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Old September 13th, 2008, 03:52 AM   #1
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Fostex FR2 LE - does it record 24 bit or not?

Jay Rose in his excellent book 'Producing Great Sound for Film and Video' refers vaguely to thousand dollar units by Tascam and Fostex and says 'These prosumer units have fewer features; and while they boast 24-bit recording, our measurements have shown this mode to sound about the same as 16-bit when you use their analogue inputs'.
(Page 176)

I bought a FR2 LE in order to record 24 bit sound.

Would anyone care to comment on Jay Rose's statement ie does this apply to the FR2 LE?

Many thanks

Richard
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Old September 13th, 2008, 04:15 AM   #2
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If you intend to record speech/vocals and ambient sounds for EFP you will be fine with either 24 or 16bits and better stay with 48khz @ 16bit as it is much easier to edit and it also saves you storage and in my case it's even saving battery power on my R44. The 48/16 sound resolution is widely used for EFP and even in studios for VO work. I assume you can benefit from highr quality when recording live music and classical instruments.

Don't worry,
T
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Old September 13th, 2008, 04:23 AM   #3
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Many digital audio recorders record with 24 bit sample depth, but the cheaper ones have so noisy analog circuitry that getting even 16 bits worth of real noiseless signal is difficult.

FR2 LE does record at 24 bits, but for the reason outlined above the real resolution is nothing near 24 bits. Let's face it: even the very best field recorders like Sound Devices 7xx series achieve "only" about 21 bits worth of S/N ratio. This is what Jay Rose refers to.

I used to have a Fostex FR2, but the reason I replaced it with SD722 was precisely this; with FR2 at 24 bit the real resolution was about 17 bits, at least now I get about 20 bits worth of resolution from SD722, depending on the microphones.

No recorder can deliver true 24 bit performance, and no microphone either. So it is more like a dream (pushed by marketing and misconseptions) than reality.
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Old September 13th, 2008, 05:28 AM   #4
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Petri, would you enlighten if Richard could get his sounds/piece released when 16bit quality is used,. I mean there are plenty of movies out that could have used the sound quality he already has in form of the FR2...
.. correct me if I'm wrong.

T
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Old September 13th, 2008, 06:31 AM   #5
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Hi Toenis and Petri
Many thanks both of you for your input.
I know that I can record 16 bit but if I'm recording music and may run into problems I would prefer 24 bit for the reason outlined by Ivan Mosny in this thread here:
What Audio Levels are best on the XH A1? - The Digital Video Information Network
As I understand it, recording in 24 bit gives you much more scope to improve the recording if there is a problem and, because you can record at a more conservative level, you are less likely to run into problems in the first place.
Is this a logical reason to record 24 bit?
Petri
If I understand you correctly you are saying the quality that can be obtained using the FR2 LE is limited by the signal to noise ratio ie there is more noise at lower levels than a more sophisticated recorder.
May I ask you a supplementary question. I have a Sound Devices 302 mixer. If I use this with the Fostex FR2 LE will the recording be of higher quality eg closer to 24 bit than 16?
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Old September 13th, 2008, 07:15 AM   #6
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All CDs are 16 bit PCM (and I can not hear the difference between 16 and 24 bit output however carefully I try), most movies are released in compressed 16 bit audio formats, also theare releases, same with DVDs, not to mention MP3 music. It is good to remember that these "mediocre quality" digital recorders like Fostex provide 20-30 dB better dynamics and S/N ratios that those big Nagra machines used in movies just 10-20 years ago! So of course the quality is good enough for everything.

But also 24 bits do give added safety in levels setting, In some instances I have set SD722 levels very conservativelly (levels set mostly by guessing, no possibility for riding leves during the recording), and had to raise levels full 30 dB in post. Still the sound is virtually perfect.

I suspect that the low S/N ratio with FR2 LE is caused by the mic preamplifiers, not so much by ADC. It is certainly worth investigating if you get better results with SD302 and line in. SD302 has really good mic preamps and good limiters, I would not be surpriced if the quality would approch SD722.

It is fairly easy to test these recorders and combinations yourself: Make a recording where you try to get the levels as high as possible, even slight clipping is no disaster. On the same track you must get also maximally quiet passage , try to do this in a quiet room, maybe at night. Copy the file to PC and run analyze found at least in Adobe Audition. The difference between lowest RMS level and highest peak value is the S/N ratio your system is capable of. Most likely it will be the microphones which are the bottleneck in this.
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Old September 13th, 2008, 08:07 AM   #7
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Quote:
Originally Posted by Petri Kaipiainen View Post
It is fairly easy to test these recorders and combinations yourself: Make a recording where you try to get the levels as high as possible, even slight clipping is no disaster. On the same track you must get also maximally quiet passage , try to do this in a quiet room, maybe at night. Copy the file to PC and run analyze found at least in Adobe Audition. The difference between lowest RMS level and highest peak value is the S/N ratio your system is capable of. Most likely it will be the microphones which are the bottleneck in this.
Thanks Petri
It's very useful to get practical advice like this. I don't have Adobe Audition and it's not cheap to buy. Can you suggest anything else that I could use?
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Old September 13th, 2008, 10:41 PM   #8
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"s I understand it, recording in 24 bit gives you much more scope to improve the recording if there is a problem and, because you can record at a more conservative level"

That's just it -- you can't on the cheaper recorders. Because the noise floor is so high, you still have to run hotter levels.
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Old September 14th, 2008, 01:11 AM   #9
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Thanks Marco.
That's very helpful.
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Old September 15th, 2008, 11:37 AM   #10
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most NLE's natively handle 24bit and 32bit float audio. they have for several years. that included FCP and Prem Pro. in fact PRem Pro conforms audio to 32bit float.

AJA, matrox, and BM cards all capture audio in 24bits


24bit does give you some extra space during recording. it also provides for greatly improved S/N when mixing since its an additive process. the NLE can very much take advantage of this when mixing tracks to help keep the noise floor down.
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