Ribbon Mic Dissection Pictures
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SilverhammerNZ
Well-known member
Thanks for those, interesting.
larry
larry
G
Guest
Guest
Thanks a lot for all those files. I downloaded them all, not on to reading.
Lots of great information in that lot - check out the pictures: I love old patent diagrams.
On US ebay there are some blurry internal pix of an RCA 44A...
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=64449&item=3739070640&rd=1
Worth a look whilst they're there.
On US ebay there are some blurry internal pix of an RCA 44A...
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&category=64449&item=3739070640&rd=1
Worth a look whilst they're there.
Rob Flinn
Well-known member
I always thought the reason for corrugating the ribbon was to prevent a low resonant frequency.
> thought the reason for corrugating the ribbon was to prevent a low resonant frequency.
No, corrugations decrease the bass resonant frequency. The zig-zag ribbon is less stiff, and also has more mass. If you stretched the foil it would resonate at 500 Hz (just-not-slack) to 5,000 Hz (about to snap). To get down to 50Hz, where you want to be, it either has to be so slack that it wants to fall out of the magnetic field, or you zig-zag it. You don't want a big zig-zag (a long ribbon bent into a short length) because the mass is high.
And the other reason is: the foil is a metal bar, same as a Xylophone. The end-to-end ring is damped but (as in a Xylophone hit off-center) ) there is a side to side ringing that isn't damped. Being very small and thin, it rings around 6KHz. And because you don't hit it, it may not ring at all. But you can't make every mike perfect, and tiny asymmetry can ring on transients. Corrugation stiffens the cross-ringing and shifts it up above 10KHz, where air damps it and the bent-foil also adds damping.
No, corrugations decrease the bass resonant frequency. The zig-zag ribbon is less stiff, and also has more mass. If you stretched the foil it would resonate at 500 Hz (just-not-slack) to 5,000 Hz (about to snap). To get down to 50Hz, where you want to be, it either has to be so slack that it wants to fall out of the magnetic field, or you zig-zag it. You don't want a big zig-zag (a long ribbon bent into a short length) because the mass is high.
And the other reason is: the foil is a metal bar, same as a Xylophone. The end-to-end ring is damped but (as in a Xylophone hit off-center) ) there is a side to side ringing that isn't damped. Being very small and thin, it rings around 6KHz. And because you don't hit it, it may not ring at all. But you can't make every mike perfect, and tiny asymmetry can ring on transients. Corrugation stiffens the cross-ringing and shifts it up above 10KHz, where air damps it and the bent-foil also adds damping.
On we go....
Some pictures of a on old Italian Geloso 'Microfono A Doppo Nastro' (dual ribbon mic). Somehow that name makes me want a beer...why is that?
With the cover off it looks like the easter-island statues. That's a big cylindrical magnet down the middle.
The ribbons are quite wide, corrugated all the way along. They seem a little loose to me but I have yet to measure the resonance frequency.
In case you're wondering, the two ribbons are wired in series but the direction is reversed ('up' and the 'down'). However, the phase of the maagnets is also reversed to put them back in phase. Could this be some kind of humbucking arrangement? Here's the ribbon assembly with the magnets removed.
Old paper-wrapped output transformer.
Stewart
:green: :thumb:
Some pictures of a on old Italian Geloso 'Microfono A Doppo Nastro' (dual ribbon mic). Somehow that name makes me want a beer...why is that?
With the cover off it looks like the easter-island statues. That's a big cylindrical magnet down the middle.
The ribbons are quite wide, corrugated all the way along. They seem a little loose to me but I have yet to measure the resonance frequency.
In case you're wondering, the two ribbons are wired in series but the direction is reversed ('up' and the 'down'). However, the phase of the maagnets is also reversed to put them back in phase. Could this be some kind of humbucking arrangement? Here's the ribbon assembly with the magnets removed.
Old paper-wrapped output transformer.
Stewart
:green: :thumb:
Marik
Well-known member
Thanks Stewart,
Cool!
It has a long corrugation pitch--I bet the ribbon is thicker, and two wide ribbons in series won't have too much resistance, so reflected impedance would not be too high. BTW, thats a big problem with Oktava ML52 double ribbon.
Nah, they do it this way (Oktava is the same) because otherwise the signals in each ribbon would cancel each other. BTW, I think if you connect them in the same direction you could fine tune them by minimum of signal.
How does it sound?
Cool!
It has a long corrugation pitch--I bet the ribbon is thicker, and two wide ribbons in series won't have too much resistance, so reflected impedance would not be too high. BTW, thats a big problem with Oktava ML52 double ribbon.
Nah, they do it this way (Oktava is the same) because otherwise the signals in each ribbon would cancel each other. BTW, I think if you connect them in the same direction you could fine tune them by minimum of signal.
How does it sound?
Yeah, I was wondering if there might be some hum rejection too as an added bonus.
To my shame, I don't know how it sounds yet! I put it under the knife before I even wired up an output XLR! It came with a strange connector and a crappy lead and I still need to hook it up.
Stewart
To my shame, I don't know how it sounds yet! I put it under the knife before I even wired up an output XLR! It came with a strange connector and a crappy lead and I still need to hook it up.
Stewart
Rob Flinn
Well-known member
What`s it sound like Stuart ?
Marik
Well-known member
[quote author="zebra50"]
Anyone want to see inside it?[/quote]
Nah, I'd rather see (and try) insides of the bottle next to it :green: :green: :green:
Well, sure... of course... what's the question.... proceed! You already know the whole drill... :grin:
The mic looks very pretty :thumb:
Anyone want to see inside it?[/quote]
Nah, I'd rather see (and try) insides of the bottle next to it :green: :green: :green:
Well, sure... of course... what's the question.... proceed! You already know the whole drill... :grin:
The mic looks very pretty :thumb:
Marik - you're too late! I was staring at the bottom of that bottle last night - hence the sore head today.
Rob - it sounds great! Big and full, with quite a high output too. To my ears it is better than the ML16, ML52, reslos and HMV mic that I have tested recently.
Here we go then...
ribbon assembly - look at the size of those magnets!
and from the back...there is a ceramic baffle that gives the mic a non-figure-8 pattern. I think it's close to hypercardioid - there is still a bit of pickup from the back.
The output stage is interesting. There is an an inductor/capacitor pair in series with the output.
OK!
Stewart
Rob - it sounds great! Big and full, with quite a high output too. To my ears it is better than the ML16, ML52, reslos and HMV mic that I have tested recently.
Here we go then...
ribbon assembly - look at the size of those magnets!
and from the back...there is a ceramic baffle that gives the mic a non-figure-8 pattern. I think it's close to hypercardioid - there is still a bit of pickup from the back.
The output stage is interesting. There is an an inductor/capacitor pair in series with the output.
OK!
Stewart
synthetic
Well-known member
That Geloso mic is awesome! I love the "Si or No" switch.
I'm very interested in the inside of ther Nady ribbon, whoever posted about that. Perhaps it could be upgraded to an RCA 44 clone? They advertise it as such, but I assume that the transformer, etc. is not up the the same snuff. I had no idea that someone was making an affordable ribbon mic, I kept waiting for the wave of Chinese ribbons to follow the wave of Chinese condensers.
I'm very interested in the inside of ther Nady ribbon, whoever posted about that. Perhaps it could be upgraded to an RCA 44 clone? They advertise it as such, but I assume that the transformer, etc. is not up the the same snuff. I had no idea that someone was making an affordable ribbon mic, I kept waiting for the wave of Chinese ribbons to follow the wave of Chinese condensers.
Sadly that geloso is rather disappointing for reasons I don't yet know. I plan to try some different transformers in there to see if that helps.
I would love to see the inside of the nady too. And those fostex 'printed' ribbons, whatever they are.
I would love to see the inside of the nady too. And those fostex 'printed' ribbons, whatever they are.
FWIW all of the china microphones I have heard using transformers sound dull kind of like a loss of information. What are the china transformer cores made of old car metal.
I have not heard a SP T3 or the SE brand ones. I have heard a M audio Luna (I think it is a 797 build) in a store but what can you tell in a loud music store?
I have not heard a SP T3 or the SE brand ones. I have heard a M audio Luna (I think it is a 797 build) in a store but what can you tell in a loud music store?
chrissugar
Well-known member
Some weeks ago I had a M Audio Luna microphone for testing. I don't know if it is an isolated case or not but that mike was one of the worst sounding condensers I tried.
chrissugar
chrissugar
synthetic
Well-known member
I meant, it looks cool. I've never actually heard one.
Rob Flinn
Well-known member
Its weird with that HMV/EMI mic. I had one of those in seriously mint condition. I thought it sounded average at best. I sold the EMI, because I knew it wouldn`t get used.
I just got a B&O BM3 the other day which I`ve yet to do a session with. The B&O seems to have quite a weak output, which I think is normal for these. Can anyone verify this?
Hey! Post number 500! :green: I spend way too much time here.
Rob, I thought the HMV was really disappointing too. It wasn't mine - I had it in to reribbon for someone. If I had onw I'd sell it and buy an SM57!
Is the B'n'O a 30 ohm or 200 ohm mic? If it's the former you can try stepping up with a transformer for a bit more level. of course.
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.
:thumb:
Rob, I thought the HMV was really disappointing too. It wasn't mine - I had it in to reribbon for someone. If I had onw I'd sell it and buy an SM57!
Cooool. So pop it open and take some shots for us!
Is the B'n'O a 30 ohm or 200 ohm mic? If it's the former you can try stepping up with a transformer for a bit more level. of course.
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.
:thumb:
