FX1 audio measurements: 92 dB DNR

J

jbeale

Active member
I tested the FX1 mic/line input in line-level mode (manual level, set at "3") using a DVD player playing a CD with the RMAA 5.4 test signal as the source.

I got a 92 dB dynamic range which is quite good, it's better than my DVX100 and in fact I wonder if I actually measured it right, but the RMAA program is pretty straightforward and I'm not sure how I could have got it wrong. The THD and IMD graphs look sort of bad, but subjectively the audio sounds pretty good to me. I did all these measurements in the DV recording mode (16 bit audio) so there is no MPEG audio encoding involved here.

Details are on this page:
http://beale.best.vwh.net/measure/audio/FX1_RMAA.html
 
When I performed tests using my Shure FP33 a few months back (rated at 100 Db S/N)
it only measured at best a fluctuation somewhere between 95 dB and 98 dB.

Again, I would be shocked if the FX1 with unbalanced line-in were anywhere close to that.
 
When I measured my own DVX100 using RMAA version 5.3 I got a 79.0 dB(A) DNR on the line input. I haven't seen the rating of 60 dB you mentioned, I'm curious where is that published and what was the test methodology?

There appears to be something wrong with my DVX100 since it has a strange comb-filter frequency response that I have never observed with any of the other 15 or so audio recording devices I have measured over the years, but I measured it several times in several ways and the results were consistent.

Overall I think the RMAA program gives reasonable results, although you can always accidentally make things worse by introducing ground loops or other noise coupling problems during the measurement. You can see some of my results for other recording gear here:

http://beale.best.vwh.net/measure/audio/index.html
http://bealecorner.com/trv900/dvfaq.html#Tech
 
Sound for 24p by Wolf Seeburg

Sound for 24p by Wolf Seeburg

Hi John,

First, let me apologise if my prior post came across inflamatory.. I was pretty shocked
your test results revealed a performance so incredible with an unbalanced connection.
I did not intend to say you were dead wrong and neither did you say they were right.
Your TRV900 site has been very helpful to me over the years (BealeCorner, right?) and
I have only respect and appreciation for your gracious contributions to the community.

jbeale said:
I haven't seen the rating of 60 dB you mentioned, I'm curious where is that published and what was the test methodology?
Click to expand...

24p for Sound and Video Assist By Wolf Seeburg, 9th ed. Feb 2004
-----------------------------------------
PAGE 201

JR: The new 24p measured with an ATB:DVX100, balanced analog input to FireWire
digital output (-not- the headphone amp), nominal = -12dBFS. S/N measured to -12
dBFS, so add +12 dB headroom for total dynamic range.
Line input can be either -10 dBV (.14% THD+N, s/n 60 dB) or -- unlike PD150 -- can be
+4 dBu (.4 % THD+N). -10 input is recommended

With -35 dBu (hot) mic: .16% THD+N 58 s/n
With -50 dBu mic: .18% THD+N, 58 dB s/n

The above might not impress you, but it's on the better side of miniDV
-----------------------------------------
jbeale said:
There appears to be something wrong with my DVX100 since it has a strange comb-filter frequency response that I have never observed with any of the other 15 or so audio recording devices I have measured over the years, but I measured it several times in several ways and the results were consistent.
Click to expand...

24p for Sound and Video Assist By Wolf Seeburg, 9th ed. Feb. 2004
-----------------------------------------
PAGE 202
Freq sweep (-10 dBV input) relative to 1 kHZ, -2 dB points at 25 Hz and 18
kHz. Very narrow dips (about 1/4 oct) -5 dB at 180 and 320 Hz. That's -incredible- for a
miniDV recorder.
Post considerations aside the Panasonic probably sounds better than most typically-
maintained Nagra IV at 7.5 ips with low-print tape. In real-world terms this is the first
prosumer camera I've seen with decent audio. . ......(snip).....
Jay Rose, June 2003 I suggest you also check dv.com for full article
-----------------------------------------

I made an extra special effort to make sure I correctly typed every letter, number,
punctuation, spacing, and spelling indentical to what is in the book, except for the
(snip) at the end of the artictle.

This serves as the basis for my comments on the DVX100 audio performance.
Hope this helps,

brian wells
 
This must look like negative political campaign, but. . .

This must look like negative political campaign, but. . .

John Beale wrote on 04-29-2005, 06:45 PM
jbeale said:
I haven't seen the rating of 60 dB you mentioned
Click to expand...
John Beale wrote on 07-25-2004, 02:32 PM
http://www.dvxuser.com/V3/showthread.php?t=7933&page=2&pp=10
jbeale said:
This is what they reported about the audio: (snip)
.....Signal-to-noise ratio, relative to a 1 kHz signal at -12 dBFS, was -60 dB for line and -58 dB for mic inputs.
Click to expand...

John,
I am not sure what you're getting at here. It sure appears like you knew about and quoted the same article nine months ago. I think you knew where I was getting my numbers.

brian wells
 
Sorry! apparently old age memory loss has set in early for me- you're quite right, I quoted the same article back then, and had since forgotten about it. Jay Rose has a lot more professional audio experience than me so I'm sure he has a valid measurement. Thank you for reminding me about it. My understanding from the passage you quoted is SNR = 60 dB allowing for 12 dB headroom, so in the measurement terms that RMAA reports that would be 72 dB SNR.

I still haven't seen, or should say I don't remember seeing, anyone else using the automated test program RMAA (RightMark audio analyser) to get numbers on video camera audio and I would be very curious to see them (for DVX100, DVX100a, FX1 and other cameras). The program is a free download and very easy to use, all you need is a decent soundcard, or even CD burner plus CD or DVD player like I used.
 
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