Baumann BME 700

Baumann BME-700

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This unusual German synth had a build volume of about 500 units and only one

useful source of information could be found on it: a report on repair work for

one of the few existing examples at www.bluesynths.com. The BME systems were

hand built and judging by some reports on build quality may have been sold in

kit form. The unit was produced in the mid 1970's.

The synth has a very interesting design, somewhat reminiscent of the Moog Sonic

and Explorer synths. It has two modulating LFO with fairly high top frequency,

two filter and two envelopes. The envelopes are either AR or ASR but they can

be mixed together to generate amongst other features an ADSR, very innovative.

There is only one oscillator but the sound is fattened out by the use of two

parallel filters, one acting as a pure resonator and the other as a full VCF.

The synth has been left with a minimum of overhead. There are just 8 memory

locations on the front panel with Load, Save and Increment buttons and one

panel of options to adjust a few parameters on the oscillator and filters. It

is possible to get extra memories by loading banks with -load: if you request

starting in memory #21 the emulator will stuff 20 into the bank and 1 into the

memory location. There is no apparant midi channel selector, use -channel <n>

and then stay on it. This could have been put into the options panel however

having midi channel in a memory is generally a bad idea.

A. MOD

Two LFO:

frequency from 0.1 to 100 Hz

Triangle and Square wave outputs

Mix control

Mod-1/2 into the VCO FM

Env-1/Mod-2 into the VCO FM

B. Oscillator

Single VCO

Glide 0 to 10s, on/off.

PW Man: 5 to 50% duty cycle

Auto depth:

Envelope-1

Mod-1, Mod-1/2, Tri/Square

Vibrato depth

Tuning

8', 4', 16' transposition

Shape

continuous control from Square to Tri wave.

Mix of noise or VCO output

C. Res Filter

Sharp (24db/Oct), Flat (12dB/Oct)

5 frequency switches

D. Envelopes

Two envelopes

Rise time

Fall Time

AR/ASR selector

Two independent mixes of Env, for VCF and VCA.

E. Filter

Frequency

Resonance

Env/Mod selector

Modulation

KBD tracking

Mod-1 or Mod-2, Tri/Square

F. Amplifier

Mix resonator/filter.

Volume

Mod depth

Mod-1 or Mod-2, Tri/Square

The oscillator is implemented as a non-resampling signal generator, this means

it uses heuristics to estimate the wave at any given time. The harmonic content

is a little thin and although the generation method seems to be correct in how

it interprets signal ramps and drains from an analogue circuit this is one area

of improvement in the emulator. There are options to produce multiple waveforms

described below.

The resonant filter is implemented with a single Houvilainen and actually only

runs at 24dB/Oct. There are controls for remixing the different taps, a form

of feedforward and when in 'Flat' mod there is more remixing of the poles, this

does generate a slower roll off but gives the signal a bit more warmth than a

pure 12dB/Oct would.

There is a selector in the Memory section to access some options:

G. Options

LFO

Synchronise wave to key on events

Multi LFO (per voice).

Oscillator

Detune (temperature sensitivity)

Multi - remix 8' with 16' or 4'.

Noise

Multi Noise (per voice).

White/Pink

Pink Filter

ResFilter

Sharp Resonance/Remix

Flat Resonance/Remix

Envelope

Velocity Sensitive

Rezero for note on

Gain

Filter

Remix

KBD tracking depth

The emulator probably gives the best results with the following:

startBristol -bme700 -mono -hnp -retrig -channel 1

This gives a monophonic emulation with high note preference and multiple

triggers.

The options from section G are only loaded under two circumstances: at system

start from the first selected memory location and if the Load button is given

a DoubleClick. All other memory load functions will inherrit the settings that

are currently active.