Ribbon Mic Dissection Pictures

[zephyrmic]

Just to let you know that I have posted some ribbon mic pics in micbuilders forum in the Photos section under zephyrmic's Ribbon Mic DIY. There is also explanation in the Files section under zephyrmic's DIY/Ribbon Mics. I bought the Zephyr ribbon mic new years ago. Still in pristine condition. The company no longer exists. I have no info about the Ellipsoid mic. Maybe someone knows about this brand. Enjoy the pics and notes on micbuilders!
Regards,
zephyrmic

 

[tchgtr]

Hi,
    I have two of those, its a BM5, them bottom half alone is called a BM6, the top half is removable and is called a BM7, together its a BM5. I'm sure there's many people that could help you, I had mine gone over by Stephan Sank in Arizona, specializes is ribbon mics, and am very pleased with his work,  just thought I'd pass the info along.

  (  BM translation for " Band - ( ribbon )  Microphone "

Thanks for that info. Do you use them often?
The Dynaco/B&O brochure I have from that time refers to it as the "Model 200". The mono version was, of course, the "Model 100". I also have the "MT-2" matching transformer, but never use it.
There is no date on the brochure, but the cost of the stereo mic then was $149.95. 89.95 for the mono.
I've often considered sending it to Sank, but decided to leave it alone while it is working. Gotta hand it to the Danes. They were way ahead of the curve on this one.

 

[audiophreak]

I  know I have some literature on this, I'll have to scan it in, then I'll post it. I've used it on a couple of concert grands with good results in combination with a LD tube mic, and also as a room mic on some Jazz guitar rigs as well.

 

[zebra50]

Thread Palaeontology!

Here's a mystery microphone.
On the back it reads "Microphone Ref No. P.A. 1008".
Looks like there used to be a manufacturer's badge on the front, but long gone. Does anyone recognise this one?

Not sure what that ribbon is made of - doesn't look original.

 

[zebra50]

Further autopsy revealed a couple of interesting features.

The pole pieces on this are adjustable. Four little discs are welded asymmetrically onto little grub screws, which are used to line them up as close to the ribbon as possible. I thought this is pretty cool. It's a challenge to cut and install a close fitting ribbon, and this takes some of the stress out of that,

Adjustments are best made when the magnets are NOT in place, otherwise the two pole pieces rush to meet one another like starcrossed lovers, and crush the newly cut & corrugated ribbon. I found this the hard way...

Also, the transformer primary uses thick solid metal hoops, with bars soldered diagonally between the hoops. Presumably for very low impedance and good contact.

Transformer measures at 1:40 (volts ratio).

BTW, if you haven't re-read the whole thread recently, then make time - it's awesome.

 

[Rossi]

Good eye, Zebra. That pole pieces adustment is pretty nifty!

 

[rodabod]

I'm going to guess it's a GEC, but I wouldn't bet on it.

 

[zebra50]

Yeah, could be a GEC. I can imagine a nice BBC logo stuck to the front!

 

[zebra50]

A bit of digging - I found this mic in this patent.

Looks exactly the same mic. The patent is by Radio Gramophone Development Company Ltd, of Bridgenorth in Shropshire. I had never heard of them, but they seem to have a museum. http://www.rgd.org.uk/
I wonder if they ever manufactured it, or if they sold it the design on to a bigger corporation instead.

 

[eabeledo]

Hi,

I've just got one of these RGDC Ref. No. F.A. 1008 microphones which is part of a larger collection of ribbon microphones I bought recently. The only visible difference is that on my example the badge is attached to the front screen with two screws. I am very curious to learn more about the history of this microphone and whether it was ever manufactured in large quantities or not; or if its clever ribbon alignment design was ever sold or adopted by other manufacturers.

Regarding it's performance, it sounds good with a reasonable output level. Not quite as deep and warm as an RCA 44 but pretty close to an RCA 74 or Electro-Voice V-2.

 

[zebra50]

Hi there!

Did you drop me an email a few weeks ago about your mic? I replied but I think the email bounced back.

I don't think they were made in large numbers. I see about 300 ribbon mics per year and have only ever seen one of these. So certainly not made in the quantities that Reslos, Cadenzas and Film Industries were.

And I have never seen these movable pole pieces in another mic.

Anyway, it is nice to hear from someone else with one.

Cheers!
Stewart

 

[eabeledo]

Thanks Stewart. No, it was not me who emailed you about this microphone. The fact that there is at least two microphones of this kind and that they are so identical to each other would confirm that they were not a prototype and that the design did go into production. Mine doesn't have any badge or logo either.

Cheers!