high pitch frequency on motu 896mk3 hybrid inputs

[Spencil_Splodge]

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

[Klaus]

I opened a tech link...
Klaus

[Spencil_Splodge]

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

[Klaus]

Please post when you get an answer
THNXS
Klaus

[Klaus]

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-s ... 1k65hz.pdf

Hmhh....

BTW 1k65hz relates to PSU ?

Klaus

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

Klaus

[Spencil_Splodge]

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.

[Klaus]

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-s ... 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/896mk3-896mk3 ... 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,

Klaus

[Spencil_Splodge]

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

[Klaus]

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

Klaus

[Klaus]

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

Best

Klaus

[Spencil_Splodge]

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.

[Klaus]

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

Klaus

[Spencil_Splodge]

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.

[Klaus]

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

Best

Klaus

[Spencil_Splodge]

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...