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Clipping with SID chip when envelope resets (e.g. notes with silence between them)

18 posts in this topic

Hi again,

 

I am possibly having another configuration issue, hopefully I'm just doing something stupid: 

 

I am experiencing a "popping" sound every time I play a note that isn't a continuous run or melody.  So if there are rests between the notes, I get a pop, like when a waveform is not starting at zero amplitude.  I don't know if that's what's happening but that is the best way to describe the sound.

 

I uploaded a youtube video to help demonstrate the sounds I am getting: http://www.youtube.com/watch?v=-jWXihu1luY

 

Near the end of the video I set the envelope so that you can hear the popping sound that I am talking about better.  But even when the envelope is not set that way, the pop is present with each sounded note. 

 

This appears to be more so with the SID chip, but I can sometimes get the Atari chip to do it as well.

 

This effect is not present when playing YMD or SID files.

 

Thanks again for the continued patience of all who witness my blunderings.

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Hello,

 

Are you using the debug version? I seem to remember something like this when the serial port is used to output debugging information. Give it a try with the non-debugging version and see if there is the same thing..

 

Jack.

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I don't think I am using the debug version, but I will re-upload the sketch just to make sure.  Will post back ASAP.  Thanks!

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Oh, I'm referring to the bit file. There was a debug bit file and a non-debug bit file. You will want to try out the non-debug bit file.

 

Jack.

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Pardon me, I said sketch, but meant the bit file.

 

I loaded the non-debug bit file using papilio loader 2.8 onto the retrocade synth, and I'm still having the same issue.

 

The sound is even present when playing using the QWERTY keyboard through the retrocade Synth dashboard.

 

What am I doing wrong?

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Hmmm, let me see if I can recreate the issue here. It's go to be something related to control because it is not happening when we play SID files... 

 

Jack.

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Just had a thought, maybe it is related to your Midi controller not sending a note-off... But you say it happens with QWERTY keyboard too. Hmmmm..

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Right, the SID and YMD files do not suffer from this issue. And yeah, unfortunately it happens across multiple controllers, including the QWERTY keyboard via USB using the retrocade Synth dashboard.

Could this be resulting from underpowering? Should I try to track down a better power supply?

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Well, let me see if I can recreate the problem here first. I might not get free time until this weekend or Monday though. But I put this on the top of my priority list.

 

Jack

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Ok, I just got some time to check on this on my side and I cannot recreate what you are seeing. I don't hear anything unexpected between notes... 

 

Can you do a little more exploring to see if you can narrow down what is happening? Maybe change instruments and see if it is more pronounced with one then another. Try with both the debug and the non-debug bit file. With the debug bit file connect to the 2nd serial port of the Papilio Pro at 8N1 9600 and see if you see anything unusual. I'm wondering if you are seeing multiple note-offs or something that is causing this. 

 

Thanks,

Jack.

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Hi Jack,

 

That's unfortunate that you can't recreate this issue, that makes it hard...hmmm

 

So, I've played around more, and the "thump" is occurring at the same time as the note, but it is actually tied to the key presses.  So, there is a small "thunk"/"click" that sounds with every key-press and the same sound with every key-release. 

 

This effect is present regardless of how I set the envelope, or which instrument I play.  It is not louder with any changes to patches, and it is present on both the SID and the YM chip. 

 

This is true of the regular version and the debug version.

 

after that I re-loaded the debug version of the bit file, connected to the 2nd port of the board via DesignLab @ 9600, played a C major scale, and this is what printed:

7owwïwwïwwïwwïwwwwïwo

 

I thought maybe I had the settings wrong, so in order to follow your instructions exactly, I used tera term to connect to the 2nd serial port at 8N1 9600, played a C major scale, and got:

wwowwïwwïwwïwwwïïwwo

 

pressing one key resulted sometimes in:

w

and sometimes:

ww

or sometimes

ïww

and occasionally

7

 

releasing the key, so far, always looks like:

o

 

For some reason, the stuff didn't copy correctly, so substitute the character: ï  above for the upside-down U, Let me know if you would rather I uploaded a screenshot or two.

 

Does any of that mean anything to you?

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Arghhh! It just means I'm an idiot! I'm sorry, I just double checked the speed and the sketch puts it at 115200 8N1. Not 9600 8N1. What do you use to connect to the MIDI port? Also, if you try to use the Dashboard with the non-debug bit file and instead of using the MIDI port use the serial port does the clicking noise remain?

 

Jack.

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Ha, should be able to sneak in and try a new serial test before I head out to work...I'll post that in a second.

As to the 2nd part of your question: I have used my MIDI controllers, and some weird nameless USB-2-MIDI converter that I got like 8 years ago off ebay. I can try using the midi connections from an audio interface next time. But when I was reading the serial output, I was using my Micro Korg as the midi trigger.

As to the third question: If I use the dashboard with the non-debug bit file, and use just the USB connection to trigger notes, the noise is still present.

I'll post back with the results of the 115200 serial results

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Ahhhh, human friendly output, here is a C maj scale:

 

Note Received: 60
Channel Received: 1
In NoteOff
60
Note Received: 62
Channel Received: 1
In NoteOff
62
Note Received: 64
Channel Received: 1
In NoteOff
64
Note Received: 65
Channel Received: 1
In NoteOff
65
Note Received: 67
Channel Received: 1
In NoteOff
67
Note Received: 69
Channel Received: 1
In NoteOff
69
Note Received: 71
Channel Received: 1
In NoteOff
71
Note Received: 72
Channel Received: 1
In NoteOff
72
 

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Hello,

 

At this point there is not much I can do on my side. I can help you come up with ideas to help narrow down where the issue is coming from, but without being able to recreate it here I'm limited.

 

For the next step, maybe you can download the latest DesignLab release and test out that you can get the Retrocade source code running on your board? Maybe that will help shake loose what is going on?

 

Also, please double check to verify that you get the same problem when using the Dashboard's keyboard controller. Please try to change the instruments on the Dashboard and see if it is only happening after certain changes are made?

 

Whatever we can do to recreate the problem on my side and pinpoint what the cause is will help.

 

Jack.

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Okay,

I'll get the source code running, that's my eventual goal anyways.

I'll post back with my next round of questions.

Thanks,

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