Royer 121 style build

Hi Guys,

Im interested in building a royer 121 style mic but seem to not be able to find any info on this within this site. the stuff i have found is out of date with its links.
Mainly interested in building a good style ribbon mic like the royer 121 for use with guitar cabs along side a SM57 and U67.
A few other people i know have also expressed some interest in this as well so it only seem right to ask you all for as much info in this as possible.
I have all the info i need to build the ribbon element with 1.8u, building the body is no problem as i have access to a CNC machine and plenty of brass.
Just need to know the specifics of whats inside the 121.
Also wanted to have some options of making it active and having a low cut on there.
all help is very welcome, thanks in advance.

regards

Spence.

As far I know there's no too much info in the net. Nevertheless you might want to search youtube for "How things are done" with "microphone" or something like that. Can't remember exact name of tv-serie. You should find two videos, one for U87, another for R121, where you can spot innards of the mic.

-Paavo

thanks pavvo, let hope some other people can chime in with some more info, would help everyone in the long run.

regards

Spence.

This is the one i found

http://www.youtube.com/watch?v=D90rQ5T2NJE

For  a start, the Royer and B&O mics have steel bodies, and for a reason too. 

If you can't find photos of inside a Royer, have a look for the B&O mics which inspired them.

Your best bet really would be to get hold of a stellar rm3 or similar, and upgrade the tranny and ribbon.  It is not a bad Royer knock off.

Cheers!

Stewart

+1 on the Stellar, really hard to beat the price for a donor.  Samar Audio reworked several of those for me and I use them every day for everything. 

Royer have a couple of patents on their X magnet systems with quite detailed diagrams too.

Thats great info thanks guys,
from what you have put i think its a better idea to just buy the stellar and change the transformer for sowter 8074 or the samar.

But also im thinking about making an active ribbon mic, so an appropriate active circuit would be nice and having a Low Cut switch in the circuit as well if anyone has the info? and what transformer would be appropriate when using an active circuit? or doesnt this matter?

Also i have noticed that on some old ribbon mics they do have capability to be cardioid, there is a switch to turn, how does it do that? is it dual capsule and one cancels the other one out, or is there some sort of screen that blocks off the back capsule?
I have designed a few body types which are in the style of a AKG 414 and a Sennheiser 409 for being donors for ribbon mics and have designed a capsule that is suspended.
Will post some pics if it goes well and if im able to get this all working!

H Spencer,

>But also im thinking about making an active ribbon mic, so an appropriate active circuit would be nice and having a Low Cut switch in the circuit as well if anyone has the info? and what transformer would be appropriate when using an active circuit? or doesnt this matter?

Check out the Royer patents - there is a circuit their and also some info on the transformer. Normally with an active mic the transformer is wound to Hi impedance and then some kind of Fet circuit is used as a buffer. Or you could use PRR or Ricardo active circuits that are posted elsewhere at GroupDIY.

For cardioid ribbon mics, the archetypes would be the RCA77 series and the STC 4033 / Altec / Western Electric mics. The 77 uses an acoustic labyrinth connected to the rear of the capsule, whereas the 4033 combines a fig 8 ribbon with an omni dynamic. Have a look at the Coutant website for pictures - it will all make sense.

Cheers

Stewart

Thanks stewart, you are a veritable fountain of knowledge!!
I will try looking for what you have kindly said.

regards

Spence.

kilmister said:

As far I know there's no too much info in the net. Nevertheless you might want to search youtube for "How things are done" with "microphone" or something like that. Can't remember exact name of tv-serie. You should find two videos, one for U87, another for R121, where you can spot innards of the mic.

-Paavo

Click to expand...

The US TV show is "How It's Made"
I've seen the episode on the REA (?) ribbon mic.  It's quite good.
Best,
Bruno2000

yeah ive seen that REA one as well, just wanted a more up to date look at active schematic for ribbon mic and having low cut in there, seems xaudio transformers could work out pretty well.

Anyone have an up to date active schematic for a ribbon?

thanks in advance.

regards

Spence.

I'm curious how owners of RCA 77's and 44's feel about the music/voice HPF, versus using a sharper active afterwards.  The original type is an additional inductor switched in circuit.  I have never seen any info about the L value used.  Anyway, additional L is a passive option to consider.

Of course the inductance value varies with the output impedance, the transformer secondary and the filter point required, so it is a bit of a movable feast. I can take some values if you like.

In practice, with my ribbons I tend to record the full bandwidth and EQ afterwards if necessary, rather than use the filter. I like the bottom end of ribbons!

>Anyone have an up to date active schematic for a ribbon?
Check out the Royer patents - here

And...

http://www.groupdiy.com/index.php?topic=5743.msg74195#msg74195

This works well.

Ricard also has a good one on the mic builders forum. I am not sure if there it has been posted here.

Cheers

Stewart

I have built ricardo's ribbon2 preamp and use it with an old 50 ohm Zephyr 55 mic, no longer produced. It works really well, and certainly improves performance over the secondary in-line transformer that came with the mic to match to valve preamps - 50 to 50Kohms impedance. I also have some notes on the building of ricardo's preamp and what I found out on the micbuilders site. Check it out.

I recommend ricardo's preamp. Easy to build on veroboard and to house in a small in-line box - I used 2 pieces of aluminium channel that fitted over each other. And the improved response of the mic amazed me.

Kindest regards,

zephyrmic

Great stuff guys,
im still in the dark about adding a low cut to a ribbon mic,
could this be easily added to this circuit?
I have some varo board so i could easily knock this up
as i have a few of those 2sk170 transistors and i have 2n3819
which are very similar i think?

regards

Spence.