u-he

Sequence2 · Post by **Sequence2** » Thu Dec 27, 2012 3:34 am

I am having some difficulties understanding how this filter works exactly (Specifically with the Offset/ Cutoff knob & the different types of filters you can use

I understand how the routing system works.. but the actual filtering has me somewhat lost and I was looking for some advice

From my knowledge of synthesis.. this XMF filter would make sense if there was a cutoff1/ cutoff2 knob (each to control the assigned filters, may it be cutoff1 controlling a LP in type 1, and cutoff 2 controlling a BP2 in Type 2) But this isn't the case

So my question is (as the manual doesn't really explain how this works)
what is going on with this filter? If I set Type 1 to LP4, use Serial routing, and BP2 in Type2, with Analogue character.. what am I doing to the sound when I turn the cutoff knob/ Offset knob

Single mode is very easy to understand as it just pans the sound between the speakers.. but it only makes sense when type 1 is set to any of the modes.. while type2 is set to 'same'

If you guys know any videos, or previous posts that explain what is going on, I would greatly appreciate the links.. or any feedback for that matter!
Thanks!!!

bmrzycki · Post by **bmrzycki** » Thu Dec 27, 2012 4:34 am

This youtube video does a great job of showcasing the pair of filters (actually 4, it's 2 pair of stereo filters) and their configurations:

The other videos by Howard are extremely useful too IMO.

Sequence2 · Post by **Sequence2** » Thu Dec 27, 2012 8:11 am

I did watch this video.. but it doesn't exactly go into detail as to how the cutoff knob/ offset knob works with other filter types as he only uses LP in the type 1 area and LP or same in the type2 area..

It's just confusing trying to understand the routing of this Filter.. I think of it as if: type1 is a Low Pass.. and type2 is a High pass.. so does this mean that in serial mode the sound first passes though a Low pass filter, then a high pass filter? and if this is the case, then with only 1 cutoff knob.. you must be defining a certain point in the spectrum (Perhaps 2KhZ) which in turn means that you cut all frequencies below 2Khz and above 2KhZ, theoretically creating a BP filter? How then does this work if you set type1 to a LP filter and Type2 to a BP filter?

-please correct me if I am wrong as I know it is 100% possible and I just don't understand this filter to save my life (which I clearly don't as the manual lacks the information to adequately explain how this works..

EvilDragon · Post by **EvilDragon** » Thu Dec 27, 2012 8:30 am

You are correct with your example above - in serial mode, Type1 goes into Type2, Cutoff sets the cutoff frequency of BOTH filters, as long as Offset is set to 0. Offset will change the cutoff frequency of BOTH filters. One filter will have Cutoff - Offset frequency, the other will have Cutoff + Offset frequency. I just noticed this.

Howard · Post by **Howard** » Thu Dec 27, 2012 9:31 am

OK, I'll work on that bit of the manual to make it more clear.

EvilDragon · Post by **EvilDragon** » Thu Dec 27, 2012 10:42 am

I wish Offset was a true offset, and not a +/- symmetrical split as it is right now, though...

^_^;

Howard · Post by **Howard** » Thu Dec 27, 2012 11:14 am

EvilDragon wrote:I wish Offset was a true offset, and not a +/- symmetrical split as it is right now, though...

^_^;

modulate cutoff and offset from the same source, and by the same amount (where there's a will, there's a way!)

EvilDragon · Post by **EvilDragon** » Thu Dec 27, 2012 11:22 am

That's a bit roundaboutish way to go about it. I'd like to be able to assign different modulations with different amounts to both, but keep a certain offset. Would be a shame to use the matrix just for this, when there could be a different mode for the Offset knob (kind of the same as Fall/Rise knob for envelopes - it has different modes there). One mode (current one) could be called "Split", the other one would be true "Offset".

Howard · Post by **Howard** » Thu Dec 27, 2012 2:27 pm

EvilDragon wrote:That's a bit roundaboutish way to go about it. I'd like to be able to assign different modulations with different amounts to both, but keep a certain offset.

Do you mean like the two VCFs in ACE?

bmrzycki · Post by **bmrzycki** » Thu Dec 27, 2012 4:01 pm

Howard wrote:
EvilDragon wrote:That's a bit roundaboutish way to go about it. I'd like to be able to assign different modulations with different amounts to both, but keep a certain offset.
Do you mean like the two VCFs in ACE?

I think he means he'd like it to operate more like the separation knob on the (imp)OSCar.

EvilDragon · Post by **EvilDragon** » Thu Dec 27, 2012 7:07 pm

Exactly!

Sequence2 · Post by **Sequence2** » Thu Dec 27, 2012 8:55 pm

EvilDragon wrote: Offset will change the cutoff frequency of BOTH filters. One filter will have Cutoff - Offset frequency, the other will have Cutoff + Offset frequency. I just noticed this.

Thank you so much for the reply! I am beginning to puzzle the pieces together..
As I have never worked with offset before on a filter.. I just had one more question
So in the example I used above, lets say were have the LP/ HP in type 1/ type 2 in serial mode set to 2KhZ
You said that one filter will have a negative offset frequency, while the other has positive offset frequency

How exactly would it affect the above example if I turned the offset knob clockwise/ counter clockwise? Would a value of +25 (offset knob) cause the set value of the cutoff (2KhZ) to.. expand in a sense? and by this I mean the width of the BP we created by using a HP/ LP filter? (Before the filters were both centred at 2kHz, now they move apart (By increasing the value of the offset knob) so the LP maybe sits at 2.5KhZ while the HP now sits at 1.5KhZ? - being offset from the frequency set by the cutoff knob)

pdxindy · Post by **pdxindy** » Thu Dec 27, 2012 9:04 pm

Sequence2 wrote:
EvilDragon wrote: Offset will change the cutoff frequency of BOTH filters. One filter will have Cutoff - Offset frequency, the other will have Cutoff + Offset frequency. I just noticed this.
Thank you so much for the reply! I am beginning to puzzle the pieces together..
As I have never worked with offset before on a filter.. I just had one more question
So in the example I used above, lets say were have the LP/ HP in type 1/ type 2 in serial mode set to 2KhZ
You said that one filter will have a negative offset frequency, while the other has positive offset frequency

How exactly would it affect the above example if I turned the offset knob clockwise/ counter clockwise? Would a value of +25 (offset knob) cause the set value of the cutoff (2KhZ) to.. expand in a sense? and by this I mean the width of the BP we created by using a HP/ LP filter? (Before the filters were both centred at 2kHz, now they move apart (By increasing the value of the offset knob) so the LP maybe sits at 2.5KhZ while the HP now sits at 1.5KhZ? - being offset from the frequency set by the cutoff knob)

that is correct... offset will change the F1 cutoff up and F2 cutoff down in serial mode... or opposite if you turn the knob the other way

EvilDragon · Post by **EvilDragon** » Thu Dec 27, 2012 9:58 pm

It's really easiest to listen to what Offset does in Parallel mode. Put two LP4 filters, raise Resonance to 50 and Keyfollow to 100. You will hear two resonant peaks, following the pitch on the keyboard. As you move offset, the resonant peaks will detune in semitones. Now try to modulate Offset with LFO. Blimey!