Barbera Media

G7 with a ribbon motor
« on: December 05, 2007, 01:06:54 AM »
Hello to all, this is my first post to this forum, but have been browsing for months and must say, this has really sparked some ideas for DIY.

With that being said, I've experimented with ribbon motor construction for the past several months and have it down pretty good. Currently i have a couple of ribbon mic's almost completed (waiting on the Lundahl's to arrive) and was thinking what this mic would sound like if it was somehow paired with the G7 circuitry. The new Royer 122V gave me this idea. So essentially substituting a ribbon motor for the capsule. Any ideas? Is this something worth looking into? Thanks all!


Mendelt

G7 with a ribbon motor
« Reply #1 on: December 05, 2007, 05:10:29 AM »
I dont think this will work.

The capsule in The G7 microphone works like a capacitor that changes capacitance when the diaphragm moves. When you put a voltage accross the plates of the capacitor you can detect this change in capacitance using an amplifier with a very high input impedance (around a gigaOhm) hence the use of fets or tubes in microphones like this.

The difficulty with a ribbon motor is that it has a very low output impedance. This can be transformed into a normal 200 ohm impedance with a step up transformer. If you want to apply circuitry to this problem you need something quite different from a G7.

outoftune

Re: G7 with a ribbon motor
« Reply #2 on: December 05, 2007, 11:48:58 AM »
Quote from: "Barbera Media"
The new Royer 122V gave me this idea. So essentially substituting a ribbon motor for the capsule. Any ideas?

im not an expert but when i checked out the Royer mic I noticed these three things:

5840 tube
cathode follower circuit
Jensen transformer

these three elements are a part of the Royer SDC mod...

http://www.diyfactory.com/projects/royerproject/royermod_2.pdf

that's probably somewhere to get started. im sure the transformer is different because of the ribbon output.

so get cracking on a 5840 diy ribbon mic and let us know!!!

im interested to hear about your ribbon motor construction too!

rafafredd

G7 with a ribbon motor
« Reply #3 on: December 05, 2007, 04:48:29 PM »
I do have a very high quality JS transformer that is 1.5:20k impedance ratio, and flat FR 20-20k that would work great for this. This way I think I would have a very high output ribbon mic. But unfortunetly I´m not on ribbon motors... yet.

Barbera Media

G7 with a ribbon motor
« Reply #4 on: December 21, 2007, 02:34:25 AM »
Sorry it took so long for me to get back here, blame it on the holiday season I guess. Anyways thanks for your thoughts, I'm just about finished my DIY ribbon mics, just waiting for the Lundahl's to get here and I'll be all set.

Now I have no idea how the R122V works but what would be needed to adapt a regular ribbon mic to make it like the Royer? Anyone here familiar with this model? Thanks so much.

beatpoet

G7 with a ribbon motor
« Reply #5 on: December 21, 2007, 05:47:37 PM »
I believe there was a thread on this a while back. I've never had luck searching here though.

Perhaps there was a common base transistor input?

G7 with a ribbon motor
« Reply #6 on: December 21, 2007, 05:57:17 PM »
Quote from: "beatpoet"
I believe there was a thread on this a while back. I've never had luck searching here though.

Perhaps there was a common base transistor input?


I've posted a version with multiple input transistors in parallel in front of OpAmp amplifier.
Some small transformer may be used before transistors to reduce their number and protect the capsule from DC bias. However I have no ribbon engine to try, but I'm going to make one using magnets from a hard drive.

Marik

G7 with a ribbon motor
« Reply #7 on: December 24, 2007, 03:51:55 PM »
Quote from: "Wavebourn"

However I have no ribbon engine to try, but I'm going to make one using magnets from a hard drive.


Before you start wasting your time, I'd like to bring to your attention the fact that HD magnets are magnetized the "wrong" way, so your motor will be quite inefficient.
There is a way of going around that, but it complicates the matters quite a bit, unless you want a hardcore DIY and start remagnetizing your magnets.
In this case the cost of bank of capacitors will be way more expensive than any even special order set of magnets of some crazy shape and size.

Best, M
Samar Audio & Microphone Design

www.samaraudiodesign.com

The Art of Ribbon Microphones


 

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