Ribbon clamps noise figure

[Guest]

After my finished ribbon mic noise oriented thesis,
I have still one problem opened:
How ribbon clamps are made?
If I did Al-Al, Al-SnZn, Al-Cu contact,
there still was noise, which can not be computed from
circuit resistances.
To measure it, I made soldered contact, and
the noise was 10 dB lower ? All was O.K. with solder. Whats the trick.
Why Olson have no soldered contact and still he
measured only ribbon resistance. And without soldering.
And what is that liquid, which uses royer in ribbon
mounting. Is there some mystery, or only my stupidity?
Here is foto of my test unit:

xvlk
[/url]

 

[gyraf]

Good question..

How do you solder to the aluminium foil??

Jakob E.

 

[zebra50]

There's something called 'alusol' for soldering aluminium (and platinum too!) - it works at a higher temperature than normal solder.

All the ribbon clamps I've seen have been silver or gold plated. Maybe that helps.

Stewart

 

[microx]

You can solder to Aluminium but better would be the stuff you can get for repairing print tracks etc. It's silver in suspension and if you coat the two surfaces it goes true "0" ohms when it dries. Dont forget that soldering is still only contact there is no molecular bonding,
Steve

 

[zebra50]

[quote author="microx"] Dont forget that soldering is still only contact there is no molecular bonding,
Steve[/quote]

Is that right? I'm not sure. I agree that there are no 'molecular' or covalent bonds going on, but I was under the impression that an alloy was formed at the interface between the solder and substrate (often copper) and so there is 'metallic' bonding in place - true overlap or mixing of atomic orbitals in the way that brass or bronze is formed.

I could be wrong.

The liquid silver sounds very useful.

 

[PRR]

Speculation:

Aluminum always has Aluminum Oxide on it, and AlOx is an insulator.

For chassis work, we use a toothed washer under high pressure to "bite through" the AlOx layer. Even this is not too reliable.

Soldering is possible with special solder and flux. Actually I think regular solder will work, the problem is that neither solder nor standard flux will remove the AlOx layer. Even if you scrape or scrub it, the AlOx layer re-forms in seconds, especially as you heat the joint for solder. I think you need a very active flux that also shields the Al from air.

I have heard of a trick. Put a few drops of engine oil on the surface. Use a small scraper to scrape through the AlOx layer. The oil prevents instant re-oxidation. Then solder the fresh AL surface through the oil. I have tried it, it is very stinky, and did not work well for me. And it requires hard scraping which would rip foil.

I don't think precious metals have any special property to contact through AlOx. Perhaps they are also "toothed" to mechanically "bite through" the AlOx layer.

 

[Guest]

[quote author="PRR"]Aluminum always has Aluminum Oxide on it, and AlOx is an insulator.
[/quote]
PRR, good speculation, I use farmaceutical petrolatum instead
of oil. Without effect.

To solder Al to Cu thin wire: I use Al soldering liquid (HF+ethanol;
it must be in plastic bottle, because of glass it eats)
Slightly wet Cu wire near the ribbon by that liquid and then use normal trafo iron
and BISMUTH solder. Everything nicely soldered. That liquid must
be used in small quantums and have very agresive fumes (only two
contact soldered discomfort air in whole room).

But it was my semipro solving. Do someone know, what is PRO solving ?
(if we are at PROdigy )?
You can not mechanicaly put off oxides on ribbon one, two micron thick...

xvlk

 

[Guest]

[quote author="microx"]You can solder to Aluminium but better would be the stuff you can get for repairing print tracks etc.
[/quote]
Yes, with several ohms per square cm... , or conductive epoxy ?
[quote author="microx"]
Dont forget that soldering is still only contact there is no molecular bonding,
[/quote]
What the hell ? Soldering, If I studied electrotechnology little, is
metalurgical contact. There are intermetalic alloys and resistance orders
of lower than every mechanical contact.
And I really measured it.
There is possibility to use amalgam (Hg alloy) to obtain soldering at normal temperature with normal metals (Cu, Ag). But not with Al.

And Royer still smears mystic liquid ....
xvlk

 

[Marik]

I think PRR is right on. I also had this problem with noise with some foils. The mystery is that resistance measures OK.

XVLK,

How your horn loading sounds like? Which frequency did you tune it?

I sent you email.

 

[Guest]

[quote author="Marik"]How your horn loading sounds like? Which frequency did you tune it?
[/quote]
I did Horn to overcome problems with big pole pieces.
If remember, Beyerdynamic handheld have it also.
Horn is half of cylinder and is depended to magnet width.

Here is sample:
http://cs.felk.cvut.cz/~vlkm3/nojman/horna.wav
xvlk

 

[Marik]

[quote author="xvlk"][quote author="Marik"]How your horn loading sounds like? Which frequency did you tune it?
[/quote]
I did Horn to overcome problems with big pole pieces.
If remember, Beyerdynamic handheld have it also.
[/quote]

Yes, RCA BK-5 also has it, IIRC.
Although it is hard to say without reference, but it sounds nice as it stands.
What was the distance from the mic?

Do I hear humbucking flaws?

 

[Guest]

[quote author="Marik"]
What was the distance from the mic?
[/quote]
... approx 0.7 meters.
There are problems with reference, because mic have
preamp inside and current output.

xvlk

 

[David Curtis]

And what is that liquid, which uses royer in ribbon
mounting.

Alcoa makes a product called Number 2 Electrical Joint Compound, designed specifically for flat Al-Al or Al-Cu contact connections. The product description says:

"No. 2 EJC has the lowest electrical resistance on flat surfaces because it is a grease type medium that dissolves the oxide on connectors. The nature of the oxide removal is not harmful. Unlike other compounds of its kind, No. 2 EJC creates a light surface etch with no deep, localized attack. It attacks only the oxide."

I don't know if this is what Royer uses, but it might be worth trying.

Here is a URL for the product sheet:
http://www.alcoa.com/afl_tele/aca/catalog/pdf/specifications/QC_Joint_Compound.pdf

--Da5id

 

[Marik]

[quote author="David Curtis"]

And what is that liquid, which uses royer in ribbon
mounting.

Alcoa makes a product called Number 2 Electrical Joint Compound, designed specifically for flat Al-Al or Al-Cu contact connections. The product description says:

"No. 2 EJC has the lowest electrical resistance on flat surfaces because it is a grease type medium that dissolves the oxide on connectors. The nature of the oxide removal is not harmful. Unlike other compounds of its kind, No. 2 EJC creates a light surface etch with no deep, localized attack. It attacks only the oxide."
[/quote]

They don't give specs for its conductivity, but I suspect it might be higher than just a few armstrongs layer of oxide. I was talking to Al foil manufacturer. His words: "Any etching material will destroy such a thin foil. I don't see a good solution for that."

As far as I know, Royer uses alcohol just to stick and hold the ribbon, prior to clamping.

 

[ebeam]

I don't know if this is practical for you, but I had an idea... If you have access to a reasonably flexible sputtering system, you could sputter etch the ends of the ribbon in some inert gas to remove the oxide layer and then (without breaking vacuum) deposit a layer of something like gold on top. Or you could sputter something solderable instead. I'm not sure how well gold sticks to Al, so you might need an adhesion layer like Ti first. The only thing you'd have to worry about is protecting the rest of the ribbon and you could use something like kapton tape or even maybe your petrolatum as a mask depending on vapor pressure.

 

[Guest]

[quote author="ebeam"]If you have access to a reasonably flexible sputtering system, you could sputter etch the ends of the ribbon in some inert gas to remove the oxide layer and then (without breaking vacuum) deposit a layer of something like gold on top. [/quote]
Yes, some associate proffesor suggests me the some, but
i will prefer to deposit gold onto Al by chemical way.
But still have no time and no summer to do it

xvlk

 

[ebeam]

[quote author="xvlk"]But still have no time and no summer to do it
[/quote]

Yeah, I feel your pain. I'm working full-time, consulting, assisting in teaching, taking classes and trying to work on my thesis research....thankfully it's just an MS.

 

[Guest]

[quote author="ebeam"]
I'm working full-time, consulting, assisting in teaching, taking classes and trying to work on my thesis research....thankfully it's just an MS.[/quote]
Yes, I have thesis closed, but there are still many related problems
which I want to be solved.
The problems are so significant, than they are in close
relation to my (new) work here:
www.tesla.cz
at the developement of the middle wave transmitters.
It is mainly EMC job and many qualified old peoples here who can
teach me much.
xvlk

 

[Marik]

[quote author="xvlk"]
my (new) work here:
www.tesla.cz
at the developement of the middle wave transmitters.
[/quote]

Hey XVLK,

Forget ribbons. Congratulations with your new job!
:thumb: :guinness:

 

[ToobieSnack]

as an electrican .... we use a product called noalox in large panels where the aluminum wire wil heat up expand and cool down and contract. ...after time the wire will be in effect... pounded/squeezed until there is an air gap... resulting in an arc...which in turn creates heat ...which burns/melts the wire for further damage...the solution for his is to add this noalox to the terminal and the connection before this damage occurs...it is designed to be conductive...and resist corrosive effects on the aluminium.
I had assumed this may be a good thing for my ribbon connection...I had no idea there may be some associated noise with a poor ribbon contact..
what is the frequency of this noise? how would you describe it?
I am curious and would like to hear more about this.
thanks
ts

PS noalox is available at any electrical supply and maybe the hardware store too.