Noise in Sound Professionals Binaural mic?

[piblondin]

I have long used a Sony ECM-MS907 plugged into the mic in on my Minidisc recorder, and it works fine, usually producing clear recordings. However, I wanted to get something a little more discreet for recording shows and picked up a pair of those binaural microphones from Sound Professionals along with one of their small stereo omnidirectional microphones. Both of these mics produce a lot more noise than the Sony. They seem extremely sensitive and there's always a hiss of background noise when I record with them that isn't present with the Sony.

I've been testing them out on my stereo at home with the Radio Shack volume attenuator plugged into the mic in jack on my recorder. I'm using manual recording levels and have tested both high and low mic sensitivity. The Sony w/out the attenuator blows them away. I know the Sony isn't a super great microphone or anything, and I am struggling to understand why there's such a big difference between these microphones. The sample recordings that I've heard from the Sound Professionals mics sound clean, so I feel like I must be doing something wrong. Any advice is much appreciated!

Also, on another subject, is there any way to prevent interference from cell phones when making recordings? Is this also a problem on flash-based recorders with integrated microphones?

Thanks for any help!

[sfbp]

Odd. I had excellent results with the SP2. Your report makes me think I should go and check. Certainly the SP2 beat the ECM-DS70P, but that may be because I bought a "cheap" one of those, and it could be fake.

One thing that springs to mind is the cabling. As you say, maybe something is being picked up. I recall this from many years ago with an extension cable for a microphone for my Tandberg tape recorder. Fine without the extra long lead.

I bet there are lots of microphone guys here who are in a much better position to comment.

[greenmachine]

The SP mic is more sensitive than the Sony, so both signal and noise levels will be higher. What you're looking for is the signal to noise ratio (SNR). Try using a the low sensitivity setting and a lower manual level setting than with the Sony to compensate for the higher sensitivity.

Using an attenuator in the signal path will negatively influence the SNR, it's only necessary for recording loud sounds.

The "Binaurals" have an omnidirectional pickup characteristic as opposed to the Sony's directional one, so this may have an influence on the SNR for sounds coming from a certain direction (speech, etc.). To compensate, move the mic closer to the source.

Edited December 30, 2008 by greenmachine

[piblondin]

Thanks, Green! I guess my issue is that for any given signal level in the recording, the noise seems much higher with the SP mics. So, say I produce recordings that reach sound level X in playback, for any given signal sound level X, the signal sounds clearer with less noise coming from the Sony. As a result, I have a tendency to make low volume recordings with the SP mics to limit the noise. But that doesn't really solve anything as I need to either jack the volume up in playback or amplify the sound file after recording.

I understand that these mics require different settings on my MD from the Sony mic, but I'm still uncertain as to how people record things as simple as a single piano or a guitar in am empty room with a clear signal and little background noise using the SP mics with strong playback volume.

Thanks again for any help!

[piblondin]

I did some more research and found that the SNR in the SP-BMC-3 is 58 while in the Sony ECM-MS907, it's 65 db. That seems like a significant difference in signal-to-noise ratios; is that what accounts for the differences I'm hearing in my recordings? And if so, naturally, my next question is: Are there any smaller mics with an SNR of around 65 db?

[sfbp]

That's slightly more than 2x as loud. One observation I would offer is this. The benefit of recording in PCM is as follows: it's not the end of the world if you record a relatively low level, because there are lots of bits of resolution to allow you to amplify (using whatever software) the parts that are inappropriately soft, and mute, quieten or even delete loud applause before normalizing what's left. Whereas if you record in one of the less-bitty formats now there is a danger you've thrown something away. I personally don't even worry about adjusting the mic myself during recording - every time I do it, I end up cursing because now it's harder work still. I don't right now recall what recorder you have, but the RH1's AGC on low sensitivity seems to work just fine for me. YMMV, of course.

My previous remarks (previous post, that is) refer to the BMC-2, so they may not apply to your BMC-3's.

[piblondin]

I recorded a show this week, but I can't help but feel that the Sony 907 would have performed much, much better with the same placement. I had mic sensitivity set to low, volume on the Radio Shack attenuator maxed out and recording volume on the RH-1 set to 24/30. I think next time I will try AGC even though everyone seems to say it's bad for music. What do you think?

Attached is a clip from the show with quiet singing, audience cheering, louder singing + band, and audience sing-a-long. It was heavily amplified using Audacity, but there isn't any significant clipping. It sounds to me like something I could have recorded with a cheap voice recorder in my shirt pocket, not what I would expect from a MiniDisc and a popular concert taping microphone. Any suggestions for improvement are much appreciated. I know I could have been closer to the sound source, although everything seemed quite loud where I was. Other than that and maybe trying AGC, I'm not sure what else I can do with this microphone. It seems like replacing the attenuator with a battery box wouldn't make much of a difference. So, I'm sort of at a loss for how to make these Sound Professionals mics work. Thanks again for any help.

Patti_Smith_12_30_2008.mp3

Edited December 31, 2008 by Big Chingy

[sfbp]

I looked at the waveform - it cuts absolutely dead at 16,000 Hz. This doesn't bode well for the sound quality, IMHO.

One thing (and I realise this may not be even remotely possible in any sort of contemporary music concert, folk, rock etc etc) is to see what the silence looks like. If it's noticeable (eg some wretched fan - machine not human, of course - in the background), I subtract it out.

Perhaps you could enlighten us as to the exact series of steps used **after** the recording was made. I don't understand the reference to Audacity, since I was presuming you did digital upload from the RH1, and then did something to the wave file later, with Audition or Nero Wave Editor or.....

I wonder about that attenuator, seems the AGC (Low Sens, Music setting) always did the job for me, maybe try that next time and just the SP mics.

[greenmachine]

Sounds very dull. Maybe rethink the mic placement. Put them as high up as possible without anything covering them.

[piblondin]

I tried your suggestion as a test at home with the stereo. It seemed to help, but the SP mics produce a near-constant hum of bass, which is better than the complete absence of bass that I seemed to get with the attenutator attached. Still, the Sony 907 with AGC on and mic sensitivity on high just seems to produce a cleaner sound, while the SP with mic sensitivity on low sounds sort of washed out and distant.

[sfbp]

Is it possible you have been shipped a dud, by accident? Doesn't sound like the mics I know and love. My other questions related to what you did to the sound afterwards. What was the original recording format? Try PCM before you get too exercised, and if you weren't doing Hi-SP before try that next.

[piblondin]

I recorded in Hi-SP. I think the only thing I did to the file before encoding as MP3 was amplify it using Audacity. I will pull another snippet from the original recording and upload that here if that might help with the diagnosis. I don't really think there's anything wrong with the microphones, but rather there's something I'm not doing correctly when I use them. I've purchased a couple other small microphones, as I think I mentioned in an early post, and they all exhibit the same differences from the 907. (Granted, I believe my Sony ECM-DS70P is a fake.) I just seem to be missing something.

Also, on another subject, the other type of event I record most frequently is talks/lectures. So far, the 907 has worked well for these. I usually just put AGC on standard and mic sensitivity on high. Again, I have trouble using the small microphones in this setting, as the microphone's noise is very present in the recording and the speaker sounds distant and washed out. It would be nice to be able to use these smaller microphones, but I haven't figured out how to do so yet. Again, any advice is much appreciated. Thank you for all your responses so far!

[A440]

The MS907 has minimal bass--its frequency response starts at 100 Hz, whereas the SPs go lower. It's also, as pointed out, directional, not omni. Both of those can make the sound seem crisper, especially if that's the sound signature you are used to.

But I definitely don't love that Patti recording. It sounds muffled, and having been at the Bowery many a time I know the room doesn't sound like that.

It may be that the attenuator is giving out--is that crackling at the beginning from the attenuator or from the mic rubbing against something? It may be that the mics are too low down--where were they? Or, again, it may be the limitations of the attenuator method.

I was a big booster of the attenuator when I started recording, because there was no input-volume control on my MZ-N707 and battery boxes were big. But since I got a mini battery module I have found it much preferable.

http://www.microphonemadness.com/products/mmcbmminminc.htm

It might be time for you to move on up to a battery module and go through line-in. It does improve the sound.

The 16,000 Hz cutoff point sfbp found is also curious, though it could be your mp3 encoder. Do the SP mics also sound muffled when you just record mic-->Mic-in from your stereo? The more diffuse sound (compared to MS907) is from cardioid directionality vs. omni sound, but listen strictly for highs. If they are not so muffled, that would also point to the attenuator.

I got the SPs for stealth, and I find omni sound more realistic, but it may also just be that you prefer the MS907 sound signature. No shame in that--you should use the mic that makes recordings you're happy to listen to.

But if you have the $ for the experiment in this dreadful economy, go for the battery module. It will also improve loud music recordings you make with the MS907.

AGC is great for lectures--though I find it pumps up the background noise if the speaker pauses. I promise you, though, that it will ruin the recording of any band with drums.

Edited December 31, 2008 by A440

[sfbp]

I don't disagree with anything you say, A440. You're the expert. However I have had good luck with AGC, sensitivity low and music setting. Even for a full orchestra - eg Dream of Gerontius

[A440]

Orchestras seem loud but are actually rather quiet. The few times I have recorded one, I could do it through the mic input without distortion, though I never tried AGC. I tried recording a church organ through Mic-in, though and got distortion when the bass pedals began.

Anyway, rock or jazz with amplification and regular bass-drum thuds don't work with AGC.

[sfbp]

I had absolutely zero problem with my BMC-2's and church organ. The first time I have ever been able to record that without problems.

[greenmachine]

Just to emphasize that it's not the missing frequencies above 16kHz or so that makes the sound dull - these frequencies are just the sparkling high end - the tip of the iceberg - many people can't even hear them, thus they're often omitted by lossy codecs. What makes it sound dull is the constant drop in amplitude towards higher frequencies from about 200Hz onwards.

For demonstration here's a graph from the sample (red) compared to the original 1978 studio recording of the song:

[sfbp]

Understood. My reason for the comment was that in all the sounds that I have watched, none of them "dropped dead" at 16K in the way this did. You're very clever to compare to the original, quite beyond me as I don't listen to that stuff - it could have been from 1998 or 1958 for all I knew.

[A440]

Just to clarify, my problem with the church organ was that I went through mic-in, which is very sensitive to bass. And when the bourdon, the deep nasal bass pipes, kicked in, so did the distortion. I think the mics were working just fine, but the bass was too much for the preamp.

[sfbp]

I'll post something shortly for you to have a listen.

First sample (about 13 megs)

Second sample (also about 13MB)

Probably won't be able to leave them there for ever.....

Let me know what you think. I was amazed because it was the first time I had ever managed to record an organ without silly problems of one sort or another.

Stephen

[greenmachine]

Unless from a very close distance, recording a church organ should be possible without distortion without external attenuation in most cases, even with highly sensitive mics. Just set the manual levels relatively low somewhere in the 10-20 of 30 range (lo sens setting). If it still distorts at 10/30, it must be an exceptionally loud organ. No comparison to rock concert levels.

[A440]

The organ was at a little out-of-the-way joint called Westminster Abbey and the levels were probably around 15/30. And everything was fine until the deep bass line kicked in. It wasn't the overall level that was the problem, but the strength of the bass, which for all I know was 32-foot horn-like pipes, probably an octave or maybe two below what's in your samples. Not a rock concert, but you could feel it.

Those are lovely organ recordings! Very improvisatory take on the Toccata and Fugue in D minor there....

Edited January 2, 2009 by A440

[sfbp]

Ah, the Double Ophecleide!

Maybe we better send someone to record the Diaphone-Dulzian at Atlantic City, heheh. Liverpool Cathedral's isn't even a real 64 but a stopped (gedackt) 32.

Luckily or unluckily for most of us there isn't a general problem with organs. However it raises another issue, IMHO. It seems likely that these very low organ tones can cause *physical* vibrations in their environment. It's known that 7Hz is dangerous to humans, so standing next to the D-D for extended periods is liable to do very bad things to you. So, I wonder how much of your observed distortion was some sort of rattling of something in the vicinity. You can observe this effect for example if you put a plastic container (thin) with some paperclips on top of a bass speaker even on the pathetic little speakers we bought for $50 for the computer (awright I know you didn't but I did). Or sometimes "stuff" that is lying around rattles and quite destroys the sound.

I'm not saying this was your distortion, just that it might have been. I have a hunch the problems I had recording organs with older equipment might have been similar. A portable such as the RH1 does get rid of a lot of the sources of noise (and electrical interference too!). I mean there are some pretty big sparks potentially flying around as these stops open and close their mouths, too - so anything wired in (as I was back then) to the same circuit as the organ blower, is going to pick some of it up. Certainly I recall hearing stop changes (electronic click, not the noise of the physical stops changing).

[sfbp]

Those are lovely organ recordings! Very improvisatory take on the Toccata and Fugue in D minor there....

Thanks.

I couldn't believe that people near me decided it was ok to talk through the first one. I almost strangled someone - but realised the encounter would be recorded for posterity on MD, so sat as still as humanly possible (I fear you can hear me breathing). I did another recording there in non-stealth mode and it came out quite nicely with the BMC-2's clipped to a glass candle holder on the end of a tall stick (ie about 8 ft in the air) well above any audience noise.