Little Phatty KB AMOUNT "stepping"- What's wrong?

[Kenneth]

Recently I've noticed considerable "stepping" when the "KB AMOUNT" parameter is adjusted. I have provided an audio clip documenting the issue at hand. If anyone has any idea what the problem is and how it may be remedied, please let me know. Thanks

Audio clip: http://soundcloud.com/ynnek001/moog-lit ... -kb-amount

[RL]

Hi Kenneth,
nothing is wrong with your Phatty, the KB Amount pot is not a controller - it is just a pot to adjust the KB-Amount. Maybe the RAC™ mode helps.
Have fun,
Rudi

[muksys]

Not all parameters have the RAC (Real Analog Control) feature. The ones that do are: Osc 1 & 2, Filter Cutoff, Filter Resonance, EG Amount, Overload and Filter EG Sustain parameters. Any other parameter is controlled via MIDI, which is where the stepping is coming from. I just tested on my LP and I get the same stepping at the KBA. Also, if you set the resonance to max then grab the cutoff and turn it real quick, you will here stepping before the RAC kicks in.

[stiiiiiiive]

Not all parameters have the RAC (Real Audio Control) feature. The ones that do are: Osc 1 & 2, Filter Cutoff, Filter Resonance, EG Amount, Overload and Filter EG Sustain parameters.

Thanks you very much for that. Very ineresting.
Let me just correct you: RAC stands for Real Analog Control.

Also, if you set the resonance to max then grab the cutoff and turn it real quick, you will here stepping before the RAC kicks in.

I cannot get that. Can you be more precise?
EDIT: ah ok, I think I get it. You mean when selecting the Cut Off frequency to be controlled by the knob, there is a little time before the RAC acts. Am I wrong?

[muksys]

Let me just correct you: RAC stands for Real Analog Control.

ah, yes yes, "Analog", haha

I cannot get that. Can you be more precise?
EDIT: ah ok, I think I get it. You mean when selecting the Cut Off frequency to be controlled by the knob, there is a little time befre the RAC acts. Am I wrong?

Exactly.

[Kenneth]

Thanks for the help everyone. Glad to hear there is nothing wrong with my Phatty, though the stepping is really bothering me. It sounds so... gross. I guess I never understood that there was digital circuitry inside the LP. I suppose I was a little thrown off by Moog always saying "100% analog signal path blah blah blah" and so forth. Does this bother anyone else?

[muksys]

Thanks for the help everyone. Glad to hear there is nothing wrong with my Phatty, though the stepping is really bothering me. It sounds so... gross. I guess I never understood that there was digital circuitry inside the LP. I suppose I was a little thrown off by Moog always saying "100% analog signal path blah blah blah" and so forth. Does this bother anyone else?

Yes & no. I can understand it. I'm happy that the parameters that matter have analog control (cutoff & resonance). A lot of the "analog" synths nowadays do have 100% signal path (oscillators, filters and amp being analog circuitry) but use digital for things like the mod bus and EG's (The DSI line uses analog for the audio and that's it. The LFO, EG and Modulation Matrix are all digital). But, that's not to say the KB Amount circuit on the LP isn't analog, it's just the parameter is controlled via MIDI. So, it still maintains the analog stamp.

[nathanscribe]

Also, don't forget that many of the highly respected classics also use digital parameter control of analogue circuits - nobody complains about the Prophet 5's resolution, for example. Digital scanning and control of parameters is what enables patch storage - without it, there'd be no memories. Any analogue synth with digital patch storage must scan the controls digitally, which means a trade-off against parameter resolution.

I doubt Keyboard CV is one of the things most people would want to tweak in real-time, and it seems that the stepping is mostly evident when you move it pretty fast.

[Kenneth]

I see what you guys are saying, and you're all making valid sense. I guess it really isn't a big deal. I've heard the Voyager has the same issue, so I'm thinking it's probably one of those things I'm going to have to live with. I have one question: if MIDI control is required in order to have patch memory, why is it that some parameters can be adjusted analogically (via RAC mode) and others cannot?

[muksys]

I have one question: if MIDI control is required in order to have patch memory, why is it that some parameters can be adjusted analogically (via RAC mode) and others cannot?

My guess is the reason for not adding RAC to every parameter was a matter of CPU usage. The processor may not be able to handle digital scanning and RAC of every parameter simultaneously. Besides, not every parameter would really benefit from RAC anyway.

[Sir Nose]

I have one question: if MIDI control is required in order to have patch memory, why is it that some parameters can be adjusted analogically (via RAC mode) and others cannot?

My guess is the reason for not adding RAC to every parameter was a matter of CPU usage. The processor may not be able to handle digital scanning and RAC of every parameter simultaneously. Besides, not every parameter would really benefit from RAC anyway.

I think it was just for cost saving as the tribute has RAC on all parameters.

[muksys]

I have one question: if MIDI control is required in order to have patch memory, why is it that some parameters can be adjusted analogically (via RAC mode) and others cannot?

My guess is the reason for not adding RAC to every parameter was a matter of CPU usage. The processor may not be able to handle digital scanning and RAC of every parameter simultaneously. Besides, not every parameter would really benefit from RAC anyway.

I think it was just for cost saving as the tribute has RAC on all parameters.

Interesting. I did not know that! How much, really, does this shave off the cost?? Is this a software thing, or does there need to be additional parts added to the board? Could the parts really be that expensive to warrant not adding them? I could not imagine it costing more than $100 to add RAC to all parameters! I'd pay extra for that.

[Sir Nose]

I have one question: if MIDI control is required in order to have patch memory, why is it that some parameters can be adjusted analogically (via RAC mode) and others cannot?

My guess is the reason for not adding RAC to every parameter was a matter of CPU usage. The processor may not be able to handle digital scanning and RAC of every parameter simultaneously. Besides, not every parameter would really benefit from RAC anyway.

I think it was just for cost saving as the tribute has RAC on all parameters.

Interesting. I did not know that! How much, really, does this shave off the cost?? Is this a software thing, or does there need to be additional parts added to the board? Could the parts really be that expensive to warrant not adding them? I could not imagine it costing more than $100 to add RAC to all parameters! I'd pay extra for that.

I think most of the cost comes into play with calibration of each unit before it leaves the factory. I know the tribute has several more trim pots inside than the stages.

[Mr Shave]

Does anyone out there actually know how the RAC works? I've always been curious, from a technical standpoint, how this technology works... it seems like PFM to me..