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Buchla 208 with 25s & tuning
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge  
Author Buchla 208 with 25s & tuning
ritchiedrums
I have the blue output going to PITCH
on the 208 with Keyboard ON both oscillators.
The 5 steps are playing in tune on both oscillators (kind of)

Another blue output is going to the 25s
Should the 25s oscillators be playing in tune with the 208??

It’s not!!

captnapalm
ritchiedrums wrote:
I have the blue output going to PITCH
on the 208 with Keyboard ON both oscillators.
The 5 steps are playing in tune on both oscillators (kind of)

Another blue output is going to the 25s
Should the 25s oscillators be playing in tune with the 208??

It’s not!!



Off the top of my head I'd guess you have modules calibrated for different v/oct levels.
ritchiedrums
they are all supposed to be 1.2v/oct.

looks like I need a tech/repair.

please PM me if this is a job for you... Guinness ftw!
Kent
I think that you simply need to scale your 25S units to be in temperance with your Easel. That’s what those little holes near “7040” are for.
ritchiedrums
Kent wrote:
I think that you simply need to scale your 25S units to be in temperance with your Easel. That’s what those little holes near “7040” are for.


Yep.... tried that already
sanders
Are the 208 and 25S close to being in tune? If so, this would indicate they're both scaled the same.

Have you tried to adjust either the pitch attentuator on the 208 or the CV input attentiator on the 25S? I should think you could approximate unison across a couple octaves using one or both attenuators (even if they're not perfectly scaled for 1.2v/oct initially).
ritchiedrums
well it looks like you all answered my question.
these 4 oscillators should be playing together in this set up.

there are several issues:

the 2 oscillators in the 25s aren't close to each other in pitch.
Neither one of those is close to the 208 scaling

really appears that I need professional help
dizzy
Peake
Just like the 208, the 25s tracking goes non-linear at and below the top point of tracking adjustment. The oscillators track very well over a very wide range together, but both with that non-linearity.

I note that the 259 upon which the 25s is based has a keyboard input jack in addition to the attenuverting jack. The 25s loses the specific keyboard input jack and uses the attenuverting input for keyboard. Not sure if checking the schemo and wiring the jack as shown per the 259 keyboard in will solve this problem (standard pots have up to what, 20% range variance?). Not sure if 259 users have this same problem when using their keyboard in jack; haven't built one.

Sometimes Buchla schematics have answers regarding trying different value fixed resistors in certain places to nail known issues, such as the Waveform offset resistor in the 258. Wondering if the 259 schemos will show such a possible, indicated tweak for linear tracking. (EDIT: No, there are no indicated tweaks for resistor values regarding tracking in the schemo, and the Keyboard inputs go directly to trimpots before joining the CV input path.)
ritchiedrums
ritchiedrums
I managed to get the 25s modulation oscillator
To play nicely with the 208 oscillators
But the complex oscillator is still way off
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