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 Forum index » Clavia Nord Modular » Nord Modular G2 Discussion
dlyeight module
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Fozzie



Joined: Jun 04, 2004
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PostPosted: Fri Jan 26, 2007 6:54 am    Post subject: dlyeight module
Subject description: is setting '4' in 5ms mode 1 sample / tap??
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While I am busy doing other things (looks over shoulder to check for suspicious colleagues), I wondered some things about FIR filters. I did some experiments with 'em before, but always used a clocked delay module with a 48kHz clock to get access to n-1, n-2, n-3, etc samples. I did not use the dlyeight module before, as the display and manual do not give any sample-accurate info, and an initial experiment didn't work out.

I ran some experiments on the demo software, using VU meters for monitoring and some simple s/h stuff to see how the dlyeight module behaves when clocked with 48kHz or 12kHz rates (see attached demo patch; don't turn up sound or activate outputs for your speakers sake).

When clocking at 48k and taking alternating outputs summed to mixers hardpanned left & right, I get 'high signal' / silence (left / right) when the delay is set to 0.02 ms (value 4). The same happens for 12k clocking when taking blocks of 4 consecutive taps mixed together and panned left / right. Can we safely assume that this delay setting is really a '1 sample per tap delay'? I noticed that the 48k experiment yields similar results at values 8, 12, 16 etc, but the 12k setting does not have this exact replication of results; am I correct to think this means it is really a 1 sample delay and not some multiple-sample delay setting that yields the same output?

My thinking is not too 'hi-fi' due to a nasty sinusitus+headache; is there anyone that understands my blabbering and can confirm or correct my thoughts?


dl8test.pch2
 Description:
File to test exact 1 sample delay setting in dlyeight module. Needs some repatching to test both 12 and 48k clocks. DON'T turn up sound; it is for testing with VU meters (in the editor) only!! Don't hold me responsible for breaking any speakers if you do

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 Filename:  dl8test.pch2
 Filesize:  1.02 KB
 Downloaded:  1480 Time(s)


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blue hell
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PostPosted: Fri Jan 26, 2007 6:08 pm    Post subject: Reply with quote  Mark this post and the followings unread

I made another test patch that makes me understand better what happens .. I think ...

first a calculation rate of 96 kHz means that one sample time is about 10 us, or 0.01 ms. So when the delay is set to 0.02 one would expect that to surmount to two sample times of delay.

In the patch I took a flip flop that I set from the signal and that I clear with the delayed signal. the idea being that the flip flop would be executed at 96 kHz so setting it one cycle before clearing it should make it toggle it's outputs.

the flipflop's output is divided by 128 to get an audible frequency.

So setting a delay time corresponding to one sample is expected to give audible output. However, I have to set the delay to 0.02 ms to get audio.

So I'm afraid I understand it no better Shocked

Is the delay not running at 96 kHz or is the flip-flop not ?


dl8test_01.pch2
 Description:

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 Filename:  dl8test_01.pch2
 Filesize:  907 Bytes
 Downloaded:  2339 Time(s)


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also .. could someone please turn down the thermostat a bit.
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Fozzie



Joined: Jun 04, 2004
Posts: 875
Location: Near Wageningen, the Netherlands
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G2 patch files: 49

PostPosted: Sat Jan 27, 2007 1:37 am    Post subject: Reply with quote  Mark this post and the followings unread

Yes, I figured that out about the 0.01 ms per sample, but maybe it's just that the display of the module is not accurate at these low rates. I also noticed that for the lowest values, it appears that single value steps do not alter the delay setting, but this happens in blocks of 4 values.

I tried to make some experimental filters or chorus-like stuff (none of which sounded good btw) and noticed that in all cases the sound did not chang at these values: 0-3; 4-7; 8-11; 12-15; 16-19. This was similar in my clock experiments. I'm not sure about it not being at 96k, but I do think it implies there's no sample interpolation.

Will have a look at your patch, Blue Hell, and see if I can figure it out some more. Nice to hear that you find the same results....

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Fozzie



Joined: Jun 04, 2004
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PostPosted: Sat Jan 27, 2007 2:56 am    Post subject: Reply with quote  Mark this post and the followings unread

The clock and the flipflop operate both at 96k; the resulting squarewave has a frequency of 48k, which is brought down to 375Hz by the 128-divider (48k/128=375). I compared the frequency to an osc, and it is indeed 375Hz. So proves imo the 96k operation.

Now I guess there are two options: the display is wrong, or the delay works in blocks of two samples. These value-blocks that I mentioned earlier apply over the whole knob-range, leaving 32 functional steps that in your patch of which 16 steps result in a signal, and 16 result in silence. Isn't this just weird? For the display setting to be correct, value 127 or .66ms should be 64 samples delay.
Correction of the above statement: there is of course the third option of my brains making some crucial error here.... will report back...

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Fozzie



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PostPosted: Sat Jan 27, 2007 4:32 am    Post subject: Reply with quote  Mark this post and the followings unread

Well, tested further a bit. I really think the display is off by a factor 2, so maybe this thread should be moved to the buglist.

In this testpatch, I use the 48k clock to clock a sequencer with 4 different values (lenght=4 and reset is at 1/4 of clock), patch the output of the seq into the delay, and readout the delay outputs with s/h's at the reset-moment of the sequencer.
The outputs show 4 pairs of the 4 sequencer values, which corresponds to a 96k reading of a 48k sequence.

I say this is all a bit weird, but my conclusion is that values 0-3 correspond to no delay (all taps reflect the input value), 4-7 to 1 sample, 8-11 to 2 samples, etc.
Hence, the max delay is 32 samples per tap, or 2.6ms total delay if I'm correct.


dl8test_02.pch2
 Description:
Another visual test patch for the delightful dlyeight module at it's lowest settings

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 Filename:  dl8test_02.pch2
 Filesize:  1.53 KB
 Downloaded:  1420 Time(s)


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Fozzie



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PostPosted: Sat Jan 27, 2007 5:12 am    Post subject: Reply with quote  Mark this post and the followings unread

Yep, definite bug here. The Dlyeight module shows the wrong display values. Check the attached file for proof. The help file / manual states that the display of the dlyeight module shows the delay per tap, but it really shows the delay per 2 taps. The attached file shows it with a panned drumsound with a stat-delay and the dlyeight module.

Bug Shocked


edit: the bug it of course pretty harmless, but the memory usage is doubled if the dlyeight module is used compared to other delay modules, so it's not just the display setting; there is actual sample memory being wasted Sad


SwedishDeleight.pch2
 Description:
Patch shows bug in the dlyeight display setting. The value shown is the delay per 2 taps, not per tap.

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 Filename:  SwedishDeleight.pch2
 Filesize:  1.08 KB
 Downloaded:  1501 Time(s)


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blue hell
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PostPosted: Sat Jan 27, 2007 6:04 am    Post subject: Reply with quote  Mark this post and the followings unread

Ah, this is starting to get interesting Very Happy

Maybe the delay does work with 16 bit samples then and not 8 ? Here we go again ....

Will try the patches later.

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also .. could someone please turn down the thermostat a bit.
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Fozzie



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PostPosted: Sat Jan 27, 2007 6:38 am    Post subject: Reply with quote  Mark this post and the followings unread

Blue Hell wrote:
Ah, this is starting to get interesting Very Happy

Maybe the delay does work with 16 bit samples then and not 8 ? Here we go again ....



You mean 32 bit instead of 16, right? Else Question

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blue hell
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PostPosted: Sat Jan 27, 2007 6:40 am    Post subject: Reply with quote  Mark this post and the followings unread

Fozzie wrote:
Blue Hell wrote:
Ah, this is starting to get interesting Very Happy

Maybe the delay does work with 16 bit samples then and not 8 ? Here we go again ....



You mean 32 bit instead of 16, right? Else Question


Embarassed still waking up Laughing

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Fozzie



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PostPosted: Sat Jan 27, 2007 7:12 am    Post subject: Reply with quote  Mark this post and the followings unread

I've tried the precision of the dlyeight outputs by feeding it an very low attenuated logic high (attenuated to the amount that it *just* triggers a trigger in on a drum osc).

The attenuation threshold for direct triggering is 0.01*0.01*0.01*0.5 (gains on levelamp modules). If the dlyeight module is used, the threshold is twice as high; the last levelamp should be >=1.0.

Here's where it starts to get weird: for a mod-delay the threshold is only 0.01*0.01*0.29 (!), as for the other standard delay modules. The clocked delay however is the same as direct triggering. For the comb filter, it is 0.01*0.01*0.01*1.5

I thought there was just one difference; either 24 bit or 16 bit. Seems there are other bitdepths as well Question

Edit: just realized, that probably the dlyeight module might be the only long-delay module at 24 bit minus one (headroom?) bit, right?
edit 2: that would be kinda ironic if it is so, as this is a non-modulatible delay, so perfectly unsuited for any PM Confused

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Rob



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PostPosted: Mon Feb 05, 2007 6:12 pm    Post subject: Reply with quote  Mark this post and the followings unread

The DlyEight module is off by 4 ticks on the scale, the knob positions 0 to 3 simply "do not work" and the input is passed unaltered on all eight outputs, so all delays are zero. At position 4 to 7 the eight delay outputs give delays of 1 to 8 samples. Then at knob position 8 to 11 the delays are from 2 to 16 samples with gaps of a sample. At knob position 12 to 15 they are 3 to 24 samples with gaps of 3 samples. Etc.

So, the display is utterly incorrect, as there are actually only 32 ranges on the knob and not 128 as could be expected from the display.

I guess one has to be Swedish and be used to lock oneself up during long dark winters to come up with the actual function of this particular module, and then, when spring finally comes, forget how it actually works and put total nonsense in the display.
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Fozzie



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PostPosted: Tue Feb 06, 2007 9:13 am    Post subject: Reply with quote  Mark this post and the followings unread

Rob wrote:
I guess one has to be Swedish and be used to lock oneself up during long dark winters to come up with the actual function of this particular module, and then, when spring finally comes, forget how it actually works and put total nonsense in the display.

Laughing
Thanks for confirming my suspicions. Do you also have some inside intel on the bit-depth? Regarding measured delay lenght, memory usage and low signal testing, the results really suggest this is a kind of double-precision delay module (24bit?).

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dasz



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PostPosted: Tue Feb 06, 2007 9:59 am    Post subject: Reply with quote  Mark this post and the followings unread

This delay display is indeed disconcerting. A tick on a knob is meant to reflect some change otherwise it should be a multistage switch (or click-knob with n settings).

I really dislike the delay (& LFO) time knob when it is in clk mode. You turn it for a while before a change happens. A way better implementation on Clavia's part would have been something along these lines -- a 1/n or n/1 button, a multiplier knob and then the delay knob would delay in terms of 1/n or n/1 (where n = ticks * multiplier). The max clk setting on LFO's is waay to short.

Btw Rob, your website link is not working. this one is http://www.xs4all.nl/~rhordijk

And nice big g2 gif! where did you get it from?
/Dasz
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Rob



Joined: Mar 29, 2004
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PostPosted: Tue Feb 06, 2007 1:40 pm    Post subject: Reply with quote  Mark this post and the followings unread

Fozzie wrote:
Thanks for confirming my suspicions. Do you also have some inside intel on the bit-depth? Regarding measured delay lenght, memory usage and low signal testing, the results really suggest this is a kind of double-precision delay module (24bit?).


As far as I know it uses 16 bit and 512 memory locations in the 5msec mode. The DlyEight does not use interpolation, while the modulatable delays do use interpolation in the 5 msec mode.

Note that the code for the different max delaytime settings differs. So for other max delay settings the display might actually be correct.
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Rob



Joined: Mar 29, 2004
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PostPosted: Tue Feb 06, 2007 1:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

dasz wrote:
Btw Rob, your website link is not working. this one is http://www.xs4all.nl/~rhordijk

Perhaps you used an old link that leads to nowhere. This one should work:
Rob Hordijk's G2 Tutorial

dasz wrote:

And nice big g2 gif! where did you get it from?
/Dasz

Did you ever take a good look at the front of your G2? Wink

/Rob
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Fozzie



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Location: Near Wageningen, the Netherlands
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PostPosted: Tue Feb 06, 2007 2:17 pm    Post subject: Reply with quote  Mark this post and the followings unread

Well, if you test the dlyeight module (input and 8th output used) side-by-side with say a delay single module, the memory usage is identical for all knob settings of delay time in both modules, but the delaytime of the dlyeight module is exactly half the delaytime of a delay single. See attached patch variation 1 and 2.

Note: I have tested all this on the demo only, but assume this is the same on the hw.


dlyeight_halflength.pch2
 Description:
Dlyeight testpatch once again. Check variation 1 and 2; notice dlyeight module total delay lenght is exactly half of the delaysingle delay time.

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 Filename:  dlyeight_halflength.pch2
 Filesize:  1006 Bytes
 Downloaded:  1491 Time(s)


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dasz



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PostPosted: Tue Feb 06, 2007 2:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

Rob, by website link I mean the e-m profile link (the www button on every post of yours -- that's not working).
/Dasz
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Rob



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PostPosted: Tue Feb 06, 2007 2:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

dasz wrote:
Rob, by website link I mean the e-m profile link (the www button on every post of yours -- that's not working).
/Dasz

You're right, my mistake! Forgot to update that old link. Embarassed

Fixed it!

Thanks! Very Happy
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dasz



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PostPosted: Wed Feb 07, 2007 11:35 am    Post subject: Reply with quote  Mark this post and the followings unread

No worries, Rob. I was on a clicking spree when I found it didn't work.
/Dasz
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