Ribbon Mic Dissection Pictures

[Svart]

i might if i get first dibs on the new batch.. :green:

i was going to use them to build my own but your ribbons came by.. an offer not to be refused.. :thumb:

 

[rodabod]

I thought I'd revive this thread a bit because I have a fair few ribbon mics which I can post the innards of.

Some of them are rare, some of them strange, and hopefully seeing the designs will help people understand how they work and help people to spawn new ideas like the ones already here have.

First up, a Dynacord ribbon mic (AKA, Beyer M260 - sounds very nice, bit different):

Next up, a Lustraphone / Grampian ribbon. Note the ribbon tension adjuster (very handy), double horse-shoe magnet assembly and the chamfered pole-pieces (if you can see them - very thin):

 

[ToobieSnack]

way super cool rbod :thumb:

these are two i have been wanting to see ..

i won one of those lustraphone/grundig mics on ebay and damn you won't beleive it ..
it travelled from the UK.... to the usa ......and BACK to the UK.. :sad:
my mailman was on vaction and ... d'oh the substitute postman (incorrectly) determined I DON"T LIVE HERE ... ARRRGGGHHHH!!!!!!

well my seller and i just did a refund and i lost out ....

oh well ... i got rbod's pics to look at now ... hehe :grin:
so you see how happy i am to se these ...


oh so ,,, : "dynacord" huh?? :wink: these must be some sleeper mics ...hehe .. I'll have to add these to my ebay search list ... hehe

ok now the lustraphone

one thing worth notice is the RTA (ribbon tension adjustment) on the lustraphone ..
what is kind of cool is the RTA looks like the one i made in my first (less than succesful) ribbon mic . :grin:

what do you think those pole peices are made of on the lustaphone?
are they fairly straigh forward blocks of metal .. (no important detail not shown in the pics)

AND wow the only sheiding the trafo has is the case???????????????
damn what trafo's do you think these are?
.. i think the trafo must have been one of the secret weapons in these mics .. along with the ribbon tension adjust ...

pretty thin ribbon too .. what are the ribbon dimensions? (another secret weapon undoubtedly)

now ...beyer clone ..

ALSO:with the beyer clone ... is there any kind of MRC (magnetic return circuit) .. looks like some yellow looking steel showing in the pics.

AND:are the ribbon clamps touching the magnet structure ?/???? (surely not) but it appers that way ... another pic .. different angle?
or maybe it cant be shown

are those ceramic magnets???? nooo must be alnico ...

funny ... my first mic the ts-1 looks like these two mics combined ... and i have just now seen these for the first time in my life... hehe .. i must be doing some things right ... hehe. :wink: LOL

any way 1000 thanks for posting these

... hehe i always get a kick ouit of those old double horseshoe designs..

OH AND MARIK nice shure 315 and 330 pics... :wink: nice mics interesting motor shape ... why this odd shape ??? eliminate parallel surfaces?

thanks again
later
ts

 

[rodabod]

TS, That was one big-ass reply!

[quote author="ToobieSnack"]
oh so ,,, : "dynacord" huh?? :wink: these must be some sleeper mics ...hehe .. I'll have to add these to my ebay search list ... hehe
[/quote]

Why I oughta! I knew I should have kept that quiet!

one thing worth notice is the RTA (ribbon tension adjustment) on the lustraphone ..
what is kind of cool is the RTA looks like the one i made in my first (less than succesful) ribbon mic . :grin:

what do you think those pole peices are made of on the lustaphone?
are they fairly straigh forward blocks of metal .. (no important detail not shown in the pics)

The pole-pieces seem like a good design. I don't know much about metals, but I would guess iron (they do have a green tinge though). The pole-pieces have a triangular cross section so that they are very thin next to the ribbon.

AND wow the only sheiding the trafo has is the case???????????????
damn what trafo's do you think these are?
.. i think the trafo must have been one of the secret weapons in these mics .. along with the ribbon tension adjust ...

Yep, no shielding. The trafos are big. They have no brand names and I do not know the ratio either. The RTA is a great feature.

pretty thin ribbon too .. what are the ribbon dimensions? (another secret weapon undoubtedly)

Ribbon measures ~ 55mm by 3 - 3.5mm (quite big).

now ...beyer clone ..

ALSO:with the beyer clone ... is there any kind of MRC (magnetic return circuit) .. looks like some yellow looking steel showing in the pics.

This mic more or less is an early Beyer M260. I'm not sure how it works (I think Marik has a better idea). It is hyper-cradioid and is cleverly vented behind the magnet to provide this pattern. I don't know about the MRC, it probably has a block of metal under the two neodymium magnets which you can see on the top.

AND:are the ribbon clamps touching the magnet structure ?/???? (surely not) but it appers that way ... another pic .. different angle?
or maybe it cant be shown

This confused me! It appears that they are. They could be insulated though. I'm not sure. Well spotted! :razz:

are those ceramic magnets???? nooo must be alnico ...

Neodymiums.

funny ... my first mic the ts-1 looks like these two mics combined ... and i have just now seen these for the first time in my life... hehe .. i must be doing some things right ... hehe. :wink: LOL

Lets hear some instruments through your new ribbon!

I'll get some more dissection pictures soon. I've got an oddball STC ribbon which is cool. You'll like the Film industries M8 too - interesting magnet structure.

Anyway, more to come soon (hopefully).

Rod

 

[Marik]

Thank you Roddy, cool pics!

[quote author="rodabod"]TS, That was one big-ass reply![/quote]

Yeah,

Toobie, with this one you just beat the heck out of me. :thumb:
If it is possible, ones again please, but little bit slower. :green:

This mic more or less is an early Beyer M260. I'm not sure how it works (I think Marik has a better idea). It is hyper-cradioid and is cleverly vented behind the magnet to provide this pattern. I don't know about the MRC, it probably has a block of metal under the two neodymium magnets which you can see on the top.

That one is not what I know. I saw Beyers with coil-like piece of wire, wound around magnetic circuit, as a magnetic return.

Any chance of the other side of the structure?

 

[mshilarious]

[quote author="ToobieSnack"]OH AND MARIK nice shure 315 and 330 pics... :wink: nice mics interesting motor shape ... why this odd shape ??? eliminate parallel surfaces?

thanks again
later
ts[/quote]

Those are my mics, Marik hosted the pics for me. I don't know the rationale for the scoop out of the front, but it does have a definite effect on the sound. The figure-8 315 sounds different front & back (warmer, more bassy from the front), even when correcting for the different offset in the ribbon with respect to the case. I assume that scoop is what causes the effect, rather than using symmetrical triangular-profile pole pieces.

On the assembled 330 (cardioid), there is a rubber horn that fits into that scoop. Looks much like a horn used for a PA compression driver (much smaller of course!)

 

[rodabod]

[quote author="Marik"]

I don't know about the MRC, it probably has a block of metal under the two neodymium magnets which you can see on the top.

That one is not what I know. I saw Beyers with coil-like piece of wire, wound around magnetic circuit, as a magnetic return.

Any chance of the other side of the structure?[/quote]

I've just re-ribboned the Dynacord so I can't get the assembly out just now. I've got another broken one on its way, so I can pull the motor out of that one.

I do have a Beyer service / parts sheet which I could post. It shows every part in a blow-up diagram. I'm not sure if it would be legal / fair to post it though? Suggestions?

Those are my mics, Marik hosted the pics for me. I don't know the rationale for the scoop out of the front, but it does have a definite effect on the sound. The figure-8 315 sounds different front & back (warmer, more bassy from the front), even when correcting for the different offset in the ribbon with respect to the case. I assume that scoop is what causes the effect, rather than using symmetrical triangular-profile pole pieces.

On the assembled 330 (cardioid), there is a rubber horn that fits into that scoop. Looks much like a horn used for a PA compression driver (much smaller of course!)

Hahaa! I know a little about this one. I have an STC microphone in the bag which I would like to show photos of.

This microphone features the same scoop (lloks like a PA horn) at the front of the assembly. I believe (correct me if I am wrong) that this is a treble-resonator which is used to extend the HF and provide a more treble-y response.

I think STC may have used a treble resonator in the 4038 but it uses a different method.

 

[rodabod]

A "Film Industries M8" microphone:

 

[ToobieSnack]

Nice pics rbod and you were right i do like that design .. :grin:

Looks like they would be a bitch for ribbon changes .. i hope that screen is actually in 2 parts (front / back) ..

this disign seems like it would radiate a lot of it's flux forward rather than in the gap ... Ring magnets (with a gap cut) might have been a better choice here .. but this mic was probably built with "readily available materials" and maybe compromises were made ...

Now possibly .... the material the pole peices are made of may have some redirecting/absorbtion qualities to rectify this .. ??????

also some effort to reduce the effects of those horizontal plane surface caused by the magnets might have been an improvement .. just grinding the magnets so they are not perfectly aligned might have been a good thing ...or putting velvet on the hz. surfaces .... but .. i could be wrong

how do they sound? difference between front and back?

thanks again for posting them .. this is getting to be a really nice thread ... :grin: i think i love it .. :wink: hehe

later
ts

 

[rodabod]

[quote author="ToobieSnack"]
Looks like they would be a bitch for ribbon changes .. i hope that screen is actually in 2 parts (front / back) .. [/quote]

Yeah your right - it splits into two parts I think, a la Reslo.

this disign seems like it would radiate a lot of it's flux forward rather than in the gap ... Ring magnets (with a gap cut) might have been a better choice here .. but this mic was probably built with "readily available materials" and maybe compromises were made ...

Now possibly .... the material the pole peices are made of may have some redirecting/absorbtion qualities to rectify this .. ??????

also some effort to reduce the effects of those horizontal plane surface caused by the magnets might have been an improvement .. just grinding the magnets so they are not perfectly aligned might have been a good thing ...or putting velvet on the hz. surfaces .... but .. i could be wrong

I wish I understood magnetics better! My advisor at uni recommended me in third year to study electromagnetics for a year - I chose microcontrollers and assembly programming - doh!

Well, I've checked with a screwdriver to check the magnetic properties on a similar Reslo assembly, and you are correct, a portion of the magnetism is lost through the front face. But, I checked the strength inside the gap and it was much, much stronger in comparison to the front face.

how do they sound? difference between front and back?

Here is where there is a slight problem - this particular one is high impedance! I did use it in front of a Marshall stack though wnd compared it to a few other mics (including ribbons). It was very very smooth (not in a rolled of treble way). It added a sort of round jazziness to clean sounds. I really liked it.

As with this type of design (magnets on one side) the sides sound quite different. I think this design is slightly crude, although I still like it. When someone places an obstruction in front of a condensor capsule, people frown. But with this type of ribbon mic design (I can't remember its name - its mentioned in the BBC mic book) people just accept the obstruction as it is inherent in the design.

On the Reslos, I have considered removing the centre magnet and narrowing the face-plate to increase HF extension.

Some of the earlier Reslo RV models only have two magnets on the back. The loss in sensitivity is not huge.

I'll try and get some STC pics up soon.

BTW, can someone explain to me the advantage of having a double-ribbon element.

I realise that in parallel, we half the ribbon resistance and also increase output. What other advantages are there? How do you mount them - in the B*eyer M160 I can only see one ribbon, the other one must be underneath?

Roddy

 

[fum]

Man, all these cool pics. :grin:

Here's what I was working on last night =)

 

[Marik]

[quote author="ToobieSnack"]

this disign seems like it would radiate a lot of it's flux forward rather than in the gap ... Ring magnets (with a gap cut) might have been a better choice here .. but this mic was probably built with "readily available materials" and maybe compromises were made ...

[/quote]

No. The magnets in this case don't radiate, but the flux "flows" from N to S poles, "finding" the shortest distance. In term of motor's magnetic efficiency, with ceramics or Alnicos this arrangment gives stronger flux in a gap, unfortunately on expense of other things. Since there are a LOT of losses in iron, much of magnetic energy gets dissipated in arrangements a la RCA 44.

[quote author="rodabod"]

BTW, can someone explain to me the advantage of having a double-ribbon element.

I realise that in parallel, we half the ribbon resistance and also increase output. What other advantages are there? How do you mount them - in the B*eyer M160 I can only see one ribbon, the other one must be underneath?

Roddy[/quote]

I made double ribbons. The second ribbon is just behind the first one. it increases the output and HF. However, as anything in life, on expence of other things. Finally, I dropped the idea. i could not find satisfying solution to overcome drawbacks. There is a discussion here. Will try to find it.

 

[rodabod]

Ok, here is something I have looked forward to posting - a B*eyer M260 ribbon assembly.

I have taken a few shots here to give you an idea of the construction.

We have three main metal parts consisting of two neodymium magnets and a piece of iron (or similar) for an MRC.

I have removed one of the brass ribbon clamps so that you can see inside the assembly a little better.

On this first picture, there is only one of the magnets in place - the other has been removed to give a cross-sectional view.

In this image you can see the venting which takes place near the actual ribbon. The open section on each side is originally covered in a mesh-cloth like fabric (like the stuff used for venting dynamic capsules). The hole in the bottom is filled when the assembly is mounted in the mic. I'd be interested if someone could maybe chip in a little theory here (Marik?). The microphone has a hyper-cardioid response. I have my own ideas about how the pattern is derived, but I'm surprised that they managed to get such a flat frequency response.

Here is the final picture which shows the plastic fitting which goes on the top. This obviously acts as a pop filter and probably helps damp the ribbon (it has brass mesh in the middle).

Now, with regards to the shape, is this designed to be a treble-resonator to increase high frequency response? Would it affect the shape of the polar-pattern?

I do love my camera's macro....

 

[rodabod]

GEC Ribbon microphone:

(I think this may be the same internally as a BBC Marconi AXBT).

It's a nice design this one. Those pole-pieces are very narrow and are round / chamferred. I'm not sure what type of magnet it is, but I'm guessing it's probably an alnico.

Thumb-screw cable connectors are funny! Still, it's better than not having the correct connector.

 

[ToobieSnack]

once again the geinous of davy ...

has he cut 2 neo's at an angle ?? and connected them to some smaller flatter neo's??

AND IS HE USING THESE NEO'S END-WISE?:??????
ARE THEY CHARGED THROUGH THE WIDTH???

i know i have considered turning my neo's sideways but thought maybe they would need to be charged in that direction... hmmmmm?????

look's like the "V" shape cut in the magnet structure gives more power at the ends of the ribbon and smoothes out the rsponse of the center of the ribbon ... (ya know the ends move a littel and the middle moves a lot)..nice dave .. i think i wil try this design :grin:

i wonder if it is really a mix of big magnets and smaller ones?

or just notched neo;s on a frame?

i think the former is correct ... what do you think?

i know i am impressed ..
later
ts

 

[Marik]

Hey Roddy,

This GEC looks like a nice design and I think you are right about Marconi. It should have a good HF extention. The round pole pieces form a HF horn.

Toobie,

I am not sure why would you want the magnets charged through the width, except for greatly reduced output due to cancellations.
Most likely you won't get any output.

The V-shaped jobbies are most likely iron (or pemendure) magnetic return circuit, with straight thinner magnets you can see in the middle part.
The idea is to leave the middle part open for a shortest front to back wave possible, while maintaining a good flux for a good output.
I was experimenting with this type of arrangement. Despite advertised advantages, in this shape it does not help much.

 

[rodabod]

Oh my,

Royer have some really nice photos.

Look what I found: their ribbon corrugator!

[quote author="Royer"]Each corrugator takes about three months to adjust properly for perfect ribbon corrugations.[/quote]

I bet yours only took a few minutes, Toobie. :razz:

I'd love to get my hands on that machine.

Woah! They've got a corrugator tour!

http://www.royerlabs.com/Royertour/Tour_SFcor2.html

 

[ToobieSnack]

hi marik ..

i still think those v cut metal peices look suspiciously like a neo .. ?? who knows? could be either..

also marik, my apologies, what i meant was through the width (not end wise) ... per the picture ... seems like those are cut neo's laying down ...

the reason i think it would be good to charge through the width is ...
you have more mass directed to the gap and a narrower flux feild ... wouldn't this be a good thing? ... like the thicker the magnet the better ..but ..since size effects frequency ...this unorthodox way of charging a magnet might have good aplication here.

rbod ya i saw that a while back and mentioned it too you ..
note the part about the temperature being critacal..

also did you see the tiny ribbons he was using ... how is he doing what he is doing .. i think he is magic .. hehe ... :grin:

any way i love this thread ...

later
ts

 

[rodabod]

For interest's sake, I've zoomed the assembly so that you can see it more easily.

So, what are we seeing here? Are the magnets simply the very slim pole-pieces with the horse-shoes at each end acting as an MRC?

Would it not be better to use magnets for the MRC in this instance to give more flux? Maybe it would be unnecessary.

I can see obviously why the centre of the assembly is narrower - to provide better HF response, but I'd imagine this would affect off-axis response in the vertical plane - maybe the effect would not be too bad though.

 

[ToobieSnack]

Would it not be better to use magnets for the MRC in this instance to give more flux?

ya that is is exactly what is was thinking ...

and just messing around with them i think they might be ok without charging differently than standard.

but i wonder ..with all the resources davy has ... if he hasn't chargred these differently??

and they looks sooo much like a stock neo tha was cut ... pretty shiny .. what is that chrome? ...polished steel? .. why all the trouble ..OR

is it a nickle plating over neodymium necessary to prevent corrosion?

where is a naked mic R*yer mic when you need one ...LOL

later
ts