Grampian mic

Just found a very old GramPiAn mic. Its the MCR model circa 1939! Black heavy round thing suspended between four springs. (freq response 60-9000Hz). If u dont know this company, they're the guys that invented the moving coil dynamic mic.

Don't know if it works, havn't tested the sucker coz it has some funky old three pin connection but it probably doesn't coz the casing looks all beat up & a bit rusty....... However! I could probably get it off the guy that owns it if i do a days stripping (paint stripping) so what i wanna know is.....

1) does anyone know about these things?
2) what would it take to fix it?
3) should i do the paint stripping is it worth it?

Hi,

Is it this one:



Here's the site the pic came from:

http://www.vintage-microphones.de/microphones/hauptteil_microphones.html

Well, I haven't heard one- I suspect that if it does work it'll be quite dark judging by the freq response, but it could be ideal for "effects" or "tonal" micing. I've got an old Grampian mic from the early 60's- the same one as Zebra50 has in his avatar. It's got very limited bottom end and a mid peak, but it's good for elec guitar solos- it's got a good edge that cuts through, and for effected vocals. You can never have too many mics, but I'm just an addict.

As far as connecting it up to test, I just get a 3-pin XLR lead going to small croc clips so I can fudge a connection while testing. When I find out if it's a go-er, and can't find an original mating connector, I then remove the original connector, place an aluminium plate over the old hole, and add an XLR "tail" with a hole and a grommet through the aluminium plate.

If it isn't working, you could always replace the cartridge with a modern dynamic or even electret or condenser capsule- it looks big enough! And you'd ben amazed at how the look of a mic can influence the attitude of a singer/performer

Mark

Drool!

We like grampian mics. If it's a dynamic then it is probably quite robust & still working. [If it's broken then you can sell it on to me for Frankenstein-ing! I'm looking for a few old mic bodies].

Like mark says, don't expect hi-fi or low noise. Do expect character.

If it's a carbon mic it could be knackered.


Worth a day stripping? Certainly :grin:

Worth a day stripping paint? Well maybe half a day. Depends how you value your time. If it's for a friend then ask for the mic and some beer.

Stewart

Cheers, (yup thats the one... i found that site but thanks anyway... there isn't enough info on grampian mics if you ask me... wonder if anyone owns the name or if a definitive Grampian website exists)

Wouldn't it just be great if it worked?!!! I mean 1939! It doesn't get much older than that. When i get round to finding out i'll let you know.

One more thing: So if its broken can any of its guts be fixed or is it a total francenstein job? What bit usually break with old mics like this?

Depends on how it's been kept. If it's a dynamic and been kept dry then there is a good chance the capsule will still work. If it's been damp the element/coil may have rotted and will be hard/impossible to repair. However, many of the big old dynamics I've seen have had little more than broken wires and broken insulation. I've had three Grampian dynamics from the 50s and 60s, and twon Grampian ribbons. All have worked fine after a little TLC (and re-ribbon).

The carbon type mic elements sometimes turn themselves to dust. I don't know the cause of this, and know of no way to repair them.

One thing that you find is that someone has already beaten you to it and replaced the elemnt. Often with an old telephone mouthpiece element, for some reason. I have had two mics like this (a Reslo and a Geloso) and now have two bits of telephone kicking around. This is really disappointing. I'd rather have the original guts so we can document and learn from it.

Cheers!
Stewart

[quote author="jaotao"]Cheers, (yup thats the one... i found that site but thanks anyway... there isn't enough info on grampian mics if you ask me... wonder if anyone owns the name or if a definitive Grampian website exists)
[/quote]
Cable and Wireless own the name!!

Hi,

I happend to have the exact same mic overhere... i bought it a couple of mounths ago in a junksale for 25 euro.. it was probably in the same state as yours is in. (shame on me not to have shared it with TT
I took it apart, spray painted it, and put it back together..
It does pay off to take it apart cause them you can remove a very old fashioned pop-shield that's inside.. it's a sort of plastic thing that goes over the capsule.. By now we have more modern popscreens for that
Just to confirm, it's a dynamic mic, not a carbon..

Putting in another connector in is not easy.. right behind the connectorpanel is a .4" thick steel plate.. that hold the whole back together.. I've already been searching for banana-style plugs to mate with the ones in there but it's a very weird diameter...

If somebody has some webspace and is willing to hold some pictures i can send them to you... otherwise send me an email address and i'll mail the pictures to who wants them....

Love this place!
Remco

Send me the pix. My email should be below (click the button). I'll put them up at the omnipressor site, if that's OK. Inside shots too?
Ta.
Stewart

i've got pics of verything, guts inside out, spraypainting.. the whole deal...

let me cook up something to send to you...

Remco

Hi Remco,

Aha! That'll be the mic you picked up with the box of goodies that time! I've got one of the pics of it in its original condition that you sent me here. Can't wait to see the restoration you've done on it!

:guinness:

Mark

hiya Mark..

That's totally correct.. that was with the stuff in the office
You've got a better memory than me! you just brought it back in my mind now

Cheers!
Remco

:?: (Y'know, there are so many little deals and transactions going on behind the scenes here. We could write a book on the sordid underbelly of the TT/Lab community! It would make a good documentary for channel 5 :green: )

Remco, thanks for the pics. I've uploaded the ones which I thought gave most detail. Please send me one of the rebuilt mic when you get time. It's a beautiful looking capsule, and IMO getting rid of the plastic disc is a good plan.









:thumb:

Jao and Remco,

Right, now I've seen the pics of the odd connectors, I know exactly what you need. They're the same as on the back of my own Grampian. I ended up replacing the aperture left when I took out the 3-pin connector with a plate and XLR tail.

The sockets fit a 3.2mm "banana" plug- like the 4mm plugs used for test equipment but smaller. Sometimes called "split pin plugs" or "bunch pin plugs". So you could make up a lead from an XLR to these pin-plugs to fit into the mic. I've got a few spare lying around, so if you PM me with your address I could find 3 each for you gratis. I'm not sure if the 3 plugs would fit into the holes with clearance, but I could post a pic of them with dimensions if you're interested.

I like to see old mics up and running rather than in a glass case!

:thumb:

Mark

Good tip on the connectors Mark. Thanks.

A couple more pix before bed time (thanks to Remco)...






ZZZZZzzzz...

Ah ha!

So it's 3.2mm... *flicking thru the electronics catalog at the moment*
It must have been something like that as 4 mm was to big and 2.8 was to small

but it you could find some please, as i can't order them out here...
need to find a different supplier

The mics does work, as i've tested it with a scope on it.. That's quiet a challenge by the way.. holding probes on the back and yelling into the front.

new pics are on their way...

Remco

> getting rid of the plastic disc is a good plan.

It is almost certainly a treble resonator, not a pop filter.

These are VERY common, I would say universal, on dynamic mikes. Anybody still use EV635, or RE-15? The holey zinc disk in front of the diaphragm can be screwed in or out to set the treble response (kids, don't try this at home). The old $5 Radio Shack omni dynamic also had a treble resonator (not adjustable). Shure SM57 may be one of the few dynamics that does not bother(?) with a treble resonator.

Without it, the high end may droop. With it, the highs are flat (or slightly humped) up to a point, and then it drops.

It does the exact same thing, except in reverse, as the bass-reflex port in a loudspeaker (and BTW most omni dynamic mikes have a bass reflex port). It converts a sagging response to a bump and a drop. If the Q and F are set right, the result is very-flat up to a point.

In this case, it may also reduce the high-freq directionality of that large diaphragm and make the response more true-omni.

Since you can get real-flat mikes anywhere now, it may not be essential to keep the treble resonator: it may have a useful mellow sound without it. But try it both ways.

If the guts were truly shot: I have taken a similar mike (US, swivel mount) and put an electret capsule on a sheet of thin plywood in the body. There was enough room for a 9V battery too. Worked very well as a talk-mike for the Jazz Band director. However the Theater dept borrowed it as a prop in a play.

[quote author="PRR"]
It is almost certainly a treble resonator, not a pop filter.
[/quote]

Thanks for clearing that up.