Lexicon Jamman/Reflex - Digital Oscillator
by Bob Sellon (System Programmer)

Although it is not a marketed feature of the Lexicon Jamman and
Reflex, both of these products are capable of generating a low
distortion sinewave at 440Hz and 1kHz. The sinewave generator was
include in the diagnostics for these systems as a troubleshooting aid
but, as I recently found out, doubles very nicely as a stand alone
oscillator. I've been using my Reflex as a bench oscillator for
testing equipment but the generator can just as easily be used as a
tuning reference (440Hz) for musical instruments. 

The Reflex I tested while writing this app note produced an output at
440.4Hz with a distortion level of 0.03% at about 8dBu and an output
of 977Hz with a distortion level of 0.014% at about 8dBu. You can
expect very similar performance as the frequency is crystal driven
and converter performace is very consistent. Please note, however,
that the performance of the oscillator is not spec'd by Lexicon so
what you get is what you get. Also note that the MIX should be set
for full WET and the OUTPUT should be full clockwise (or set to
taste). 

To run the sinewave generator on Reflex do the following:

    1. Press and hold the STORE/CLEAR and PARAMETER/LEARN buttons 
       on power up until the letter 'd' appears in the display. 
    2. Release both buttons and wait about 2 seconds.
    3. Press the STORE/CLEAR button. The display will now show a 
       number between 0 and 15. 
    4. Turn the right hand encoder (PROGRAM SELECT) until the number 
       2 appears. 
    5. Press and hold the PARAMETER/LEARN button, then press
       STORE/CLEAR and release both. The number 4 will appear in the 
       display indicating that 440Hz mode is selected. 
    6. Turn the right hand encoder to the 12:00 position to select
       1kHz (1 displayed) or leave it alone for 440Hz (all other 
       positions select 440Hz). 
    7. Press the STORE/CLEAR button to enter the selection. The
       letter r appears on the display indicating that the generator 
       is "running". 
    8. Press any key to exit the generator. 
    9. Turn the encoder to display the number 9 and press STORE/CLEAR 
       to exit the diagnostics and run the normal operating system. 

To run the generator on Jamman:

    1. Press and hold the RESET/BYPASS and FUNCTION buttons 
       on power up until the letter 'd' appears in the display. 
    2. Release both buttons.
    3. Press the RESET/BYPASS button. The display will now show a 
       number between 0 and 15. 
    4. Turn the right hand encoder (MODE SELECT) until the number 13 appears. 
    5. Press RESET/BYPASS and release both. The number 4 will appear in the 
       display indicating that 440Hz mode is selected. 
    6. Turn the right hand encoder to the 12:00 position to select
       1kHz (1 displayed) or leave it alone for 440Hz (all other 
       positions select 440Hz). 
    7. Press the RESET/BYPASS button to enter the selection. The
       letter r appears on the display indicating that the generator 
       is "running". 
    8. Press any key to exit the generator. 
    9. Turn the encoder to display the number 9 and press RESET/BYPASS
       to exit the diagnostics and run the normal operating system. 

It's a little crude (actually very crude) but what the hey. If you
need a 440 or 1KHz sinewave in a pinch, it's there. 

If you are troubleshooting either of these products, you can run the
generator to determine if audio problems are in the input section (AD 
converter, etc..) or output section (the DA converter, etc..). 

BUGS, etc...:

In using the generator on Reflex, I've noticed that it occasionally
produces some distortion at the zero crossing (usually the first time
it is run). When it happens, it is not at all subtle and appears on
every cycle. When I exited the tool (by pressing any key) then
ran it again (starting at step 4 above), the distortion went away.
This is apparently a software bug that was not picked up during
testing.   

As this is a none critical "extra", Lexicon has no current plans to
fix this bug. This is an "as is" utility.


If you have any questions or comments, I can be reached at
rjs@lexicon.com or mutmax@aol.com.
Bob