How often do you have to calibrate VCOs?

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tvh
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How often do you have to calibrate VCOs?

Post by tvh » Wed Feb 17, 2016 9:38 am

So in my quest to cheap out a little at Front Panel Express, I ordered a panel for 3 VCOs right next to each other...Not thinking that I may have to get onto the boards in the future and the spacing is a bit tight. :bang:

As I attach the components to the panel, I was planning on calibrating each one, then do the one next to it for easier access. Is this going to come back to haunt me in the future, should I just re-order 3 separate panels for them?

Or is calibration done only once and then just use the tuning knob on the front from here on out. VOCT and TUNE should be reachable in the future but the other ones will be tricky if all pcbs are attached to the panel.

Don T
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Re: How often do you have to calibrate VCOs?

Post by Don T » Wed Feb 17, 2016 9:49 am

tvh wrote:So in my quest to cheap out a little at Front Panel Express, I ordered a panel for 3 VCOs right next to each other...Not thinking that I may have to get onto the boards in the future and the spacing is a bit tight. :bang:

As I attach the components to the panel, I was planning on calibrating each one, then do the one next to it for easier access. Is this going to come back to haunt me in the future, should I just re-order 3 separate panels for them?

Or is calibration done only once and then just use the tuning knob on the front from here on out. VOCT and TUNE should be reachable in the future but the other ones will be tricky if all pcbs are attached to the panel.
Why not use side-adjust trimpots? That way, assuming you can position them for easy access from the side, even with the boards stacked, you won't have to take the module apart. There are quite a few pin-out options for trimpots, so you can order a specific one that will be facing the best direction for your module. See the right column in the datasheet below:

Bourns 3362 Series Trimpots

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terjewinther
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Re: How often do you have to calibrate VCOs?

Post by terjewinther » Wed Feb 17, 2016 5:07 pm

tvh wrote:Or is calibration done only once and then just use the tuning knob on the front from here on out. VOCT and TUNE should be reachable in the future but the other ones will be tricky if all pcbs are attached to the panel.
The only trimmers you are likely to need in the fairly short run (of some years…) are the scaling trimmers, ie. VOCT trimmers.

In the old days (1970s) some service manuals quoted you should deliver your analog synth to a qualified service shop once every six months. These days, people hardly calibrate their stuff every 10 years.

Component drifting with age is hardly a problem these days, not enough to offset waveshape calibration and stuff like that, anyway.

If you are into music that needs close tolerance frequencies, and want to have you gear running precisely, my guess would be that you need to re-calibrate the VCO scaling every 3 years or so.

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tvh
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Post by tvh » Thu Feb 18, 2016 7:44 am

Don That's a good idea - I think my next set of three down the road, I'll do that.

Sounds like calibration isn't necessary very often at all..so I'm not up the creek without a paddle...thanks for the info! :sb:

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