OS 2.0 Question

[LPF83]

Hi.. just a quick question asking for clarity the release notes don't seem to address: 

"New 4-Pole low pass filter type with fuller bass at high resonance"..

is the new filter type basically Q compensation for the existing 4 pole analog filter, or is there a new digital filter type, etc? 

Thanks

[BT]

Hi! The OB-X8 signal path is and remains entirely analog. This OS update did not add a digital filter emulation to the OB-X8, instead the new Xa 4-pole filter mode uses CV control over the existing circuitry to dynamically scale gain, feedback, and resonance to retain bass frequencies at high resonance levels. 

[g3o2]

Quoted comment Marcus Ryle comment from the official OS 2.0 Youtube video;
https://www.youtube.com/watch?v=44M6VwTDRdU

To add some more detail regarding the new filter type: The entire audio signal path in the OB-X8 continues to always stay 100% analog. What has changed is the way that the analog circuitry is configured and controlled under the control of the firmware. The new filter mode doesn't replace any of the existing six filter modes, it is a new seventh mode. Of the six existing modes, only one is a 4-pole, and it is exactly the same configuration as in the OB-Xa and OB-8 (utilizing the same authentic Curtis CEM3320 filter chip that was in the originals). It was very important to us to replicate exactly the analog circuitry and performance from the originals, so the OB-X8's existing 4-pole mode works exactly as it does in the originals, which means that the resonance amount is limited, and the amplitude of the output decreases as resonance increases. Although I do love the sound of the original 4-pole filter, especially at lower resonance levels, I honestly have long lamented (since the '80s!) that it loses "girth" as you increase the resonance. While we were brainstorming new features that we could add to the OB-X8 firmware it occurred to us that we could utilize the programmable circuitry around the filter, namely the input, output, and resonance VCAs, to provide gain and feedback compensation dynamically depending on resonance level. And while we were at it, we let the resonance VCA increase further than before, so that more extreme 4-pole resonance sounds can be achieved. The result, IMO, sounds really great, and brings to the OB-X8 a new filter mode that never existed in any of the classic Oberheim's (and without having to give up any of the old ones).  Hope you all enjoy it as much as I do!

[LPF83]

Excellent, thanks for the info!

[the_s_rabbit]

Cat's out of the bag now! With that much control over the circuitry via firmware, there's no reason to not beg for the low pass / notch / high pass blend feature.

For real though, the new 4-pole mode is a killer addition, and totally unexpected.

[ladygaga]

Quoted comment Marcus Ryle comment from the official OS 2.0 Youtube video;
https://www.youtube.com/watch?v=44M6VwTDRdU

To add some more detail regarding the new filter type: The entire audio signal path in the OB-X8 continues to always stay 100% analog. What has changed is the way that the analog circuitry is configured and controlled under the control of the firmware. The new filter mode doesn't replace any of the existing six filter modes, it is a new seventh mode. Of the six existing modes, only one is a 4-pole, and it is exactly the same configuration as in the OB-Xa and OB-8 (utilizing the same authentic Curtis CEM3320 filter chip that was in the originals). It was very important to us to replicate exactly the analog circuitry and performance from the originals, so the OB-X8's existing 4-pole mode works exactly as it does in the originals, which means that the resonance amount is limited, and the amplitude of the output decreases as resonance increases. Although I do love the sound of the original 4-pole filter, especially at lower resonance levels, I honestly have long lamented (since the '80s!) that it loses "girth" as you increase the resonance. While we were brainstorming new features that we could add to the OB-X8 firmware it occurred to us that we could utilize the programmable circuitry around the filter, namely the input, output, and resonance VCAs, to provide gain and feedback compensation dynamically depending on resonance level. And while we were at it, we let the resonance VCA increase further than before, so that more extreme 4-pole resonance sounds can be achieved. The result, IMO, sounds really great, and brings to the OB-X8 a new filter mode that never existed in any of the classic Oberheim's (and without having to give up any of the old ones).  Hope you all enjoy it as much as I do!
sprunki retake

Cool update.  Polychain especially but the rest two.  16 voices with the module or go nuts and have three modules with the keyboard.  Crazy.  Thanks Sequential.  Great job.

[waxdoctor]

Cat's out of the bag now! With that much control over the circuitry via firmware, there's no reason to not beg for the low pass / notch / high pass blend feature.

If that were possible... A dream would come true...

[Teiko]

Personally I am not sure if this would be possible. As far as I understand the whole point is that there is only a kind of gain compensation.

But technically from my experience this is something totally different to having a function which is sweeping continously between filter types.

Of course if they would find a way to implement this I would love it .. nevertheless I would appreciate when old bugs would be fixed first

[BT]

Unfortunately, continuously variable filter type selection would require a hardware revision of the main boards in the OB-X8.

[jeffreestar]

Personally I am not sure if this would be possible. As far as I understand the whole point is that there is only a kind of gain compensation.

But technically from my experience this is something totally different to having a function which is sweeping continously between filter types.

Of course if they would find a way to implement this I would love it .. nevertheless I would appreciate when old bugs would be fixed first PolyTrack

It's highly probable that the "new 4-pole low-pass filter type with fuller bass at high resonance" refers to an enhancement of the existing 4-pole analog filter, most likely through Q compensation or a modification of the filter's analog behavior.