Conference napalm::commusic_v1

    	I will start it out by naming my two MONO's:
    
    	1.)	KORG MS-10	-	From time to time I have thought
    of selling this and have even put ads here and in other Conferences.
    It is a somewhat limited board in that it has only one VCO and one
    EG to share between the VCF and VCA.  But whenever it's come down
    to the wire, sitting down, fiddling with knobs and patch cords
    (it has an overiding patch-panel), I just can't part with that warm
    sound.  No digital instrument can match this keyboard for some of
    the sounds I've used (and many people have told me so).  I also
    think it to be a great first-instrument for learning sound production
    (it was my first), and I hope to keep it for my kids to learn on
    (if they are interested, of course).
    
    	2.)	YAMAHA CS-15	-	I bought this one because of
    its versatility.  It is basically two separate synths controlled
    by a single keyboard.  This allows for some great sound layering.
    While I have this much control in my CZ101, it still has so much
    richer of a tone.  Not the same as the MS, but it gives the most
    heartwarming strings.  The VCF on it can switch between HPF, BPF
    and LPF - something I don't see too much of anymore.  Sure it's
    got a lot of knobs, but I like it that way.  In concert, I only
    use a few patches, so its not a problem.
    
    
    	Dan

    I have two analog synths, which I expect to hang to essentially
    forever.  They are worth far more to me than I could ever get for
    them on the used synth market, and one of them is a killer no matter
    how you look at it.
    
    I speak, of course, of my Roland Juno-106 and MKS-80 "Super Jupiter".
    
    The -106 is a 6 voice, very simple architecture analog synth with
    a basic MIDI implementation.  It has, per voice, 1 LFO, 1 VCO, 1 HPF,
    1 VCF (LPF), 1 VCA and 1 ADSR.  There is a "suboscillator" that
    provides an octave down by subdivision, to fatten things up, and
    the VCO supports sawtooth and pulse-width-modulated waveforms. 
    The LFO can be routed to the VCO for pitch or pulse width modulation,
    and the VCF.  The VCF and VCA share the same ADSR, although the
    VCA can take a simple "gate" instead of the ADSR.  The onboard memory
    holds 128 patches, most of which are surprisingly good given the
    machine's simplicity and cost.  I am quite fond of this instrument.
    It has a 5 octave keyboard, no velocity or aftertouch in the keyboard
    or sound generators.
    
    The Super Jupiter is a "top of the line" analog synth.  It is 8
    voices with two oscillators and ADSRs per voice, plus all the usual
    gimcrackery.  Its sound is, to put it bluntly, gorgeous.  It is
    one of the few pieces of high tech gear I have ever bought that
    totally lived up to my expectations and then some.  It cost me a
    small fortune ($2600 with the outboard programmer), but it has proven
    to be worth every cent of it.  While I look forward to the forthcoming
    (just a few more weeks now) acquisition of its digital offspring, the JX-10
    "Super JX", there is no way I will ever part with my Super Jupiter.
    
    len.
    

    > Crumar Orchestrator
      This weird box has been with me since 1978. At the time it was
    the only polyphonic multitimbral synth I could find in my price
    range. The keyboard is split at A below middle C. There is a mixer
    panel and voice selector switches for each timbre, PER SIDE. The
    only voice with conventional ADSR is 'brass', which also has an
    expression pedal. there is a separate bass line volume which covers
    the bottom two octaves. Simultaneous brass, bass, cello, violin
    and harpsichord, all realtime mixable.
    
    > Fender Rhodes 1974 73-key Stage piano
    Bought this one new, too. Rarely roadied. Always in good tune. I
    spent a LOT of time 'voicing' it, adjusting tine - to - pickup
    relationships, until I got it right.
    
    All right. Nostalgia is one thing, but fiscal reality is another.
    Until all this MIDI junk came along, I thought these keyboards might
    actually be WORTH something. I advertised a lot of stuff in the
    paper 6 weeks ago or so, and no one even CALLED on the Rhodes @$250
    and the Crumar @$200. So, there they are, gathering dust and taking
    up room....
    
    kmII_who_is_picking_up_on_the_little_underlined_comments_near_your_
    _name_thing

    Analog "holdout" seems to imply holding on to an outdated technology
    for some sort of nostalgic reasons....
    
    
                       BULL DO-DO!
    
    I think the anaog technology has steadily advanced and will continue
    to do so. Other (DX, sampling) methods are just an addition to,
    not a replacement for, analogs...
    
    I've got all 3 types in the studio. I'd hate to part with any...
    
    Edd who_uses_HIS_Rhodes_as_a_synth_stand_cuz_he_couldn't_sell_it_either
    

    
    Agree with Edd. Everything in it's place. Have an ARP 2600
    that I added touch sensitivity and other mods. Ok. So it's
    only a single voice, but what you can program!
    You get realtime feedback about what a little more modulation
    does here, or "what if I connect the VCF out back into the
    VCO!?" experiments etc.
            
    Its that instant feedback that also makes it a valuable tool
    for learning about synth sound generation and programming.
        
    It has a "user-defined" architecture. Most of the new stuff,
    even Super Jupiter (I would love one) are locked in.
    Which doesnt make them unusable, of course! But, well, you'd
    have to hear what I mean...
    
    The Oberheim expander is the closest thing to 6 2600's 
    in a box.(I would love one)

    Ron_who_is_er_was_hoping_to_sell_the_Rhodes_ASAP
    

    I too have a Rhodes, and an ARP Oddysey. Boy do I love their sound,
    but I have decided that the Rhodes is just too heavy to carry up
    and down the stairs to my apartment for every gig (or into the other
    guy's basement etc.) 
    
    I now have an Oberheim Martix-6 which allows for a fairly flexible
    patching scheme (not quite as much as an Xpander). 
    
    Right now I just use the Rhodes at home (and NOT just as a synth
    stand) and take the Oberheim and the DX7 to gigs.
    
    	- Rick
    
    (still looking to sell the Rhodes and ARP and a Sound City electronic
    piano...)
    
    

    I have a Yamaha CS-15 solo synth, also. To elaborate on .1, it's
    similar to a mini-moog. It has one voice that consists of two of
    the following: VCO, VCF, VCA, ADSR. It also has one LFO, and a neat
    "external" input jack that lets you tap in between a VCO and a VCF.
    This external input has a sensitivity knob that allows it to trigger
    one of the ADSRs.
    
    I used to use it in my rack because of the great "solo synth" sound
    it has. Now, it's just boxed up in a corner. I'm keeping it because
    they are getting more unusual all the time.
    
    Peter
    

Great note.  I was gonna start one like this, but have been kind of blinded
by MIDI as of late.

I have an ARP Avatar that I love.  The only problem with it (and all guitar
synths with a pitch-to-voltage converter) is that there is a noticable
delay between picking a note and the actual firing of an oscillator.
It also glitches every so often.  This leaves me with an interest in being
able to control it with a keyboard.  There are a couple of ways of doing
this:

	1.  MIDI it and drive it with my little DX.
	2.  Get an Oddessey or 2600 to drive it.

I almost bought an ARP Omni recently for $75, but found out that the Omni
doesn't have any gate, trigger, or cv outputs ( :-( ) and thus can't control
an Avatar.  

I am still thinking of MIDIing it up using an intel 8051 microcontroller 
chip interfaced to an A/D, D/A, and a few comparitors.  Maybe I could use
the same box to MIDI up my Simmons drums (which are all analog too, by 
the way).  I don't know, it might be too much work...

Todd. who_still_enjoys_so_called_obsolete_technology

Geez, we should have an "obsolete technology" get-together.  I know the
Oddessey, Avatar, and 2600 ARPs are compatible and can be rigged up to
communicate with each other ala analog.  Are the Moog gate, trigger, and
cv voltages compatible with the ARPs?

I think the ARPs are 0-10V - I'd have to check to be sure tho...

Todd.

    
    Arp gate and triggers are 0 to 10 volts. I believe that
    Moog use 5 volts (something also reminds me they want
    asserted low too, like you get a pullup on the gate
    in jack that you have to pull down to ground.
    
    SOME Omni's did have CV and gate/trigger in's and out's.
    
    Gee. I was thinking also about the Midi-to-CV box. Tend
    toward Z80 implimentation myself even tho the 8051 has
    a uart. In any case, also thought that the flexible
    way to go would be to downline load the firmware to RAM
    via system exclusive message. This way you can make updates
    or change the personality of this little midi-box (sequencer
    anyone?). You still need a minimum midi-boot rom (ignores
    everything but system exclusive; very few lines of code
    and prom could be hand blown if no access to prommer.)
    
    You then can use this same little design for all sorts of
    midi-mischief. Whaddya think?
    
    ron
    

    
    I agree, it's good to see that "old" instruments are still loved
    and far from forgotten. (Some people still use acoustic instruments,
    right?)
    
    I too have a Yamaha CS-15 which is far from dying of neglect. It
    sits right next to my other analogue synth, the Polaris. As I think
    I wrote elsewhere in this notes file, I've been quite pleased with
    the Polaris and have suffered no problems. It is fairly flexible
    in terms of the interconnection of the various analogue processing
    units. Bascially it looks like:
    
    [osc1]--->[vcf1]--->[vca1]-
            /   |         |    \
      [noise] [adsr]     [asr]  -----  output
            \   |         |    /
    [osc1]--->[vcf1]--->[vca1]-
    
    There are various combinations of frequency modulation, tuning, etc.
    available on the oscillators. Touch sensitivity is independently
    selectable for both envelop generators. The above is repeated 6
    completely independent units yielding 6 voices. These may be used
    in poly or mono mode.

    It also has 3 pedals: metronome (sp?), sustain and an assignable
    pedal (may be assigned to a variety of voice parameters such as
    overall volume, vibrato, pitch bend, detune, etc.).
    
    Unlike the CS-15, it has full MIDI: usual MIDI note ON/OFF, velocity
    and program change stuff (on any channel) and every parameter is accessible
    (for both read and write) via MIDI. It also has the capability of looping
    its own MIDI out back into its MIDI input, which comes in handy
    when using the internal sequencer and linking 3 or 4 patches together.
    
    By devious means I also managed to get the complete MIDI spec. from
    Rhodes. This included a description of the internal software
    architecture, which turns out to be an object oriented system. The
    machine has an 80186 controlling all the analogue elements through
    12 bit d/a converters.
    
    The only other analogue keyboard is the grand ... one day there
    will be more, you just can't beat the sound.
    
    Robert
    

    What a great note!!  I currently have 3 "analog" instruments, and
    2 non-analog: a 1976 Suitcase Rhodes at home, a Mellotron in the
    rehearsal studio (which I'm gonna sample *real* soon), an Oberheim
    OB-8 (which I will never, ever sell), a DX-7 and a Mirage.  I too
    believe that both analog and non-* have their relative places, both
    are useful, though I like the analog sound a lot better.
    
    I have had tons of analogs in the past: 3 Crumars (orchestrator,
    traveller-1, Stratus), 2 slab pianos, a Minimoog [every night, I
    repeat 100 times "I never should have sold my Minimoog..." 8^( ],
    a Farfisa (of course), a Korg CX-3 and MS-20, and others.
    
    Thankfully, Oberheim seems to be dedicated to continuing instruments
    that have at least partial analog design, like the Matrix-12 and the
    Xpander.  Who else still makes analog machines?
    
    /Andy

>    SOME Omni's did have CV and gate/trigger in's and out's.
Hmmm, the early ones or the later ones?
    
>    Gee. I was thinking also about the Midi-to-CV box. Tend
>    toward Z80 implimentation myself even tho the 8051 has
>    a uart. In any case, also thought that the flexible
Yea, I would use the built in uart of the 8051 for the MIDI port.
The baud rate is easily programmable to MIDI spec too.  Of course being
familiar with the 8051 has a lot to do with it too :-)

>    way to go would be to downline load the firmware to RAM
>    via system exclusive message. This way you can make updates
>    or change the personality of this little midi-box (sequencer
>    anyone?). You still need a minimum midi-boot rom (ignores
>    everything but system exclusive; very few lines of code
>    and prom could be hand blown if no access to prommer.)
Sounds like a great idea.  Of course if one has access to a prom
blower, a new prom could just as easily be substituted into the box
for an alternate function (a la MIDIVERB/MIDIFEX).  How about having
two proms - one that is a generic MIDI implementation for the box, and
one for the specific function...

I could probably also train my C64 to do this job too.  All that would
need to be done then is to build a MIDI interface (or buy the cheap sonus),
and build an A->D/D->A board to stick on the back.  This way the C64 would
behave as the generic MIDI box, and I would have a disk drive to boot 
(pardon the pun).  Could also use the Commodore as the development system
(I already have an assembler/debugger for it).
PROBLEM:  If used the C64 to do the MIDI->CV function for the ARP, it would
tie up the C64 and thus I would have no MIDI sequencer :-(

Todd.

    I saw a stack of three (!) Roland DSQ-100s at the EUWurlitzer in
    Framingham this weekend.  The DSQ-100 is a DCB sequencer (I.e.,
    not MIDI) that was used with the old Roland CV synths.  I believe
    there is a DCB (Digital Control Bus?) to CV converter available,
    so you can use the DSQ to sequence any old CV-based synth.  I have
    a DCB cable that came with my MSQ-700 (The -700 could speak both
    MIDI and DCB; I have no use for the DCB side of it) that's free
    for the asking if anyone can use it.
    
    I think EUW was *giving away* the DSQs, if you bought something
    else.  Don't know how much you have to spend.  Give the boys a call
    and tell 'em Len sent ya.
    
    Seems to me that it ought to be possible to build some traditional
    analog modular hardware that was digitally controlled and use a
    PC (not specifically IBM's of course) to control the routing.  You
    could draw the voice configuration on the screen and save it to
    disk.  Voila - a "programmable" modular synth.  The Oberheim Matrix
    family comes close, but why not go all the way?
    
    len.
    

    
    Its more expensive. Note that there is a system
    like this in the back pages (product announcements)
    of one of the last 3-ish Keyboard Mags. Not bad.
    I think sound generation is all fast hardware...
    Also. There was a lonnnnnng time ago a system
    sorta like this at MIT. Doodle on the screen with
    a light pen and have all sorts of acoustic fun.
    
    An alternative: Develop software to interpret the 
    interconnection that's puts  on the screen and 
    turn it into the right system exclusive message
    to control an Oberheim. Yes, you are limited to
    certain architectures, but it might be useful.
    
    Ron  

Does anybody know anything about the ARP sring ensemble?

How does it relate to an Omni?

Does it have gate/cv/trigger I/O?

Todd.

    
    The String Ensemble was a buyout from Solina in Italy
    that ARP slapped a nameplate on.
    
    The Omni was a redesign (read: semi-lifted) from that
    architecture in order to use 'american' parts so that
    ARP could manufacture this successful (back then) kbd
    and make more $$$. It added CV,gates, etc. The chorus
    unit was vastly different. You can tell the sound of
    a S. Ens., An omni gives you a harder time identifying.
        
    Omni II was a redesign to add features. notebly a VCF.
    This was a big seller. 
    
    Something tells me that there was a retrofit kit for
    S Ens. to add CV out etc. But I'd hve to look at the
    schematics (I think I have them) to double check.
    
    RR
    

    Just to put in my 2 cents ...
    
    I would be lost without my Axxe, Odyssey (ARPs) and of course my
    OB-Xa.
    
    It's VERY easy to program nice fat sounds quickly on the Xa.  Maybe you
    can't get all the nuances of the Matrix or JX stuff, but considering
    that my time is VERY limited, I'll take that hit.
    
    The Odyssey makes a great bass machine (as does the Axxe) and when both
    are slaved together, the effects and sounds are great.  I just got done
    building a remote keyboard out of the Axxe (yanked the kybd and PPC
    sections and mounted them in a walnut strap-on box).
    
    Oh yeah - (maybe this has already been asked - sorry if so) does anyone
    know about the CV-MIDI converted supposedly made by JLC, or any other
    CV/MIDI stuff for that matter?  Does it work with ARPs, and how much is
    it? 
    
    Finally, you guys can drool along with me.  One of my friends just
    bought a mint Moog Prodigy for $50.  What a steal....
    
    
8^)

    
    where'dya get the walnut strap-on box?
    
    (Ah, so nice to hear ARP raves...)
    
    Ron
    

I've got a question for Ron.  
How come the hex-fuzz on the Avatar is so noisy?  It is virtually useless 
without a noise gate.  Is this a general characteristic of the Avatar, or 
is mine broke?

Todd who_is_prejudice_against_noise.

    erk. I'd have to check the schematics, of which I may
    not have any for the Avatar. But:
    
    I'd really be surprised that there's no gating at all.
    Is it ambient noisy or get more noisy with even a small
    signal?
    
    I'd just be guessing right now. See what I can do
    (gotta remember to check this AND the String Ens too?)

	RR    

The noise does not rise with a rise in signal level.  The noise is on the 
floor...

Todd. (who_would_rather_see_the_noise_in_the_cellar)

Re: .20 (where'd you get your box?)
    
    Actually, Ron, I built it from scratch.  Had a lot of nice (but small)
    spare pieces of walnut lying around, and decided to get the ~25 lb.
    metal Axxe off my neck and onto a rack (where it belongs).  I may do
    this for my friend's $50 Moog soon, too - but not out of walnut.
    
    There was a hassle involved with this - the PPC (Proportional Pitch
    Control - aka pitch bend/mod for you non-ARPists) has 5 leads and the
    kybd itself has 5 leads.  Had to get a piece of 12 conductor #22 and
    build my own cable.  I'm not convinced that was the best way to go, but
    hey - I'm a woodworker, not a hardware wizard.  Wonder if 50 additional
    ft of cable will hurt my power supply?
    
    BTW - I almost built one out of plexiglas, but I couldn't see sinking
    $50 for a blasted piece of plastic.
    
    And, since I can slave the Axxe to my Odyssey, I can use the thing not
    only for leads but for nice fat synth bass.  Yes, I *am* gloating -
    this is the cutest thing I've done for years.
    

>8^}  the_gloater_who_also_has_cats_and_would_like_to_see_len's_cat

    Well, a chance to do remote diagnosis.
        
    1. Is the noise the same on R or L out as main out (you
       may need to use a signal to get same relative levels first.)
       Same as "mono out"?
    
    2. Is the noise there (main out, I guess) no matter if the
       "Guitar volume" slider up or down? 
    
    Gotta know the above first. Therer are some possibilities:
    
    The front end has LM1458's as preamps, and a 301 for mix.
    You could replace with TI TL0x series and be better off
    in general. Bit I think thats not the problem.

    The avatar has 4 or 5 clock signals flying around, not all
     syncronized. Beat  products on the supply lines could fall
    into 'audio space' and generate some 'noise'.
    
    The Noise circuit itself is CMOS pseudo-rand shift register that
    runs at 15v. THis could be bleeding into the audio chain somewhere.
    We'd have to jump a line to ground in there to test this.
    
    Ah. Last but not least is the majic of getting the grounds right.
    It was an art that no one really had down at AR. It was mostly
    trial and error around the packaging constraints and board layout.
    (Layout was trial and error too) We followed the rules, but there
    was a fumble-factor involved from a proto on the bench to it's
    getting into a real case...
    
    Answer the above Ques. first.
    
    rr

    OH and:
    
    RE: -n
    Long cable wont affect power supply in that case.
    
    Re: -m (maybe not even in this note:)
    
    I lied. No Omni I or II had CV out. Gate,trigger out
    and Filter CV in on II. CV out was considered for 
    II, but fell outside the market price window. 
    String Ensemble has none of these ins or outs.

    rr
    

I can't believe I'm just getting around to this topic!

With the exception of a CX5M, most of my stuff is analog.  I use the CX
mainly as a practice keyboard and the analog stuff for "serious" synthesis
(that is, when it's set up.  My analog machines are in the closet right
now.).

I have a lot of PAIA stuff because it is cheap and there is so much you
can DO with it, if you know what you're doing.  I also have 2 electronic
music composers I built around 14 years ago, and other other home-builts
like ring modulators, mixers, phasers, sample-and-holds, a theremin, vocoder,
etc. (why buy when you can build?).  I much prefer analog sounds to
digital where new sonorities are concerned, as they tend to be more dynamic.

I ABHOR digital noise sources, sampled voices, canned drums, and DX7 electric
piano.  --Wouldn't mind a nice CZ 5000 though...

John M.

    	RE .27
    
    	I was wondering how long it would take you to reply to this
    one.
    
    	Dan

Shees, thanks for all the work, Ron.  I guess I didn't expect you to
spend the whole weekend looking this stuff up, I just thought you might
know the answers off hand (kinda like Non-DEC people expecting us to have 
*all* the answers to *all* questions concerning DEC hardware and software).
The reason I didn't reply right away is because I don't know the answers 
to your questions offhand...

I'll go home and fire the avatar up, and look into the questions in .25.
From memory, the noise generated seems almost pseudo-random, and is 
probably due to the "white" noise generator.  As I recall, The noise 
generator board is attached to the top of the Avatar, and the guitar 
processing exectronics are attached to the bottom of the box, thus I 
will try lifting the top off (or just hinging it up) and see if it helps.

I have the schematics as well (service manual), but as I stated above,
I just figured that you might know off the top of your head...

Thanks for the help so far.

Todd. who_will_have_the_answers_tomorrow

Ok.  Avatar noise test results...

Results:
The noise is evident no matter what output I use on the Avatar (guitar mono
out, guitar/synth left, guitar/synth right, synth out with guitar mapped thru
synths VCF and VCA) as long as the hexfuzz is switched in.  When not in hexfuzz
position (IE: clean guitar), the noise doesn't exist.

Sidenote:
For those interested, the Avatar requires a hex pickup (a big pickup 
containing one little pickup for each string) be mounted on the guitar.
The Avatar passes the signals from each string through a hexfuzz (6 little
fuzz boxes - one for each string) which converts the signal from each guitar
string into a square wave which in turn drives logic circuitry that tracks 
the frequency.  The designers fiqured that they might as well make the
hexfuzz signal accessable and rightly so - it is a very nice "clean fuzz"
not containing any of the intermodulation distortion common to regular fuzz
boxes.

Onward:
I made a mistake when I said that the guitar electronics were on a different
board than the synth's white noise generator-they are both on the same board
(shame on ARP - they should be put out of business for that ;^) ), but the
noise of interest sounds like the noise that is typical of a regular pedal-type
guitar fuzz box or any other effect that really cranks the gain.  This would
explain why it is only heard when the guitar is in the hexfuzz mode.

Hypothesis:
I feel that it is the op-amps-that-clip-the-signals-into-square-waves that
are the culprits.  I would like to play with another Avatar to determine 
whether the noise is occuring by design or there is somthing wrong with mine.
Any other avatar people out there?  I remember seeing one for sale somewhere
in a notes file - I will try to get in touch with who ever it was that was
selling it.

Final note:
By shipping the Hexfuzzed signal through the VCA, I can gate the noise by
applying an envelope with a fast attack and fast release.  Kind of glitchy
tho...

Author:
Todd. who_has_all_the_answers_today

    
        
   Wrong, Todd. Noise gen is on board A, preamps and fuzz
    are on board E. Noise gen circuit is on ground sheild.
    
   Ok. For you avatar fans with schematics:
   If noise is the same with vol up or down, it aint getting
    in at the squelch circuit.(Z10 etc)
   If noise is same on L or R out as mono out, you know that
    the noise starts on the preamp board.
   
    To double check that the Noise gen circuit isnt coupling in,
    stop the clock, ground pin 9 on Z4c.

    AND now that we know the noise only occurs with fuzz
    enabled (Z7 Z8), it looks like the culprits ARE the
    1458 amps and/or diode noise. The DC gain there is about
    -19, which doesnt seem like alot compared to the preamps.
    You could swap all these 1458's for TL072s and be better
    off...unless it's diode (junction) noise OR layout...
    
    Now all signals on board E are audio with two exceptions: the
    E' module. ARP didnt give out schematics for this, or module
    D' on board D. I think E' is a period to voltage converter,
    for which I have a hand-drawn schematic. Not sure about the
    other. E' MAY be a source of (layout or ground coupled ) noise.
    
    Really does look like the fuzz circuit, but...
    
    rr        

I should have noted that the noise increases as the volume increases.  What
it sounds like is a very high gain amp with a very low level signal going
into it (IE plugging a mic into the aux inputs of a stereo and cranking
the volume way up). Very lo S/N ratio.

What does the clipping?  Are the amps being overdriven on purpose?

Todd. (who_thanks_Ron_for_his_effort)

    Which volume increase? As the volume slider goes up or the signal
    input goes up?
    
    The "back-to-back" diodes do the clipping. Look at each as a
    resistor, even though they are voltage-dependant resistors.
    The stage gain without either of them is  -Rf/Rin = ~-19.
    (The diodes at low signals are high resistances, so these
    resistances in parallel with Rf just reduce the gain a bit.)
    
    As the input sig goes + or - enough to get the output to swing
    .6v or so ( or .3v for germanium) a diode starts to conduct. 
    Theres a small non-linear region, but basically the output clamps
    at .6v or -.6v. The diode looks like a small resistor now.
    
    Looks like the noise is a combination of the noise due to this
    LM1458 stage (SWAG:smallish) and the noise out of the preamp
    stages times -19 (SWAG:largish!).
    
    Why not get out the old soldering iron and replace them with
    TL072s! They are quieter. Want some help?
    
    ron_the_tinkerer

Re: Mr. Ross (aka ARP wizard)
    
    Here's one for you - my Axxe and Odyssey both exhibit a strange
    characteristic whenever I throw the transpose switch. 

    If I throw down 2 octaves, the entire range is sharp (tho noticably
    more so toward the bottom).  If I throw up (pardon me) 2 octaves, the
    entire range is flat (tho noticably more so toward the top).  In
    addition, the keyboard seems to have a scale problem - notes toward the
    top tend to be flat, notes toward the bottom tend to be sharp.

    Both these dudes are vintage (1976-77 time frame).  Is there something
    I can do to correct this, or do I just have to put up with it?


8^)

Re: .35

    I use the best instrument I have - my ear.  When compared to:

	a) my Oberheim
	b) my Rhodes
	c) my TX7 module
	d) my other TX7 module
	e) my friend's DX7
	f) etc.   ...

    ... the pitch varies.  (It also varies between units, so I know I'm not
    going crazy.)  If I retune the oscillators, the pitch comes back into
    line, bit this is a hassle trying to do this on the fly live.

    BTW - the Odyssey is *much* worse than the Axxe.  Thanx in advance.


8^)

    
    	Don't know if it is the same, but I used to have an Arp 2600
    which was definetly out-of-tune in the extreem registers.
    
    	Turned out that the keyboard scaling, which was set with a
    knob with a set-screw, was wrong.  Careful tweaking put things
    back in turn.
    
    	You got such a knob?
    
    							- Karl

RE: < Note 518.33 by GNERIC::ROSS "ah" >

>    Which volume increase? As the volume slider goes up or the signal
>    input goes up?
    
As the volume slider is raised, the noise increases.

>    Why not get out the old soldering iron and replace them with
>    TL072s! They are quieter. Want some help?
    
Are the TL072's a direct fit?  
Of course I need help ;^)

Todd.

Re: .37 (keyboard scaling set-screw)

    I haven't seen any such beasty labeled.  That's where I thought Dr. Ron
    could help me out.  You got any ideas, Karl?

    Hey, Todd - why don't we get together after our tutorials from Ron and
    see if we can brute force solder the Axxe, Odyssey & your Avatar right
    onto your Omni's mother board?  Might make for some nice fireworks... 


8^)

    
    erk. what have I started!? Anyway:
    
    Do you have an Odyssey or an Odyssey II? The II was a re-design
    of the orig. for latest cost-effective design. The II was
    'orange and black with wood sides', I think, otherwise 'cream
    and black' or so...different electronics.
    
    Gee, this is probably an old 'analog oscillator' problem of tracking.
    There are trim pots (yuk) inside the unit for "volts per octave"
    (flat or sharp across the kbd); "UP 2 oct" (get it right on, also
    sets "DOWN 2 oct" but only if the power supply is adjusted) ; and 
    "second voice kbd CV" (2 notes on the kbd in tune.) 

    Not a big deal to trim, but you have to do it. The vcos really did
    only track a limited range, usually your ear notices high freq.
    more for tuning purposes. Are you using your ear as reference or
    what exactly?
    
    ron_who_sees_a_possible_new_profession?
    

Re: .40

    er ... well, I guess I can , uh - hmmm ... I may as well admit it - I'm
    no hardware whiz.  Some of what you've posted just doesn't make any
    sense to me.

    First, the Odyssey unit is an O_L_D one - plastic 1 piece case, with no
    PPC section (although I'd like to find one).  The serial number is 136
    (I TOLD you it was old), and if I remember correctly, it *is* a model
    II.  What did you mean by "if the power supply is in adjustment"?  Is
    there something I have to do here?

    The Axxe, on the other hand, is one of the newer models - fake wood on
    the ends, PPC, and all that jazz.

    I guess what I was looking for is "the trim pots look like ___ and are
    located ___.  To adjust them, simply ___ and voila!  It's fixed." Oh
    well - life's never easy.  Thanx in advance for whatever help you might
    be able to give me.


8^)

PS - when you get these answered, I've got a BUNCH more for you   ;-} 

    
    Hm....still not sure which you have. I have schematics for
    the old odyssey.
    
    If you go inside it youll see trim pots on the boards. All
    I mean is that these need adjusting in a certain way. I 
    can send you the procedure. The power supply ALSO has trimers
    on + and - 15 volts. You need a DVM in order to set these
    exactly. The up/down 2 octave circuitry relys on them being the same
    voltage within millivolts (but opposite polarity of course)
    
    The AXXE has slightly different circuitry, I'm sortof surprised
    you have the SAME problem on it (do you?)

    I can send you the trimming procedures, or?????
    
    rr
    

    
    I just re-read your original problem description.
    Sounds like tweaking 2 iddy biddy trim pots is 
    all you need. 
    
    Todd: Tl072s are same pinout. Active Electronics has
    them. But...I cant guarantee that the noise will go
    away. If its a layout problem or something else...
    I could guarantee that it wont hurt to try other
    than the $5-$10 for parts.
    
    If you guys want to get together I'm game. 
    
    Ron
    

Re: .42

    Yeah, I have the old Ody alright.

    If you don't mind, go ahead and mail the procedures to m/s DYO.

    The Axxe does the *same* thing, although it is definitely not as bad as
    is the Ody.  It becomes painfully obvious, however, when you throw up
    or down 2 octaves.

    Thank yew fer yer support.


8^)

Re: .43 (getting together)

    Would like to, except that I'm a bit far south to buzz up for an hour
    (I'm in Dayton, Ohio).  A previous note was written in jest.  Sorry.


8^(

    Node "4DEDIN::" huh?
    
    You mean DEC *never* gets you to the mill vacinity?
    Not even to take a course in Bedford on PDP-8 Macro
    or something?  People pro-active, indeed...
    
    I just purused the axxe schematics... Same problem.
    Almost same +/- 2 octaves circuitry. Do the classic OD
    first and you should know what you're up to. The 
    procedures are written for a tech with a DVM.  You
    could do it by ear, I bet. Dont touch the power supplies
    unless you have a Digital voltmeter,tho...
    
    Have to tune my 2600 too. These adjustments, BTW, are 
    similar to what was mentioned about other Arps in an
    earlier note...no magic, just analog.
    
    rr
    
    
    
        
    

Re: .46
    
    Meester Ron - could you please post the voltages values?  I can get my
    hands ona DVM (and maybe even someone who knows how to use it!).

    I'll try to tune the things this weekend.  If they die, I'll let
    you know.  Thanks for all your help.


Meester Brad	8^)

    It's probably better to wait for the procedures.
    Im too lazy to type in 4 pages plus some sort of
    representation so that you can find the right
    trim pots and not doodle with something you dont
    want to.
    
    The power supply is set for ACAP (as close as possible)
    +15v. and -15v. Both units. This you could check easily.
    
    will send tomorrow! Soon enuf?
    
    ron
    

    
    but it's not the power supplies that are the problem.
    
    Hope that;s clear...
    
    rr
    

    I have an old (whiteface) ARP Odyssey that I can't seem to part
    with. It was my first synthesizer (bought in 1973). The thing goes
    out of tune a lot, but it has such a FAT sound! Does anybody have
    any schematics ? ...any idea how to calibrate an Odyssey? Otherwise
    I might have to buy a sampler, and sample the Odyssey's best sounds
    in order to stay in tune while playing.
    
    Mike D.

I've a friend with an Odyssey and an Avatar.  He bought 
schematics and user manuals this summer by mail order (from the 
company that bought out Arp's part deparment when they folded?).  
I believe you get get repair parts from them also.  He's out of 
town for a few days, but I'll see if I can get the info posted 
here next week.

John

Order ARP info from:

		Music Dealer Service
		4700 W. Fullerton
		Chicago, IL  60639

Service manuals (with schematics):	$20
User manuals:				 $5

Prices were valid 8/86.  They DO carry replacement parts.

John

    Phone number, John?
    
    Todd.
    

Unknown. Sorry.

John

    RE: .52
    
    Thanks!! Sounds like they'll have exactly what I need.
    
    Mike
    

    Can someone tell me a little about the Moog Rogue?  I can pick one up
    for 60 pounds.  Howz it compare with an SH-101?
    
    matty

    A guy I played with several years ago had a moog rogue. I seem to
    remember it came out as a sort of cheap version of the minimoog for
    those that really wanted a minimoog but couldn't afford the real thing.
    It was a LONG time ago so I may not remember correctly, but I think the
    main limitations from today's point of view are no presets (everything
    programmed from the front panel) and no midi.
    
    Tony I

    The Rogue had two oscillators allowing for detuned types of sounds not
    possible on an SH-101.  One four-pole filter, one envelope
    generator/VCA stage.  It also allowed you to "overdrive" the audio
    chain to get ruder sounds.  It was otherwise quite similar to the
    little synth Moog made for Radio Shack, except it retained the bend and
    mod wheels that the RS synth lacked, and there was no polyphonic
    "organ" voice.  No arpeggiation or sequencing supported.
    
    							Brian

Yes -- one up from the Micromoog (single oscillator), one down from the
Prodigy (better filtering?). Consider a used Multimoog (half a Micromoog
plus aftertouch).

Richard.

Sorry, that could have been a lot clearer/more accurate. 

A Multimoog is half a MINImoog, i.e. two oscillators and associated gubbins
PLUS aftertouch on the keyboard (still no MIDI, of course).

I have one, and it's great (Multimoog, that is). It also had Moog's 'open
system' on theback (lots of ins and outs) which the more modern machines,
such as the Rogue, lack. You can use the ins and outs to patch in pedals,
or cross-patch, say, key voltage to filter.

Richard.