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MA Cotter Co Pickup Transfromer [message #13666] Mon, 21 April 2008 16:19 Go to next message
Mr Vinyl is currently offline  Mr Vinyl
Messages: 407
Registered: May 2009
Illuminati (1st Degree)
Hi all,

I was recently given a MA Cotter Co. Moving Coil Pickup Transformer Mk2L. That's all it says on it. Accept for the Serial number on the bottom. Does anyone know anything about this unit? How to use it? How much it is worth? I know absolutely nothing about step-up transformers. Any help would be appreciated. Oh the unit also has on it what looks like a Clearaudio logo.

Thanks in advance.


Re: MA Cotter Co Pickup Transfromer [message #13667 is a reply to message #13666] Tue, 22 April 2008 00:34 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18669
Registered: January 2001
Illuminati (33rd Degree)

Phono matching transformers are for moving coil cartridges, which output about 10x less voltage than moving magnet cartridges. Typical MM cartridges output around 5mV, but MC cartridges are closer to 0.5mV.

A pickup transformer is used to step up voltage about 10x. Of course, this also provides an impedance transformation. Source impedance of a MC cartridge is much lower than a MM cartridge, so it works out. Most MM cartridges are loaded with 47KΩ, but the best load for a MC cartridge is usually between 100Ω and 1KΩ.

Since a transformer giving a 10-fold voltage increase provides a 100-fold impedance increase, the typical 47KΩ load is transformed to a 470Ω load on the cartridge. You can decrease load impedance by adding a shunt resistor, or increase impedance by decreasing the turns ratio of the transformer.

Moving coil cartridges are usually pretty sensitive to load impedance, so it is worthwhile to match load to whatever the manufacturer specifies using a shunt resistor. You might even try a few values above and below the manufacturer recommended load to see what sounds best.


Re: MA Cotter Co Pickup Transfromer [message #13668 is a reply to message #13666] Thu, 24 April 2008 10:53 Go to previous messageGo to next message
Bill Epstein is currently offline  Bill Epstein
Messages: 1088
Registered: May 2009
Location: Smoky Mts. USA
Illuminati (2nd Degree)
Back in the mid-Eighties, the Mitch Cotter transformer was very highly regarded, much as the Klyne is today. Never heard one, tho'.

"How they accomplish this, we do not know. But Mitch Cotter is on the trail." Mitch Cotter, for readers who are younger than I—which seems like just about everybody these days—is an audio engineer who developed an especially nice series of phono products back in the 1970s, including a superb and still-competitive moving-coil step-up transformer". - Art Dudley; Stereophile


Re: MA Cotter Co Pickup Transfromer [message #13669 is a reply to message #13666] Sun, 27 April 2008 01:59 Go to previous messageGo to next message
doak is currently offline  doak
Messages: 1
Registered: May 2009
Esquire
I have lots of info on tbis and other M.A. Cotter equipment.
Contact me directly.
Doak


Re: MA Cotter Co Pickup Transfromer [message #13670 is a reply to message #13669] Mon, 28 April 2008 14:15 Go to previous messageGo to next message
Mr Vinyl is currently offline  Mr Vinyl
Messages: 407
Registered: May 2009
Illuminati (1st Degree)
Hi,

I e-mailed you but received no response. Did you receive my e-mail? Thanks for any information you can provide.

Mr Vinyl

A public Thank You to Doak.... [message #13671 is a reply to message #13669] Tue, 29 April 2008 11:39 Go to previous message
Mr Vinyl is currently offline  Mr Vinyl
Messages: 407
Registered: May 2009
Illuminati (1st Degree)
It was nice talking to you. Thanks for all of your help.

Vinyl Rules Dude!

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