Royer 121 style build

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Spencerleehorton

Well-known member
Joined
May 12, 2012
Messages
4,031
Location
Felixstowe, Suffolk, UK
Hi guys,

have got some 25mm pipe and making some ribbon elements for about 5 pairs of royer 121 style ribbon mics.
would like everyone to chip in any ideas for it all, i have written down a fair bit of info about it all and will transfer all that in this post, along with how i am going to build the bodies.
i am also game to build a pair that are active just need a little help on the circuit.

look forward to your thoughts.

regards

Spence.
 
Cool project. A few very basic thoughts that I'm sure you've considered:

There are those chinese mics with body style similar to Royer, might save you some work. DIY is cooler of course.

Seem to recall that the Royer transformers are toroidal. Marik does toroidal ribbon TX, might be able to help you out. I'm sure there's a line to be walked as to not step on Royer's toes.
 
Hi Dylan,

first of all im only going to be making a two pairs of these and they will only be for myself, i am sharing the information so if anyone else wants to do the same they can.
I will be winding my own toroidal transformers and making my own element and body, only bit i wont be making are the XLR connector!
I have a couple of ribbon transformers i can use first of all to compare to, which i think are the ones you refer to.
much cheaper for me to build the bodies rather than buy those other mic's and much more rewarding.
I have access to CNC and lathe machines if needed.

regards

Spence.
 
Spence,

Certainly didn't mean to imply you had any intent beyond DIY... thinking more about ethics of sourcing components from outside parties (who may or may not be interested).

Great that you're winding them yourself, the total DIY projects are always the best.

Excited to see how this turns out.

Dylan
 
I have couple of transformers that I have bought which I'm gonna use, a Sowter one and a Russian one. I also have access to a winding machine and have some ferrite cores to experiment with.

Regards

Spence
 
Spencerleehorton said:
I have couple of transformers that I have bought which I'm gonna use, a Sowter one and a Russian one. I also have access to a winding machine and have some ferrite cores to experiment with.
That's good for 'normal' transformers & cores.  To wind a toroid, you need a 'flying shuttle' winder.
 
You didn't say but are those steel or iron tubes?  That's what the Royers use and its part of their magnetic circuit.

Are you using someone's kit for the innards?
 
Here is some info I thought would perhaps help with this project.

Measuring resonance of a speaker technique can be used to measure the resonance of the ribbon.

Ribbon mics give the flattest response  with a transformer load at least five times the nominal impedance of the ribbon.

Connect microphone in series with a resistor, then feeding the output of an audio generator to the mic/resistor, then monitor the variations in the microphone impedance with frequency.

I will need to clarify a few things with the above, what resistor in series?
What variations in impedance are we looking for?

Also I will be using the hum bucking effect for the element, but would also Ike to clarify how the body is used to extend the capsule element?

Any help with any of this please share.

Regards

Spence.
 
This seems to be the right idea!

http://hyperphysics.phy-astr.gsu.edu/hbase/class/phscilab/speakerres.html

Also it seems that the tuning range for the ribbon is 16hz - 45hz

Think I've heard 40hz is a pretty good mark!

I've yet to experiment with this but I'm sure once I've hooked it all up I will learn a lot more.
More info will follow.

Regards

Spence.
 
the royer 121 have an offset ribbon transducer, you will try to replicate that? that would be very interesting.

http://recordinghacks.com/microphones/Royer-Labs/R-121
 
Hi,

To my knowledge, the offset ribbon is all in where the magnets sit in comparison to where the ribbon is held, giving the ribbon more voltage difference once side, magnetic field, ie, brighter and darker side.
I have CAD designs which look at this but obviously won't be sharing this info.
I do need to some more pipe as need to do a matched pair for overheads and guitar cabs.

Regards

Spence.
 
Spencerleehorton said:
Ribbon mics give the flattest response  with a transformer load at least five times the nominal impedance of the ribbon.

Connect microphone in series with a resistor, then feeding the output of an audio generator to the mic/resistor, then monitor the variations in the microphone impedance with frequency.

I will need to clarify a few things with the above, what resistor in series?
What variations in impedance are we looking for?
Flat impedance doesn't translate to flat response.

I presume you've got BBC Engineering Monograph No4 on their 4038.

One thing you WILL see on a impedance plot is unwanted resonances in the ribbon itself.  Your damping on both sides of the ribbon should control this.

Worth reading is anything by Gayford including Microphone Engineering Handbook which he edited.  This out-of-print book is silly money but parts have been scanned & are on the WWW.

There's the Neumann book by Peus on their website though that's better for condensors than ribbons.  Still essential reading.

You gonna share some of your design thoughts?
 
Hi Ricardo,

I don't know what you mean by flat impedance as I didn't mention this before, the information that I have used is taken from some comments that Dave Royer has said.
Thanks for all the info you have put I will see if I a nan get hold of the documents you have said and give it all a good read, hopefully it will shed Bit more light on everything.

As per my design ideas, I feel it's right to say that I am loosely basing the style of this ribbon mic on information that I have gathered about the Royer 121, the shape of the mic externally will not look the same as the 121 as it is in a 35mm pipe rather than a 25mm, so the capsule element will all be internal but same dimensions as original hopefully, so more like the 101 style.
The element will all be held by the top cap, cotton wool will be put in the cavity between the element and the transformer, the XLR cap is held by another cap which is secured by 3 grub screws.
I have a disk cutter which will cut the slots on a jig.
I have the mesh cut to size which is inserted and retained.
I am using a Russian transformer which I have lying around which is good for ribbon mics 1:36 ratio and a Sowter vintage ribbon transformer.

Hope that covers my design.

Regards

Spence.
 
Royer have a couple of patents which are worth reading too.  The one I saw was about their 'X' magnet circuit.

Good luck in your design and I hope you will publish.

Have you got means to measure frequency response of mikes?
 
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