Please verify this bug

Tim Kleinert

IMPORTANT UPDATE: I found a robust workaround for this patch described lower in this thread.
Direct link:
http://www.electro-music.com/forum/post-409316.html#409316

As some of you might know, the delay lines have been bothering me since I bought my G2s two years ago. Evil or Very Mad

There was always something strange going on with them when using them for high accuracy stuff like physical modelling.

For a long time I believed that the 16 bit dynamic depth was the culprit, but somehow that didn't scan right. The artefacts I was repeatedly confronted with sounded very different from the kind of typical harmonic distortions you get from low dynamic resolution. And anyhow, 16 bits would still be good enough. Proof is the CombfFilter module, which is based on the same 16 bit memory, but doesn't produce those artefacts and sounds much much better for physical modelling applications.

But using the comb filter module all the time is restrictive in its own right, as it uses considerable more DSP and only offers logarithmic delay length response (very convenient for some purposes, less so for others).

I'm currently working on a patch similar to AAS string studio. It was initially based on comb filters, but I started breaking it down to delays (for DSP/polyphony reasons) and ran into those same old gremlins again. Evil or Very Mad

But I think I got them this time.

Please try out the attached patch. If you get what I got, then you should hear a strange cyclic rustling coming out of delay line 2. But please notice that no audio is running into delay line 2! Shocked

There is, however, audio running into delay line 1 (whose output isn't going anywhere). Turn off audio into delay 1, and delay 2 becomes silent too.

Or, turn off constant modulation value going into the time mod input of delay 2, and it also becomes silent.

I suspect that something funky is going on with the readout pointers, causing delay 2 to sometimes fetch a few samples of what is in delay 1.

Could you please verify this.

thanks,
tim

Bugreport 220506.pch2

Description:

notorious delay line weirdness possibly detected!

Download (listen)

Filename:

Bugreport 220506.pch2

Filesize:

1.35 KB

Downloaded:

2156 Time(s)

mosc · Posted: Wed Mar 22, 2006 10:12 am Post subject:

Yep, I think you have certainly identified a problem. My G2X V1.4 does exactly what you say it does.

I moved this to the Bugs forum... Idea

Tim Kleinert · Posted: Wed Mar 22, 2006 10:16 am Post subject:

Yeah, even the demo version does it. Shocked

So, good that you moved it to the bugs section, where it belongs now.

Ha! This is a personal victory for me. Twisted Evil

! FINALLY, I found what was going on all the time! Ah, the relief.

But -will Clavia ever fix it? Confused

cebec · Posted: Wed Mar 22, 2006 10:17 am Post subject:

i can confirm it on the Demo, too...
i would e-mail Clavia, and link them to this thread, perhaps...

Tim Kleinert · Posted: Wed Mar 22, 2006 10:54 am Post subject:

Well, at least I can go on with the patching now, knowing that it's not my fault.

I'll have to live with the artefacts though, until Clavia comes up with a fix. Rolling Eyes

Chet · Posted: Wed Mar 22, 2006 11:06 am Post subject:

That's excellent detective work, Tim. Clavia should be able to track it down pretty easily now.

v-un-v · Posted: Wed Mar 22, 2006 11:37 am Post subject:

Getting the same sound on the demo version here too.

Actually I quite like this sound- it reminds me of the noises/ feeling that you get when you stand under major electricity grid overhead powerlines!!

There are many quirks in hardware modulars and some would even argue that these quirks add character.

This has always been my complaint with the digital stuff- that it's too perfect.

Oh well- well spotted anyway Smile

mosc · Posted: Wed Mar 22, 2006 11:40 am Post subject:

3phase · Posted: Wed Mar 22, 2006 12:34 pm Post subject:

3phase · Posted: Wed Mar 22, 2006 12:37 pm Post subject:

Tim Kleinert · Posted: Wed Mar 22, 2006 12:45 pm Post subject:

I don't need the sound of "electricity grid overhead powerlines" in my waveguides, thank you. Laughing

v-un-v · Posted: Wed Mar 22, 2006 1:41 pm Post subject:

blue hell

dasz · Posted: Wed Mar 22, 2006 2:41 pm Post subject:

Nice find. Could also be some memory which is not cleared fully Wink

/Dasz

Antimon · Posted: Thu Mar 23, 2006 5:24 am Post subject:

Ah! Good work spotting that. I've run into this before as well, with a feedback loop over a delay that started living all by itself without any input when the delay length attenuator was modified by a MIDI send module.

/Stefan

dorremifasol · Posted: Wed Nov 15, 2006 4:12 pm Post subject:

I don't know if this the same bug but I find it extremely disappointing. I really love Tim's NL3 unison patch but I can't use it because there is some background noise going on when the delays are modulated. This is a really big bug! It shortens the (quality) sound possibilities by a largue amount, as the modulated delays are now useless, in the quality sense.

I'm posting this patch wich shows clearly the background noise I'm refering to. Sorry if this topic has been discussed before.

By the way, this is my first patch Smile

sorry, a bad start.

delay noise.pch2

Description:

weird delay noise

Download (listen)

Filename:

delay noise.pch2

Filesize:

1.83 KB

Downloaded:

1802 Time(s)

Axiom Crux · Joined: Sep 16, 2008 Posts: 8 Location: Detroit Florida

So can someone at clavia fix this already!!!!!!!!!!!!!!!!!!!!!!

drapdap · Posted: Thu Oct 22, 2009 5:49 am Post subject:

Chrono · Posted: Fri Oct 23, 2009 4:59 am Post subject:

that bug has been bothering me as well. it took me some time in the beginning before i really noticed it. But it seems to produce unwanted noise and sounds low quality. and this should still be fixed as i think clavia (nordkeyboards) is a high quality product range..

shall we just collect Signatures from everyone and send the mail to the nords chief. and just bother them a bit untill they cant go around it.

Tim Kleinert · Posted: Fri Oct 23, 2009 1:04 pm Post subject:

rutgerv · Posted: Wed Dec 11, 2013 12:10 pm Post subject:

I just want to confirm that I've identified the bug too, after spending more time with my G2. It's even in some of the preset sounds that Clavia delivers with the G2. Check for instance the 'G3' organ emulation patch. This has similar noise generated in the leslie emulation section. Strangely enough, only audible on the left channel.

Tim Kleinert · Posted: Sat Mar 28, 2015 9:48 am Post subject:

As described in the elaborations of my newest design...

http://electro-music.com/forum/topic-64110.html

...there's a robust (albeit a bit expensive) workaround for this bug. Smile

I described it pretty well there, so I'll just copy/paste the relevant paragraph here for reference: