RCA/GrundigGRM /ribbon mic **thanks PRR/Marik/xvlk*IT WORKS!

[ToobieSnack]

hi all

I have wonderful... strong output on this mic...I can't be happier

I do have some issue but a solution is at hand and I wil soon implement and post my improvement...

xvlk....I am very interested in your comments

Yes, you can use it for nice, welvet sound, but (because of very
wide magnetic part) you will have 5 kHz cutoff.

yes i do have a nice velvet sound and a cutoff at 5k is ok for a vocal mic...even preferred.... however...??

xvlk will you please tell me how to calculate this frequency cutoff?
is it becuase my magnets distance between the magnets?
or the distance from the front of the ribbon to the back of the magnet structure???
I know it involves the physical dimentions....
the mic is done and I can't change this...correct?

ALSO:

what you can do is to plate magnets and pole pieces by welvet and hope that it helps.

do I apply velvet to my parts inside the mic (magnet and iron)?
can i apply velvet with glue to the magnet structure and iron?
will this velvet installation help me acheive higher frequency...maybe 10-15k?

thanks
ts

 

[Guest]

[quote author="ToobieSnack"]
xvlk will you please tell me how to calculate this frequency cutoff?
is it becuase my magnets distance between the magnets?
or the distance from the front of the ribbon to the back of the magnet structure???
[/quote]
approximately width of the magnetic structure distance from the ribbon
to the end of the magnetic structure. = lambda/2 of cutoff begining
frequency.
for 10 kHz cutoff beginiong, some 6 mm.
It is useful in microphones making via modelling.
If you make half scale model, you will have cutoff octave higher.

do I apply velvet to my parts inside the mic (magnet and iron)?
can i apply velvet with glue to the magnet structure and iron?
will this velvet installation help me acheive higher frequency...maybe 10-15k?

If you have iron or magnets or any solid part in the mic, you have zero of particle velocity on it. And that ribbon (if it is near the structure) will have the some zero velocity if it is near to this structure.
But if you use porous iron, or simply gluing e.g welvet on the iron,
you will have not zero velocity, because transmission coefitient and impedance in the welvet is not identical that in the air.
It can do something, but I had no time to measure it. But you can see this
on the oldies ribbons...

xvlk

 

[ToobieSnack]

thanks xvlk

this is a question that has plagued both fito and i for some time..

now we can more accurately create optimum designs.

together with PRR's ref's we should have a great amount of valuable info for future designs.

1000 thanks
later
ts

PS fito this may be another good reason for the slots in the side of your "shaker" mic.

 

[ToobieSnack]

I am trying to make the necessary mods for this mic.

i need a question answered please...
i posted it here:

http://www.groupdiy.com/index.php?topic=7841

can someone PLEASE help me....

seems like I am having to beg for a lil help....

maybe it's just me but it seems this way :sad:
is it because no one knows the answer????... oh please ... i think not... :?

later
ts

 

[ToobieSnack]

ooops .... working on 2 ribbon mics can be confusing...
i meant post the above question here:

http://www.groupdiy.com/index.php?topic=6973

sorry if i caused any confusion

thanks
ts