Category Archives: Discrete Music

Time-Lag Accumulator

For a while, I’ve been meaning to recreate the ‘Time Lag Accumulator’ used by Brian Eno and Robert Fripp on their early ambient music. The setup was simple - two tape decks with a single loop of tape, guitar feeding in one. The output of the second deck was fed back and mixed with more guitar. A very simple delay, 3-5 seconds in length.

This was pretty easy to do using Ableton Live and 10 ‘Simple Delay’ plugins, although this is cumbersome:

Ableton Live - Time Lag Accumulator

I included to inputs to the loop - a microphone feed (from guitar, mic, whatever) and a MIDI instrument channel. The MIDI instrument is fun to play with, but I’d love to connect the Rhodes once I’ve finished cleaning it up…

Links:

TimeLagAccumulatorProject.zip - Ableton Live Time Lag Accumulator

Frippertronics - Wikipedia entry on Eno/Fripp’s Time Lag Accumulator

SM57 Tape-Op Mod, Part II

Removing the transformer from an SM57

Tonight I got around to the destructive part of this mod. I pulled the SM57 apart, which is pretty straightforward. A small screwdriver to loosen the XLR connection, and then you can just unscrew the mic capsule from the body. Cut the wires, and you’re ready to attack the transformer.

I put the body of the mic in a pot with a small amount of water - the water just covered the body while it was on its side. I heated the water, and as it approached a boil, I picked up the mic body with needle nose pliers and an oven mitt. Then I used the needle nose pliers to grab the transformer, and it slid right out of the mic. Check the gallery to the right.

I cleaned up the glue from the transformer, in case I need or want to use it again. If I don’t like the way this mod sounds, I could hot glue the mic back together (for better or worse).

The only comment I have on this step is the effect of the hot water on the exterior of the microphone - it seems to have really affected the finish. It’s much rougher on this section of the microphone now than it is on the capsule end.

The only remaining step is to connect the mic capsule directly to the XLR jack and screw the body back together. Pin 1 will still go to the body of the mic, and the blue and red wires will go to pins 2 and 3. I’ll just have to try one arrangement, look at the polarity, and flip as needed. I’ll post again once I’ve finished!

Finally, a Rehearsal Space

It only took two years, but I’ve finally found a place I can really dig into my drum kit. It’s about time. I’ve been moving one or more sets with me for the last 5 years, and in that time I’ve never developed a real practice regimen. Hopefully I’ll be able to visit a few times a week and step it up a level.

Rehearsal Space

Links:

Charlestown Rehearsal Studios

Stick Control for the Snare Drummer

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

Links:

Tape Op - Best recording magazine available.

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

Gearslutz Forum #2 - More discussion.

Matt McClure - Rooster Tail Productions

Matt McClure

Quick update - the Boston Section of the Audio Engineering Society had its monthly meeting tonight. Matt McClure from Rooster Tail Productions came up from Nashville. He talked a bit about the Nashville studio model, as well as how he got to where he is. It was a great presentation, and I saw a video camera running, so I imagine it will show up on the website soon.

The flier for the presentation is available here, and the Boston AES podcast of his presentation is here.

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…

Tremolo Pedal - Getting Back to Work

I’m picking up the tremolo I’ve been working at off and on since 2005. I started the project when my friend Keith bought a Rhodes that summer - I figured it would be a great project. The circuit is straight forward - it started as a Tremulus Lune, with a few modifications. I never got around to prototyping it, until this past summer. An expedition to Peru, and a move, then a graduate class all interrupted work.

Work remaining to be done:

Dremel out stops for the potentiometer anti-rotation tabs

Paint the enclosure

Labels

Clearcoat

Transfer the circuit to a protoboard from the breadboard (document circuit mods! before I forget)

Final assembly

I also need to inventory the parts I have - I may need to order a few more components (9V voltage regulator?).

unfinished pedal case

A New Year…

The new year calls for new plans. I decided not to take any grad classes during the winter to bring the creative back into focus. The projects are lining up - I’m probably being a bit ambitious. I’ll do my best (better than last time) to keep everything up to date on the site. I’m also looking into using blogger or wordpress instead of iWeb for the site. I’ll probably wait until iWeb ’09 is released to make that call.

The big goal for the year is creative output, for the first time in two years.