Concerning audible clicks with data writing, Rob Wrote
>The source turned out ot be subtle voltage drops to the
>phantom power supply circuit each time the hard drive started the
>write cycle.
Aha! My little brain had thoughts of amplified internal bleeding ;^)
within the unit itself, but this explaination makes much better sense.
Mark
=20
On 8/21/05, Rob Danielson <> wrote:
>
> Something very similar was happening with the first 744's and your
> detective work is very consistent with their findings. I took an
> early unit to the woods and promptly cranked up the gain. The files
> made by the two mkh mics had very low frequency bumps at exact
> intervals-- about every 5 seconds as I recall. The NT1A's files were
> fine. The source turned out ot be subtle voltage drops to the
> phantom power supply circuit each time the hard drive started the
> write cycle. I never learned why the mkh's were affected and not the
> NT1-A's. Of course, Sound Devices was able to make a modification to
> remove the audible bumps entirely which all later units have.
>
> It never occurred to me that the periodic disc sounds with my NH-900
> HiMD are write cycles because the period is so long, about 8 seconds.
> Make sense, what else could it be? In quiet locations, I put it in a
> leather carrying case to absorb the clicking.
>
> In Len's critique of the M-Audio recorder's specs, he mentions the
> challenge of running the 48 volt phantom supply to the mics on such a
> low voltage. Some of the phantom supplies I tested with the NH-900
> had less noise when operating on higher voltage. Does the MD-MS722
> run on more voltage?
>
> Sounds pretty pronounced if you're getting audible interruptions at
> record level 10. But then, the bumps were always there in the same
> proportion with the 744, just much harder to hear. I agree with Curt,
> maybe try varying the powering demand placed on the mic pre circuit
> with different mics and even an external phantom unit? Rob D.
>
> =3D =3D =3D
>
> At 8:56 PM -0700 8/19/05, Dan Dugan wrote:
> >A few months ago my beloved Sharp MD-MT90 finally gave out, and I
> >replaced it with a new recorder. They don't make them like they used
> >to. The MD-MT280E has a plastic case and feels cheap. It has fewer
> >buttons, and displaying remaining time requires going through a
> >rather obscure menu process that I'm still not comfortable with. No
> >rechargeable battery, just one AA cell.
> >
> >Fortunately it sounds just as good as any Sharp, but I ran into
> >something new the other day. It was quite breezy where I was
> >recording, and I wanted to make sure none of the wind noise
> >overloaded, so I could filter it. I turned down from my usual record
> >level of MIC L 17 to 12. That's 10dB down at 2dB per step. I figured
> >I'd boost it back up in post. It was a quiet location.
> >
> >When I loaded the disc into Pro Tools and jacked it up 10 dB I got an
> >unpleasant surprise. There was just audible above the mic hiss some
> >clearly digital hash that would come and go periodically. From the
> >timing of it I'm sure it was when the data was being written to the
> >disc. (Did you know that MD recorders don't record continuously? The
> >disc only spins about 1/5 of the time.)
> >
> >I was recording 4-channel, with an MD-MS722 doing the rear channels.
> >Sound from that, using the same gain process, was fine.
> >
> >-Dan Dugan
> >
>
>
> --
> Rob Danielson
> Film Department
> University of Wisconsin-Milwaukee
>
>
> "Microphones are not ears,
> Loudspeakers are not birds,
> A listening room is not nature."
> Klas Strandberg
>
>
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