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high pitch frequency on motu 896mk3 hybrid inputs

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Discussion related to installation, configuration and use of MOTU hardware such as MIDI interfaces, audio interfaces, etc. for Mac OSX

Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Spencil_Splodge » Fri Jan 06, 2012 7:14 am

I don't know if PSU could cause that frequency - it's obviously not regular A/C hum, but it is a switching mode power supply (I believe) which if not filtered correctly could cause issues such as RFI/EMI and noise on digital/audio circuits? Again, I'm no hardware person :)
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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Klaus » Fri Jan 06, 2012 8:10 am

I opened a tech link...
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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Spencil_Splodge » Fri Jan 06, 2012 8:12 am

Good, that puts two of us on their case. My tech links have been there since 16th Dec though, and they are still 'unread' :-S
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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Klaus » Fri Jan 06, 2012 8:18 am

Please post when you get an answer
THNXS
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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Klaus » Fri Jan 06, 2012 12:55 pm

Klaus wrote:And here is a screenshot of Cuemix FX FFT analyzer, 4 channels open in a realworld situation...gains set to +35db.

http://www.redmountain.ch/896mk3H-FFT-screenshot-1k65hz.pdf

Hmhh....

BTW 1k65hz relates to PSU ?

Klaus


Now with the right screenshot , not nice, 1k65hz @ -72dbfs...

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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Spencil_Splodge » Fri Jan 06, 2012 1:55 pm

Yes, not good. I get similar results. I'm also trying RMAA on it just for the hell of it. Can't get good results with that, unsurprisingly - makes the unit look bad!

Also note there is a harmonic of the tone at a lower amplitude (around 3500Hz) which you can also see on your screenshot - this increases, of course, with gain. There are also some sub-tones either side of the primary 1650Hz tone.

Not happy with this at all... finger is on the returns trigger, just giving Motu a chance.
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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Klaus » Sun Jan 08, 2012 3:05 am

Klaus wrote:And here is a screenshot of Cuemix FX FFT analyzer, 4 channels open in a realworld situation...gains set to +35db.

http://www.redmountain.ch/896mk3H-FFT-screenshot-1k65hz.pdf

Hmhh....

BTW 1k65hz relates to PSU ?

Klaus


I also made a Cuemix FX FFT screenshot of both - 896mk3 and 896mk3H - for reference 6 inputs open with +53 dB gain, just for comparison....

http://www.redmountain.ch/896mk3-896mk3H-FFT-screenshot-1k65hz.pdf

So the new 896mk3H has 8dB more PSU bleeding than the 896mk3 ( FW )

Now I remember a gig last year where I was searching for a tonegenerator to shut off, since it sounded like in the old analog days when a tone generator was on but not routed...
( Soundcraft... )

And now with 8db more bleed, :mumble:

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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Spencil_Splodge » Tue Jan 10, 2012 4:45 am

Ok, after a bit of a wait in a phone queue I got through to the phone tech support. The person I spoke to was friendly and helpful and was asking the right kind of questions. They have now taken ownership of my TechLink and are investigating it with the engineers. They also apologised for the wait on the TechLink I had with them.

Just thought I'd add this as a fairly positive Motu tech support experience - obviously, it's not progressed very much yet, but thought I'd chip in on something positive as to not just post negative experiences in these forums :)

I'd also like to add here that, although this tone/hum issue is serious for me, the other aspects of the product have been very impressive. I used the 896mk3 Hybrid to interface to Sonar X1 and to live mix, with 6 monitor mixes, and record 3.5 hours of around 12 tracks of audio at ~1ms buffer size (as reported in Sonar anyway) - no glitches or drop outs...

I really hope this issue is resolved soon :)
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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Klaus » Tue Jan 10, 2012 5:38 am

Thank you for posting ! ( my tech link is still unread, but there is hope )
I sent my one back and am hoping for a PSU replacement in these units...
Just can't take the *stage whining*
Please continue post results

Best

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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Klaus » Sat Jan 14, 2012 9:20 am

k
my tech link is read...
Hoping for a fix...that eliminates the whining completely...

Best

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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Spencil_Splodge » Mon Jan 16, 2012 5:48 am

Cool - yes me too!

I'm currently working with Tech Support to see if they can replicate the issue and they have also got the developers interested, so this is good progress so far. Maybe there's still hope on this one!

Spence.
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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Klaus » Mon Jan 16, 2012 8:42 am

Here the consensus seems to be that this is a power supply issue...
It's an universal PSU and varying the line voltage influences the 'whining'
We could be wrong though.
But not all units seem to be the same...!

Best

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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Spencil_Splodge » Tue Jan 17, 2012 2:08 am

Yeah, I fear it's the PSU too... especially now you say that varying the input voltage alters the tone...

Out of curiosity, what is your normal mains voltage? I'm in the UK so mine is 240V. I'm wondering if in the US they even have the issue when the input voltage is 120V???

Thanks.
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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Klaus » Tue Jan 17, 2012 10:11 am

Switzerland > 240V, sometimes 238V, sometimes 244V...
or even different :D

Best

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Re: high pitch frequency on motu 896mk3 hybrid inputs

Postby Spencil_Splodge » Mon Jan 30, 2012 8:27 am

Just to let you know, I'm still in communications with Motu regarding this issue. There has been a delay due to NAMM 2012 - most of them were off to that event! :)

I will post once I get some more info...
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