Buchla and Tiptop Audio — 248t

Manual PDF

Tiptop Audio / Buchla 248t MARF Cheat Sheet

What it is

The 248t MARF is a 16-stage dual function generator / sequencer / arbitrary CV programmer.
It has two independent Function Generators (FG1 and FG2) that read the same bank of 16 programmed stages in different ways.

Each stage can store: - Voltage value - Time value - Pulse 1 on/off - Pulse 2 on/off - Voltage behavior: quantized, sloped, range, source - Timing behavior: time range, external/internal source - Stage behavior: stop, sustain, enable, first, last

Quick Start

Basic 16-stage CV sequence

Set a Function Generator to internal stage advance.
Set its Mode to run using Start.
Program stage voltages with the top row sliders.
Program stage times with the bottom row sliders.
Patch:
Voltage Out or ART Out → oscillator pitch
Pulse Out 1 → envelope gate
Add pulses to desired stages with Output Pulses 1/2.
Use Stage Number to select a stage for editing.

Simple looping sequence

Mark one stage as First
Mark another as Last
The FG will loop between them

Quantized melodic sequence

For desired stages, enable Quantize
Choose Key
Choose Scale:
10 = Major
11 = Minor
12 = Chromatic

Glide / portamento

Enable Sloped on desired stages
Slew amount follows the stage’s interval time

Variable stage timing

Use bottom sliders for stage times
Set global Time Multiplier to scale all stage times
Or use Time Source = External and feed CV into A/B/C/D

Core Concept

The module has 3 main areas:

1. Function Generators (left side, two identical sections)

Each FG reads the programmed stage data and outputs: - pitch/CV - time CV - programmed pulses - reference ramp - all-stage pulse stream

2. Programming Section (center)

This is where you edit what each stage does.

3. Sliders + stage LEDs (right side)

Top 16 sliders = stage voltage / external source selection
Bottom 16 sliders = stage interval time
16 LEDs between rows = stage indicators

Programming Workflow

Select a stage

Use Stage Number switch: - left/right steps through stages - hold to scroll quickly - wraps around from 16→1 and 1→16

Edit selected stage

Use the programming controls to set: - pulses - voltage mode - operating mode - time range - internal/external sources

Apply to all stages

While holding Stage Number so stage LEDs scroll, press a programming function to apply it to all 16 stages.

Stage Programming Reference

Output Pulses

Each stage can independently output: - Pulse 1 - Pulse 2

Switch behavior: - press up = add pulse - press down = remove pulse

Voltage programming

Per-stage options:

Quantize / Continuous

Quantize on = 1V/oct quantized output
Continuous = unquantized CV

Sloped / Stepped

Sloped = glide between stages
Stepped = hard step

Range

Full = 0 to 10 V
Half = 0 to 5 V
Limited + octave offsets = 2 V span with offsets

Source

Internal = use stage voltage slider
External = use one of external CV inputs A/B/C/D selected by slider position

Operating mode

Per-stage options:

Stop

FG halts on this stage until a Start pulse is received.
The stage still observes its interval time.

Sustain

If a high gate is present at Start, the FG holds on the stage as long as gate stays high.

Enable

FG waits on the stage until Start input > 5 V.

First / Last

Defines loop start and loop end.

Time programming

Per-stage options:

Time Range

Four selectable timing ranges from: - 0.002 s minimum - up to 2 minutes maximum

Manual notes default panel range as: - about 2 to 30 seconds on the sliders unless otherwise modified

Time Source

Internal = use time slider + range setting
External = use external CV input A/B/C/D

If set to External and no CV is patched, interval defaults to fastest value of selected range.

Function Generator Operation

Each FG has its own transport and addressing controls.

Mode controls

Advance

Manual step to next stage.

Start / Stop

Starts or stops internal clock, manually or by pulse input.

Status LEDs

Green = running
Yellow = hold/waiting
Red = stopped

Red stop can happen because of: - stop command - programmed stop stage - stage address set to continuous

Stage Address controls

Reset

Returns FG to: - first programmed First stage, or - Stage 1 if no First is set

Display

Shows current stage position without interrupting operation.

Cont / Strobe

Continuous = sweep through stages with address control, internal clock stopped
Strobe = load stage corresponding to current stage address

Internal / External

Selects whether stage position is controlled by: - internal address control - external CV at Stage Address input

Presets / Scales / ART

Presets

Load

Press Load, then stage button 1–12

Save

Press Save, then button 1–12

Saved: - all stage settings - slider values

Important: - after loading a preset, physical sliders are “caught” only when moved past stored values

Key / Scale

Key

Press Key, then select 1–12 for: - C, C#, D, D#, E, F, F#, G, G#, A, A#, B

Scale

Press Scale, then: - 10 = Major - 11 = Minor - 12 = Chromatic

ART + Auto Tune

ART Out sends digital pitch data for compatible oscillators like the 259t
Press Autotune once = send tuning message
Hold Autotune = send initial tune message

Tiptop recommends using Half range (0–5 V) or Limited range with 259t for practical pitch range.

Clear / Reset Behavior

Clear switch

Pressing up clears all 16 stages and resets programming: - Pulse 1 and 2 cleared - Voltage mode = Continuous / Full Range / Internal - Operating mode cleared - Time range = 2 to 3 seconds - Slider values set to current physical positions

External Input Calibration

If 0 V external input does not produce 0 V behavior: 1. Unplug A–D inputs 2. Set both FGs to STOP 3. Press External switch 4 times 4. LED flashes about 2 seconds

Inputs / Outputs Reference

Voltage ranges below are included where stated in the manual.
Some jack thresholds/scales are described functionally because the manual does not specify an exact full range.

Inputs

External Inputs A, B, C, D

Type: CV inputs
Use: per-stage selectable source for voltage or time
Range: not explicitly specified in manual
Notes:
for voltage source selection, slider picks A/B/C/D
for time control, if no CV present and source is external, time goes to fastest setting

FG1 Start input

Type: gate/pulse/CV input
Use: start, sustain hold, enable logic
Threshold: Enable requires > 5 V
Other exact acceptable range: not specified

FG2 Start input

Type: gate/pulse/CV input
Use: same as above
Threshold: Enable requires > 5 V
Other exact acceptable range: not specified

FG1 Stop input

Type: gate/pulse input
Use: stop transport
Range: not specified

FG2 Stop input

Type: gate/pulse input
Use: stop transport
Range: not specified

FG1 Advance input

Type: pulse input
Use: manual/remote stage advance
Range: not specified

FG2 Advance input

Type: pulse input
Use: manual/remote stage advance
Range: not specified

FG1 Stage Address input

Type: CV input
Use: externally control stage addressing when set to external
Range: not specified

FG2 Stage Address input

Type: CV input
Use: externally control stage addressing when set to external
Range: not specified

FG1 Time Multiplier CV input

Type: CV input with attenuverter
Use: scales stage durations globally for FG1
Range: not specified

FG2 Time Multiplier CV input

Type: CV input with attenuverter
Use: scales stage durations globally for FG2
Range: not specified

Outputs

FG1 ART Output

Type: digital pitch/control output
Use: ART oscillator control
Range: digital ART signal, not standard analog voltage range

FG2 ART Output

Type: digital pitch/control output
Use: ART oscillator control
Range: digital ART signal

FG1 Voltage Output

Type: CV output
Use: stage voltage output with modifiers applied
Range:
Full: 0 to 10 V
Half: 0 to 5 V
Limited: 2 V span with octave offsets
Quantized mode: 1 V/oct pitch behavior

FG2 Voltage Output

Type: CV output
Use: same as FG1
Range:
0 to 10 V full
0 to 5 V half
2 V span limited modes

FG1 Time Output

Type: CV output
Use: outputs voltage proportional to interval time slider
Range: not specified

FG2 Time Output

Type: CV output
Use: outputs voltage proportional to interval time slider
Range: not specified

FG1 Pulse Output 1

Type: gate/pulse output
Use: stages programmed with Pulse 1
Range: not specified

FG1 Pulse Output 2

Type: gate/pulse output
Use: stages programmed with Pulse 2
Range: not specified

FG2 Pulse Output 1

Type: gate/pulse output
Use: stages programmed with Pulse 1
Range: not specified

FG2 Pulse Output 2

Type: gate/pulse output
Use: stages programmed with Pulse 2
Range: not specified

FG1 Reference Output

Type: CV/ramp output
Use: downward ramp over stage duration
Range: not specified

FG2 Reference Output

Type: CV/ramp output
Use: downward ramp over stage duration
Range: not specified

FG1 All Pulses Output

Type: pulse output
Use: emits pulse on every stage address change
Range: not specified

FG2 All Pulses Output

Type: pulse output
Use: emits pulse on every stage address change
Range: not specified

Controls Reference

Sliders

16 Output Voltage sliders

Set per-stage voltage
In external voltage-source mode, select A/B/C/D source instead
Output range depends on stage range mode:
0–10 V full
0–5 V half
2 V span limited

16 Interval Time sliders

Set per-stage interval time
Also generate corresponding Time Output CV
Default panel behavior roughly 2 to 30 seconds, modified by time range and multiplier

Programming Section switches/buttons

Output Pulses 1, 2

3-position momentary
up = add pulse
down = remove pulse

Clear

momentary
up = clear/reset programming

Stage Number

3-position momentary
scroll/select stages for editing

Quantize / Continuous

3-position momentary
up = quantize
down = continuous

Sloped / Stepped

3-position momentary
up = sloped
down = stepped

Range selector

momentary options:
full
half
limited ranges with offsets

Voltage Source: Internal / External

3-position momentary
selects internal slider or external A/B/C/D source

Stop

3-position momentary
up = add stop stage
down = remove

Sustain

3-position momentary
up = add sustain
down = remove

Enable

3-position momentary
up = add enable
down = remove

Cycle First / Last

3-position momentary
define loop start/end points

Time Range switches

4 momentary switches
select timing range from 0.002 s to 2 min

Time Source: Internal / External

3-position momentary
selects internal timing or external A/B/C/D timing CV

Preset / scale buttons

Load

Recall preset

Save

Store preset

Buttons 1–12

preset slots
key selection
scale selection:
10 major
11 minor
12 chromatic

Key

Select root note

Scale

Select scale type

Hold / Initial Tune / Autotune

press = autotune message
hold = initial tune message

Function Generator controls per side

Advance button/input

Manual stage step

Start button/input

Start/hold/enable interaction

Stop button/input

Stop transport

Reset

Return to first programmed stage or stage 1

Display

Show current FG stage

Cont / Strobe switch

continuous address sweep
stage strobe load

Internal / External switch

Select internal or external stage address source

Stage Address knob

Sets stage address in internal addressing mode / continuous sweep context

Time Multiplier knob

Global time scaling: - 0.5x to 4x

Time Multiplier CV attenuverter

Amount/polarity of time multiplier CV

ART gate source switch

Selects ART gate source: - Pulse 1 - Pulse 2 - All

Useful Patch Ideas

1. Dual related melodies

FG1 Voltage Out → Oscillator 1 pitch
FG2 Voltage Out → Oscillator 2 pitch
Same programmed stages, different loop boundaries via First/Last

2. Sequencer + envelope source

Voltage Out → oscillator pitch
Reference Out → LPG CV
Pulse 1 → gate/trigger for articulation

3. Addressed wavetable-ish CV scanner

Set Stage Address to External
Feed slow CV into stage address input
Use Voltage Out as a scanned arbitrary function

4. Rhythmic modulation source

Use Time Out as a second CV lane
Set time source to External if you want time sliders as pure CV without affecting stage timing

Practical Tips

Half range is easiest for tonal pitch work.
Sloped stages create pitch glide tied to stage time.
Use First/Last creatively to make different loop windows for FG1 and FG2.
All Pulses Out is useful as a derived clock.
Reference Out is excellent for LPG plucks and decays.
In External voltage source mode, the top slider selects which external input is active for that stage.
After loading presets, sliders use a pickup/catch behavior.

Specs

Width: 72 HP
Depth: 45 mm
Power: +12 V 340 mA, -12 V 30 mA

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