Background noise with DPA 4088, DAD6001BC and Motu traveler

[waigy]

I recently treated myself to a DPA 4088 and the DAD6001BC microdot to XLR adapter.

 

I noticed this background noise (recorded at maximum trim and gain) when it's plugged into my Motu traveler using the Motu's phantom power.

The noise in question is the sort of buzzing, not the hiss, it's at a low level, but may be noticeable in recordings.

I get the same noise using my AKG C1000S, but only when the AKG is switched off, as soon as I switch it on the noise disappears.

The DPA doesn't have an on/off switch.

 

I tried the DPA in my behringer PA using it's phantom power and that noise isn't there.

 

Is this noise a possible fault of the DAD6001BC or the traveler?

[paulears]

That's processor noise - very common with cheap internal soundcards. As the MOTU is a decent bit of kit, it's unlikely to be that - however, it's possible that it's actually produced in the computer and is then being transferred by the firewire cable. To rule it out, try another computer. If the noise remains, then you have a dodgy MOTU, and it is it's own processor clock leaking into the audio. If on another machine you get the usual noise free result, then at least you know the culprit. If the recording computer is a laptop - well worth unplugging the power supply, a common source of odd noises!

 

I'm not sure if big ferrite beads on a firewire cable would work? Worth trying?

[waigy]

Thanks for the reply Paul, I tried the mike plugged into the traveler with no pc attached and I get the same noise so it isn't pc related.

[waigy]

After a few checks on this noise problem, I’ve came to the conclusion that the fault is the traveler’s phantom power supply.

If I have my headmike plugged into channel one on the traveller and I switch on the phantom power for channels 2,3 and 4, the noise changes pitch getting lower as each extra channel is switched on.

It sounds like the phantom power supply is struggling to supply power.

 

I contacted Motu, but they only repeatedly told me to send the unit for repair and, as it’s out of warranty, I can’t afford the £150 to do that.

 

I was wondering if there’s anything I could do myself to fix this problem, I’m ok with soldering and taking electronic components to bits.

If I knew what to look for I could maybe replace any needed components/capacitors etc.

I’m assuming that the traveller uses an inverter as it can supply 48v power when it is powered by 18v or even 5v via firewire.

[Sound Man]

What about something like one of these to power your mic from.

 

David

[waigy]

What about something like one of these to power your mic from.

 

David

 

That's exactly what I was thinking about in the meantime (I'm already watching a ps400 on ebay), but I'd prefer if the traveler was fixed (cheaply).

[waigy]

I've just found out on motunation that the problem I'm having is very common with motu travelers, not just the MK1.

Lots of people complaining about noisy preamps when using phantom power.

I feel a bit let down after spending what I think is a lot of money to get a decent bit of gear that would do me for a lot of years.

I also think that motu should fix this for free if it's an inherent fault, even out of warranty.

I've hardly used my traveler, I always look after it and it's in my living room 99% of the time.

 

Seems that the seperate inline phantom power supply is going to have to be the solution.

 

I always liked the thought of being able to go to the top of a mountain and recording my geet at very high quality with my traveler and laptop.

I'll still be able to do that, but I'll just have to carry a few car batteries with me.

 

Does anyone make a 4 car battery belt for wearing round your waist?

Gap in the market?

[waigy]

Updating this in case anyone has the same problem as me.

 

Just got a behringer micropower PS400 portable phantom power supply to power the mike, problem solved, no buzzing noise.

 

So the noise was definitely caused by the traveler's phantom power supply.