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Will TRP help?

I wonder if anyone could comment... I've recently purchased the Royer SF12 at a decent second-hand price. I've only had the chance to try it out once on the application for which I bought it - for small ensenble choral recording. I really liked the tone and the imaging, even though the mic placement was not ideal (too close). However, the noise generated between mic and pre at 60db was to my ears an annoyance - not terribly loud, but still a nuisance. I was using Metric Halo ULN2 pres, which are very quiet and have plenty of gain, so I'm thinking that the SF12, while excellent for some applications, may not be ideal for this type of recording. For the life of me, I can't find anywhere on the net the specs on the SF12's self noise.

My questions are two: has anyone here had success using the AEA TRP with the SF12 on quiet applications like choral recording? I guess I'm wondering if the TRP will be a magic fix. I'm pretty sure it won't be curing a mic's own self-noise though - so it's probably a silly question.

Secondly - and this question is only asked because I don't know the noise specs of the SF12: would a pair of Coles 4040s be a quieter alternative?

Any comments would be welcome.



aracu Sun, 10/15/2006 - 11:53
By making it wider or narrower, you can adjust the angle
relative to the distance in front of the source, being determined
by the acoustics of the room and other factors. The 90 degrees
may be correct according to a rigid theory...but not ideal for every
situation. A slight adjustment is not going to automatically
produce a black hole.

Simmosonic Tue, 09/12/2006 - 15:30
Duckman wrote: Can a ribbon get noisier with age?

I can't imagine any mechanism there for it to do so in any significant way, but I'm not an expert on noise. Also, when it comes to ribbons, I tend to agree with Remy - noise is part of the deal.

If the ribbon was stretched or otherwise damaged or impeded in its movement it might require more gain to get the same output, which could be interpreted as being noisy. But if that happened, you'd probably hear more than just noise. Or, perhaps the magnet has suffered some damage or wasn't fully magnetised, and therefore the current induced into the ribbon is lower.

I think you need to compare your SF12 with another one, through the same preamp and so on, as a point of reference. You could use a two channel preamp, with one side of each SF12 on the same sound source at the same time. Match the gains, then remove the sound source and check out the noise.

Pro Audio Guest Sun, 10/15/2006 - 12:07
I am not talking about a "black hole"-- but you cannot escape the laws of physics. What good is picking up 20 degrees on the sides when it messes with the center balance? There is more to the equation than ideal accpetance angle-- look carefully at the polar plot.

I have never had a problem with acceptance angle with my SF12. Have you had such problems? IMO it would be better (and much easier) to pull the SF12 back a few feet.


DavidSpearritt Sun, 10/15/2006 - 13:42
Rich is spot on. The 90 degrees of Blumlein is essential to keep the linear distribution of phantom source location across the stereo image between the loudspeakers. If its less or more than 90 degrees then there will be compression or stretching distortion of source position, which is quite undesirable.

The correct localisation of sound sources with Blumlein is its number one characteristic, if you don't want that, then a pair of omnis or cardioids is a better bet.

Duckman Sun, 10/15/2006 - 17:38
Just a slightly tangendental question... when using MS technique on a choir, is it important to have the sound source confined within the range of the Mid microphone, or can some elements of the choir be singing directly into the Side microphone, off axis to the Mid. I'm thinking in terms of a micing a choir in a fairly confined space, kind of, but not quite, in a semi-circle around an MS setup. Would that work in theory?

Duckman Sun, 10/15/2006 - 17:48
PS Dave and Rich, have you found that the TRP has added anything to your ribbon sound not already present with the top-notch preamps you already use?

Also, how do you plan on using the TRP on location conveniently... is it rack-mountable... or is there any special casing you use to carry around portable equipment like the TRP?

Duckman Tue, 09/12/2006 - 20:00
Simmosonic wrote: I think you need to compare your SF12 with another one, through the same preamp and so on

Yes indeed... but pretty well impossible for me, unfortunately.

I'll probably end up with the Coles. Seems like they're quieter and have more sonic extension.

Would love an SF24, but the price ... I'm not in this professionally and can't really justify it. The Royer design is so bloody convenient!

Strangely, Schoeps have become an option for me now...

FifthCircle Sun, 10/15/2006 - 21:32
Sonarerec wrote: By definition a ribbon mic is fig-8, so I really can't imagine any benefit to adjusting the bodies (in the case of two SF1s) to be wider than 90 degrees. Then you'd have a hole in the middle of the front image.


I've been doing this for years with my 426. There have been situations where I like a given position and either pattern manipulation or angle manipulation makes the recording work perfectly. I will never go wider than 90 degrees, but I have gone as narrow as 75 degrees- usually for closer mic'd chamber music.

I'm of the opinion that I don't care if it is "correct" acording to the book. If it sounds good, it is good, and I break the "rules" to make my recordings work.

That being said, there is a mic with an angle adjustment. I'm blanking on the exact one, but it is either the B&O stereo ribbon or the Speiden stereo ribbon. I'm pretty sure it is the B&O, but I'm not 100% sure.


mdemeyer Tue, 09/12/2006 - 20:11
Actually, on a stereo mic like this, a good 'first level' check is to do a test comparing the two channels (for noise level). Then swap the channels (to make sure the two channels of your pre have the same noise level. If there was something wrong with the mic, which is really two independent mics in one housing, it is unlikely that both channels of the mic would have exactly the same problem. So, if they are both the same, I'd say 95+% chance this is just the noise floor of your system.

You might also want to look carefully at the noise floor of your system. Short the mic input with 150 ohms and then measure the noise floor with the max gain (assuming you are using that with the Royer) on the preamp. Carefull attention to grounding and stray magnetic fields from racked gear can really pay off. (I'm working down the noise in my portable rack as we speak...)


Duckman Tue, 09/12/2006 - 23:03
Thanks Michael. I will try testing each mic.

Have already tested the preamp noise - and hope I did it correctly - wired pin 2 and 3 of an xlr plug together for a terminal, and recorded the sound of each channel. They were very quiet at 60db gain, and quite in line with the impressive specs of the unit (Metric Halo ULN 2). Plug the Sf12 in however... :-)

Duckman Wed, 09/13/2006 - 03:28
Simmosonic wrote: That *is* strange. If you can't afford an SF24, how can you afford a pair of Schoeps?!?!

There's an ebay listing for a mk2 pair of caps. Adding two new CMC6 bodies would make it around $3300, depending on the bidding. A brand new a pair of schoeps caps and bodies would cost around $4600 - according to one Melbourne dealer. If you know of a cheaper deal, please let me in on it. I'm pretty green about all this and am still finding my feet as to where to look for the best deals.

Re the SF24, my local dealer could get me one for around $5400 - and that's the cheapest I've seen it. Frontend Audio has them listed for $6805

Both prices are beyond me - I'm prepared to spend around $4000

Problem with the second hand schoeps deal is that the Mk2 would probably be a bit dark for micing a choir from a few meters away.

I'm open to any further ideas about a better deal on the SF24.