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Sound Systems  Random Stuff  Ampex  MS Recording  Radar Sites  Bad Ideas  Lactose Intolerance  Laws for Audio Engineers 

Products


Click on pictures for more information.

Universal Attenuator Networks

image linked to pads Universal Attenuator Pad 

Need to build a fixed attenuator pad for a project or installation? This handy circuit board can be configured for commonly used balanced or unbalanced configurations. Kit or Assembled, as you like it.

image linked to ubw image linked to ubw

Universal Boom Weight

Currently out of stock. New tubing coming in, it will be heavier, but also more expensive. Probably June until this item is back on the shelf.

Does your Beyer/AKG/KM boom stand seem like it needs some Viagra? An add-on 2.6lb counterweight for these boom stands helps balance the boom arm, especially when using heavy microphones like the RE20 or U87.

image linked to pzm image linked to pzm

An elegant solution to improving the performance of the RS PZM microphone. This board replaces the battery box and its crappy little transformer and allows the microphone to be P48 phantom powered.

The SolderBuddy ACS

image linked to solderbuddy/index.htm image linked to solderbuddy/index.htm

Tingler Innovations has a new version of this handy tool that is made from cherrywood. The new version is shipping now. Click the image to learn more.

The VersaVice RMI

image linked to solderbuddy/vv.htm image linked to solderbuddy/vv.htm

A handy companion tool to the SolderBuddy or a useful tool all by itself, the VersaVice is a low-profile miniature vice. Use it to hold the SolderBuddy at right angles to your bench, or by itself to grab a d-sub connector. Click the image to find out.

If you have to have a vice, make it a VersaVice!

The Artful Solderer

image linked to artful image linked to artful/index.htm

This handy booklet teaches the art of soldering. Even if you can't join two wires together with bubble gum, Lee Tingler shows you how to do it with solder. It's as easy as one, two, three! By the way, he also shows you how to use bubble gum in an emergency to join two wires.

The Artful Solderer is available from Uneeda Audio. Click the image for more information.

Articles and Reviews

These are articles that I've written over the last 30+ years. Some have been published in magazines, some are excerpted from manuals that I've written, some are the result of email flurries, some were created as a result of need, and some just popped out.

RoHS — How the Rules of Hazardous Substances, an EU directive, affect you and me out here in the colonies.

CD Trustee A way cool program for creating a database of your CD collection.

Thinking about speakers throughout your home? Check my article out.

What makes headphones loud? Find out here.

How to connect loudspeakers totalling 2-ohms to an amplifier that can only drive a 4-ohm load.

Neuman TLM-103 product review.

AKG Solidtube microphone product review.

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DIY

Passive Preamp A short article telling how to build your own "passive" preamp (which in reality is a volume control pot mounted in a box).

Radio Shack PZM microphone modification.

Power Supplies A short article about using 3-terminal regulator ICs to build small regulated power supplies. This is a companion piece to building a 48V supply for phantom powering microphones.

Design your own attenuator pads.

stdval A program for finding the nearest standard value of a resistor or capacitor.

AB Switch for Microphones 

Useful Information

Ampex Transistor Cross-Reference

Phantom Powering for condenser microphones.

T-Power. How it works, why it works, why it's not compatible with other microphones.

Sound System and Other Stuff

M-S Recording Resource.

Miscellaneous Stuff of various sorts.

Impdance Balanced Output Circuits. A rethinking of the problem of balanced outputs on TRS jacks. A better way.

Laws for Audio Engineers.

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Phantom Powering for Condenser Microphones

Sometime around 1970, Neumann introduced the Fet-80 series of condenser microphones that were solid state and remotely powered via the microphone cable. In typical German fashion, they decreed that these microphones were the be-all and end-all to microphones of any sort, and they promptly discontinued all of their vacuum tube microphones. Of course, nearly 40 years later, we know different, with the venerable U47 now selling for the price of a car. Here then, are a series of articles, that explain this important concept and how it works. BTW, Neumann "gave" the idea to the industry; apparently they trademarked the term, phantom power but gave the concept and the term to our industry. There! Something for free from Neumann!

Click Here. 

Radio Shack PZM Microphone modification

pzm/t_pzm_cfg1_34_b.jpg The Radio Shack PZM microphone is a low-cost microphone capable of fairly high performance. Many modifications have been published for this microphone; the simplest simply replaces the battery with two 6-volt smoke alarm batteries.

You can learn more about pressure zone and boundary microphones here.  

The RS microphone, no longer available new, is fair game for modification. Its puny unshielded output transformer is a magnet for hum and a source of sonic pollution. Uneeda Audio makes a kit designed to rid the microphone of these parts and make it work in a P48 environment.
The PZM Page 
The RS PZM Modification Kit 
Price List 
Assembly Guide (2006, 800kb pdf) 
the RoHS Directive (21k pdf) 
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RoHS and A Plea For Conservation

In 2006, the member states of the EU placed into action a set of rules designed to keep certain hazardous substances out of the waste stream. Concurrently, they also placed rules about WEEE, Wast Electronic and Electrical Equipment and its disposal. The body of this legislation has come to be known as RoHS: Rules of Hazardous Suhstances.

The Directive  and WEEE have a far reaching effect: any manufacturer who hopes to sell their product within the EU must conform to RoHS. Without so much as a filibuster, they have more or less forced us to comply. This is actually good, because Congress is so completely hamstrung by special interests that this would never have made it out of committee within our lifetimes.

Cynical, me? NOT! Realistic? YES!

Here then, is my plea  for some moderation in our love affair with cheap goods, abandonment of the bean counter's mantra about repair cost, and a more common sense approach to keeping old gear out of the landfill.

Don't toss that old thing! Repair it, FreeCycle it, E-Cycle it, or Re-Cycle it!

Theremin

The theremin continues to interest people year after year. Here is a reprint of Lou Garner's DIY project that appeared in Popular Electronics over 40 years ago(!).

Arthur Harrison's  way-kewl Theremin pages. DIY Here zzounds -- More Theremin info 

Sound System and Other Random Stuff


M-S Recording Resource

This is a collection of files describing some of the hardware used for M-S recording. There is a short discussion of the theory, several decoder circuits, and a bibliography.

  • Bibliography - Revised 2006
     An overview and bibliography of articles and papers about MS-Stereo technique along with brief descriptions of the three MS decoder circuits.
  • Circuit 1 Simple decoder #1, viewable gif.
  • Circuit 1 (pdf) Simple decoder #1, PDF format.
    This is a simple decoder circuit using two opamps to perform the sum and difference operation. Good for conceptual understanding.
  • Circuit 2 Simple decoder #2, viewable gif.
  • Circuit 2 (pdf) Simple decoder #2, PDF format
    This is a slightly more complex circuit using four opamps to perform the sum and difference operation. This circuit does not use a diff-amp to perform the sum and difference operation.
  • Circuit 3 Complex Decoder, viewable gif.
  • Circuit 3 (pdf) Complex Decoder, PDF format
    This circuit has a stereo spread control, which varies the output's separation from mono to normal stereo to super-stereo.
  • The classic Neumann passive MS-matrix circuit
     A blast from the past, this circuit shows how it used to be done.
  • Return to top 


Radar Sites I Have Known

I spent four years in the US Air Force, during the time that young men were being sent to VietNam to die in the name of Democracy. That's a statement of fact, at least how that fact was sold to the American People. For me, joining the Air Force was my countermove to being drafted and a becoming an unwilling member of the Army, which would have nearly guaranteed me a free trip to VietNam.

Instead, as a voluntary Air Force enlistee, I got to spend the majority of my enlistment stateside, with my last major tour being in South Korea, at Osan Air Base. My job title (AFSC) was 30454, Ground Radio Communications Equipment Repairman. It was nearly all tube gear, mostly UHF AM, 225-400mHz, about 100W output. There was some prehistoric digital gear, all discrete, with germanium transistors everywhere. You had to go to a special school to learn about that gear, and I believe that one of the selection criteria was how well they (the ruling class) believed you were likely to stick around after four years.

That was not for me. I was assigned this AFSC because I had an FCC commercial radiotelephone license when I enlisted. I was supposed to be a clerk (because that was the opening that they had at the time I enlisted, and I was under the gun because I had already received my order to report for induction), but I waved my license around and someone finally noticed. A few weeks later, I was summoned to appear to take a test. This was aparently (unbeknownst to me) the final exam for the 304x4 tech school. I must have passed, because a few weeks after that, I received orders to report for duty in Charleston WV. No tech school. So much for the know-it-all in my flight (Jones) who said, "They never give DDAs in electronics."

The gear that my AFSC qualified me to work on was in use at Radar Sites, and there was a network of them all across the United States, and a few other places as well. Each site had search and height radars and radio gear to communicate with military aircraft in their sector. I don't know if we fed radar coverage to the FAA for commercial aircraft. The time I spent at three different radar sites was good time, away from the pomp and circumstance of the big bases, with their collection of military brass and the merde de poulet associated thereto. At the radar sites, it was mostly just do your job. Inspections were infrequent, as was the time doing seemingly meaningless duty, like painting rocks. The mess halls were run by a military cook, but staffed by civilians, so there was no KP. Really, it was not a bad gig.

I spent my stateside time at three different radar sites (which are now all closed/deactivated):

  • 783rd Radar Squadron, Charleston, WV
  • 776th Radar Squadron, Point Arena, CA
  • 757th Radar Squadron, Birch Bay, WA

I haven't had the opportunity (or the desire) to return to Charleston. Point Arena is on the California coast, on Hwy 1, and that is without a doubt, my favorite stretch of road in the world. I've been up and down that road many, many times, and I've stopped in on occasion to see what's left of the radar site. I last visited the site in October 2008. It's a remote location (150mi N of San Francisco), so if you're stationed there, your off-duty times are spent on site, or in one of the neighboring towns. You need a weekend to get to San Francisco, because it's about 3.5 hours one-way to get there. The site is decaying, and some of the buildings are falling in on themselves. It's the gravity of the situation, y'know?

n.b. If you just drive up there, you'll get as far as the main gate. If you want to look inside, that requires an appointment with the caretaker.

In May 2009, I was able to return to Birch Bay and see what is left of the site. This site is far less remote, being about 30 minutes north of Bellingham and 60 minutes south of Vancouver BC. The DOD gave the site to Whatcom County, and they in turn leased part of it to the Lions Club, who turned it into a camp for kids with special needs, Camp Horizon.

These links take you to sites created for each of these former radar sites. I don't know when I'll get back to Charleston.
783rd Radar Squadron. Not yet. Highly unlikely.  776th Radar Squadron. Online. Pictures added Nov 2009.  757th Radar Squadron. Online.  Return to top 

Bad Idea Dept.

Have you ever had the idea of making adaptors to convert a common-ordinary extension cord (with NEMA 5-15 connectors) into a speaker cable? Did you shelve the idea quickly after the briefest reconsideration? I hope you did!

These guys got the same idea and actually tried to take it to market, but I guess they never thought twice about what they had really done. These are two separate instances of the same idea, almost 10 years apart.

Click on the pictures!
image linked to images/jcon.jpg image linked to bad_idea/pe1.jpg image linked to bad_idea/se1.jpg image linked to bad_idea/speakerlinx.jpg

Don't even think about trying this. Do you know the expected lifespan of a 8-ohm loudspeaker that has been connected to 120VAC? Yeah, I know about Cerwin-Vega (who used to do this); that's a special case.

These are real data sheets. At least the developer/inventor(?) of these products thought so. I picked the J-Con one up at the 1996 AES convention. A friend picked up the SpeakerLinx one at the 2005 NAMM Show. The product pictures were taken at that NAMM Show.

Talk about a bad puppy that keeps coming home!
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Privacy Notice

I respect your privacy. That's it, period. Nothing more, nothing less. It doesn't get much simpler.

This site does not use cookies or any other fancy/wierd stuff to harvest, collect, or otherwise obtain any information about you, your computer, your ISP, your wife, kids, or pets. People or companies who engage in this practice are some of the most reprehensible slime to inhabit our planet. It's sad that the Internet is rife with this sort of behavior.

If you communicate with me, I'll likely save the email, but that's the extent of it. I don't compile mailing lists from this information. I don't send spam. The information goes nowhere.

I find it a sad commentary on the business world that I must make this disclosure. I consider our right to privacy to be sacrosanct. Obviously others do not.

This is the best that I can do: I respect your privacy. Please respect mine.

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  • This is a cookie-free site.
  • No data collection.
  • No PopUps!
  • No funny business.

Copyright Notice(s)

© 2004-2008 by Rick Chinn. All rights reserved.

The materials on this page and pages linked to it (including any drawings or photographs) are copyrighted and I am the copyright holder unless otherwise noted. I reserve all rights to this material. If you want users on your site to access this material from your website, please ask for permission to link to this site.

The article on the Theremin appeared in Popular Electronics in 1967 and they hold the copyright on it.

The article, Equalizing for Spectral Character appeared in an old (1964) Langevin Recording Equipment catalog. They, or their successors, still are welcome to the copyright for the article.

Christopher Hicks holds the copyright for the PZM modification page bearing his name.

The acronym "PZM" is a trademark owned by Crown International, a Harman International company. Its appearance here in no way alters their ownership of same. Likewise, Radio Shack is a trademark of Tandy Corporation. They still own the trademark; why would I even think I wanted to own it?

Other trademarks used are owned by their respective owners.

This site is hosted by GoDaddy.com   They had a good price for web space and their support has been first rate. image linked to http://www.adobe.com/products/acrobat/readstep2.html Many documents on this site use the Adobe Acrobat (pdf) format. image linked to http://www.winzip.com/ Some documents on this site require an unzip utility. Get the latest version from WinZip.
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