Category Archives: Audio/Electronics Theory

SM57 Tape-Op Mod - Plans

Back in the March/April 2006 edition of Tape Op, I saw an article about modding an SM57.  The premise is that the transformer adds a lot of unpleasantness to the sound.  The solution?  Remove the transformer!

Of course, the transformer is in there for a reason.  The two biggest reasons are to balance the output, and provide better voltage/impedance matching.  Removing the transformer will then unbalance the output (which could cause noise issues if you’re dealing with a significant cable run), and knock down the voltage output (by 10-20dB, reportedly).

With a small stack of 57s, it seems worth a try.  I’ll report back on my progress.

 

SM57 - Pre-Mod

SM57 - Pre-Mod

 

Links:

Tape Op - Best recording magazine available.

Gearslutz Forum #1 - Discussion of the mod outcome, plus pics.

Gearslutz Forum #2 - More discussion.

Catching Up: ProAud and the AES Journal

I spent the evening doing some reading - trying to manage the flood of ProAud discussion list emails I’ve received in the last few days, and browsing the latest AES Journal (Volume 56, Issue 12).  There are a few topics I want to dive into further, but there’s never enough time.  I imagine the list will continuing growing, but hopefully I’ll be able to dig into some of these topics over time:

 

Fractional Delay Filters (for delaying signals by non-integer multiples of the sample rate - useful in musical instrument modeling).  References to follow up on:

Principles of Fractional Delay Filters (Valimaki and Laakso)

Splitting the Unit Delay (Laakso et al.)

Efficient Algorithms and Structures for Fractional Delay Filtering Based on Lagrange Interpolation (Franck)

 

Grounding and shield termination - the work of Jim Brown, Bill Whitlock, and Henry Ott (among others).  References:

Journal of the AES Volume 43, Issue 6

AES Standards AES54-1, AES54-2, AES54-3

Noise Reduction Techniques in Electronic Systems (Henry Ott)

 

Listening Quality Tests.  References:

On Some Biases Encountered in Modern Audio Quality Listening Tests (Zieli’nski, Rumsey, Bech)

Are You Hearing What I’m Hearing? (Rumsey)

 

More to follow…