Ancient Ribbon Mic

[Phildo]

A friend brought a (as far as we can tell from cursory web trawling) 1940's/1950's "Reslo" RV Ribbon mic round to my studio last night.

After a bit of footling around, we got it to work (much against my expectations, as it had been in a dusty attic for anywhere up to 30-odd years). It sounds great - especially on my friend's voice (very thick folksy sort of tone), and I was basically wondering if any of you guys here know anything about the use and care of these intriguing wee beasties.

I know that they're very fragile, that you should ALWAYS use a pop shield, and it appears to have a figure-of-8 pickup pattern but that's about all.

I did notice, when we had the top off, that the ribbon looked like it had a couple of slight horizontal "creases" in it. Is this normal? It didn't seem to affect the sound, which seemed smooth and silky, lots of LF, and a top end which seemed to roll off quite gently around 12-14K (picked up a shaker nicely - much better than a dynamic, anyhoo.

Damn! a quick thought - can I use this in conjunction with one of my ECM8000s for rudimentary M/S recording? Record the ribbon on to two tracks, flip the phase of one of them, pan them to opposite sides of the stereo and stick the omni in the middle. Does anyone know if this will work?

Cheers,

Phil

 

[Track Rat]

Thses are touted on e-bay as the mics the Beatles used back in the "cave" days. I've never used one but have been curious to try one. I've seen a lot of new old stock ones for sale.

 

[darrin_h2000]

cool.

 

[Phildo]

Thses are touted on e-bay as the mics the Beatles used back in the "cave" days. I've never used one but have been curious to try one. I've seen a lot of new old stock ones for sale.

I've seen the "Beatles" stuff, too, but my one's actually just like the one on this link although in much better condtion. Chrome's a bit corroded in places, but there's no reason not to have it re-chromed one day!

http://www.neweraantiques.com/detail.cgi?2317?photo

 

[Track Rat]

That's an older vintage than the ones I've seen. They were square (almost looked like a small electric razer).

 

[Jetphase]

...don't apply phantom power to 'em....

...don't blow into 'em....

...ALWAY use a pop filter...(i like the stedman metal grid filters)

...enjoy it !...especially on electric guitar cabs....w/pop filter....my coles and rca's "absolutely" rule for electric guitar and drum overhead/room mics....

JET

 

[littledog]

Damn! a quick thought - can I use this in conjunction with one of my ECM8000s for rudimentary M/S recording? Record the ribbon on to two tracks, flip the phase of one of them, pan them to opposite sides of the stereo and stick the omni in the middle. Does anyone know if this will work?

I was gonna let someone else grab this one, as I'm a little shaky on the mechanics of MS. Please, anyone, jump in and correct me if I'm wrong, but I don't think what you are proposing will work. You'll merely be cancelling the ribbon mic signal leaving only the ECM 8000.

Ideally you would use the figure-of-8 mic with a cardioid, and send both signals to a preamp that includes an MS decoder feature. Here's where I'm not sure what the decoder actually does, but through whatever magic, you end up with a nice stereo sound (though usually not super-"wide") that is remarkably mono compatible.

Harvey mentioned on an earlier thread you could create a "home-grown" MS using three cardioid mics without a decoder, but my instinct is your particular variation would not work.

 

[DigitMus]

Actually, an omni can be used with a figure 8 for M/S, though cardioid is the most common, any pattern can be used (check "On-Location Recording Techniques" by Bruce Bartlett, Focal Press ©1999). The technique Phil propses is proper, too. (Although you are reversing the polarity on one of your fig-8 tracks, not "flipping the phase" - but that's just semantics )

Scott

 

[Light]

The M/S thing will work great (and will probably sound great too, but then I have a bias towards that method). Jetphase was right, though. No phantom, always use a pop screen, and don't get too loud if you close mic with them.
When I was at school for this stuff, we had a very famous engineer come in to do a demonstration. (I don't really want to mention any names, but you have probably heard of him. You have absolutely heard of his most famous clients.) He was recording a rock group from the school, and the guitar player was playing extremely loud, and in a booth. The school had a few RCA 77s, which students where not allowed to use, but of course he could. He put one in front of the guitar amp, and one of the students asked him, "Won't that blow out the ribbon?" He said, "I used to do this with (guitar hero's name) all the time." The Mic proceeded to die with a noisy click on the very first take. He certainly taught all the students something that day. Be careful with that thing, it should sound great.

 

[Phildo]

God, but I love this board. Cheers for all that, guys. I'm recording my band on Wednesday, so I'll let you know how the mic sounds when used in anger.

Looking forward to putting it in front of our guitarist's AC15 (we record at home, so any mic-troubling volume shouldn't be present!). Hopefully my s/h Joemeek channel will be here by then.

Now all I need to do is source some Telefunken valves for my B***inger mic pre...

 

[littledog]

The technique Phil proposes is proper, too.

Scott

I defer to your superior knowledge about MS, Scott, (since I know very little about it) but, if what you say is true:

• What is the purpose or advantage of having a preamp with MS decoder built in, if apparently it is not necessary? I was under the impression it was a necessary component for a two mic MS technique.

•If you record the ribbon mic to two tracks and flip the polarity of one, why aren't you merely cancelling the tracks?

 

[Phildo]

I asumed that there'd be no phase cancellation because the signals would be panned to the opposite sides of the stereo spectrum - if the track was summed to mono then they should simply (as you say) cancel each other out leaving only the omni signal - hence mono compatibility!

 

[DigitMus]

I believe Harvey covered this somewhere, but anyway...
No, the two figure 8 channels don't cancel, because they are hard panned to opposite sides - they would cancel if you panned them center. The 3 channel set up : MID, fig-8, and fig-8 reverse polarity, with the 2 figure 8s hard panned is exactly what a mid side decoder is. The only advantage to it is by taking the decoding outside of your console, you only need 2 channels. The disadvantage is, if you record with a M/S decoder, you have to set the width of the stereo field at the time, you can't adjust it afterward. (BTW you adjust the width by varying the amount of the side channels, the fig 8 + and - , relative to the center mic.)

Scott

 

[Phildo]

Questions, always questions...

Right. So it should work.

My next question is: "Does this setup give a sense of L/R separation - ie if a source is moved in front of the mic from, say, L==>R, will the recording reflect this. More to the point, HOW?"

Dang those psyychoacoustics!

 

[littledog]

Thanks for the great explanation, Scott. Another spoonful of earth has been shoveled into the yawning chasm of my ignorance!

 

[DigitMus]

You're welcome, littledog.
Phil - it's more physics than psychoacoustics, but suffice to say that it works. Go ahead and try it - walk past the mics whistling "Mary Had a Little Lamb" and listen to the movement. Then play with the stereo spread a little. Then sit a couple of (acoustic) guitarists about 5 feet apart and record them. Play around; have fun!

Scott

 

[Light]

Yes, M/S (which stands for Mid/Sides, by the way) does give a very strong stereo image, though not as wide as a spaced pair or Deca tree, it is wider than an XY setup, and potentially wider than ORTF. If it is recorded to three channels, you can control the perceived width, which is pretty cool.
So, how does it work? Let us first explain exactly how to set up M/S. You want the capsules as close to coincident as possible, which means that in a theoretical sense you want them in the same place. That is of course impossible, but you can get them very close. There are two mics, one figure-8 (bidirectional), and another one. The other one can be almost anything, including another bidirectional, but is usually a cardiod. You split the signal from the sides mic (the bidirectional) and send it to 2 channels. Do this after the preamp, by the way, as mic level signals are not really strong enough to drive two preamps with out some kind of transformer. To start with, pan the sides mics right down the middle (or to one side or the other. The important thing is that they are paned exactly the same.) Flip the polarity of one of the channels. Set one channel to unity (0 dB), and adjust the other until the sound disappears. Now pan the two channels hard left and hard right. The sound will reappear, but it will not be stereo, or particularly interesting. Now bring in the mid mic, and pan it right down the middle. As you adjust the level of the mid mic, the stereo image will seam to become wider and narrower, and you will have stereo separation of the two sides of the sides mic.
So why does this work? It is an issue of phase incoherence. When a sound arrives on one side of the sides mic, it creates a positive signal, and is creating a positive signal on the mid mic at the same time. If the same sound comes in to the sides mic from the other side, it creates a negative signal in the side mic, while still creating a positive signal in the mid mic. This cancels out in the speaker which is reproducing both mics in there original polarity, but in the other speaker, the sides mic has got its polarity reversed, so the sound is not canceled out. Of course, the sound which originally came in with a positive phase is now negative in the channel with its polarity reversed. I have included an illustration, which will hopefully be helpful. The drawings are a little rough.

 

[littledog]

Light:

Whoever you are and wherever you come from, I hope you plan on sticking around. That was one hell of a great post!!!

 

[Phildo]

I've said it before, and I'm going to say it again.

I LOVE THIS BOARD!!!

Thanks, Light. I think I've got the gist of it now. I think...

 

[Light]

It can be tough to get your mind around it, and it is hard to verbalize it, but M/S stereo micing extremly useful, especially if what you are doing is going to be broadcast in mono (on an AM radio, and even many FM stations.) Glad to be of assistants. The only problem with M/S is that the mics are in the same place (coincedent). Because of this, the sounds from both sides arrive at the mic at the same time, so your only stereo imaging is coming from level differences. Your ears, of course, hear level differences in real life, but they also hear differences in time. You get a stronger sense of direction from timethan from level. There are many other stereo patterns which can give you a more complex stereo image. If you want to learn a little more about stereo micing, you should check out DPAs website. They have good basic discriptions of stereo micing, though they do not go into great depth on the physics.

http://www.dpamicrophones.com/eng_pub/MicUni/131.html

DPA also markets the microphones which were formally known as Brüel & Kjær to the entertainment industry. Brüel & Kjær make the best messurment microphones in the world. They are quite expensive (to say the least), but most of the lower cost microphone companies and all of the speaker manufactures use Brüel & Kjær mics for testing there own products. If you can ever afford them, get em. My favorites are the 4011 and the 4006. The 4011 can not be beat for acoustic guitar (I have also used them to mic Marshell cabs, and it was amazing). The 4006 makes the the best room mic for drums I have ever used.

And there I go, talking too much again.
Light

"Cowards can never be moral."
M.K. Ghandi