ribbon mic:2b or not 2b OR..THE TOOBIE D-2b MkII audio clips

[Guest]

[quote author="ToobieSnack"]Xvlk these are the pcm files you requested [/quote]
Thanks, Tobbie, nice frequency characteristic.
But some comments on noise figure .

In my editor I can see FFT picture of your record.
Some -80 dB bellow 0. How to iterpret it ???

80 - 10*log10(4096) - 10*log10(1.5)

where 4096 is number of FFT points and 1.5 is Hamming windows equivallent noise bandwidth.

Result is 80 -36.1 - 1.8 = 42.1 dB It may be usable for shellac disc records or magnetophone casette, but not for CDs.

This is my record recorded by two chineese ribbons (arranged as Blumlein pair) and followed by my own developed preamp directly to CD recorder. It is excerpt from live recording in gothic style church.

http://www.rudolfinea.cz/hanka.wav

I mean, that my record may be good for LP manufacturing, but for CD
it is rather noisy.
Computing... It is distant recording (some 5 meters in front of solist) and it is still 16 dB better than your 3 feet distance.
Yes, chineese microphones have some 6 dB worse noise parameters than
perfect large-ribbon microphines, but still better.

You may firstly determine, where is problem. The best will be to do some measurements, what is dominant source of noise.
In well developed ribbon mic recording system dominant noise source
MUST be ribbon resistance.

Trace your system with resistors bridged by tin wires.
Solder resistor with appropriate resistance and tin bridge to the system like dummy microphon, dummy ribbon, etc.

Record sample and then split tin wire (during record).
If you measure noise level (i.e. via FFT, to ommit spurious frequencies)
then you must compute equivallent noise resistance in the point
like Ap=10*log10(1+R/Rn) ,
where Ap is differency between noise levels, R is connected resistance and
Rn is equivallent noise resistance.

If you are somewhere Rn close to R, you have 3dB noise figure in this point. All points before will be worse.

Best regards,
xvlk

 

[ToobieSnack]

hi everyone ...

xvlk so wonderful to hear from you again. :grin:
very nice audio clip .. thanks...
is there any compression on that? .. the music is very subtle and has contiuious levels. dynamic subjects are more difficut to record ... like my guitar (as we all know)
ALSO: i know you said you were very busy on much bigger things but my offer still stands if you would like to be involved with this project. i would love to have you as a team member.

i have done some work to reduce resistance.
i have sent a pcm file to roddy for upload here ...
i would be so pleased if you would listen to this file and get the FFT results.
what computer program do you use for FFT?
any macintoch programs for that?

also sorry but my math is not very good.. i can only build by intuition and then test ... :sad:

it is true some analysis would save me much time..

i have recently found this set of calculators for magnets and i wish i had seen this before ...

here is the link .. (zebra you might want to add this to the meta if it is not already there)

http://www.magnetsales.com/Design/Tools1.htm

i have recently downloaded a demo of a FEA (finite element analysis) program i hope to try out ... but it will probably be pretty complicated (maybe worse than CAD) :shock:

and roddy that royer clip sounds so loud i wonder if that had been mastered or if it is a raw audio file? says it is from a cd so i imagine it has been mastered ..

i just can't seem to get my audio to hit as hard as i would like .. back to mastering class i guess ... hehe :wink:

anyway roddy will have the new audio up soon ...

enjoy!
looking forward to your comments and suggestions

thanks
ts

 

[rodabod]

[quote author="ToobieSnack"]
i have sent a pcm file to roddy for upload here ...[/quote]

Cool, I'll put it up in a minute. I have FFT analyzing tools in Soundforge (apparently) so I may have a go too.

i have done some work to reduce resistance.

I'm thinking about making an add-on for my multimeter to give *100 resistance to allow me to easily measure ribbon resistance. This would make things easier. Any ideas anyone?

Also Toobie, read the BBC monograph which I put in the groupDIY email account. It covers ribbon thickness, width, and lots of other stuff.

Go to:

http://www.gmail.com

Login name: groupdiy

Password: thelab

also sorry but my math is not very good.. i can only build by intuition and then test ... :sad:

Sometimes simple maths can help though. If you don't understand something, just ask! That's how you learn (it's just a shame that maths is so boring).

i have recently found this set of calculators for magnets and i wish i had seen this before ...

here is the link .. (zebra you might want to add this to the meta if it is not already there)

http://www.magnetsales.com/Design/Tools1.htm

Right, what can I use these for? I have some neos which I plan to use some time - can these calculators help me in any way?

i have recently downloaded a demo of a FEA (finite element analysis) program i hope to try out ... but it will probably be pretty complicated (maybe worse than CAD) :shock:

What is FEA for??? I've never heard of that.

I've listened to "Wise Old Man" (with vocals) and I really like it. It fits together really nicely. I thought it had that cool mystical feel and it reminded me a little of Led Zeppelin in that way. Great song.

 

[rodabod]

Ok, here is the raw PCM file which Toobie sent for analysis:

http://myweb.tiscali.co.uk/rodabod/D2-bMkII.wav

I listened to it in Soundforge, and noted that when normalized, the noise level was sitting at -45dB, so I suppose the dynamic range has been limited to 45dB in this recording due to noise.

However, I didn't think the noise level was too bad in a musical sense.

I will read XVLK's post regarding FFT analysis and see if there is anything I can learn from the file.

By the way TS, I was wondering if "Wise Old Man" might sound better if the vocals were only single-tracked for the verses but double-tracked for the chorus?

Anyway, speak soon,

Roddy

 

[ToobieSnack]

I listened to it in Soundforge, and noted that when normalized, the noise level was sitting at -45dB, so I suppose the dynamic range has been limited to 45dB in this recording due to noise.

so... how bad is this?
what is my goal here?
what is r*yer's noise florr?

one thing that is most likely the culprit is ...

i have the trafo mounted into my cable (not inside the mic) like grundig did.
I have about 18" of wire from the motor to the trafo ..

this makes it easier to swap out different trafos and migrate trafo's to new designs ...

also my space inside th mic is very limited (just under 3/4" square is all ther space i have for mounting a trafo internally..

small size was a goal from the start .

if i find a trafo small enough i wil mount it MUCH closer to the motor and this should reduce my resistance and thus also noise ...

anyway ...argghhhh this hunt for the resistance fox is very frustrating ! :sad:

anyway not much more i can do here ... except maybe silver wire and silver contacts .. ????

Right, what can I use these for? I have some neos which I plan to use some time - can these calculators help me in any way?
Quote:

i have recently downloaded a demo of a FEA (finite element analysis) program i hope to try out ... but it will probably be pretty complicated (maybe worse than CAD)


What is FEA for??? I've never heard of that.

the magnet calculators with the yokes is waht we need .. just enter your size, grade of neo , and gap and it will tell you your calculated guass .. before you waste time building like i hvae .. :sad: but bot really i learn too. :grin:

my mic calculates out at about just above 4000 gauss.

the FEA is finite element analysis... this is what they usefor aerospace ,,, auto crash simulations and the simulation of movement of finite particles of matter or magnetic energy ... so .. you can see the flux around the model and the effects of different magnet shapes/configurations.

OH and BTW one thing i noticed too is that the wires seem to have a microphonic effectc when touched ?????

does this mean that the wire used effects the sound?
i mean is the wire acting like an element of sorts?
also wire guage must be a factor too ..
a fine balance between to big and too small???

anyway now i am rambling .... not sure where to go from here.. :sad:
high quality wire is probably my next step (i can afford)
then moving the trafo closer ...
then crossing my fingers and praying ... lol

later
ts

 

[rodabod]

[quote author="ToobieSnack"]

I listened to it in Soundforge, and noted that when normalized, the noise level was sitting at -45dB, so I suppose the dynamic range has been limited to 45dB in this recording due to noise.

so... how bad is this?
what is my goal here?
what is r*yer's noise florr?[/quote]

How long is a piece of ribbon? Heheh. Well, you might want a better dynamic range if you want to take advantage of the dynamic range offered by newer digital mediums. What is the dynamic range of a standard CD?

one thing that is most likely the culprit is ...

i have the trafo mounted into my cable (not inside the mic) like grundig did.
I have about 18" of wire from the motor to the trafo ..

this makes it easier to swap out different trafos and migrate trafo's to new designs ...

What??? Trafo mounted 18" away?? What sort of cable?? That is a major culprit.

The Grundig one was a second step-up transformer for tape-machines. There was still a transformer to step the ribbon up to low impedance.

I looped a section of noise from your recording and there is some 60Hz hum in there. I reckon it will improve greatly if you get the transformer next to the ribbon motor. The ribbon motor should attach to the trafo via thick wire - preferably some solid copper wire.

also my space inside th mic is very limited (just under 3/4" square is all ther space i have for mounting a trafo internally..

That's tight. You'll just need to make room though.

if i find a trafo small enough i wil mount it MUCH closer to the motor and this should reduce my resistance and thus also noise ...

Yeah, you are going to need to. The transformer need very good shielding (ie. needs to go inside the mic case). The cable in series with the ribbon before the transformer has resistance too.

Think of it as a voltage divider - say your ribbon is 0.2 Ohms, your cable is 0.1 Ohms and your transformer input looks like say, 0.5 Ohms. The cable is stealing some of your signal and is also increasing noise by picking up RF, etc.

anyway not much more i can do here ... except maybe silver wire and silver contacts .. ????

Please don't make it audiophool! Still, I believe Royer use silver wire from the ribbon motor to the transformer input....

OH and BTW one thing i noticed too is that the wires seem to have a microphonic effectc when touched ?????

Yeah, the wires can be microphonic with all that gain...

does this mean that the wire used effects the sound?

Well, it can only really degrade it if it is too thin I suppose.

i mean is the wire acting like an element of sorts?

I suppose so, but not really. Wire generates current if you heat it up too...

also wire guage must be a factor too ..
a fine balance between to big and too small???

Just stick with good solid core within the mic. You can't really go too thick, unless it gets in the way of the ribbon! Beyer use solid copper ~ 1mm thick wire (very hard to bend).

anyway now i am rambling .... not sure where to go from here.. :sad:

No, No. This is how you progress.

high quality wire is probably my next step (i can afford)
then moving the trafo closer ...
then crossing my fingers and praying ... lol

Move the trafo closer first. Get it in the mic case if you can.

Use shielded mic cable to connect the ribbon to the trafo if you are keeping it outside. Shield the trafo if it is outside!!

When recording next, move the mic around and see if the noise increases or decreases in level depending on where it is.

Good Luck.

 

[TomWaterman]

I like your playing style Toobie - sounds nice. Congrats on your progress.

Just a thought but are you recording sat next to your computer? I think I detected a key click to punch out at the end? This may be too obvious to point out (but I thought I would!) Is it possible that a lot of your background noise is within the room - it sounds like theres a fan there underneath the HF noise from the Mic....

Tom