Excessive PCM-D50 noise level?

[Allan Black]

Alistair, IMO it's apparent you're not getting a loud enough signal into the D50 to get above its residual noise.

If you really want to get clean nature sounds on the D50 from where you locate, I'd put a JuicedLink C231 mixer in front of the D50. I've just got one and it's very quiet, and I'm pretty sure I can boost the signal into the D50 above its noise, I'm checking it out.

But for nature recordings, what I used to do was plant a Sony HI-MD Minidisc as close as I could get to the area where the sounds would originate.

This was many years ago when the HI-MDs first came out and I used the Audio Technica AT822 mic. After some experience, I could set the correct level which was well above the equipments noise level and I got a good clean 90 minutes continuous. HI-MDs now are very cheap on Ebay.

Cheers.

[Alastair Traill]

Thanks Jeff for contacting me privately. I will check your references ASAP.

It is a pity your post was not accepted. Several times I have prepared a post only to have it disappear when I press the “submit” button. I understand your frustration. I find that the longer I take to prepare the post the more likely it is to disappear. My workaround is to prepare my post in Word and then copy and paste to DVInfonet, sometimes I have to do this more than once before it is accepted.

[Alastair Traill]

Originally Posted by Tsu Terao

Alastair -

"What kind of windscreen are you using? For any outdoor recording, you MUST use a windscreen w/ the PCM-D50"

Hi Tsu, thanks for your reply

I have the Sony ADPCM1windsock for my PCM-D50. It was very expensive for what it is, it is hard to fit and falls off without warning. It also took several months to be delivered.
However as everyone agrees it is an essential accessory.


"Have you tested it indoors, in a closet where there would be no wind movement?"

Yes. I have tested this recorder indoors with no wind movement. The noise still occurs and as it remains constant irrespective of microphone orientation I assume the noise comes from within and is not “environmental” as Sony suggest.

"I use it outdoors w/ a homemade ripstop nylon windscreen, at volume setting 6, and have no problems. Without the windscreen, all I get is wind noise."

At a gain setting of 6 on mine the ambient sounds are "drowned out"

[Alastair Traill]

I am pleased to report a sudden and inexplicable improvement in the recordings produced by my PCM-D50. Without knowingly changing anything I can now record at gain settings above 4 without introducing undue noise.

In a quiet enough environment I can use the full gain setting of 10 using either the inbuilt mics or a Senheiser K6/ME66. My only guess as to the reason behind this improvement is that there may have been a dirty contact somewhere that has cleaned itself with use.

I would like to thank everyone for their comments and suggestions.

Thanks to all
Alastair Traill

[Andrzej Duda]

Alistair

Are you sure it is not the -20dB switch?

[Tsu Terao]

Originally Posted by Andrzej Duda

Alistair

Are you sure it is not the -20dB switch?

[Recording the sound of a palm slapping forehead]

[Alastair Traill]

Originally Posted by Andrzej Duda

Alistair

Are you sure it is not the -20dB switch?

Andrzej and Tsu,

I am quite sure it is not the -20dB switch. I know this switch works but as yet I have had no occasion to use it, my problem has always been to get enough signal. I only hope that this improvement whatever its cause is long-lasting.

Andrzej, do your PCM-D50 problems persist?

[Clement Lainier]

Dear Alastair,
I very happy finding your post on this forum, after some hours of search.

3 weeks ago I bought a sony pcm d50 and I have exactly the same problem.
A noise appears around 4/5 gain level, that is very very uncomfortable and, i think, this is not normal. My pcm d50 is useless if I use a gain above 5.


One question : did you tried to connect the sennheiser k6/me66 on the "line in" connection ? Or did you only connected it on the mic connection ? In the case this noise come from the preamp, the line in connection would ignore the pcm d50's preamp, and logically ignore the noise...


Any suggestions or help to fix this problem would be very appreciated.


(sorry for my bad english ! and best wishes from france)


clément

[Alastair Traill]

Originally Posted by Clement Lainier

Dear Alastair,
I very happy finding your post on this forum, after some hours of search.

3 weeks ago I bought a sony pcm d50 and I have exactly the same problem.
A noise appears around 4/5 gain level, that is very very uncomfortable and, i think, this is not normal. My pcm d50 is useless if I use a gain above 5.


One question : did you tried to connect the sennheiser k6/me66 on the "line in" connection ? Or did you only connected it on the mic connection ? In the case this noise come from the preamp, the line in connection would ignore the pcm d50's preamp, and logically ignore the noise...


Any suggestions or help to fix this problem would be very appreciated.



Dear Clement,

Sorry to hear that you are having the same problem as Andrzej and myself. It spoils what is otherwise a great little recorder. I would be interested to hear what sort of response you get from Sony. Neither Andrzej or myself were impressed with the responses we got.

In answer to your question I only connected the external mic to the mic input.


(sorry for my bad english ! and best wishes from france)


clément

Dear Clement,

Sorry to hear that you are having the same problem as Andrzej and myself. It spoils what is otherwise a great little recorder. I would be interested to hear what sort of response you get from Sony. Neither Andrzej or myself were impressed with the responses we got.

In answer to your question I only connected the external mic to the mic input.
In a day or two I intend to post further details of the improvement I reported on the 24th of July.
Andrzej sent me a sound spectrograph of the sound from his PCM-D50. I am hoping he will post it soon.

[Rick Reineke]

I do not own a PCM-D50, but on other systems, I have encountered noise coming from the "plug-in power" on the 3.5mm mic input, when using self-powered mics. ie: battery. On these systems, usually a capacitor needs to be soldered into the mic connector to shunt the plug-in power to ground.

On Zoom H series recorders, plug-in power can be switched on/off via the software menu. (one thing Zoom did right) On many other portable recorders and many body-pack transmitters I've encountered, it cannot. I am not privy to the D50's internal workings', so this is just a consideration. Cheers, Rick

(do not confuse "plug-in power" (bias power) with "Phantom power")

[Clement Lainier]

Dear Alastair and Rick,
Thank you for your responses

The sennheiser k6/me66 has is own preamp, after reading some articles on it, I really think it must be plugged into the "line in" connection. (Not the mic connection)
I would like to know if it will be a solution for me to use an external microphone with external preamp/phantom power (like the sennheiser k6/me66) to bypass my "useless" intenal pcm d50 preamp.

I have made a small record for you to get an idea of my problem. The link is : http://dl.free.fr/fdJ5iWTVm

(you have to follow the link and click on "telecharger ce fichier" to download the file. MP3 320 kbps/16 bits/44100 mgz format)

This is a record made with my pcm d50 with internal microphones, in a total silence room. The rec level gain is "6,5". As you will hear there is many noise, even in a silence room...

[Steve House]

Originally Posted by Clement Lainier

Dear Alastair and Rick,
Thank you for your responses

The sennheiser k6/me66 has is own preamp, after reading some articles on it, I really think it must be plugged into the "line in" connection. (Not the mic connection)
I would like to know if it will be a solution for me to use an external microphone with external preamp/phantom power (like the sennheiser k6/me66) to bypass my "useless" intenal pcm d50 preamp.

I have made a small record for you to get an idea of my problem. The link is : Free - Envoyez vos documents

(you have to follow the link and click on "telecharger ce fichier" to download the file. MP3 320 kbps/16 bits/44100 mgz format)

This is a record made with my pcm d50 with internal microphones, in a total silence room. The rec level gain is "6,5". As you will hear there is many noise, even in a silence room...

All condensor mics, such as the ME66/K6, have their own built-in preamp but those are NOT preamps that raise the signal to line level. The mic output is still mic level - the ME66 is a fairly hot mic, true, but it doesn't even come close to sending a line level output signal from its preamp stage. If you want to use a prosumer or professional mic in order to bypass the mic input preamps on the D50, you'll also need to get an actual preamp such as found in a mixer that takes the mic up to true line levels, nominally -10dBv on consumer gear. But a note of caution ... it might not actually be possible to bypass the preamps even by using the line-input. I can't locate a schematic so there's no way to know for sure about the D50, but to save money some consumer gear designers will simply pad down the line input to mic level and send it on through the mic preamps, same as signals from the mic level input.

Is the noise you're referring to in your recording the continuous sort of crackley hiss that runs through it? I also hear some traffic noises (?) and other faint distant rumblings coming in sort of low and faint and what might be some breath sounds and motion in the room.

[Andrzej Duda]

Recently I could compare recordings of "silence" made by Alastair and me.
The recordings were made in a quiet room, gain was set at 10.
My impression is that there is no significant difference between
the two recorders (at least when gain is set at 10).
SonyInGain10.jpg = spectrum of my Sony.

I've tried something else.
I connected 2 K3 Sennheiser mics through the external mic input.
Gain at 10, highpass filter was on, 24 bits, 44.1 kHz. And the "silence" was recorded.

Senn 10 On.jpg = the spectrum when the Sennheisers were on.
So it's the noise of the amps + mics + silence.

Senn 10 Off.jpg = the mics were still connected but off (no signal from the mics).
It's the noise of amps only.
The spikes at 50Hz, 150Hz and 250Hz are strange since the recorder is powered with batteries.

As you can see the amps seem to be OK, noise less than -105dB.

So, what does it mean?
The silence was not that silent (I doubt it) or
the mics, both Sennheiser and Sony, are too noisy (that's what I think) or ...

I'm afraid we are at the beginning.

[Darin Boville]

Originally Posted by Alastair Traill

I would like an opinion as to whether the noise level of my Sony PCM- D50 is excessive. If I am in a very quiet environment I can hear through my headphones a build up of noise level as I increase the gain. The noise I hear is also recorded. It starts when the gain reaches 4 on the control knob. At 5 the noise is quite obvious. At 6 it starts to register on the meter i.e. around minus 46 db (the meter's lowest reading is minus 48 db). At the maximum level of 10 the meter reads minus 26 db.

I have tried the various record modes, the low cut filter, a memory stick as well as the built-in memory and the noise pattern is the same. The noise sounds a bit like rain. I have only used the built-in microphone and there is no handling or wind noise during the tests.

Sorry to revive this old thread but I'm having exactly the same issue described above. I'm a photographer doing a little bit of video. I thought I would learn the basics of sound recording and I happened to have a Sony PCM-D50 purchased for a project a few years ago. But when I use the built-in mics I hear rather pronounced noise. I don't recall this being the case when I initially purchased the unit.

I'm getting basically the same result as the OP--noise starts around a gain of 4, at 6 I'm at -40db. Sounds like rain, as he described. I've checked the attenuator, checked all the settings. Everything seems as it should be.

Two notes/possible clues:

1) When I first tried the unit yesterday the noise was far worse than I described above. It was crazy. While wearing headphones I was playing with the angle of the microphones, clicking them back and forth and the noise suddenly lessened to the numbers described above.

2) For reasons that are unclear my db scale is different than that of the OP's. My scale run -50 -40 -24 -12 (highlighted) -6 0

3) I tried plugging in a cord to the line-in port and changed the mic/line-in setting to line, as described earlier in this thread. Just a cord, no mic. I then wheeled through the gain, hearing only the faintest bit of noise through the higher end of the range, finally near 10 hearing a faint but noticeable level of noise. If this is really the pre-amp noise and how it is supposed to be then I am very impressed.

So, is my unit working correctly or is the built-in mic noise (at the "improved" level) abnormal? I'm a novice at this and have little to compare it to.

A second question, if the contacts or wiring of the mics is an issue has anyone disassembled their unit? Something doable? There are two screws which appear to be holding the mics in place. They are tempting me despite my lack of knowledge of electronics!

All advice welcome,

--Darin

[Rick Reineke]

Testing with an unterminated line input is not an accurate test, as is the internal mics with ambient noise present (despite the ambient noise which you may hear as silent.. is not) The only accurate mic test would to dissemble, remove the mics and terminate the input to the proper resistance and reference test parameters (whatever they are).