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Help me Remy et al !

Ok heres the deal, Im recording 3 actors/commentators using (rented)
Sennheiser HMD-25 headsets, (saw/heard them on a Nascar broadcast, told myself I would try them one day). Great isolation.
These things have NO BALLS whatsoever, trying to get enough level Im bringing my preamps out of the sweet spot into distortion. Were talking 50 + dBs from the preamp.
Preamps tried so far (Mackie 1402 VLZPros) (Digi 002R) (Digidesign Control 24s) (dbx 386) NO MACKIE OR dbx FLAMES PLEASE, its just for spoken word.

One guy, 2 ladies, the guy is screaming which is fine, but still sounds weak and thin, no bottom. Actually, there seems to be no proximity effect either!

Sennheisers website states minimum terminating impedance must be at least 1K ohm, so Im assuming the mics are around 150 ohm impedance, but they sound like I need 3K ohm preamps.

I called a guy who does a Poker tournamnet show, he also uses them and found the same issue. He still has no answer.

Im bringing in my Grace 101, and True systems P-Solo in on Monday, but if anyone of you can tell me what preamps broadcast people use to pump these headset up, please let me know.

Since this is a pilot Im just going to fly by on this, but I would like to know for the future.

Could there be a wiring issue, could 6 headsets have miswired XLRS?
3 rentals, and 3 purchased?

Stumped in Hollywood.
(Play with that Remy!)


CharlesDayton Sun, 03/26/2006 - 15:28
I wonder if its the nature of these headset mics? I mixed a show where they used 6 countryman headset mics, and the audio I got was underrecorded. Great isolation, but no level. One funny aside (or not so funny at the time); Dave Navarro was one of the players on the show(a card show), and he wore longish metal earrings, so every time he turned his head, guess what I heard whacking into his mic?
The small amount of on set sound I've done, I used Tram lavs and never had a problem.

Try your question over at Lots of mixers there.

Sorry for your troubles.

RemyRAD Sun, 03/26/2006 - 18:57
TVPostSound, I think the problem that you are probably experiencing is one of no proximity effect since I believe these are actually omni-microphones, like many lavaliers? Now, I think the best thing you may want to do is add a low-end equalization bump to approximate the sound of some proximity effect, just to fatten them up and/or a little shot of extra presence for Annunciation intelligibility?

Having the assumption that sportscasters have a tendency to get "excited", I would imagine these particular microphones are also protected from excessive sound pressure level in a stadium like environment, with some kind of built-in padding, or just because they are a super small condenser which are naturally lower in output level and more tolerant of high sound pressure level already? I personally would mix them in a mono sound field and/or narrow stereo if they are fixed in their position and not doing a lot of moving around. I would then add a substantial amount of compression and limiting to pump them all up and keep your level consistent, something I had to do with the John McLaughlin shows . A limited amount of bandwidth limiting is also not a bad idea for talking head shows, you don't need the rumble or the hiss of the HVAC.

Beware that individual compression and limiting on each microphone will accentuate and cause you considerable phasing artifacts, unless all of their detectors are linked together. That's why I believe in taking these microphones and compress and limit them as a mixed subgroup source and not individual sources.

If you want to take it one step further, 3 downward expanders for each microphone may improve the phasing problems while certain individuals are quiet when someone else is talking. Setting the threshold on the downward expanders is a bit tricky and should be done pre-fader at the insert of your console and with a proper audio test with the on microphone talents. You can also take advantage of phase cancellations in this application by inverting the phase of your "middle" person. This can sometimes help reduce some of that hollow like effect from having multiple microphones on from being in close proximity to one another.

Talking heads for most of my career.
Ms. Remy Ann David

TVPostSound Sun, 03/26/2006 - 19:28
Yes, Sennheiser also equips the HMD25 with omnis, butt hese puppies are definitely Super Cardioids. Definitely highly directional, great isolation.
Sennheiser failed to publish the response curve on their website.

Since no one steps on each other, I had the luxury of time today, and edited out all the bleed, and compressed with plenty of make up gain.
Ironically having no bottom will end up fine in the mix.
The room was fairly quiet, and the program material fills any holes just fine!!!

As a side note I'm an old dog, as opposed to dogg, I dont record to
-.01dBFS, I usually record VOs at the level it will end up in the mix, then a little compression to control peaks, and thats it. I record to real Dorrough VU meters not peak meters.
But these guys are low.


RemyRAD Sun, 03/26/2006 - 20:50
Your peculiar description may also indicate that these kinds of microphones could in fact be " DIFFERENTIAL MICROPHONES". A differential microphones generally requires 2 identical omni-capsules. 1 closest to the sound source and the other one away from the direct sound source. They are connected out of phase to one another. A differential microphone is absolutely excellent for canceling out an over abundance of ambient noise. They also create a peculiar response curve that is more reminiscent of what you're describing. They generally do sound quite a bit thinner since the process also cancels out much of the lower frequency content. One must keep the direct sound source as close as possible to the primary capsule. A differential microphone is basically a creative use of spaced omnis that are electrically out of phase to one another. Several communication microphones of the past were known as " noise canceling microphones" and generally work on the same principle. Everything is canceled out except the one sound source you want that is closest to one of the capsules. In a communications microphone it is generally the capsule, in the front of the push to talk microphone body with the second Omni capsule on the back. They are also all generally not of the highest fidelity and therefore suffer from the squeaky sound quality that you described.

Squeaky broad (or that arthritis is killing me)
Ms. Remy Ann David