Flexor NBL Alias Saw OSC: help needed

Cochise · Post by **Cochise** » Fri Oct 19, 2007 12:02 pm

I'm in doubt about the right place for this post.
I tried time ago the Flexor forum, but got no answer.
Problem Solving looks to me for generic issues, then...

1) Driving two of such OSC with the same freq, or with partials, I have beats, like having the twe OSC slightly detuned.

2) The phase knob and the phase mod feature have no audible effects on the sound.

I'm using them anyway wrong, or there's still something faulty in my system?

Shroomz~> · Post by **Shroomz~>** » Fri Oct 19, 2007 1:05 pm

Hi there,
I can answer your first question.

The reason for the beating is dsp distribution. As far as I know, when you load those 2 OSCs they will load on 2 separate dsps & this is the problem. After loading them, just put a sample delay after the OSC which needs delayed & adjust until they're in sync (if it's hard sync you're after). You can use a scope to do it visually if you don't trust your ears.

It was for this reason that I made MegaMulti. It has 5 multi OSCs which load on a single dsp allowing easy to set up hard sync, but it's limited to 3 voice poly unfortunately.

Shroomz~> · Post by **Shroomz~>** » Fri Oct 19, 2007 1:21 pm

Should have said that using a sample delay to solve the problem will probably mean you have to set it up each time you load the patch.

Best bet is probably to just detune the 2 oscillators slightly to get around the 'beating' issue. It will more than likely sound fatter anyway.

Cochise · Post by **Cochise** » Sat Oct 20, 2007 9:56 am

HI Shroomz.
Just tried Megamulti. Your module is really nice sounding, nice to handle and to look. Thank you very much for it.

As for the Flexor OSC, I don't think any longer those beats are a frequency issue, since they've not a constant cadence. Tweaking fine tune I get real constant beats but I never get a linear sound suitable for LFO based processing.
I wasn't able to find a sample delay between free modules, but better listening to that sound I'm not in the opinion this trick can solve.

The two samples I'm gonna attach will explain better than words.
In the first, two NBL Alias Saw running the same freq; in the second, one OSC has the freq doubled.
There's no modulation source and no parameters are edited during recording.

Shroomz~> · Post by **Shroomz~>** » Sat Oct 20, 2007 3:26 pm

Thanks for the feedback about MegaMulti, glad you like it.

I'm not sure that I can help you any further with regards to the Flexor OSCs, as I don't have them yet, so can't test them myself.

Cochise · Post by **Cochise** » Sun Oct 21, 2007 7:28 am

Shroomz II wrote:Thanks for the feedback...

Is it ring modulation used for the first 2 of the 3 mod input?

It would be also very useful to me being able to achieve partials and being able to use some OSC out as mod source inside the Megamulti.

The three voices max polyphony often is not a problem. Less than that is required for my drones, leads and FX.
Even some sort of harmony+melody parts can be performed with 3 voices..

Having 6 DSP available I never can get more than 2 -5 voices, unless I'm using a simple synth inside a simple project or I manage to track down some take using a separate project.

roy thinnes · Post by **roy thinnes** » Sun Oct 21, 2007 12:54 pm

Hi Cochise,
just connect the GateIn of the Flexor Oscs with the GateOut of the MVC.
After that, you won't hear these phasing artefacts. And tweaking the Phase knobs will change the sound, promised.

Cochise · Post by **Cochise** » Mon Oct 22, 2007 7:04 am

Hi Roy,
unluckily I've the same behaviour using NBL gate OSCs or syncing them by a gate2sync module. I get sounds like the one in the 2nd sample even playing two notes having a gap of 12 semitones, using a single OSC poliphonically

Holding the sound, the waves stay aligned during the first seconds then start to sweep.
It has quite random floats, but sounds more like a frequency than a phase issue

roy thinnes · Post by **roy thinnes** » Mon Oct 22, 2007 2:34 pm

strange. you connected the oscs like this

and get a sound like on your mp3?
Assuming your scope system is running stable, is it in slave mode? (sample frequency issue?)

Cochise · Post by **Cochise** » Mon Oct 22, 2007 6:05 pm

Yes, I tried connecting the OSCs the way you show. One of the two OSCs has the coarse range set 12 semitones up, in my patch.

Scope is running in master mode at 44.1 KHz, 6ms as ULLI setting.
I've had this specific problem since I got Flexor, and I reinstalled the whole system more than a couple of times since then.

I'm currently working on a project and the system is about stable. I actually had a couple of crashes in circumstances of almost full DSPs load; this happened two times during the last months.
Non Adern OSCs and the other modules in the patches I use are anyway working.

I've some doubt about the behaviour of some other Flexor module, like the Audio2Gate for example; but maybe it's just I don't yet understood how it works...

roy thinnes · Post by **roy thinnes** » Wed Oct 24, 2007 12:23 am

Cochise wrote:One of the two OSCs has the coarse range set 12 semitones up

ok, I see. In your first post you said that the oscs have the same freq.
mh, yes, that's true, the Flexor oscs have a problem in the scenario you described. But I would like to call it a feature, not a bug

. If you want a static, clean sound you have to go with the cw oscs.
Regarding your other note (problems with Audio2Gate), all I can say is I never had problems with it. It's fun to play around with it (eg replacing drums of a drumloop)

valis · Post by **valis** » Wed Oct 24, 2007 1:40 am

The NBL oscs are 'non bandwidth limited' and hence exhibit ALAISING, which is what causes the beating. This is by design as the oscs are design to be fast and thick for bass sounds, with a somewhat 'gritty' or 'thick' sound.

Flexor3 includes a selection of oscs that are largely free of aliasing and would work better for what you're experiencing.

Cochise · Post by **Cochise** » Wed Oct 24, 2007 7:59 am

roy thinnes wrote: mh, yes, that's true, the Flexor oscs have a problem in the scenario you described. But I would like to call it a feature, not a bug . If you want a static, clean sound you have to go with the cw oscs.
Regarding your other note (problems with Audio2Gate), all I can say is I never had problems with it. It's fun to play around with it (eg replacing drums of a drumloop)

I'm often not about a static clean sound, of course, but if the things moves following rules defined by me, or following rules I know, there's no need to fool around too much, when setting modulation parameters in the patch.
I'll follow your advice using other saw OSCs and adding tricks as detuning and/or phasing when I'll be looking for non random sounds.

As for the audio2gate: I never tried it with drum sounds.
For non drum sound I'm still working with env follower and gate compare, since i was not able to find the way with such module.

At the end I'm happy,since I was in the 'my hardware may be faulty' mood.

Cochise · Post by **Cochise** » Wed Oct 24, 2007 8:15 am

valis wrote:The NBL oscs are 'non bandwidth limited' and hence exhibit ALAISING, which is what causes the beating

I've to learn about aliasing at this point, since I'm absolutely not able to figure out by myself the rule those beats are following..