Ribbon material (a silly question!)

Hello,

Here it cames: About ribbon material for a DIY ribbon mic: Has anybody tried just plain aluminium foil (yes, the one found in almost all the kitchens in the world) ? Guessing you are answering NO, is it because it's thick for the purpouse ?

What do you recommend ?

Thanks in advance.

Hi Kat,

Yes you're right. The plain aluminium foil is too thick for the purpose. I think you'll get a bad bass response.

You need to use signwriters aluminium leaf. Thickness 0.2-0.6 micron.

Info about making and changing the ribbon yourself can be found here.
http://www.lkmusic.co.nz/ribbonfix.htm

Hope this helps!

I believe some people are using 1.5 micron-2 micron foil. Which I hear is similar to the stuff used in production mics.
The cheapest place to get it is looks to be.
http://www.lebowcompany.com
but still not cheap. I have not tried it myself. Must be easier to work with than the damn leaf(DAMN YOu LEAF! :evil: ).
Hopefully Marik or Zebra50 will come by and give us their impression.
Check out the meta thread on mics, there is alot of information.

What kind of mic is it?

2-to-3 um was recommended to me by a current manufacturer of ribbon mics. For repairs to common medium-length ribbons like the reslos and grampians I have been using 2.4 um aluminium foil from Advent research materials (www.advent-rm.com IIRC but do a google search). It is not cheap. Cutting is OK but you need to use a new scalpel blade. Don't sneeze when handling it! Actually it's a good idea to wear a dust mask or wrap a cloth over your nose and mouth.

Cheers!
Stewart

Is it significantly easier to use than the signwriters leaf? or just more durable?

I can't answer this because I've never seen the signwriter's stuff. It is a lot thinner than kitchen foil, though.

[quote author="zebra50"] It is a lot thinner than kitchen foil, though.[/quote]

Ha! :green: :green: :green:
No kidding here!!! I would say 'bout 50-100 times difference. :shock:

The kitchen foil is basically unusable, unless you want to check how bad a ribbon mic can be. I cannot stress enough the idea that theory for ribbon mics works only in a "linear area". Whenever some parameters are changed drastically theory fails.
Same with ribbon thikness. The theory says that thikness does not influence frequency response of the ribbon--its ouptut only. Although it is true, there is however another 'indirect' effect--the thicker ribbons are much more prone to resonances, and subjectively sound like the top is smashed. With kitchen foil, beside extremely low output, there is no top whatsoever--dont ask me what happens with resonanses there. Also, compliance is completely screwed up and the ribbon works rather as a marimba bar, than a nicely suspended flexible transducer.

DAMN YOu LEAF!

Click to expand...

Couldn't agree more! I am not sure how Larry does it. Probably he will chime in and give some insights on his method. I tried this leaf a few times--no luck. It will whether fall apart when I pick it up, or when I corrugate it, or when I install it, or.... when I finally succeed.... it would not keep its tension over a week. Interesting thing (back to theory failure)--I did not notice any sensitivity improvements using it. Got the hint?

There is another very important consideration, which is ribbon's impedance. With foil that thin, the ribbon resistance would be about 0.5-1 Ohm, which with 1:40 output transformer translates into 800-1600 Ohm (!) output impedance of the mic. Without special precautions (as a SS impedance converter) it is basically unusable with "normal" pres, or ribbon will be loaded by input impedance of the pre, resulting in severe bass response 'damage', as well as loss of 'naturality' of the sound.

Marik, so what material do you use for your ribbons? i tried the leaf and got output but exactly as you said it died after a few days and my pre didn't seem to like it much at all, even through a trafo..

Hi I've had bad results and spent a lot of time with signwriting leaf too. A bloke I work for has an old Tannoy ribbon mic that he re-ribboned using silver foil from a cigarette packet, and it works really well, I used it recently on some backing vox.

Would there be any interest in a group buy of some foil? I'd be willing to put in $20 or so.

Thanks to all. It makes logic, but I'm surprised with the bad results with leaf :? , so Marik, what do you use in your fantastic mics ?

I've got the magnets (a hard work), the 1:37 Lundahl trafo, a basic idea of the mechanical design and just wondering about ribbon material ....

I am using a 1.5um I got from one ribbon manufacturer.
As for where you could get it.... well, a lot of choices. The cheapest--to unroll an old paper in oil cap. The smaller voltage rating--the thinner the foil. In addition, you can put the foil on clean and clear glass and roll it with ball bearing, using very thin oil. I have a few old 400V Illinois caps, which gave quite satisfactory results.
If you want to go an expensive (and may be the right) way, check this:

http://answers.google.com/answers/threadview?id=362221

You will find anything down to 0.3um (don't even think of trying it :grin: ). Something between 1.5--2.5um should give good results. Lebow seems the cheapest for budget sheets, but they have minimum order of 3 sheets. Please keep in mind I never tried those, so cannot guarantee anything.

Should I start saving up foils from my cigarette packs for you guys? :wink:

> Should I start saving up foils from my cigarette packs for you guys?

I have heard of butt-foil from someone else, who did emergency repairs on RCAs back in the day.

My impression/recollection is that cigg-pack foil has changed since those days. It used to peel easier, and wasn't all waffled.

[quote author="NewYorkDave"]Should I start saving up foils from my cigarette packs for you guys? :wink:[/quote]

:grin: :grin: :grin:

Yeah, I heard about it. Also, I read (I think from Scott Dorsey, IIRC) about use of Wrigley's chewing gum foils. Our local Barbacoa wraps their burritos into something similar. I never bothered checking all these, so even forgot about it.
I would think if you want to check the concept, anything (exept of kitchen foil) more or less thin and flexible should work. And of course, if you like the results, by all means use it.... and report here :wink:

The traces of refried beans on the foil will probably lower the resonant frequency, and will certainly affect the compliance.

:wink:

Hey Marik....a little off topic, but how exactly do you secure your magnets? I scanned old threads and didn't see a mention of it. Are you using some kind of glue or is it mechanical?

[quote author="NewYorkDave"]The traces of refried beans on the foil will probably lower the resonant frequency, and will certainly affect the compliance.

:wink:[/quote]

The black beans work better.... but only if you use guacamole (extra $.75)
:roll:

[quote author="ebeam"]Hey Marik....a little off topic, but how exactly do you secure your magnets? I scanned old threads and didn't see a mention of it. Are you using some kind of glue or is it mechanical?[/quote]

I roughen the magnet's surface and use epoxy. I am thinking of ordering custom made magnets of special shape, so I could secure it strictly mechanically.

[quote author="Marik"]
There is another very important consideration, which is ribbon's impedance. With foil that thin, the ribbon resistance would be about 0.5-1 Ohm, which with 1:40 output transformer translates into 800-1600 Ohm (!) output impedance of the mic. [/quote]
What output impedance ?
that 800 - 1600 Ohms is ribbon mic intrinsic noise resistance.
But good ribbon transformer have 6 dB noise figure with 0,5 Ohm
ribbon. There is 1600 ohms of transformer noise resistance.
You can make lower intrinsic noise resistance of ribbon mic with thick
ribbon, but only with special transformer you can improve overall noise.

xvlk
P.S To make ribbon material is difficult and it is secret of mic manufacturers. It is not impossible by DIY, but no ribbon maker
publish it.

Dear XVLK,

This statement, as well as one in another thread on the top of the page (you did not post a follow up):

http://www.groupdiy.com/index.php?topic=1641&postdays=0&postorder=asc&start=30

makes me wondering if we are talking about different things--I am unclear what do you mean.
Please find attached a chapter on transformers, as used in ribbon microphones, from Microphone Engineering Handbood Edited by M. Gayford. Although, it is not highly theoretically or mathematically inclined, it gives an idea what I am talking about:

http://home.comcast.net/~markfuksman/RibbonTrafo.JPG

The transformer I am using is a Lundahl LL2911, which is a very good iron, specifically designed for ribbon microphone use.


PRR,

Probably you could chime in and explain what am I missing.