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no audible effect sweeping the filter frequency with envelop amount zero

Hi ppl,

Don't know if this behavior of the filter section is an issue but it seems strange to me.

With the filter envelop amount set to zero there is no effect on the sound at all sweeping the filter frequency.
I'm using the init patch.

Only if I set the envelop amount to a negative value and the sustain to a high value lowering the frequency filters the sound.

If setting the envelop amount to positive values and sustain to zero or a high value again no filter effect is audible.

Is this correct?

Thank you in advance.

Re: no audible effect sweeping the filter frequency with envelop amount zero
« Reply #1 on: January 08, 2018, 07:08:44 AM »
I'm not 100% sure I understand the issue. Are you saying that turning the filter cutoff knob only has an effect if the filter envelope amount is set to negative values (plus full sustain)? Or are you saying that the filter envelope settings have no effect on the sound, except for when the filter envelope amount is set to negative values (plus full sustain)?

As a general rule: The filter frequency setting that you adjust with the filter cutoff knob affects the initial filter frequency, which also determines how much you will hear the filter envelope affect the filter frequency.


Examples:

If you want to modulate the filter frequency with the filter envelope at positive settings, you have to set the initial filter frequency to a lower value with the help of the cutoff knob. If the filter cutoff frequency is set to 100% and the filter envelope amount is set to 100% as well in this case, you won't hear the filter envelope cause any effect, as the filter is already wide open and there's nothing to add on behalf of the envelope at positive settings. Accordingly, if you want only the filter envelope to control the filter frequency, you have to set the initial cutoff frequency to zero.

If you want to modulate the filter frequency with the filter envelope at negative settings, you have to set the initial filter frequency to a positive value. If the filter cutoff frequency is set to zero and the filter envelope amount is set to 100% in this case, you won't hear the filter envelope cause any effect, as the filter is already closed and there's nothing to substract from on behalf of the envelope at negative settings. Accordingly, if you want only the filter envelope to control the filter frequency, you have to set the initial cutoff frequency to 100%.
« Last Edit: January 08, 2018, 07:31:22 AM by Paul Dither »
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Re: no audible effect sweeping the filter frequency with envelop amount zero
« Reply #2 on: January 08, 2018, 07:58:44 AM »
Have you made sure that the Velocity and Key Amount are at minimum ? They could be offsetting the filter cutoff frequency, rendering the cutoff knob seemingly inoperative temporarily.

« Last Edit: January 08, 2018, 08:00:44 AM by AlainHubert »
Minimoog D (vintage), DSI OB6 (module), Oberheim Matrix-6 (MIDI Controller), DSI REV2-16, Behringer DeepMind 12, Mac Mini Unibody 2010 (audacity).

Re: no audible effect sweeping the filter frequency with envelop amount zero
« Reply #3 on: January 08, 2018, 08:40:55 AM »
Thank you both for your information and hints.

I found out it wasn't correct.  ;)

Using "Reset Globals" turned the machine back to normal state.

I think the problem with the global section is if you accidentally adjust something also by external midi data without knowing you don't know what's wrong and it persists unfortunately. If I remember correctly it has happened before.

And I think there are hidden parameter, in this case something like a global offset of the filter frequency.
« Last Edit: January 08, 2018, 08:44:22 AM by SynthPlayer »

Re: no audible effect sweeping the filter frequency with envelop amount zero
« Reply #4 on: January 08, 2018, 09:07:57 AM »
That's good to know ! Thanks.
Minimoog D (vintage), DSI OB6 (module), Oberheim Matrix-6 (MIDI Controller), DSI REV2-16, Behringer DeepMind 12, Mac Mini Unibody 2010 (audacity).

Re: no audible effect sweeping the filter frequency with envelop amount zero
« Reply #5 on: January 09, 2018, 11:54:32 AM »
There are no hidden Global parameters for filter frequency offset. If you send external MIDI data to the Rev2 that certainly could have an effect on the sound engine without you knowing, depending on what is sent.
Dave Smith Instruments

Re: no audible effect sweeping the filter frequency with envelop amount zero
« Reply #6 on: January 10, 2018, 02:01:06 AM »
There are no hidden Global parameters for filter frequency offset. If you send external MIDI data to the Rev2 that certainly could have an effect on the sound engine without you knowing, depending on what is sent.
Hi Robot Heart,

I'm not sure. The synth had behaved as if there was a high offset added constantly to the filter frequency, so that it was no more possible to reduce the filter freqency to lower frequencies to filter the sound.
Only with a high negative env amount and a high sustain it was possible to reach an audible frequency.

This behavior persists between patch changes and switching on/off.

How do you explain this behavior without an high filter offset, which is stored anywhere but is unaccesible (hidden)?

Using "Reset Globals" instantly cures the wrong behavior.

br
« Last Edit: January 10, 2018, 02:03:42 AM by SynthPlayer »

Re: no audible effect sweeping the filter frequency with envelop amount zero
« Reply #7 on: January 10, 2018, 10:44:53 AM »
Hi SynthPlayer-

Because I am an employee of Dave Smith Instruments, I can tell you definitively, there is no hidden Global parameter for filter frequency offset.

If you can replicate the behavior, please contact our dedicated support channel with the exact steps to follow and we will help you troubleshoot: support(at)davesmithinstruments.com
Dave Smith Instruments

Re: no audible effect sweeping the filter frequency with envelop amount zero
« Reply #8 on: January 10, 2018, 10:58:10 AM »
Synthplayer, an explanation could be that, since the REV2 is heavily controlled by software, there might have been a glitch that would have offset the cutoff value sent to the filter via the DAC from temporary faulty data in memory ? Doing a reset would have clearly that altered wrong data, perhaps ? Without necessarily having been caused by some "hidden" parameter.
RAM memory has been known to change state, by different software/hardware glitches in the past.
;-) 
Minimoog D (vintage), DSI OB6 (module), Oberheim Matrix-6 (MIDI Controller), DSI REV2-16, Behringer DeepMind 12, Mac Mini Unibody 2010 (audacity).

Re: no audible effect sweeping the filter frequency with envelop amount zero
« Reply #9 on: January 10, 2018, 11:35:33 AM »
Synthplayer, an explanation could be that, since the REV2 is heavily controlled by software, there might have been a glitch that would have offset the cutoff value sent to the filter via the DAC from temporary faulty data in memory ? Doing a reset would have clearly that altered wrong data, perhaps ? Without necessarily having been caused by some "hidden" parameter.
RAM memory has been known to change state, by different software/hardware glitches in the past.
;-)

I think it's a bit presumptuous to suggest an error like this without any data to support anything of the nature. In my view making such a statement only serves to alarm users when there is no cause for alarm.
Dave Smith Instruments

Re: no audible effect sweeping the filter frequency with envelop amount zero
« Reply #10 on: January 10, 2018, 12:52:56 PM »
Have you checked the pot mode setting in the globals and checked that no USB or MIDI cables are connected to your instrument when you observe this behavior? It could be something as simple as not being completely aware of how the pots behave on the instrument given current global settings.
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Re: no audible effect sweeping the filter frequency with envelop amount zero
« Reply #11 on: January 11, 2018, 08:04:24 AM »
Synthplayer, an explanation could be that, since the REV2 is heavily controlled by software, there might have been a glitch that would have offset the cutoff value sent to the filter via the DAC from temporary faulty data in memory ? Doing a reset would have clearly that altered wrong data, perhaps ? Without necessarily having been caused by some "hidden" parameter.
RAM memory has been known to change state, by different software/hardware glitches in the past.
;-)

I think it's a bit presumptuous to suggest an error like this without any data to support anything of the nature. In my view making such a statement only serves to alarm users when there is no cause for alarm.

That was certainly not my intention. There is no cause for alarm, since this might have been a once in a million fluke.
But memory data can become corrupt, without apparent cause, even though it's extremely rare. Either from a glitch on the power rails, an unknown obscure software bug under a very specific occurence, or even cosmic rays from the Sun.
Flash RAM is not immune to this. But that's no cause for concern, unless you have very valuable data in memory.
That's why it's always a good idea to have a backup of any important data. Not only of your patches in a synth, but with any computer device, be it smartphone or personal computer.

BTW, in DSI's own REV2 user's guide manual, on page 66, it is stated: "If you're trying to track down a problem, it's sometimes a good idea to reset the Global parameters to their defaults. This is a quick way to make sure that the Prophet REV2 returns to its factory settings".
Suggesting that some of those parameters might have been changed, either inadvertently or else.
Minimoog D (vintage), DSI OB6 (module), Oberheim Matrix-6 (MIDI Controller), DSI REV2-16, Behringer DeepMind 12, Mac Mini Unibody 2010 (audacity).

Re: no audible effect sweeping the filter frequency with envelop amount zero
« Reply #12 on: January 11, 2018, 01:52:34 PM »
We're certainly not suggesting that parameters may change on their own. It is possible for Globals to be changed inadvertently though, either from user or MIDI input.
Dave Smith Instruments