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Author Topic: FR2LE LED noise  (Read 1097 times)

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Online heva

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FR2LE LED noise
« on: August 05, 2015, 03:38:53 AM »
Recently I tried my Fostex FR2LE with a pair of dynamic mics (beyer m101's). Using the firmware v1.30 option to add +12dB gain (and 'trim' and 'level' fully open) I've found that the LED from the 'REC STBY' causes interference in the signal, mostly in the Left channel. The LED flashes in continuous pulses while recording and this is found back (though quite soft) in the recording. Using XLR cables where pin1 IS connected to the casing causes the 'spikes' to be louder.
It seems to me not mic related, it also happens using an XLR with a 150ohm resistor on it.

Any other FR2LE users around to check this or any tech-savvy with an idea?


Offline tonfunk

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Re: FR2LE LED noise
« Reply #1 on: July 13, 2018, 09:45:33 AM »
Hi,

I experience the exact same issue on my FR2LE. Sorry for the late response, but I do not own the model very long and stumbled across this thread searching for others experiencing this issue.
Did you find any cure to the problem in the 'meantime' that you could share with me?

BR

Offline H₂O

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Re: FR2LE LED noise
« Reply #2 on: July 13, 2018, 10:45:08 AM »
How is the unit being powered? 


Sometimes ground loop issues will cause these types of symptoms.  I have seen the exact same behavior on a Korg MR-1 when I have my Pre-amp (EAA PSP-2) and the MR-1 running off the same battery or power source.  Never had this problem with the PSP-2 and Tascam DA-P1


This is probably because the Korg's ground isn't the same as the PSP-2 (meaning the Korg doesn't treat the - lead on the battery as Ground)
 
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Offline mjwin

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Re: FR2LE LED noise
« Reply #3 on: July 13, 2018, 01:43:49 PM »
I've never noticed this problem with my FR2LE, but then I always use high output mics & never need to switch in the +12dB gain. But, in the interests of science, as they say, I've just given it a go.  With 150R resistors between  XLR pins 2-3, & the gain & level cranked up to max, I neither hear any periodic noise nor see any sign of it on the spectrum.  I simply get white noise at -65dBFS (Left), -66dB (Right).

When recording, the "REC STBY" LED flashes in unison with the CF card write cycle, so there's actually a lot happening inside the machine at this point.

How old is your FR2LE, btw?   My machine is quite old, about 11 or 12 years.  s/no 0960847TE, but I've had no probs.   If the noise had increased over time, I'd suggest that possibly the power supply filter capacitors had deteriorated. Other than that, it's hard to say. 

In my test above, the FR2LE (v.1.30) was running stand-alone with a 7.2V RC battery pack.  If you have power supply &/or USB  cables connected, it might exacerbate the problem. Bit annoying really, as the front end of this machine was really impressive for its time (& still is). It's the user interface, h/phone & main outs which let it down.
« Last Edit: July 13, 2018, 01:45:35 PM by mjwin »

Offline willndmb

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Re: FR2LE LED noise
« Reply #4 on: July 13, 2018, 09:58:31 PM »
I never noticed anything with mine
Akg 480
Mics - AKG ck61/ck63 (c480b & Naiant actives), SP-BMC-2
XLR Cables - Silver Path w/Darktrain stubbies
Interconnect Cables - Dogstar (XLR), Darktrain (RCA > 1/8) (1/8 > 1/8), and Kind Kables (1/8f > 1/4)
Preamps - Naiant Littlebox & Tinybox
Recorders - PCM-M10 & DR-60D

Offline borjam

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Re: FR2LE LED noise
« Reply #5 on: July 14, 2018, 06:17:17 AM »
I have used the +12 gain option and I haven't noticed anything odd at all.

Powering with a Tamiya compatible battery.
"Don't worry about the drums. I'm a percussionist, I can play on carton boxes" - Peer Wyboris

Online heva

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Re: FR2LE LED noise
« Reply #6 on: July 14, 2018, 09:26:41 AM »
IIRC it happened using the Fostex power adapter.

Using high(er) output mics, an external 12v battery and NOT using the +12dB option, there's no problem.
Solid as a rock actually.

Offline tonfunk

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Re: FR2LE LED noise
« Reply #7 on: July 14, 2018, 03:25:10 PM »
Dear all,

first of all, thank you very much for the quick response, much appreciated!

I did a second test recording today using 156Ohm between (wav attached). At this, I used the internal power supply, preamps trim and line gain fully clockwise (normalized and rendered to mp3 in a daw). The issue is still present, but far less audible compared with the contact mic recording using battery power.

heva, in case you hear the periodic 'led noise' in my recoring, could you confirm that we are talking about the same issue?
willndmb, would you consider my recording clean as yours, or do you hear the same as I do? (just to check if I am gotten paranoid about the sound issue :)
mjwin, following up on your question, I do not know how old the recorder is, SN is 0963067TS. In case you have any further details or recommendation for recapping or improvements of ground connection for the unit, please let me know. Otherwise I think the unit might be still usable with proper selection of input sources and careful gain settings if I did not miss the point.

Thanks in advance for the feedback!

Offline mjwin

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Re: FR2LE LED noise
« Reply #8 on: July 14, 2018, 06:05:04 PM »
I did a second test recording today using 156Ohm between (wav attached). At this, I used the internal power supply, preamps trim and line gain fully clockwise (normalized and rendered to mp3 in a daw). The issue is still present, but far less audible compared with the contact mic recording using battery power.

Your file FostexTest.mp3 is very loud!  I assume that when normalising the file you boosted the level by about 50dB.  On my machine when playing back the original file recorded at maximum gain, max trim, +12dB boost, the background noise is about -65dB rms, or -52dB peak.

I do hear the periodic noise bursts in your recording, but they are only slightly above the background noise level and are probably within the machine specification.  Check the original file to measure the actual noise levels, which should be approximately as above.

When you say that your "contact mic recording" has more noise, are you connecting a piezo, or Hi-Z contact mic straight into the XLR inputs of the FR2LE?  If so, this could be the cause of the problem.  Contact mics require a high impedance,  "hi-z" or "instrument" input to work correctly.  The best way to do this is to use a (cheap) DI box which is commonly used for guitar pickups. You just need to connect it between  your contact mic & the FR2LE.  If you have one of these or can borrow one to try, you might find that it solves the problem.

Offline tonfunk

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Re: FR2LE LED noise
« Reply #9 on: July 15, 2018, 03:47:14 AM »
Hi mjwin,

yes, it is loud. As pointed out in the previous post, the recording was normalized before rendering to mp3.
In the original file, the noise floor peaks at -52.4dBFS (w/o +12dB boost), but comparable though.

I am aware of impedance matching and used impedance transformers in conjunction with my contact mics / hydraphones (both from Jez French). I tested this combination on my RME Babyface at home without issues.
So it looks like those simply do not work properly with my FR2LE due to high sensitivity to impedance mismatch.

BR

Offline willndmb

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Re: FR2LE LED noise
« Reply #10 on: July 15, 2018, 05:35:30 PM »
Dear all,

first of all, thank you very much for the quick response, much appreciated!

I did a second test recording today using 156Ohm between (wav attached). At this, I used the internal power supply, preamps trim and line gain fully clockwise (normalized and rendered to mp3 in a daw). The issue is still present, but far less audible compared with the contact mic recording using battery power.

heva, in case you hear the periodic 'led noise' in my recoring, could you confirm that we are talking about the same issue?
willndmb, would you consider my recording clean as yours, or do you hear the same as I do? (just to check if I am gotten paranoid about the sound issue :)
mjwin, following up on your question, I do not know how old the recorder is, SN is 0963067TS. In case you have any further details or recommendation for recapping or improvements of ground connection for the unit, please let me know. Otherwise I think the unit might be still usable with proper selection of input sources and careful gain settings if I did not miss the point.

Thanks in advance for the feedback!
i never recorded just "open air" but that def seems louder and hissy compared to anything I can think of with mine
Mics - AKG ck61/ck63 (c480b & Naiant actives), SP-BMC-2
XLR Cables - Silver Path w/Darktrain stubbies
Interconnect Cables - Dogstar (XLR), Darktrain (RCA > 1/8) (1/8 > 1/8), and Kind Kables (1/8f > 1/4)
Preamps - Naiant Littlebox & Tinybox
Recorders - PCM-M10 & DR-60D

Online heva

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Re: FR2LE LED noise
« Reply #11 on: July 16, 2018, 05:04:46 AM »
IIRC my pulses where clearer, but since this appeared in church, it could be interference related from something there?
GSM.masts not far away, old electric circuits in combination with very low output mics?

 

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