July

July 2

HAPPY INDEPENDANCE DAY!

The 4th is one of my favorite times of year, as it presents an opportunity to record some interesting sounds. I do find myself longing for the good old days when they used to do fireworks that had a really loud BOOM! to them. These days, the fireworks look pretty, but the bass output of the explosions is seriously curtailed. I recorded two different fireworks displays last year and both were mostly high frequency transients. I had measured some of the 24/96 recorded tracks I made on the MOTU 896 and found rise times in the microsecond range for each of the explosions. In the waveform editor, it looks like spike noise and at low volume, it sounds like ticks, It's one of those curious sounds that only take on the correct quality when played loudly.

Speaking of playing loudly, I've had my fill for a few days after that blast last Thursday. But I realized that I had forgotten to mention that I rewired the power plug on the amplifier rack. I switched to a 4-wire electric range cable of 6AWG and 50 ampere capacity. A matching outlet was installed on the end of the temporary cable. It makes a good, secure electrical connection that is sure to stay cool under the most demanding loads.

Four wires was necessary, over three, because of the need to isolate neutral from safety ground. Not having these two isolated results in a lot of hum due to eddy currents flowing as ground loops.

In the "Oh, by the way" department, the wife and I have so far collected four Korean Drama series on DVD. The latest soundtrack I ordered was from Winter Sonata. Interestingly, it came with sheet music for each of t he solo piano tracks. A very nice touch. Amazing, considering the CD and the music book cost $10.99 from YesAsia.com.

 

 

July 30

CLEANING GHOSTS FROM THE MACHINE

It's been a slow month around here, as I am fully-utilized on a renovation project upstairs, and am also starting a new financial career. However, I do still tinker in here now and then.

For a number of years in recent history, this sound system has been plagued by clicks, static and crackling noises, particularly in the right channel. I decided to get to the bottom of it this month. The problem was somewhere in the external processor loop. Naturally, I was suspicious of the Carver C4000, due to it's propensity to have problems with intermittent pushbutton switches. Alas, that wasn't it.

There are several devices in the external processor loop, and I bypassed them one at a time with RCA coupler jacks, until I heard the static crackles no more. It turned out to be the Technics SH-8020 Equalizer. And I narrowed it down to the 32KHz EQ band gain pot. The answer was simple: clean the pot. My solution was a can of STP (Stop That Pig!) Silicone Lubricant. Using an extension tube, I was able to direct a very small quantity of the lubricant directly into the slot of the sliding pots. The lubricant worked beautifully, removing the noise without harming the smooth, viscous feel of the pots. I placed that unit back in service and it works great now.

I had another issue with the left subwoofer cabinet, when a pure 16Hz tone was fed to it at about 60 watts. It sure sounded like a wire was slapping against the partition between the Bassmaxx drivers, and by golly, that's what it was! It was a knocking sound, but it seemed to come from the sides and back of the cabinet, not the drivers. To test my hunch, I hefted the cabinet into a 45 angle, drivers facing upward. The knocking ceased. This simply underscores the fact that one must tie down all wiring inside the cabinets. I had a heck of a time trying to redress the wire, working via a small opening where the binding terminal panel normally sits. Removing this gave me a 2" x 3" window to work, using a 16" piece of 10 awg solid wire as a tool to reposition the upper wiring away from the partition.

 

   
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