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HD mk2 tracking problem
MUFF WIGGLER Forum Index -> The Harvestman  
Author HD mk2 tracking problem
rydan
Have a strange problem here:

I send the HD 0 volts to the primary osc 1V/oct input, and tune it to a C, say C3.

Then, I send it 1 volt, and I end up with a C4 approximately 20 cents low. Then I send 2V, and end up with a C5, still approx 20 cents low. In fact, if I send it 0.085 Volts (one semitone up), I get a C#3 approximately 20 cents low.

So, seems it starts to track at approximately 0.02V, or so, not at 0V. Seems to be the same for both primary and mod osc, and behaves the same in both cases I've tested it in (one doepfer linear PSU, and one TipTop Zeus).

Any ideas? Is this adjustable? The two trim resistors on the back, do they adjust tracking in any way?
rydan
Well, one of the questions I can answer myself. The trimpots do indeed adjust tracking, but since there's nothing wrong with the tracking, but rather a small offset in the absolute beginning of the range, adjusting the tracking won't help much...
governor blacksnake
I'm having trouble reproducing this error. What is your CV source?
rydan
Expert Sleepers ES-4. Also tested with Maths channel 2 (monitored with volt meter with good resolution). It appears that the pitch doesn't change at all between 0V (or -1V for that matter) and approx 0.02V. From 0.02V and on, tracking is perfectly linear. Same behavior on both primary and modulator. Feels to me as if a voltage reference for 0V is off somewhere.

Guess there could be something strange with my unit. Ulf from escape from noise has promised me to borrow another unit and compare, but he doesn't have any at the moment, so perhaps best to wait and see if another unit behaves differently.
governor blacksnake
I just tested some of the HD2 units here using a quantizer module and your suggestion of C3 as a start frequency. In the lower octave, any deviations from the "expected" scale frequency (versus the initial frequency) were well within the just-noticeable difference of frequency discrimination, which satisfies the expected usage of that input jack. I tried testing the performance within the 20mv threshold that you describe, but I was running into the limitations of my portable voltmeter and the mechanical ability of my fingers to set the potentiometers precisely at that scale.

So, the units I tested here are able to play notes in tune starting from 0V input (as well as no physical input at all) to the notes in a 12TET scale as quantized. I suggest either setting the start frequency of the Hertz Donut one octave lower, and transposing your output from Silent Way one volt upward (fine tuning on the module to match your expected frequency), or creating a custom calibration for the module in Voice Controller to get the proper performance from that last 20mV at the very beginning of the scale that your setup is having trouble with.
rydan
Yes, there are workarounds, all I'd really need is a 50 or so mV offest to the CV signal, and it'd be fine. Anyway, I'll team up with Ulf and compare it to another unit, and we'll see if that behaves differently. (From your tests, I'd say that's likely. A 20 cent pitch drop when playing octaves is pretty noticeable...)
rydan
Well, got another unit from Ulf, and it displays the exact same behavior. So, question is, is this a problem in the V1 firmware (this unit also has the "fine tune when set to tracking bug" so, guessing it's a firmware 1.0 version) since you don't have it on your units, or am I simply less tolerant to tracking errors?

It's an error of 20 or so cents, so to me at least it's very noticeable.
rydan
Playing octaves, 3V, 2V, 1V, 0V sounds like this:

[s]http://soundcloud.com/rydan/phmk2-tracking-problem[/s]
rydan
Just tested on a third HD mk2 on a friends modular. Same problem.

Any chance to get this fixed in firmware?
mmmcc666
I've just got my HD2 and I love it!
But I have noticed the tracking problem described here.
Intellijel uScale's lowest C which I assume is 0V is definitely not in tune when controlling the HD2. All the octaves above it are exactly correct.
Would be great to call it a perfect modules if a new firmware can fix it.
rydan
There's hope...
tronabetes
mmmcc666 wrote:
I've just got my HD2 and I love it!
But I have noticed the tracking problem described here.
Intellijel uScale's lowest C which I assume is 0V is definitely not in tune when controlling the HD2. All the octaves above it are exactly correct.
Would be great to call it a perfect modules if a new firmware can fix it.



Just got an HD mkii and noticed this... otherwise pretty pleased.
Funky40
governor blacksnake wrote:
but I was running into the limitations of my portable voltmeter and the mechanical ability of my fingers to set the potentiometers precisely at that scale.
.

so that answer was 3 month ago.
have you in the meantime a better voltmeter etc. ?
would like to hear back on that "issue".
.....just wanted to take a HD2 beside my PH2
rydan
Any news or updates? I have the exact same problem on my PistonHonda mk2 by the way.

Does all units have this, or is is just some? I'm starting to believe this is a hardware problem of some kind, either with the modules themselves or some combination of module and powersource...
clusterchord
was this ever resolved? three and a half years have gone by..


in other words, im looking to get HD2, but wonder if this was fixed, and if it was, what firmware version do i need.


thanks
dysonant
clusterchord wrote:
was this ever resolved? three and a half years have gone by..


in other words, im looking to get HD2, but wonder if this was fixed, and if it was, what firmware version do i need.


thanks


I've had a HD MKII for about 2-3 years and it's always worked really well and stays in tune. It can be off by a few cents octave to octave, but nothing that gets in the way of making harming music.
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