Topic: Clippy mics on Edirol R09-HR -> Battery box or PIP??

[TheJez]

Hi all,
I've been recording mostly loud concerts with my Edirol R09-HR and a set of coresound stealth cardioid mics (with accompanying 9V battery box) for many years, with very satisfying results. However, for high dynamic concerts (e.g. just the sound of footsteps on the stage between songs, mostly low volume songs and a few loud songs), the large amount of self-noise of the coresounds is rather disturbing.
Especially for these kinds of shows I am considering getting a pair of Clippy mics with the EM272M capsules. The Edirol recorder can provide PIP to the microphones, I think the voltage is something like 2.7V.
I am wondering if it would be advisable to get/build a 9V battery box for the Clippy's, or if the recorder-provided PIP would be sufficient?
Is there a benefit getting a battery box? If so, is it a practical or theoretical benefit? (Unfortunately the coresound battery box can't easily be used for other mics due to special connectors used...)
Thanks in advance for your opinions, ideas and advices!

[Rairun]

I always use my Clippys with an 8V battery box, but I haven't actually tried using a lower voltage. Not sure how well they would fare. Either way, just beware that they are very sensitive mics, and they managed to overload a Zoom F3 when I stood about 2 meters away from the PA stacks (at this show: https://www.youtube.com/watch?v=ykiB_YYoYis - the audio your hear are from CA-11s, but I tested the Clippys during the opening act). I had set the inputs to MIC (maximum input level of +4 dBu); it might have been OK if I had set them to LINE (maximum input level of +24 dBu). Tbh, I never really use the Clippys for music - they are good for field recording.

Are you sure microphone self-noise is the issue here? Before buying the Zoom F3, I taped with a Roland R-05, and I ran into self-noise issues as well at high dynamic concerts. I'd set the gain for the loud songs so they wouldn't clip, which meant the gain staging for the quiet songs was far from ideal. When I fixed the level in post, what I would hear was the R-05's self-noise, not the mics'.

I'm asking you this because if you were already setting the gain properly for the quiet songs, then yeah, giving more sensitive mics a try would make a lot of sense. But if the gain staging is less than ideal because of the loud songs, sensitive mics won't help much. The quiet parts will still be relatively quiet to the recorder. What you need is multi-stage ADCs, probably.

[robgronotte]

I've used the CSCs for many years and have never had any problem with noise that didn't actually come from the room or occasionally if I bump the mics. I also suspect the noise could have another source, but it would probably help if your described it. Are you certain the mics aren't damaged? They're very fragile, which is the only thing I don't like about them.
Have you tried a new battery in the box?

[TheJez]

Thanks for thinking along here! These kinds of shows always seem challenging to me for a couple of reasons:

• There is no support act that I could use to set the recoding levels correct
• I know there will be a few parts that will be relatively loud compared to the rest of the show, but no idea when they will be or how loud they will be. Therefor I tend to set the levels conservatively. I don't like noisy recordings but I really hate clipping recordings! Changing levels during the show is also something I try to avoid.
• Because of the huge difference in volume of the songs, the show needs some post processing to make it a pleasant listening experience afterwards. Just normalizing isn't sufficient, it really needs dynamics compression to assure the quiet parts become loud enough for playback. As a side effect, obviously, the noise in the quiet parts also gets 'extra' amplified.

What I did so far is removing the noise with Audition before doing the dynamics processing. The noise is well-defined becuase of the almost completely silent parts in the recording. This certainly helps, but especially with the very quiet parts, there will be noticable artifacts due to the noise removal process.
For those who want to listen for themselves, I've uploaded a sample of such a recording. It is fully unprocessed, starting with a 'loud part', followed by a quiet part. The applause is the loudest and shows that I could/should have set the recording level higher:
https://drive.google.com/file/d/1ZiLCcv0kI1K5xeoUX1n-YaxfOOobUMHj/view?usp=sharing

Prefereably, in the furture while recording such performances, I'd like to lower/prevent the noise as early in the process as possible. The repliers so far questioned the source of the noise, and maybe they're right. I was blaming the self noise of the CS mics because of the info on their website:

One of our modifications alters the microphone's sensitivity to approximately -70 dB (0 dB = 1 Volt per microbar), making them ideally suited for recording extremely loud sound sources without danger of overloading your mic pre-amp. This very low sensitivity makes these mics less suitable for recording quiet sound sources.

and

Thanks to our modifications, the microphones have an undistorted dynamic range of over 90 dB, compared to the unmodified capsules' approximately 60 dB dynamic range. They will handle sound pressure levels of more than 138 dB. They are designed to operate into a nominal impedance of between 4.7 and 10 KiloOhms. Their self-noise level is approximately 35 dBA. This is far below the ambient noise level at concerts. (Note that the self-noise specification also makes these mics not especially suitable for recording very quiet sound sources.)

Maybe someone who can do the math and listen to the sample I've uploaded can tell better if it's the mics or the recorder who's to blame for the noise, and if using a pair of Clippies with their low self noise would have helped in such situations.
It seems the challenges with setting the record level correct in high dynamic shows could be avoided by using a multi-DAC system like the F3, but I'm not very fond of its form factor for my general purposes  . The recently announced Zoom H1 XLR might be a better option in that respect, so I'm keeping a keen eye on its reviews and reports once it becomes available.

The feedback so far is really appreciated, but my initial question hasn't really been addressed yet: IF I'd be using a pair of Clippy mics, is the recorder-provided PIP sufficient, or is it advisable to use a ~9V battery box? If so, what would improve compared to PIP?

[TheJez]

I've used the CSCs for many years and have never had any problem with noise that didn't actually come from the room or occasionally if I bump the mics. I also suspect the noise could have another source, but it would probably help if your described it. Are you certain the mics aren't damaged? They're very fragile, which is the only thing I don't like about them.
Have you tried a new battery in the box?

I'm sure the mics are fine and I regularly replace the battery in the box. With loud shows there is no problem. With loud parts in high dynamic shows there is no problem either. It's just the quiet parts in high dynamic shows where the noise is much more apparent than I'd like...

[Rairun]

I do believe those mics are even less sensitive than my CA-11s. I don't have the exact specs for the CA-11s, but I know through testing that they are about 20 dB less sensitive than my Clippys (EM272M). I'd wager their sensitivity is around -52 dB. So for all I know, we are hearing microphone self-noise in your recording too - I have no experience with mics like yours.

But I've also noticed that your highest peak is at -21.5 dB. Selecting the music sections only (the -21.5 db peak is a single particularly loud clap), you're peaking at -27.5 dB. The quietest musical part (with the pulsating bass) is peaking at -51 dB! That's incredibly quiet. Most handheld recorders have a self-noise of around -95dB without adding any gain. They reach higher EIN specs by having gain that adds comparatively little noise in relation to how strong they make the signal, i.e. +20dB gain which adds 5dB of noise means: -95 dB (baseline) + 5dB (gain noise) - 20dB = 110 dB EIN. If you're not taking full advantage of that relatively clear gain, and you're using such a low sensitivity mic, you're going to bring up the recorder's base self-noise in post.

Note that the Clippys are a whooping 40 dB more sensitive than your Coresound mics. You would almost surely be unable to be as conservative with your gain staging as you currently are (a good thing! you're being too conservative). The thing is that you don't need to use new mics to fix this issue. I'd definitely try being more precise with gain first.

Here is a sample of a show I recorded with an extremely high dynamic range:

https://www.mediafire.com/file/gu1au5uu2lc1q8y/sufjan_sample.flac/file

You can clearly hear the Zoom H1's self-noise during the second song. It's a little bit of an issue, but nowhere near as bad as what you're getting due to using little to no gain. In my situation, there was nothing more I could have done with the gear I had. A Zoom F3 would have improved that quiet section greatly.

In short: use more gain, you can afford it. If it doesn't help at all, the issue is your mics. If it helps a little, but not enough for your liking, then get a better recorder.

[TheJez]

Hi Rairun,
Thanks for your clear analysis, this is very helpful. I will surely try to set the gain higher next time, although it's still scary to do without knowing what the loudness of the louder parts will be. I think I might ask Santa for a multi-adc recorder to prevent gain issues alltogether. My next high dynamics show will be in March 2025, so there's still enough time...
The Clippies have been ordered and are on their way. Once they are in, I think I will do some testing with the CS and Clippy mics side by side to verify the noise levels while recording 'silence' at different gain levels. Would be interesting... I still don't know if I should be using a battery box with the Clippies or just the PIP of my Edirol. Anybody some thoughts?
Your sample sounds very clean regarding noise by the way! Thanks for sharing. It proves that 'it can be done' 

[nulldogmas]

I will surely try to set the gain higher next time, although it's still scary to do without knowing what the loudness of the louder parts will be.

If most of the music is peaking at around -12dB, you're almost never going to get a stray transient that clips. And to catch any such rare cases, I would suggest turning on the limiter, since that's exactly what it's there for.

[Rairun]

Re: PiP, I found these answers:

https://www.birdforum.net/threads/use-of-lavalier-pip-mics-and-question-on-power-requirements.450505/#post-4579958
https://gearspace.com/board/low-end-theory/1377651-clippy-em272-used-music-recording.html

It looks like they work pretty well from 2.5V to 9V, but you'll probably only find out how high an SPL they can handle at 2.5V if you run a test yourself. If you were recording quiet music, I'd say go for it with the Edirol's PiP - but since there are going to be loud passages as well, it's hard to tell.

[TheJez]

I will surely try to set the gain higher next time, although it's still scary to do without knowing what the loudness of the louder parts will be.

If most of the music is peaking at around -12dB, you're almost never going to get a stray transient that clips. And to catch any such rare cases, I would suggest turning on the limiter, since that's exactly what it's there for.

Yeah, normally this would indeed be the case. However, with this particular type of concerts (most songs very quiet, one or two songs much louder), this strategy doesn't really apply. I'd hate the limiter kickin' in all the time during the loud songs....

[robgronotte]

If it is predictable which songs will be louder, you can adjust the recording levels for those particular songs.

[TheJez]

Re: PiP, I found these answers:

https://www.birdforum.net/threads/use-of-lavalier-pip-mics-and-question-on-power-requirements.450505/#post-4579958
https://gearspace.com/board/low-end-theory/1377651-clippy-em272-used-music-recording.html

It looks like they work pretty well from 2.5V to 9V, but you'll probably only find out how high an SPL they can handle at 2.5V if you run a test yourself. If you were recording quiet music, I'd say go for it with the Edirol's PiP - but since there are going to be loud passages as well, it's hard to tell.

Thanks for looking these up. I think I already found those myself but was looking for some confirmation/advise. I will try to get the right connector (4-pin mini-xlr) to re-use my Coresound battery box for the Clippies (which should arrive today!). I guess the greatest benefit of the battery box would be an improved maximum SPL, which is hard to prove/measure, but would be good to have...

[TheJez]

Today I received the Clippy mics, and I did some tests with them to compare the noise against the Coresound Stealth mics.
I made a long 'beep track', containing a 1kHz beep in blocks of '1 second long beep, 1 seconds long silence'. I played this through my stereo set in my living room, at a moderate volume that would keep the neighbours happy and allowed me to set the record level of the Edirol to 'max' without clipping. The mics (a pair of CS, a pair of Clippies) I put at ~50cm from the speaker.
Next I recorded the beeps with each pair of mics, the Edirol mic gain set to both 'low' and 'high', and the record level to 10, 20, 30, 40, 50, 60, 70, 80 (=max).

I found that the volume (average RMS) of the beeps are ~-24dB for:
- Clippy high 40
- Clippy low 80
- Coresound high 80
which makes this set of recordings a nice comparison.

With the Coresounds, there is a very clear noise, both in the silent parts as in the beep parts. With the Clippies, the noise is much much lower. I'd say ~18db less.
Also I see that with 'mic gain high', there is even a bit less noise, but I'm affraid using this during concert recording won't give enough options to set the record level right, due to the high sensitivity of the Clippies...

If anybody wants to compare for themselves, I've made the three mentioned recordings available. It's only about 4MB:
https://drive.google.com/file/d/1_BHOJKKZ4C07t_mwfkCNQg1qD7kRIuei/view?usp=sharing

Next step is recording a live show with the Clippies and see how it comes out...
I really love my Coresounds, as they so nicely reduce crowd noise and room acoustics, but they just don't seem to be suited very well for those high dynamic recordings...