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DSI - Poly Evolver PE Conversion

Posted: Sun Nov 08, 2009 6:43 pm
by synthmax
Just saw that an upgrade kit is now available for Poly Evolver keyboards to go from endless encoders to potentiometers. The knobs on the PEK are pretty crummy, so does this pretty much solve the unreliable knob issue?

http://news.harmony-central.com/Product ... r-Keyboard

Re: DSI - Poly Evolver PE Conversion

Posted: Sun Nov 08, 2009 8:09 pm
by Shanesaw
Hope they come out with an upgrade kit for the MEK as well. I gotta try one of the PEK "pot" editions...

Re: DSI - Poly Evolver PE Conversion

Posted: Sun Nov 08, 2009 10:55 pm
by xpander
synthmax wrote:The knobs on the PEK are pretty crummy, so does this pretty much solve the unreliable knob issue?
actually, DeOxit is solving the unreliable knob issue for the most part. they'll send you a little tube for free & have complete instructions on their website:
http://davesmithinstruments.com/support ... enance.php

and here's a letter from dave (on their website) regarding PEK encoder issues. excellent support!
note from dave regarding PEK encoders

Re: DSI - Poly Evolver PE Conversion

Posted: Thu Nov 12, 2009 4:13 am
by johans121
Long time, no post. Anyway... Has anyone here swapped out their encoders for potentiometers on their PEK yet? I'm curious to what their impressions are. Is there any loss in resolution?

Re: DSI - Poly Evolver PE Conversion

Posted: Thu Nov 12, 2009 1:37 pm
by steveman
Shouldn't be any loss in resolution as pots are continuous value changing. Just depends what res the pots are scanned at. It's not just a pot replacement, it's a board replacement.

Re: DSI - Poly Evolver PE Conversion

Posted: Thu Nov 12, 2009 6:25 pm
by johans121
steveman wrote:It's not just a pot replacement, it's a board replacement.
I understand this mod is a board replacement, otherwise people would have been performing this mod starting in 2005 when the PEK was released :)
steveman wrote:Shouldn't be any loss in resolution as pots are continuous value changing. Just depends what res the pots are scanned at.
With all due respect.... what you said isn't entirely accurate.

Encoders are scanned - discreet values are immediately available for the cpu to digest. There's no guessing what the value is.

Pots are usually used as voltage dividers. The voltage coming out of the pot will most likely be fed to an Analog to Digital Converter (ADC) where the ADC takes an analog voltage, quantizes it, and then spits out a digital signal for the CPU to digest. Hopefully the 'ADC' guessed right while quantizing the signal.

In short encoders are scanned, pots are not. Infinite encoders have 'infinite' resolution in a digital system - pots do not due to the conversion of thier output.

With the pot replacement, there are two possible sources for a loss of resolution.
1 - An analog signal has to be quantized and converted to a digital signal, which we just

2 (and the biggest concern) - Pots only have 270 or 300 degrees of travel. All of the possible values that particular control can output have to be represented in that arc. Think about what the word resolution means for a second. You used to have a control that you could spin until you found the specific value you were looking for (assuming the crappy encoders on the PEK were actually working right) - spin them fast for course tuning and then turn them slow for fine tune control. With a limited travel pot on the other hand, if you are trying to nail down a specific value you have to have a very accurate pot and a very steady hand.

Now before this conversation spirals down into the mire with people debating about the quality of components now-a-days and cost benefit analysis that went into the design, I just want to make sure I am clear. I am not arguing whether or not the mod was expertly designed to minimize the loss of resolution. I was simply presenting a case that there IS a possibility for a loss of resolution in this digitally controlled system going from a digital control input to an analog control input that needs to be translated.

If someone has performed this mod, please let me know what your impressions are.

Re: DSI - Poly Evolver PE Conversion

Posted: Thu Nov 12, 2009 11:03 pm
by steveman
You're right on every count and obviously well across potential issues. Guess I should have kept quiet :shock: just wasn't sure of your level of knowledge...

Re: DSI - Poly Evolver PE Conversion

Posted: Thu Nov 12, 2009 11:26 pm
by danbroad
The feel of the encoders on the P'08 and PEK were enough to make me consider the longevity of the synth when I tried them out. Compared to the pots on the Access Virus TI, they felt insecure and I couldn't escape the feeling that they might break off in my hands if I ever got carried away. I'm sure, however, that they're perfectly strong.

Just makes you wonder how the ergonomics of a synth, and the littlest touches on the interface are no small part of its saleability.

It's well documented that many people base their car purchase on the sound of the doors shutting. They hear a dull, strong 'thud' and they associate that with an air of quality. It's the same with synths for me. Nicely moulded pots with just the right balance between inertia and ease of rotation, that feel strong without a hint of wobble - it gives me an air of longevity and build quality.

Good pots are found on any Virus, the Moogs, the more expensive Nords and the like. MIDI controllers are pretty much a who's who of terrible, cheap feeling pots - with the exception of the Akai controller for Ableton, which felt like it was hewn out of rock.. The DSI stuff sits somewhere inbetween. With the new pots, I'm sure it'll feel like a different synth.

Re: DSI - Poly Evolver PE Conversion

Posted: Sat Nov 14, 2009 12:17 pm
by solitud
I`m also interested in the Pot replacement. My encoders feel cheasy and start dying away after one year usage. I contacted DSI. Now I have the option for an encoder based board replacement (for free) or the Pot upgrade for 399$.
Does anyone know how good is the build quality of the new pots?

Re: DSI - Poly Evolver PE Conversion

Posted: Sun Nov 15, 2009 3:08 am
by Cybananna
I haven't posted in ages, but I saw this.

I just installed the PE upgrade. So far I love it. the pots feel nice and I haven't noticed any "resolution" concerns. The remaining encoders are the Evolver style. Much better than the original PEK pot.

Totally worth the cost. Yea, it's a bit expensive, but to make such a great synth as the PEK work as it should, it's worth it.

Easy to install too.