Ribbon Mic Dissection Pictures

[Marik]

I'm surprised no-one has commented on this. it's quite unusual (at least I haven't seen it in any of the other ribbon mics we've looked at.

Well, I guess everyone knows that that's the trick to extend frequency response of the mic in upper band. The idea is to bring the resonance peak frequency of the trafo just little below 20KHz, and thus, to equalize the natural top roll off. It might be done by careful transformer design, which would mean some other drawbacks, so this introduced inductance is much simpler and elegant idea, with the same result.

BTW, Stewart, I am a little bit jelous. You, British guys, are exposed to some of very fine ribbons, which are mainly not very common in US. I think most of them could benefit very much from trafo's replacement, with increased performance--looking at both, HMV and EMI structure I can say their motors have very smart and thoughtful design. Keep 'em komin'.

 

[zebra50]

Hi Marik,
Thanks for the explanation :wink:

It's true! There are some good british and european ribbons to be had, and some russian ones not too far away. And the prices are not too bad, (but getting steeper all the time).

But what about the american mics - RCAs, altecs etc??? There are some great american ribbons, but they are almost impossible to get hold of here. So we need some pictures of those mics here!

The trnasformer I modified for that grampian made a massive improvement to that mic, actually, so I think you're correct - there is good milage in playing around with the trafos. I'm going to start winding at the weekend.....

:thumb:

 

[Marik]

[quote author="zebra50"]

It's true! There are some good british and european ribbons to be had, and some russian ones not too far away. And the prices are not too bad, (but getting steeper all the time).

But what about the american mics - RCAs, altecs etc??? There are some great american ribbons, but they are almost impossible to get hold of here. So we need some pictures of those mics here!
[/quote]

You know the expression--"Neighbour's lawn is always greener" :green:

For some more (esp. RCA!) ribbons look here:

http://www.coutant.org/contents.html

 

[Rob Flinn]

Here`s some pics of my BM4 which has a broken ribbon at the moment. I took some pics of this because it is already apart & doesn`t work.

This picture shows the ribbon assembly. The chromium plated ring appears to just hold the two magnets, which are glued (I think) inside. You can makea out the remains of the ribbon, which is unusual in that it is only corrigated at the ends & is sort of scooped in the middle to make it kind of rigid. This is similar to the Beyer ribbons, but the B&O have longer ribbons in them.

This pic shows the transformer, choke, impedance selector switch (this is a BM4), & music & speech switch.

If you own one of these mics I don`t recommend taking it to bits unless you have to. If you do start at the plug end. Take that off & de solder the wires to it. You then need to undo all the screws & then tease the assembly out from the head end. The picture above shows the transformer which I managed to snap one of the wires really close to the bobbin. You can see that I just managed to get a blob of solder on, which I think will connect when I get it re ribboned.

 

[zebra50]

Hi Rob,

Good to see the pictures - nice looking beast - looks very Royer/Speden in form, doesn't it?

Good luck with the re-ribbon. The clamps look easy enough to get to, but making those corrugations would be the challenge.

Stewart

 

[Rob Flinn]

Good luck with the re-ribbon. The clamps look easy enough to get to, but making those corrugations would be the challenge.

I hate to say it but I was going to take the cowards way out on this one & send it to Stephen Sank & get an RCA ribbon put in it when I get some money.

 

[Gus]

you might wan to read this thread




http://recforums.prosoundweb.com/index.php/m/22060/0#msg_22060

 

[Rob Flinn]

Gus

Yes, interesting thread. I have a good friend who`s ears I trust who had 2 B&O BM3`s re ribboned by Stephen Sank & he`s very pleased with them.
It`s very difficult to choose someone to do this sort of work. Without having previous experience of what they can do, one is just going on other peoples opinions.

Thanks anyway

 

[mshilarious]

I didn't see any Shure ribbons yet, here's what I've been working on:

The top mic is the 330, which is cardioid. The blue fabric covers the back chamber of the mic, inside it's just hollow, no labyrinth or anything. On this mic, the cork on the back of the magnet assembly was glued to the mic and disintegrated when I removed. Rather unnecessary since the magnet assembly is also bolted :?

The 315 (figure 8) is on the bottom, and the magnet assembly for the 330 in the middle. The assemblies are identical except there is a rubber horn that fits on top of the 330's magnets (not shown). On the 315 the transformer and back of the impedance selector switch can be seen.


Here's a closeup of the ribbons. The 330 (back side) is the stock ribbon that I retensioned; it was badly sagged. The 315 (front side) I replaced with aluminum leaf. My corrigations don't look as nice, but the mic sounds really good.

Both mics had their grills covered inside with fabric, and fine wire mesh screens directly in front of the ribbons, which are not shown here.

Edit: Mmm, fotolog appears not to like links. Strange it worked when I tested earlier . . . can anybody host these for me?

 

[Marik]

Send the pics to me and I'll put them up.

ribbonmic(at)comcast(dot)net

 

[microx]

Hey ZEBRA 50

Faustino Primero! Now yer on my manor. Full bodied gran reserva from the province of Rioja. If you like that then look for "Viña Ardanza" and "Reserva 904" from "Bodegas Rioja Alta" also wines from the region of "Ribiero Duero". They beat the pants off anything French at five times the price.
Oh yeah, nice mic pics, you will get mine this weekend.
Steve

 

[Marik]

Here are two american classics mshilarious sent me to post:

 

[zebra50]

Wow! Looks good.

I'll see you and raise you an old Melodium lip microphone.....

Looks like a very primative motor. This mic is a bit past it's best, and unfortunately the transformer is missing. IMotor looks to be in OK condition so I may resurrect it sometime

 

[fum]

Hey there,

Peeps have been asking to see the inside of the ShinyBox ribbon mic, and I'v been feelin like total hell (for almost 3 weeks now). So, since I'm not gettin much else done, and I'm sittin on a stack of these, thought I up a pic here. click on the view original size, as it gets much bigger ( Thanks Ethan for the code that makes it small in the forum !! ):

Regards

ju

 

[CJ]

Great shot!
:guinness:

 

[fum]

thanks, my little digicam has a closeup mode. Doesn't use flash (so it's kinda yellow), but you can get right in close on stuff =)

ju

 

[Svart]

sitting on a stack of them? more to sell?? :green: i got 4 to buy if you got them..

 

[fum]

This is from the R&D stack... :grin:

ju

 

[Svart]

aww shucks. I have some old beyerdynamic trafos i would like to try, but i DON'T want to take my two ribbons apart! I like them as they are.. :green:

 

[fum]

You could always send them to me, and I can tell you how they sound :wink: :green: :green:

ju