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SawBench Detuned

It seems that my SawBench is permanently tuned approximately -47 cents too low (using A=440Hz as a reference).

I would like to tune to A=440Hz.

Is there any way to fix this permanently? Thanks.

Comments

  • Yeah mine is having this issue too :/
  • We'll be looking into this shortly. From what we recall it was more like 10-20 cents. It could be that newer firmware or unmatched VCO transistors caused this..
  • The amount of detuning I get seems to vary every time I turn it on. I just turned it on and checked and it's 24 cents flat. Then I turned it off and on again and it came back 14 cents sharp. Maybe there's some pitch adjustment parameter that's not being initialized in the firmware? Whatever it is doesn't seem to reset after playing with the pitch bend controller.
  • thanks for that info. tomorrow evening we will check this in detail. there's a calibration procedure but it's a first-order approach. in other words. "ah, it's better than before, let's carry on". but it could be much better.
  • ok, we ran a bunch of tests on our showroom model. seems like a cold start yields a more detuned VCO. leaving it on for a while and then a power cycle yields far better tuning. our model tended to settle around 2 cents. our unit could never be detuned more than 20 cents, btw. it might vary from unit to unit..
  • My Sawbench now seems to be bang-on A440 every time now, even starting from cold and measuring the pitch then.

    I'm rather surprised that it has done this. The only change is that I'm using a new PSU. I did have a 12V supply but a few days ago, it started humming and shortly after went to 0V.

    I replaced it with a 9V supply.

    Could it be that a different PSU would allow the tuning to be accurate? That is the only thing that has changed since my Sawbench was new.
  • Interesting! The Sawbench' internal regulator should keep a steady 5V on which all circuits (digital and analog) depend. But if your external power supply is a bit too weak it may give huge "ripples" causing some power dips that would be noticeable on the Sawbench.. That's just my theory, though.
  • edited December 2018
    Yes, it is interesting isn't it?

    I'd like to know if anyone else's Sawbench which has tuning inaccuracies is helped by using a different PSU. I replaced mine with a brand new, nothing particularly special, model.

    BTW, thanks for the replacement firmware chip! I got it today and it's just been installed.
  • NP :) The current rating on the PSU is important. 1A or more should do it. Having said this there are huge quality differences even at that mimimum.
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