641&set=a.4589470022856.2181275.1475271891&type=1&theater (https://www.facebook.com/photo.php?fbid=10202965183718641&set=a.4589470022856.2181275.1475271891&type=1&theater)
https://www.facebook.com/photo.php?fbid=10202946398129013&set=a.1729232758712.2097575.1475271891&type=1&theater (https://www.facebook.com/photo.php?fbid=10202946398129013&set=a.1729232758712.2097575.1475271891&type=1&theater)

Title: Re: Multiple Measurements with 2 USBPre2's
Post by: Mark McFarlane on March 10, 2014, 03:15:57 pm
Are you running on a Mac? If so, you can use the Aggregate Device setup.  On Windows I think you may need a special driver (ASIOFORALL or something like that) to use multiple devices.
Title: Re: Multiple Measurements with 2 USBPre2's
Post by: Arthur Skudra on March 10, 2014, 04:10:53 pm
Hello,
I have two USBPre2ís and was interested to know if anyone had experience using more then one device to acquire measurement traces with Smaart 7.  I have used a Ocatacapture for more then one trace, but never two separate devices.  Any gotchas?

Thanks
Dave
Unless I missed something, the USBPre2 does not have an external word clock synchronization capability, so no, you won't be able to use two of them simultaneously with Smaart 7, even if you set them up as an aggregate device.
Title: Re: Multiple Measurements with 2 USBPre2's
Post by: Adam Black on March 11, 2014, 09:26:55 am
Any gotchas?

Using multiple devices is one thing and is not inherently a problem. The gotcha is if you'd like to use one device for your reference signal and another device for your measurement signal. I.E. Cross device transfer function. The software isn't the issue for this scenario. What is the problem is both devices need to be on the same clock, or you'll get clock drift. So the feasibility of this setup is determined by your intended use case.

-A
Title: Re: Multiple Measurements with 2 USBPre2's
Post by: Mark McFarlane on March 23, 2014, 01:13:03 pm
Unless I missed something, the USBPre2 does not have an external word clock synchronization capability, so no, you won't be able to use two of them simultaneously with Smaart 7, even if you set them up as an aggregate device.

OSX provides for clock synchronization for devices that can't connect via word clock. I have no idea how well it works, but it may be good enough,.  Easy enough to test, just put reference and measure on the same device, then put them on different devices and see if you get the same result.

http://support.apple.com/kb/HT1215?viewlocale=en_US&locale=en_US (http://support.apple.com/kb/HT1215?viewlocale=en_US&locale=en_US)
Title: Re: Multiple Measurements with 2 USBPre2's
Post by: David Sturzenbecher on March 23, 2014, 02:39:37 pm
 I was unable to get this to work as Smaart only saw one USBPre2 driver.


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Title: Re: Multiple Measurements with 2 USBPre2's
Post by: Mark McFarlane on March 23, 2014, 03:50:49 pm
I was unable to get this to work as Smaart only saw one USBPre2 driver.


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Did you select the "Allow multi-device transfer function" checkbox under the Transfer Function configuration Options dialog?  I just did a quick test and Smaart 7 allows me to set up a transfer measurement using an aggregate device.
Title: Re: Multiple Measurements with 2 USBPre2's
Post by: David Sturzenbecher on March 23, 2014, 07:10:19 pm
Yeah, I did. But there was no way to differentiate what I/O was from the first USBpre2 and the second


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Title: Re: Multiple Measurements with 2 USBPre2's
Post by: Mark McFarlane on March 23, 2014, 11:56:42 pm
Yeah, I did. But there was no way to differentiate what I/O was from the first USBpre2 and the second


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When you aggregate devices under OSX' Audio Midi Setup, the first device you select gets inputs 1-n, the next device gets inputs n+. e.g., If you aggregate two dual channel devices 1-2 are from one device, 3-4 are from the other device and it SHOULD show up in Smaart as a 4 channel input device, theoretically. 

Sorry, I don't know your experience level with OSX Aggregation but it sounds like you may be helped by studying up on it.  All I tested in smart was to see if it 'saw' aggregate devices, I combined a 32 channel device with the built-in laptop inputs and it saw the device. I didn't actually 'use' the device but theoretically it should work, Smaart should have no way of knowing it is anything other than a normal device.
Title: Re: Multiple Measurements with 2 USBPre2's
Post by: David Sturzenbecher on March 24, 2014, 12:10:46 am
You asked earlier and I see that I never responded ... But I am running on windows. I am guessing that OSX Aggregation is a Mac only thing...  I honestly know nothing about them.


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Title: Re: Multiple Measurements with 2 USBPre2's
Post by: Mark McFarlane on March 24, 2014, 10:39:21 am
You asked earlier and I see that I never responded ... But I am running on windows. I am guessing that OSX Aggregation is a Mac only thing...  I honestly know nothing about them.

Yep, Device Aggregation is the name for a specific OSX feature. 

Have you installed the USBPre2 ASIO drivers?  They include low level WDM drivers and if you select the WDM drivers in Smaart you may see both devices inputs.  Depending on your version of Windows ASIO4ALL may or may not work, it hasn't been supported in 6 years or sound back when I looked at it a decade ago it was hit or miss.

http://www.harmonycentral.com/articles/aggregating-audio-interfaces-w-30956616

If you want to invest more time in getting this to work, contact Sound Devices, and also make a post on GearSlutz' recording forum, I think you are more likely to find someone who has tried to solve aggregation under Windows in a recording forum.  On Mac's its been a built in feature for many releases, and doesn't always work perfectly.