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Re: [TenTec] EV638 update for Orion

To: tentec@contesting.com
Subject: Re: [TenTec] EV638 update for Orion
From: Jim Brown <k9yc@audiosystemsgroup.com>
Reply-to: k9yc@arrl.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 16 Aug 2014 10:57:12 -0700
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
There is no good reason to use a transformer with a pro dynamic mic with a ham rig. In an XLR, pin 1 is the shield, pin 2 is mic +, pin 3 is mic return. To connect it to a ham rig, connect pin 2 (mic+) to the mic+ pin on the radio, tie pin 3 (mic return) and pin 1 (shield) together and connect them to the chassis.

An alternate wiring that also works fine -- mic+ to mic+, mic return to mic return, and shield to the chassis.

73, Jim K9YC

On Sat,8/16/2014 10:47 AM, K8JHR wrote:
A few random ideas ...

I would try to find a data sheet on the microphone that should indicate what the transformer does and how it is wired. I would also scour the internet and look for an inexpensive dynamic microphone cartridge to wire into it. I recently "restored" an old Shure "550" Unidyne (the larger, original Elvis type microphone built in 1947) and used an inexpensive dynamic mic cartridge I purchased on eBay for $10. (I can send you photos and a sound sample if you like.) It turned out swell, but I would be tempted to look for a little better one next time.

DATA SHEET --

http://www.coutant.org/ev638/ev638.pdf

More info on it:

http://www.coutant.org/ev638/index.html

THIS MODEL CAME AS HI OR LOW IMPEDANCE - WHICH THE
CUSTOMER SPECIFIED ON ORDERING IT...  So I would
think your idea of converting it may be a good one...
but it may depend on the cartridge, and not the transformer,
and other guts, I am not sure - some microphones use the
same cartridge and use transformers and switches to
change impedance, but others seem to use different
mic cartridges as well, so that needs to be checked, but
think the product data sheets suggest the inquiry is
a good one.


I would not try to fit the odd HEIL HC5 cartridge, myself, as I think you can do better for less. You could buy an inexpensive, maybe used, Samson RS10s or something similar and cannibalize it for the cartridge within.

Another option is use the high impedance mic with an inexpensive mic preamp that would better match the mic to the rig (it would use the Line-IN input on the rear of the rig if there is one.) I sometimes use the M-Audio AudioBuddy preamp with my high impedance 1968 vintage Shure PE-53 Sphere-o-Dyne microphone and the output of the preamp makes it virtually indistinguishable from a more recent low impedance mic. (I can send a sound sample if you like...)

Although I have not fully thought this out... it occurs to me that a direct box (DI box) might be used to match it to the rig... or you might use an in-line high-to-low-impedance transformer to better match it to the rig. Need to sleep on that idea...

You might also find you are sitting too far back from the mic to get its best audio output. Proximity effects... where you sound more full and bass-y up close, and thin and tinny far away, may be causing you to reap less than its full capabilities. Some guys use that mic as a "harp mic" cupping it in their hands, with a harmonica, and so you, too, may benefit from re-setting the MIC-GAIN after moving closer to it, maybe speaking 3-4 inches from it, slightly off access to avoid breathing into it, and maybe you will sound better. Perhaps a number of the above suggestions will improve its performance... such as close talking it, and inserting an in-line impedance transformer, or running it on a suitable preamp, or ... or...

What is the inside diameter (ID) of the mic case that holds the cartridge?

Random thoughts... maybe something will get the click for you.

Happy days.

---------------  K8JHR  --------------------------------

On 8/15/2014 4:30 PM, Bill Ogden wrote:
I have an Orion 1 and an Electrovoice 638 Hi-Z microphone
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