Van Alstine rev 2 ABX Switch Manual - page 5
Quick Blind Test mode:
The “stop” key enters and exits quick blind test mode. In this mode the front panel LED’s are turned off
and the volume display is set to “00” so no indication is given to the listener as to what components are
selected. If the “toggle” keys on the remote (keys 3, 6, and 9) are used to compare source A / B or amp A /
B or speaker A / B even the remote operator can lose track of what is currently selected. After deciding
what sounds best (or worst) pressing “stop” again exits quick blind test mode and reveals what is currently
selected.
Blind Test Example: say you want to compare A source, B amp, A speaker, with L/R volume = 90/89 to B
source, A amp, C speaker with L/R volume set to 99/73
1) select A source (press “1”)
2) select B amp (press “5”)
3) select A speaker (press “7”)
4) adjust both volumes to 90 by pressing the volume up/dn buttons
5) be sure arrow on display points to the right. If it does not, press the “prev ch” key
6) Since both volumes are set to 90, set the right side volume to 89 by pressing the “chan dn” button
once
7) Press “on-off” followed by “enter” to define this system as the “enter” system
8) In a similar fashion, select B source (press “2”), A amp (press “4”), C speaker (press “9”), adjust the
L/R volumes to 99/73 using volume up/dn, chan up/dn, and “prev ch” buttons, and define this
system as the “input” system by pressing “on-off” followed by “input”.
9) By alternately pressing “enter” and “input” the ABX switch should change between these two
systems. Make sure the systems are defined correctly and make any final volume adjustments.
Press “on/off” followed by “1” to enter blind test.
Blind test mode:
Once two systems have been defined with the “enter” and “input” switches, and the volume of the two
systems is closely matched, you are ready for blind test mode. It is important to realize that volume has a
tremendous effect on how the brain perceives audio. A system that is slightly louder than another system
has a tremendous advantage in being selected as the better sounding system. Take care.
Press “on-off” followed by “1” to enter blind test mode. The LED’s will go out, the relays will click, a “1”
will be displayed (to indicate test 1), and “blind test” will be displayed. A random number is “grabbed”
when the button to enter blind test mode is pressed. That number is used to select either system “enter” or
system “input” for the 8 tests that are used in blind test mode. The volume up/dn and chan up/dn buttons
will either advance or retard the test number. Wrap occurs, so test 8 plus vol up will go to test 1 and test 1
plus vol dn will go to test 8. Once the 8 tests have been listened to and you decide what you like best (or
don’t like) you can reveal which system goes with which test. Press the “mute” button to toggle the LED’s -
in this case from off to on. You can now step through the tests again, using the volume up/dn, and see
which system was selected for each test. It should be noted that there is a 1 in 256 chance that all 8 tests
will select the “enter” system so no changes will occur throughout the entire test. Likewise there is a 1 in
256 chance that all 8 tests will select the “input” system. To exit blind test mode press “on-off” followed by
“0” or simply press the “stop”.