Mic Transformer and Mid-Side Encoder

[GlenGlenn]

Having problems using the mic pres on your old reel-to-reel? That's because they are probably designed for high-Z microphones and modern mics are Low-Z. You need a mic transformer and good ones can get pricey.

Ever tried recording in Mid-Side stereo with your reel-to-reel? It's problematic because you can't use the mixer or DAW technique - both solutions yield a line-level L/R output and your deck has mic-level ins.

Any solutions out there you guys can think of?

How about a Passive Mid-Side encoder built with transformers?

Take a look at this one.


more info on The Dovetail and Mid-Side stereo recording at http://www.glenglenn.com

 

[stellavox]

Hi Glen,

Welcome to the forum and thanks for the post.

I think it's fair to say that most of this thread's readers/posters use their/our machines for playing back pre-recorded tapes.

Regarding recording however, you raise a couple of good points; which I'd like to "amplify" for those who may be unfamiliar with some of the terms/techniques. The "really big" pro machines were designed for studio use and many of them seem to only have balanced line (high level) inputs and outputs, because any low level (microphone) sources were amplified by a preamp earlier in the recording chain. Smaller pro decks - designed for location recording had both low and high level inputs, typically with balanced (low impedance (Z), XLR inputs, and MAYBE an unbalanced, high Z input. Many "pro-sumer" decks, like the Technics 1500 series have low-level inputs BUT these typically seem to be UNbalanced and a lot have 1/4" phone jacks on the front panel. These as you mention, were probably designed for dynamic or maybe electret condensor mikes that have a much higher Z. To use lower impedance "professional" microphones (typically with 250 to 600 ohms Balanced output) requires the use of a matching transformer). And, as you mention, incorrectly "mixing impedances" can sure screw up the sound.

Regarding MS recording. I've used ORTF and spaced omnis BUT my Synchron Condensor mikes (ever heard of them?) are cardoid so I have to live with that pattern. Rich Brown has always liked spaced omnis and currently has a GREAT set of VERY unusual mikes.

Charles

 

[GlenGlenn]

I think it's fair to say that most of this thread's readers/posters use their/our machines for playing back pre-recorded tapes.

To use lower impedance "professional" microphones (typically with 250 to 600 ohms Balanced output) requires the use of a matching transformer). And, as you mention, incorrectly "mixing impedances" can sure screw up the sound.

Charles

Thanks Charles. You're absolutely right on all accounts. I really wanted to use the tube mic-pres on my deck (Ampex 1260) for recording, but my modern low-Z mics wouldn't let me. The impedance was all wrong and I got distortion. I hope this offers a solution to any that wish to use their wonderful machines for recording, especially in Mid-Side. To my ears it's a beautiful stereo image. Thanks for clearing things up.