Audio Notes

My phone installations have an auto start feature for display. Having an audio CD play from the beginning every time the user picked up the receiver was a little more complicated than one might think. Most people assumed that I was using some sort of answering machine or a professional phone system.

I found that regular audio CD-Rs burned from standard CD burners would play on either modified consumer grade CD players as well as a custom computer set up using CD-ROM Drives. Both in the long run have proved to be less expensive and easier to obtain than professional phone equipment. However, once again, the trick was to play the track from the beginning, right after the viewer picked up the phone.

 

Computer Controlled Configuration

The computer controlled configuration features a Macintosh running Mac OS 7.5.3, a device called an ADB I/O, and 3 external SCSI CD-ROM drives. An AppleScript running in a loop on the Mac monitors the receiver hooks through the ADB I/O and tells the appropriate CD to start playing or to stop depending on the state of the receiver hook. As for the age of the technology, remember these works were completed in 1998. Other than the ADB I/O you may be able to find all the equipment for next to nothing. This set up has and will run on a Mac as slow as a SE30. If you would like to purchase an ADB I/O please write Griffin Technology and ask them to resurrect it.

You can use this same set up if you gather the following:

An ADB equipped Apple Macintosh running Mac OS 7.5.3 (Free)
An ADB I/O (rare, no longer in production)
An AppleScript extension called
AudioCDgh v. 1.1.2
written by Glenn R. Howes
This AppleScript
A text version can be found here.
Up to 4 Mac compatible
SCSI CD-ROM drives.
Stranded Category 5 Unshielded Twist Pair cabling for audio and remote communications.

With the script running on a properly configured Mac you should be able to have auto start audio delivered from up to 4 different CDs to the output of your choice. The set up can work with multiple track CDs and but will always start with Track one.

 

Modified CD Player Configuration

WARNING! The following contains instructions on modifying consumer grade electronics. ATTMEMPT AT YOUR OWN RISK! I am not responsible for any injury or damage occurring from the following instructions. This will void your warranty!
IF YOU ARE NOT FAMILIAR WITH ELECTRONICS DO NOT ATTEMPT!

I have found that home stereo CD players like the Magnavox CDC748 (see image) with separate pause and play buttons can be wired to remotely play when viewer action completes a circuit.

The action would be similar to the viewer pressing and holding down the play button on the deck. In fact this is one of the first tests to see if a CD player is capable of this type of operation.

Step 1:
Find a CD Player with separate pause and play buttons.

Step 2:
Insert and audio CD, press and hold the play button. If the first track starts and continues to play uninterrupted then, most likely the deck will work.

Step 3:
Unplug the CD player from power source.

Pull the cover off the CD player and locate the play button contacts on the controller board. CAUTION! STAY AWAY FROM POWERSUPPLY AND OTHER HIGH VOLTAGE ELEMENTS!

Connect the CD player to a power source and insert CD.
STAY AWAY FROM INTERNAL MOVING PARTS and HIGH VOLTAGE!

Test by momentarily placing a small, insulated jumper wire between the play button contacts. If the CD starts and plays uninterrupted during the period that the jumper is completing the circuit then you should be able to use this deck for the delivery of auto start audio.

Step 4:
Solder wires to the play button contacts and run the wires to the location of your choice. I have used Stranded Unshielded Twisted Pair Category 5 cable for all communications and audio with theses works. I have used cable lengths up to 25 feet for remote auto play operation and audio with UTP CAT 5 cable. Your mileage may vary.

I have found that most Magnavox decks and one model of Technics are capable of this. Other variations of this type of procedure can also be attempted like using "previous track" button instead of the play button. Once again your mileage may vary.

Good luck and be sure to test your set up thoroughly before attempting to exhibit in any public setting. SAFETY FIRST!

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Phone installation. Arizona State University Art Museum 2000.
The Magnavox CDC748 with separate pause and play buttons.
Click on image to enlarge.

The Magnavox CDC 748 with the top off note the wires leading to the back of the play button. Click the image to enlarge.

Contact wires soldered to the play button contacts. Note other button contacts available for experimentation.
Click image to enlarge.
Computer controlled set up with ADB I/O and CD-ROM drive.

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