Buchla 261e mystery!

[Nosferatu]

Are there anyone here with hands on experience with:
http://www.buchla.com/200e/261e.html

I dont really understand how it works, the sales info speaks of a modulation
oscillator! For example if the principal osc uses a sine and you modulate it
with a sine from the mod osc what hapends? FM, Waveshape, PD, AM,
wavetable scrolling a'la' PPG??
Perhaps anyone has a oscilloscope picture to share of said modulation?

It talks about a *multi dimensional voltage controlled timbre space*??

Hmm, i see now there are a MOD section for amplitude ,timbre and
frequency!

[trent saburo]

The 261e is divided into two sections for the principal and modulation oscillators. The output of the modulation osc can be internally bussed to the frequency of the principal oscillator (FM), its amplitude (AM), or the gain into its waveshaper. Or, combinations of the three. No patchcords necessary.

The multidimensional timbre space refers to the multiple parameters present in the waveshaper section (timbre, symmetry, high order).

The 259e is similar in structure, but features two banks of digital waveshaping tables (with the ability to crossfade between the two), and the ability to internally modulate this parameter instead of AM. I like it more due to the capability for crazy, out-of-control digital noise with a healthy dose of aliasing.

[mosc]

trent saburo

I missed your earlier post.

Your web site is quite interesting. I enjoyed very much your module demos on YouTube. There are a few similarities to the Klee Sequencer being developed by the DIY guys here. I love those "archaic" digital sounds.

[cbm]

I have some experience with the 261e; it's an extremely dense module. There are two VCOs, a Principal Osc and a Modulation Osc. The Mod Osc can track the Principal Osc, or be controlled independently.

There are three types of internal, patch-cord-less cross modulation available: Pitch, Timbre, and Amplitude. These can be on in any combination.
- Pitch is linear FM.
- Amplitude has a "null point" where it is really ring mod.
- Timbre controls the Timbre of the Timbre section (sorry for that lame description. See below for a little more)

The Timbre section of the Principal Osc has three parameters: Timbre, Symmetry, and High Order. Timbre adds harmonics as you increase the value. Symmetry controls how different one half of the waveform is from the other. High Order acts a little like a high pass filter. I don't think it really is one, as it can add harmonics, but it does shift the emphasis towards the high end, somewhat like a high pass.

All of the example on my Buchla page were done with the 261e: http://www.xfade.com/Buchla

I think it is a very capable waveform generator. Nothing else like it that I know of.

[Nosferatu]

Thanks for your briefing, i found out some reviews of the system!

It seams that the 259e are discontinued?

It seams that for the 259e in these reviews its all digital oscillator
that sweep wavetables as to modulate the spectrum!?

http://www.soundonsound.com/sos/mar06/articles/crosstalk.htm
http://www.keyboardmag.com/story.asp?storyCode=11606
http://www.soundonsound.com/sos/jan06/articles/buchla200e.htm?print=yes

But are the 261e all analog? Or digital core with analog shaping?
It says that only the shaping section are analog?
Buchla speaks of an anti alised design in the Keyboard mag
rewiev for the 261e which suggest its also digital but with analog
waveshapers.

[cbm]

[Nosferatu]

I have some additional questions!

1: On 261e there are two holes below the large frequency knobs, it seams to be trimmers, what do they trim?
2: Are the large frequency knobs quantized for easy octave/ratio settings as seen on the graphics's of the panel?
3: There are 4 chromate'd 3,5mm jacks atop the module two of them have a sign of a sine, what are these jacks output for?
4: There are two narrow black buttons just above the two large frequency knobs what do these buttons do if pressed?
5: Can you get your finger between the cv in knob and the shape knob?
6: You dont append to have a picture of the backside of the 261e ?

[cbm]

[Nosferatu]

>The reason I like this knob behavior is that the knobs are still live, so
>that you can play a note over MIDI, and then jerk an oscillator around
>freely in pitch, knowing that the next note will be in tune.

Clever and peculiar!

>I find it quite useful to have the sines available.

Hmm, sort of dual outputs.

>Not buttons. Fine tune knobs.
Ahhh i see!! quite small ones.

Thanks for the quick reply!

[drewskee]

Does anyone know if it is possible to change the audio mini jacks to banana jacks and if so how? I've been thinking of buying one or two of these oscillators to add to a Serge system. Any thoughts/ideas would be most appreciated!

[cbm]

Mr. S -

I think that swapping the minis for bananas would be next to impossible. The minis are mounted to the panel p.c. board. Banana jacks are deeper than this, so anywhere there's a banana, there's hole in the panel board for it to poke through. Next time I pop one out of my case I'll take a look, but I'm pretty sure this is a non-starter.

-C

[Peake]

Aren't the control and audio paths purposely separated due to the relatively high DC voltages (15V, IIRC, from controllers in the older 200) versus the 1V or so audio path? To keep you from patching up a damaging pathway?

It's not a big deal in actual use.

[drewskee]

What about the Modulation Index Input Jack, knob and button above the Mod Osc?

1) Does this allow for you to inidvidually set the amount of Mod Osc -> Main Osc modulation for Timbre, AM and FM as well as allowing you to determine the amount/direction of modulation from a single external source to Timbre, AM and FM?

2) Or does the Index knob set the depth of Mod Osc -> Main Osc and the jack/knob combination allow you to modulate the DEPTH of Index with the external source either +/-?

[cbm]

Your second choice.

The mod type button, with the three LEDs, sets the destination. It can be any combination of the three destinations.

The depth is controlled by the manual control, as well as an invertible, attenuated CV input.

[drewskee]

[cbm]

No, the depth is common to all three mod types. Like I say, you can have any combination of them, but they share a single depth amount.

At the risk of sounding like a broken record, this is an amazing oscillator.

[Nosferatu]

When FM'ing it does it THZ or just positive Lin?

[cbm]

[Nosferatu]

Thanks! Then we know its Pos lin and not THZ.

[blue hell]

[Nosferatu]

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[blue hell]

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[Nosferatu]

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[blue hell]