Skip to main content

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.



Pro Audio Guest Thu, 09/07/2006 - 13:39
A well designed ribbon mic will produce virtually no self noise.With ribbons, There are no active electronics to produce noise, so any noise generated(barring a damaged mic) is a product of mic pre's ,cables, or anything else in the signal path.

With the powered mics (R-122, R-122V and SF-24)Royer claims that the self noise spec is

Boswell Thu, 09/07/2006 - 13:59
With passive mics like ribbons and dynamics (a ribbon is like a moving-coil dynamic but with only half a turn on the coil), the only self-noise is the thermal noise of the equivalent resistor. The critical thing, especially with ribbons, is to match them to the preamp. The AEA TRP should do exactly that for you. However, its quoted noise performance of "-130 EIN noise figure" is not meaningful without a source impedance being specified.

I for one would be interested to hear your comments on how the combination performs.

DavidSpearritt Thu, 09/07/2006 - 14:10
All I know is the SF12 is a bit noisey when I used it with the AMEK 9098, which is a very quiet preamp. I recorded string quartets with it and you can hear the hiss quite clearly. If I use condensers with the AMEK, there is no audible noise from the mics or the preamp.

The SF24 is quieter than the SF12 but only by about 2dB or so, but this is a noticeable and significant improvement. I imagine the ribbon pre will be the best preamp of any for use with the SF12, to minimise the self noise.

RemyRAD Thu, 09/07/2006 - 16:37
Ribbons mics have always gotten' a bad rap for producing more noise. It may be true but there isn't another solitary mic that sounds like a ribbon. So, I live with a little perceptual hiss if the ribbon IS the sound I'm lookin' fer! Considering the proliferation of software "noise reduction" capabilities, not to mention a little downward ducking at the threshold of the noise would make me not worry about some puny little noise before I record?? It's almost not werth disscusin;?

MS Remy Ann David

Duckman Thu, 09/07/2006 - 18:10
As a beginner, I confess, I'm still on the learning curve even with basics like ohms and the figures and symbols indicating a pre-amp's noise signature. However, with the help of Rich, I've discovered that the ULN2 pres are very quiet - at least as quiet as Millennia - and that the input impedance (3.3k ohm) is right in the pocket as regards the output of the SF12 (300 ohm). Just to check, I sent samples of the preamp self-noise to the guys at Metric Halo, and it passed with flying colours.

So I'm assuming now that most of the fairly substantial noise I'm hearing is in fact the microphone itself. I might be asking too much from it! Nevertheless, I still hope that the TRP is even quieter and look forward to hearing about it over the weekend, Dave.

Are the 4040's quieter?

Duckman Fri, 09/08/2006 - 04:19
Remy Ann - agreed on the sound of this ribbon at least. Very natural and smooth. I haven't heard any other ribbons apart from samples of the SF24 on the Royer site - samples that amazed my ears! and some Coles 4040 samples which amazed them even more! None of these samples, though, approached the same level of noise I experienced with the SF12. Perhaps I could learn to live with it - quite happily - if it were just a tad quieter.

Duckman Fri, 09/08/2006 - 04:41
Pace Boswell - I'm hoping now that those 18000 ohms of the TRP will help reduce the SF12's own noise. Thank you for the excellent insight. I've actually got a TRP on order now - with the option of exchanging if it makes little difference; so I should be able to hear for myself. But am still very interested to hear the insights and views of my betters.


Duckman Sun, 09/10/2006 - 18:17
Well, I've managed to answer my own first question (-:
Was able to test the SF12 on a TRP over the weekend. The sound of the mic definitely improved: more body and depth; but it made no difference to the noise generated by the mic. Alas!

Would anyone like a used SF12 in excellent condition??? :-)

Any news about TRP with your Coles, Dave?

Simmosonic Sun, 09/10/2006 - 22:40
For what it's worth...

Before I had my custom preamp made for the SF12 I was using a pair of Amek PurePath preamps, or else the preamps on my old and much loved Studer 169 console - depending on the tone I wanted to impart on the recording.

With less-than-ideal preamps, I found that much of the noise was simply due to the higher amounts of analog gain required. So I got into the habit of running the electronics at lower levels and making up the level with digital gain in mastering. My recordings would typically sit between -30dB FS and -40dB FS, then I'd 'amp it up' in Wavelab. No problem...

Some people may disagree with that, but if you're recording 24-bit and have a decent AD converter, there's no problem sitting around -35dB FS...

Simmosonic Mon, 09/11/2006 - 01:00
Duckman wrote: I'll try that tonight.

Good luck with it. Remember, it's not going to do anything about the microphone's self noise, that's there to stay. But on less-than-ideal preamps it might make a difference.

My old Studer 169 was a lovely, lovely, lovely sounding console. The preamps were very good (as far as transformer balanced preamps go), but with the kinds of gain needed for the SF12 on soft sources I could hear the preamp noise increase considerably when the gain knob was turned beyond about 2 o'clock. So, I used to try to find the point where I thought I was getting as much gain as possible before the preamp noise became significant.

In those days I was using a Prism AD124 AD converter feeding a Tascam DA45HR 24-bit DAT recorder. When I found that ideal noise point on the Studer's gain curve, the recording level would be sitting somewhere between -40 and -30dB FS on the Tascam.

Of course, someone who is a lot smarter than me when it comes to noise might be able to prove that this is all bollocks, the signal/noise relationship remains linear and I'm kidding myself. And they may be right...

DavidSpearritt Mon, 09/11/2006 - 03:12
Well I connected up the AEATRP to the Coles 4040's tonight and played my D35 into them in Blumlein. I had sloppy old toneless strings on, but the bass end was almost uncontrollable, the Coles have HUGE somewhat muddy bass (actually proximity effect), but the top end is really extended and its all VERY quiet. Had to get the pair at least 1.5m away before it sounded half normal. TRP has plenty of quiet gain.

When I put some decent strings on, and get a good sample recorded, I will post it. Very impressed, particularly of the low noise floor and the sweet natural tonality.

Duckman Mon, 09/11/2006 - 04:11
Simmosonic wrote:
Good luck with it. Remember, it's not going to do anything about the microphone's self noise, that's there to stay. But on less-than-ideal preamps it might make a difference.

Thanks Simmo. Yes... the ULN2 I'm using is very quiet at high gain, so I'm thinking that isn't the problem.

I fear the mic is to blame - at least the one I own. Can a ribbon get noisier with age?

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.

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...

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... :-)