Ribbon Mic Dissection Pictures

[Guest]

The crinkles are put in the ribbon so it can flex or vibrate with the sound waves, cutting the flux between the poles. I have read several ways to do this in a DIY fassion. Use an old camers lense, use a tube squeezer (a greaed contraption to squeeze the last drop from a tube of paint, or toothpaste) plastic gears. How many to put in ranges quite a bit. 13 to 20 or so per inch I think is the range. My guess is, it sort of depends on how deep the crinkles go as to how many to use.

As for tension, The others are the experts but I think it is a thing you get evperience with by emperical trials. The ribbon is supposed to be tightened until it just stops it's sag.

Now, The real experts will come in and say what really happens.

 

[zebra50]

I think it is a thing you get evperience with by emperical trials. The ribbon is supposed to be tightened until it just stops it's sag.

Part of it is 'suck it and see', and practice certainly seems to help. However, you can measure the free air resonance frequency of the ribbon and adjust to taste. Marik and I are trying to get our act together so that we can post some reliable details on how best to do this.

The annealing thing is new to me.

Stewart

 

[SilverhammerNZ]

Reslo:

This mic still works well, I have put a low impedance transformer in it.

Interesting ribbon corrugation.

Larry

 

[Guest]

What is that "hair" in the back of your mike? Should the magnetic material go all the way around the gap, or is it open at one end like a horseshoe?

 

[zebra50]

That's some ribbon! Not original, I'm guessing :green:

Do you have a pic of the mic grill so I can try to recognise the model?

Cheers!
Stewart

 

[SilverhammerNZ]

As far as I know the ribbon is original. I certainly haven't been there. It's a very neat fit and sounds as you would expect so I doubt it's a homemade fix. I have run new wires to the "motor" because I replaced the transformer to a low impedance type.

The hair in the back is like "horsehair" (may not be, it's just looks like it) Hair felt (or horsehair) has been used on ribbon mics before to damp the reverse side. I have an article that states in regard to the RCA MI-1000C Ribbon:

An acoustical labrynth in the cylindrical section below the magnet structure is filled with hair felt.......

I'm sure the Reslo is a less sophisticated arrangement.

Larry

 

[SilverhammerNZ]

Re Model:

http://members.iinet.net.au/~vk6ft/micman/reslo.html

It's essentially the top one (RV). Although mine doesn't have that model number on it, it has: URH "something ribbon high impedance" I think.

Yes the magnets at the rear are horeshoe shaped, there's two, top and bottom with the hair filling the gap between so the rear of the ribbon is pretty much covered up.

Larry

 

[Consul]

You know, that method of corrugation doesn't look like it would be hard to do. It would also go well with the 1" x 1/4" x 1/4" magnets I have on the way.

 

[zebra50]

Actually if you look closely it is regularly spaced - flat, curve, flat - , but the spaces between corrugations are larger than their other mics that I've seen. Interesting! Good data - thanks!

Stewart

 

[smilinfu]

We have 2 theories stated so far about the purpose of the corrugations. Any other thoughts? Has anybody tried one without corrugations at all? Just curious to hear what the result was. Interesting to the see that the Reslo has so many fewer ridges than most but still responds well.
How long is that element?

 

[SilverhammerNZ]

We all know about using gears to impart corrugations, but I have also heard of a "crimp" being used, the Reslo looks like it may have been crimped.

The element is about 1and1/4" long.

Larry

 

[Guest]

I read an article by a mike restorer (can't remember who) who got in an RCA ribbon that didn't work. The cause was a ribbon with no corrugation. He fixed this one thing and it worked to spec. His theory is interesting. Low paid workers would smuggle out parts, one at a tine and build a mike up at home to suppliment their income. The couldn't get the ribbon right most of the time and sold it cheaply. Even if it is not a true story it is a good one.

 

[b3groover]

Anyone interested in pics of a Shure 330?

 

[rafafredd]

for sure!

 

[HiString]

Thanks b3, that will save me dismantling mine :grin: then re-installing the digi camera's software.

 

[zebra50]

Somewhere I have a file of old ribbon mic patents - anyone interested?

Stewart

 

[smilinfu]

Definitely like to see the patent information. You can never have to much information.

 

[Marik]

The Reslo is known for its weird corrugation. Stephen Sank told me that it's made out of thicker Duralum which tends to get hard with time, and should be replaced.

The corrugation is made not only for stiffening ribbon in vertical plane, it also determines compliance, and keeps the tension uniform in the long run. There were however, quite a few ribbon designes where corrugated were only ends (two-three pleats), and the rest was stiffened by means of slight curve in vertical plane. It helped, when using thicker ribbon, to avoid resonances--the middle part worked in a piston-like mode.

For corrugator gears look in old printers. I was able to find wide enough, with different pitches in some Hewlet Packards.

 

[SilverhammerNZ]

The Beyer MC500 has a small "piston" type ribbon, one corrugation each end and a flat bit in the middle with some thin longditudenal impressions.

 

[Marik]

[quote author="SilverhammerNZ"]The Beyer MC500 has a small "piston" type ribbon, one corrugation each end and a flat bit in the middle with some thin longditudenal impressions.[/quote]

Yes, they use cheap and thicker foil. Since their ribbons are short, they have to do that. Needless to say, they use cheap trafos as well, with all consequences.