Teletype timing issues

I got my teletype yesterday and have had a chance to play with it.

I’ve noticed some timing issues:

  1. When clocked by the internal metronome, the tempo changes noticeably when the mode switches between tracker and edit/live modes–it’s not a glitch, the tempo changes enough to cause very audible timing issues when running through a delay.

1a) When in tracker mode, scrolling down through the values causes tempo glitches while scrolling.

  1. There is a significant and jittery lag between the trigger output and CV output. I tested with the onboard “4TRACK” scene and observed c. 700us-5ms of lag between the trigger output going high and the CV output changing. See attached scope trace. I verified that slew is off, which is confirmed by the very crisp CV trace.

I only got out the scope to confirm what I was hearing: small but pretty obvious glissandos at the beginning of some notes.

The other attached image shows the rest of the patch, namely a Model 37 LFO clocking the teletype and no other connections.

Any ideas? Thanks!

thanks for the heads up-- i hadn’t seen this issues before, and they may have been introduced with firmware upgrades over the many months. will do some testing-- after taking a little break.

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Was timing tested with previous firmware versions?

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with initial versions of TT i certainly did not notice timing inconsistencies.

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Another data point.

Latency from trigger 1 in -> TR A out is excellent at about 50us, and quite jitter-free.

But pulse time is quite variable (see first pic, persistance is turned on): when commanded to TR.TIME A 5, it’s anywhere from 1 to 10ms. When commanded to TR.TIME A 50 (second pic), it’s 40-50ms.

Might this be connected to the lost command issues of teletype remote?

If the incoming trigger period is less than (TR.TIME - 10ms), the teletype’s trigger output never goes low (or I just can’t see it because it’s so narrow).

In the range of (TR.TIME - 10ms) to (TR.TIME), the trigger output looks inconsistent/glitchy.

Edit: increasing the incoming clock period (i.e. slowing it down) has no effect on the 10ms variation in pulse output time.

watching with interest. . keep up the good investigative work john!

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More data to support (1) in my original post:

Using the “Triangle Mountain” scene, PARAM knob full CW, trigger out A shows the same duration jitter and runs at about 16.7Hz in edit and live modes (and scene select), and 15.7Hz in tracker mode.

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This isn’t timing related, but it appears a slowly changing trigger input will fire the input again as the voltage goes back down. I discovered this while attempting to use my Pressure Points’ channel pressure outputs as trigger sources: they reliably trigger the teletype but give a second trigger upon release.

I confirmed the behavior by sweeping a voltage source into the teletype’s trigger input: it always triggers on the up and down slopes.

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Watching with interest.

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