ribbon mic: proper ribbon tension

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ToobieSnack

Well-known member
Joined
Mar 3, 2005
Messages
493
hi all there is some info here on this but....

can anyone tell me a step-by step procedure for determining proper ribbon tension?

I have heard ...clarence cane... does this by blowing on the ribbon and observing it's motion.

and I have hear of tuning the ribbon for a certain "resonant frequency"? (i think)

what equipment would i use for this?

I have a signal generator.
and a scope (which i barely know how to use...most of it is obvious)
and a dmm

BTW what is the definition of: "resonant frequency"?

thanks
ts
 
Tune for the bottom of the audio band. In practice, this is just tight enough so it don't flop. When it quivers, it should look like about the same rate as a large HiFi woofer's lowest thud.
 
thanks PRR...

coincidentally that is what i did...

i blew on it softly and adjusted the ribbon ...looser and looser ..until the ribbon started to flutter a tiny bit..

knowing that a breath blown across the mic at this volume approaches the limit of of the SPL for this type of mic... i can tune to this and the use damping/pop filtering and common sense to maintain a signal with acceptable parameters...

this is the best I can do by eye...

is there also a "super guru" "tech head" way to determine this?

with math,fancy lights,graphs and squigly lines: :wink: ...lol... :grin:

later
ts
 
[quote author="ToobieSnack"]I have heard ...clarence cane... does this by blowing on the ribbon and observing it's motion.
[/quote]
Dear Tobbie,
in normal magnetic field {0.8 T and higher} effect of ribbon tension
to overall equivallent compliance {it is, what determines low freq cutoff corner} is fraction part in compare with transformer inductancy
{view via gyrator like compliancy = capacity}. It is in main interest to design transformer to good low freq parameters.
Yes, you can see connected / disconected input winding of transformer
on the ribbon, i.e. like it moves for slow air disturbances.

But you need correct pretension of ribbon. Need it for subsonic stability
of the transducer. But nearly not effect to low freq. In nearly I mean, that
diferent series of trafo permalloy changes it more.

Good luck, xvlk
 
xvlk, could you elaborate on that a bit more? So, could you have a ribbon with higher resonant frequency (say 100-200Hz) and couple that with an appropriate transformer to get a low frequency cutoff which is acceptable?

I tried searching and didn't see this really covered in detail before. Is there a good reference?
 
I've always heard that the ribbon resonant frequency is supposed to be where you want your bass rolloff to be... I'm guessing if you have resonance at 100hz you might have to EQ an already fragile signal.

What I do to tune is use WHITE NOISE.

I shoot white noise at my mic, and then do an FFT analysis of the waveform compared to the response to the same noise from a reference mic (C414 or something.)

It's pretty cool to see the actual freq. response of the mic anyway...
 
n rap
thanks for the info

i am getting GREAT! sound and high output.... :grin:

Is my goal to minimize bass to reduce proximity effect?

I do get some distortion "up close" at about 3-5 cm ONLY with the lowest not I can hit with my voice

absolutely NO problems with acoustice guitar.....mebbe a little rolloff at about 6k as predicted...

how do I do this FFT (BTW is that fast forier transfer...i forget.... :oops:)

what equipment do I use?

instructions?

thanks
later
ts
 
[quote author="ebeam"] So, could you have a ribbon with higher resonant frequency (say 100-200Hz) and couple that with an appropriate transformer to get a low frequency cutoff which is acceptable?
[/quote]
Yes, you can lower ribbon low cutoff by the input transformer change to
one with higher primary winding inductancy.
But situation is not so simply. Ribbon is coupled inductor system at low
part of audio spectra. It is because there are gaps between ribbon and pole pieces and under that "gap critical frequency" velocity transformation
can not occurs. You can measure this frequency simply without input transformer on the "Gayford bridge".
Now, if you connect transformer to the ribbon, you "make" other
lo freq cutoff. And these cuttofs couples. This explains walley on frequency characteristic at approx. 100, 200 Hz which occurs on many
ribbons. I have somewhere von Braunmuehl s measurement of
production Olson microphone. On this measurement is that walley.
But on the Olsons specimens measurements there are no walleys.
I think, that Olson uses (for himself, and american studios) superior pieces of microphones and somewhat worse pieces he exported to the europe :-( .

Is it an answer???
xvlk
 
Werner's paper Electrical Loading of Mics shows "walleys".

Journal Of The Audio Engineering Society
October 1955, Volume 3, Number 4
On Electrical Loading of Microphones
Richard E. Werner
Radio Corporation of America, Camden, New Jersey

"The series of lesser resonances at odd multiples of the fundamental are due to higher modes of vibration in the ribbon and are perfectly normal in a ribbon microphone. In high-quality ribbon microphones these higher-order modes are of a minor nature and do not detract from the excellent transient response and low distortion which are recognized as the outstanding attributes of the ribbon microphone. It is apparent, however, that these resonances complicate considerably the mathematical expression for the microphone's output impedance."

As far as I can figure, Olson was still hanging around RCA at the time this was published.
 
[quote author="PRR"]
PRR, thanx a muuuuuuuch for a paper.
There is seen equivallence of resistance control
in the electrical / acousticall part in the region above
low - frequency corner.
Under that corner, there coupling of ribbon to the electrical part
is missing and then there is low - freq. boost. But that "boost" is
because graphs are "relative to no load".

That "voice choke" is the some, because of bad iron choke
with dominant resistive part.


This paper would be interesting to Marik, because I told to him the
some some half - year ago. And he dont believe me...

xvlk
 
HOLY SH!T PRR!!! :shock: :grin:

what an EXCELLENT reference!!!

once again ...WAY MUCH...thanks

some great reading ... i have it archived

and i'll study this and ....I will have the answers ...or maybe more questions...but at least my brain cel will have fun... :wink:

1000 thanks
ts
 
[quote author="ToobieSnack"]HOLY SH!T PRR!!! :shock: :grin:
[/quote]
WHAT SHIT???????????????????????????
??????????????????????????????????????
PRR thanx,
every forgotter ribbon paper is good thing,
and this is somewhat delicate.
What shit is about method to obtain low cut on the ribbon mic
with load impedance. It can be useful to make remote - proximity
effect correction, just via paralel resistive fedback of inverting mic preamp.

xvlk
 
ok ..my apology.... maybe we have again some language barrier or ...mis conception .... or maybe not... :?

xvlk this statement is american slang ... and expresses excitement and "wonderfu joy" and suprise.... sorry for my use of american slang...

I hope this did not cause any confusion.......

PRR this is a great reference .... xvlk... I will read more and try to understand your last comment ... this is beyond my knowledge at this time....

thanks
ts
 
haha that's funny bill ... at least more amusing than this little misunderstanding :oops: .... lol ... :grin:

I'm pretty easy going ...so ... if i sound harsh your probably just not understanding my humor or my sarcasm .... or in this case just a little american slang :oops:

reading your quote is what really made it funny....

"Adjust R116 for least smoke"

I though "Adjust Remarks for least smoke"

haha lol

once again my apology for any confusion I might cause .... :oops: :grin:

later
ts[/u]
 
OK id did some testing with my TCA ribbon mic....

i now hear this low end frequency boost....

using my voice i found that ONE note , sang at the same approximate volume level, created an output higher than that of ANY other note... even notes lower than this frequency had no "boost" effect....

NOW questions:

is this correctable with my tension adjustment?
how will the tension affect this "boost" frequency?
eg: will tightening it move this "boost" frequency up or down?
Is this boost just a common thing with ribbon mics and "boost" frequency is tuned for a specific desired frequency?
AFTER tuning can i further improve low frequency at the trafo?

OR:am i at the mercy of this coupling in the gap between my ribbon and my hardware.... with no hope of changing or improving this?

xvlk: i like this idea about "remote" control for this proximity "boost" ....
how can we do this? :grin: :grin: :grin: !!!!!great idea!!!!!

as always your kind comments help and suggestions are sincerely appreciated

thanks
ts
 
Toobie, I guess my approach may be just too relaxed but, what I do is this: ribbons are meant to be "transparent" sounding mics, right? In other words, they should sound pretty much the way a signal would in real life (providing there's no proximity effect to boost the LF, etc).

Taking this as my starting point, I simply listen to it with the mic's hood off (I'm talking about my own mic here, with the vari-tension system adjusting on the top end of the iron) and adjust/slacken the ribbon until it sounds natural. It just happens to sound natural when it is quite close to being slack (but not yet slack).

Clearly, to get the best, most natural sound you will need to look at other weak links such as the ribbon material itself and its thickness, as well as the right corrugation (in my experience deeper corrugations are better). The right answer I guess is that it will sound "natural" as it should once you've achieved a balance of all of the above. Use your intuition and your ears.

Then again, I don't particularly love maths, graphs and the like and find that I trust my ears the most, so for me it works to experiment and come up with the solution that sounds the best. To the theoretical and technically minded out there this must sound like trying to reinvent the wheel, I know, but I just happen to enjoy these experiments immensely :grin: !
 
[quote author="El Fito"]... and your ears.
[/quote]
No earphones are so transparent enough to allow hear
ribbon mic variations. I think, electrostatic STAX may be good,
I don t know, I haven t still hear ribbon to the electrostatic earphones.

just idea,
xvlk
 

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