TRAVELER mk3: phantom power adds a lot of noise

[planktone]

...

something is really wrong with the phantom power supply of the traveler mk3 ...

i used an external ( not expencive ) battery operated phantom supply to compair it with the internal one
i connect a condencer microphone in a silent studio and gave it enough gain to listen the room noise.

this link is to a sample recording
http://files.getdropbox.com/u/137991/tr ... supply.mp3
you hear first the external supply, then the internal.

it is a big differnce ...

i did also a check with a test microphone dummy and made a plot with travelers spectogram



this isn't normal for a unit claiming it is 192 k / 24 bit ...

can anyone do a similar test ?

w.

[James Steele]

From your screenshot, I see you are using Windows. You double posted this also in the OSX forum. Please don't do that. I am deleting the other post.

[planktone]

...

i use my traveler as wel on windows as on osx

i don't see this as a windows problem, the traveler also has this typical ( and disturbing ) noise when it is used as standalone unit.
i hope mac - users don't mis this threat as it is only in the windows - hardware section. i can understand they don't follow it. thats the reason i made the double post ...

maybe we need a hardware - not related to operating system too in the forum ? or where do you think in can post this to have both users reading it ?

for me this is a problem of mayor concern ... this is not the noise you expect from a 192k / 24 bit unit ... and i don't like the idea to carry all the time an external power supply with me as motu support suggested ....

regards,

w.

[1nput0utput]

I don't see this problem on any of the four mic inputs. I'm using the DC power supply. Are you using FireWire bus power?

[planktone]

it has it when it is powered by main or firewire bus
did you added enough gain ? no pad ?
thx for testing
w.

[TheRealRoach]

Is this noise continuous? Or it is intermittent?

[1nput0utput]

it has it when it is powered by main or firewire bus
did you added enough gain ? no pad ?
thx for testing
w.

Of course you will hear self-noise when you add enough gain. That is normal for any pre-amp.

[planktone]

>> Of course you will hear self-noise when you add enough gain. That is normal for any pre-amp. <<

i dind't changed the settings of the traveler preamp, i powered first the mic by the ( 60 euro's chinees brand ) external supply , second with the internal one. the first part of the recording has a lot of room, mic & pre-amp noise, the second part got the same but adds this typical strange motu traveler phantom power noise.

to honnest, i am very satisfied with the pre-amp noise ( as long i don't use the internal power supply ) of my traveler.

i talked with my supplier about it. he sended me a new interface and i felt really sorry for them as it had the same noise. it returned for check and repair / modification for nearly 2 months.

i quote my supllier: " das ist de facto ein bestehendes, bauartspezifisches Problem. Ich empfehle die Rücksendung zwecks GS (vorbehaltlich Überprüfung und ggf. Abzug) auf Kd.-Kto. und Néubestellung eines anderen Interfaces. >> Translated by babelfish: that is in fact an existing, design-specific problem. I recommend the return for gs (subject to examination and if necessary departure) on Kd. - Acct. and order of another interface. "

today i have a third ( new ) one ... and it has the same noise

i discoverd it begin this year when i was recording some chamber music in a littel church using a sennheiser mkh 30-40 ms-set and 2 dpa's for ambiance. first i tought it was the typical noise of an airplane high in the sky ... but it stayed and didn't changed. i was very lucky to have my old 896 with me as we couldn't get rid of the disturbing noise.

i understand it is somewhere at the bottom close to silence ... but is it clearly audible above the room, mic and pre-amp noise.

motu tech support advised me to use and external ... a bit strange for me when i read at the front of the unit 192/24 ...

w

[makko]

...

maybe we need a hardware - not related to operating system too in the forum ? or where do you think in can post this to have both users reading it ?

I am new here.. and it amazed me that there wasn't a subforum like you describe..

[TheRealRoach]

There are a few things we need to know:
- what are the specs of your computer (including whether it is a laptop)?
- what exactly is this "60 euro external supply"? A mic preamp? A DC power adapter for your Traveller?
- what model is your microphone?

[planktone]

here some info:

- my motu is standalone, not connected to my laptop ( pc ) or mac. it is powerded by the external mains supply that came with it ... actualy it doesn't matter how it is powered ... i also have tried it with a car battery to be sure it wasn't the ( swiched ? ) motu mains supply generating this noise.
- the 60 euro's external power supply is a phantom power supply, not a pre-amp. just an external 12 volt dc supply, inside the unit a dc-dc converter making 48 volt of it and 4 times 2 6.8 k resistors as you expect from a phantom supply.

- i have it with all my condensors. sennheiser mk's, dpa's, neumann, earthworks ... the example is a neumann that sounds clean on all my other equipment.

w.

[planktone]

how it is tested ...

http://files.getdropbox.com/u/137991/tr ... supply.mp3



w.

[TheRealRoach]

Well given the method of your testing it seems to be that you're right about a design flaw with the Traveller, especially since MOTU suggested you use an external 48V supply instead of the internal, and since you experienced the problem with 3 different Traveller units. The only other thing would be to have more Traveller users test their equipment with the exact gain settings and configuration that you used and screenshot the spectrograph.

I would post your images from your last post, as well as simple instructions on how to re-create your test and post it on gearslutz.com. There is way higher user traffic on that forum.

[APADRecordings]

This noise issue is found in the Traveler MKIII but varies from unit to unit. It seems to exist with some new (late model) microphones. I have the issue with a Holophone H3D and with one of my ADK TL microphones. It is not something that a manufacturer like MOTU could anticipate. It seems to be a problem with dynamic loading of the regulator in the phantom power supply caused by the microphone taking power dynamically.

I'm on a trip right now but will return July 8 and test a "fix". If it works I'll be glad to post the results here.

So, to repeat, it is not a pre-amp problem but one caused by the way some newer microphones utilize the phantom power supply.

[planktone]

So, to repeat, it is not a pre-amp problem but one caused by the way some newer microphones utilize the phantom power supply.

i agree it is a phantom power supply problem.

looking for your solution

i had the same problem with my sound devices 722
all 722 users got an ( hardware ) upgrade for free to solve the problem
could it be an example ?

w.