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Re: fostex fr-2le high frequency noise

Subject: Re: fostex fr-2le high frequency noise
From: "Curt Olson" flipov411
Date: Mon Jun 23, 2008 6:34 am ((PDT))
Thank you for this report, Carter!

Curt Olson

On Jun 22, 2008, at 6:22 AM,  wrote:

> 2a. Re: fostex fr-2le high frequency noise
>     Posted by: "carterscholz"  carterscholz
>     Date: Sat Jun 21, 2008 2:15 pm ((PDT))
>
> In case anyone else runs into this problem with the Fostex FR-2LE,
> here is what I've observed since my original post: this high-frequency
> artifact occurs consistently when using the supplied AC power supply,
> when phantom power is turned on.  It has not occurred when using fresh
> batteries.  I have once encountered a similar, lower-level pulsed tone
> at the end of a long recording when using alkali batteries that were
> running down.
>
>
> --- In  Carter Scholz
> <> wrote:
>>
>> Hi,
>>
>> I recently bought a Fostex FR-2LE and I've been making some test
>> recordings with it.  I've noticed a steady tone that shows up only
>> when phantom power is turned on.  When sampling at 96/24, the tone is
>> on both channels at about 30,700 Hz; with trim and gain up full,
>> using AT 3032s, it is about -66 dB (L channel) and -72dB (R
>> channel).  If the internal mics are used, with phantom on, the tone
>> is there, but at a lower level.  When sampling at 44/16, the tone is
>> somewhere around 16 kHz, about the same levels.  If phantom is turned
>> off, and internal mics used, there is no such noise at any sample 
>> rate.
>>
>> I assume this is electrical noise from the switching circuit used to
>> generate the P48.  Has anyone else observed it?  Is this typical of
>> the Fostex, or do I have a bad unit?  And why would it change
>> frequency depending on the sample rate?
>>
>> It's a small amount of noise, but if you shift the 96/24 file down
>> three octaves, it is definitely audible.
>>
>> Carter Scholz




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