I had no prior knowledge that the multiturn trim "octave
spread"(intonation) could calibrate the upper to lower octaves of
one oscillator "correctly' several times as you turn the pot from 1
extreme to the other....unless....
.... the range of the spread can stretch 3 octaves of pitch to
fit over 5 octaves of keys ? or compress 5 octaves of pitch down
to 3 octaves of keys? and thus the the oscilliscope would stop
beating as you found octave 4 and octave 3?
-----Original message-----
From: "Quazimodo"
noddyspuncture@...Date: Sun, 24 Jan 2010 03:00:16 -0700
To:
yamahacs80@yahoogroups.comSubject: [yamahacs80] Re: Here's a strange tuning issue...
Thanks for your replies guys,
Laurie, I have a 'feeling' though that this might be a fault. It is
quite a severe symtom affecting only two cards (one more than the
other) I had to do quite an adjustment to VR2 (the octave) to bring
the loweroctave 'in' in card 6. And I use a scope where you can
actaully see the waves 'beating'. I adjust until they are virtually
motionless, so it should be spot on. If it was a heat issue wouldn't
there be more voices reacting in a similar way?
Anyway there is one other thing. Have you noticed - and it's probably
easier with a scope as you can ∗see∗ it happening - that with VR3 (the
multi-turn '2 tune pot) you can actually tune though the 'correct'
pitch about 5 or 6 times from one end to the other? It caught me out a
few times as only one of the settings actually works with the rest of
the tuning set-up. If you pick the wrong one - it'll all look and
sound right but you'll never get the 4/8/16 feet in.
I wonder if there is a trick to knowing exactly which one (of the 5 or
6 posssibles) it should be? They must have had something at the
factory because you can waste a hell of a lot of time searching it
out! I assume they are 'harmonics' of the correct waveform thatare
being caught there!?
Cheers,
TOM
--- In yamahacs80@yahoogroups.com, "Laurie Curry" wrote:
>
>
> I always tune mine "hot"....I let the CS80 warm up to temperature
with
> the lid down and my "half"
>
> Â case cover on...all screws are out for lid and M board
> Carriage...... master tunes, detune II and fine tunes at center
> "0'..both banks set to 2 foot .. after a couple hours in warmup,Â
I
> open the lid, cover the top and back of the M board carriage
with a
> folded towel to keep heat in, and I raise the carriage.... I
cover
> the keybed with a towel to keep any foreign objects from coming in
> contact or falling into the lower half of the CS80....
>
>
>  With the Mix setting 100% to bank  II, I start adjusting.....
>
> (to eachyour own......I am one of those who touches the foil side
> lightly behind the blue pot to find oscillators....as shown to me
from
> the yamaha tech in the 80's)
>
> the mini blue pot is the adjustment for tuning the 2 foot..... the
> first larger trim is the "octave calibration"...
>
> I play the low range osc1 into a tuner and mark its sharpnes
or
> flatness... then I search for osc 1 again using the upper
> octaves.....If they are both equally sharp or flat I do not adjust
> this pot...
>
> I only adjust the little blue one.....counter clockwise sharpens the
> pitch, clockwise flattens.....
>
> You want to use an insulated scewdriver as a metal one will alter
the
> pitch you are reading as you adjust....
>
> on the other hand if the reading of the upper is sharper than the
> lower, you need to turn thelarger pot clockwise, and counter
> clockwise if the upper is flatter than the lower octave....once you
> are sure the upper and lower octaves are at the same place in
> shap/flat..... tune the osc into tune with the little blue one...
>
> after bank 2 is done for all 8, adjust mix 1 in the same way.......
>
>
> at this point once the 2 foot is in tune, I usually close the
CS80
> up and let it sit for an hour to 'rewarm" itsself....upon returning
I
> recheck the 2 foot with the lid downin both banks to see if
everything
> has stayed in the right place... taking note of which mix may need
> further tweaking...
>
>
> once I raise the lid I repeat the covering with towels and raise the
> carriage....
>
> I will repeat the 2 foot process if there was any change searching
for
> the bad osc...
>
> Â If allsgood , 4 foot on bank II using the second large trim pot
> from top.... (I use the low range from this point on) tuning the
> oscillators into pitch.....
>
> You will notice thet the trims are easier to adjust in the
> lower footage as they arent as touchy as the 2 foot trims...once
4
> foot is done in both banks move to 8' and finally 16'.....
>
>
> Close her up and play her for a while........ should sound
sweet...to
> the ears...
>
>
> I experienced results like yours between 16/ 8Â before too after
a
> sure tuning, but I found it was because the osc cards had cooled off
> while I was adjusting....and when It rewarmed, the spread on 2 went
> out so slightly it wasobvious in the lower octaves...
>
>
> -----Original message-----
> From: "Quazimodo" noddyspuncture@...
> Date: Sat, 23 Jan 201014:14:14 -0700
> To: yamahacs80@yahoogroups.com
> Subject: [yamahacs80] Here's a strange tuning issue...
>
> This is a strange symptom - wonder if any tech's here might have
come
> across this one before..?
>
> Today I tuned a CS80 - sinewaves on CD, CD player and CS80 into
> Oscilloscope. Everything seemed to tune up great, visually and audio
> wise. However when I closed the lid to play her - I noticed a couple
> of notes (in the lower octaves) were quite flat. I investigated and
> voices 5 and 6 on channel I were the culprits. Note, I had switched
> footages to 16' and 8' (where I normally play) and this is where the
> problem revealed itself.
>
> I went back to 'tweak again' but I noticed that when adjusting the
> first two settings as written in the manual (the keyboard 'spread'
> adjustment) that this is done onthe 2' footage setting. When Iwent
> back to that 2' footage, everything was fine again. It was all in
tune
> and perfectly set.
>
> It is when I switch away, down to the footages I use most often 16'
> and 8' that the problem arises.
>
> Next I tried something - just using my ears I 'tweaked' the second
pot
> down on the culprit cards, under the fine trimmer, the one you
adjust
> in connection with the fine one, until those flat low notes sounded
in
> tune. This is totally workable and she plays beautifully down on the
> 16' and 8' settings, but now when I go to higher footages then those
> same notes are miles out. Obviously something isn't quite right
here.
> What would cause the 'keyboard spread' to vary between footages?
>
> Obviously, once set at 2' it should be correct for all footages,
> otherwise there would be a seperate 'spread' adjustment for each. So
I
> have ineffect 'botched' it!! Haha!
>
> Please, does anyone know where I should start investigating this
> wierdfault?
>
> Hope someone can help
> Cheers
> TOM
>
>
>
>
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
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