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Shure Mic Mixer Transformers



 
 
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  #1  
Old August 31st 18, 01:31 PM posted to rec.audio.pro
mcp6453[_2_]
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Default Shure Mic Mixer Transformers

Has anyone here evaluated the mic transformers in Shure M67/M267 mixers?
These mixers are going for low prices on eBay, so I wonder if the
transformers are worth $5 each salvage. Are they 1:1?
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  #2  
Old August 31st 18, 05:49 PM posted to rec.audio.pro
Chuck[_11_]
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Default Shure Mic Mixer Transformers

On Fri, 31 Aug 2018 08:31:22 -0400, mcp6453 > wrote:

>Has anyone here evaluated the mic transformers in Shure M67/M267 mixers?
>These mixers are going for low prices on eBay, so I wonder if the
>transformers are worth $5 each salvage. Are they 1:1?

They may be one to one. They aren't very high quality and occasionally
the windings will open.
  #3  
Old August 31st 18, 11:23 PM posted to rec.audio.pro
Paul Babiak
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Posts: 26
Default Shure Mic Mixer Transformers

On 08/31/2018 08:31 AM, mcp6453 wrote:
> Has anyone here evaluated the mic transformers in Shure M67/M267 mixers?
> These mixers are going for low prices on eBay, so I wonder if the
> transformers are worth $5 each salvage. Are they 1:1?


Lot's of info about these out there. Transformers are 1:14

Have a look at this:

https://messageboard.tapeop.com/view...&highlight=m67
  #4  
Old September 4th 18, 03:17 PM posted to rec.audio.pro
Scott Dorsey
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Default Shure Mic Mixer Transformers

Paul Babiak > wrote:
>On 08/31/2018 08:31 AM, mcp6453 wrote:
>> Has anyone here evaluated the mic transformers in Shure M67/M267 mixers?
>> These mixers are going for low prices on eBay, so I wonder if the
>> transformers are worth $5 each salvage. Are they 1:1?

>
>Lot's of info about these out there. Transformers are 1:14
>
>Have a look at this:
>
>https://messageboard.tapeop.com/view...&highlight=m67


There are two kinds of transformers in there.

The input transformers are indeed high ratio, and they are awful like most
high ratio transformers are. Top end quality is poor, distortion is high,
which is a consequence of trying to put so many turns on the secondary like
that. Shure did this because the high ratio means you can skip a gain
stage and these were just intended for voice applications anyway so who cares?

The output transformer, though, is a low ratio (probably 1:1) transformer
with a funny tertiary winding intended for a mike level output. It's
hard to screw up a dry 1:1 transformer, so I would not be surprised if that
one turned out to be actually useful.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #5  
Old September 6th 18, 06:50 AM posted to rec.audio.pro
Phil Allison[_4_]
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Posts: 347
Default Shure Mic Mixer Transformers

Scott Dorsey wrote:
>
>
>
> The input transformers are indeed high ratio, and they are awful like most
> high ratio transformers are. Top end quality is poor, distortion is high,
> which is a consequence of trying to put so many turns on the secondary like
> that.
>


** The turns ratio is said to be 1:14 which on squaring gives an impedance ratio of 1:200. So a 250ohms mic is converted to 50kohms at the output.

Electrical performance is mediocre at best, UNLESS you REVERSE the direction of conversion and use the same tranny to provide a balanced output at mic level. Distortion all but disappears and response is much wider than before.

Passive DI boxes use such transformers.



...... Phil



 




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