OR-0016
Tekura
Oregon, USA · 1979 – c. 2001
Ser. Type 1050 · Ser. No. 02207-A
1986 · effect
Issued as VST3 · AU
Restored 2024 from 1986 hardware.
Tekura 1050 — Reconstruction Filter
Tekura Type 1050 · Reconstruction Filter · restored from Ser. No. 02207-A · Tekura, Oregon, USA, 1986
The restorer's note
The output stage of a converter, isolated — the whole difference between "cheap digital" and "good digital," made a knob. Zero-order hold for the buzzy, imaged top; band-limited for the clean. One of Tekura's earliest designs, and still exact.
Acquisition
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The plate
The controls
The controls.
- Mode Zero-Order Hold as issued
- Chooses how samples are turned back into a continuous signal: Zero-Order Hold, which leaves the stepped images in; Band-limited, which filters them out cleanly; or Brickwall, which filters them out with pre-ringing.
- Rate 8.0–48.0 kHz · 44.1 kHz as issued
- Sets the modeled converter's sample rate, which sets where the reconstruction images fall in Zero-Order Hold mode.
- Bandwidth 8.0–22.0 kHz · 18.0 kHz as issued
- Sets the low-pass corner of the converter's output stage, after reconstruction.
- Ringing 0–100 % · 50 % as issued
- Sets the pre-ringing before a transient in Brickwall mode; it has no effect in Zero-Order Hold or Band-limited mode.
- Input -24.00–24.00 dB · 0.00 dB as issued
- Sets the level going in, in decibels, before the signal reaches the restored circuit.
- Output -24.00–24.00 dB · 0.00 dB as issued
- Sets the level coming out, in decibels, after the restored circuit and the Mix blend.
- Mix 0–100 % · 100 % as issued
- Blends the restored circuit against the untouched signal at equal power, from the untouched signal alone at 0 % to the circuit alone at 100 %.
- Bypass Off as issued
- Takes the restored circuit out of the path and passes the untouched signal, delayed to match the circuit so nothing shifts in time.
A stored setting is numbered, never named: the trace's overlay reads SETTING 04/09. The thumbwheel's position is the setting, and it applies as it clicks into place; ▲ ▼ step one at a time and stop at the ends. STORE asks STORE NN?, and a second press keeps the present state as SETTING NN. Holding STORE on a user setting asks CLEAR NN?, and a second press clears it.
Listening
Listening
Demonstration recordings, prepared at the bench.
Twelve kilohertz, held
The mix runs dry for five seconds, then the converter model: Zero-Order Hold at a 12 kHz Rate. The images sit above the passband, unfiltered — here, the reconstruction is the instrument.
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Forty-eight down to eight
Rate falls from 48 kHz to 8 kHz in one continuous move, Zero-Order Hold throughout. At the top the model is nearly transparent; by the bottom the images have walked down into the music.
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Three reconstructions
The same figure at a 16 kHz Rate, three ways: Zero-Order Hold with its images, Band-limited clean, then Brickwall — Ringing raised to 100 % puts the pre-ring in front of every hit. Bandwidth closes to 8 kHz at the end.
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