Music 5000 in B-Em

[CHRISJJ]

Do you mean this one. ? http://www.retro-kit.co.uk/user/custom/ ... ematic.pdf

Yes. Though I see a better scan would be useful. I will make one when next I have the original to hand.

The Kicad is very close.

Close != cigar

[Coeus]

Worth checking. E.g. count the bursts.

This is what I have as the waveform recorded from the hardware Music 500:

[CHRISJJ]

Worth checking. E.g. count the bursts.

This is what I have as the waveform recorded from the hardware Music 500:
02_phset_test.png

Great. That matches the "Expected" of the latest test spec.

Thanks.

[dp11]

Worth checking. E.g. count the bursts.

This is what I have as the waveform recorded from the hardware Music 500:
02_phset_test.png

Could I have the audio file ? to compare with .

[Coeus]

Could I have the audio file ? to compare with .

It's at: https://drive.google.com/drive/folders/ ... share_link

[hoglet]

Hi Steve,

I'm getting a bit confused...

This is what I have as the waveform recorded from the hardware Music 500:

02_phset_test.png

That doesn't match the recording here:
https://drive.google.com/drive/folders/ ... share_link

That only seems to have 14 "hits", not 16 as I would expect for this test case. Is it cropped?

Can you comment on what you are getting on real hardware re: the spacing between the first two hits?

Dave

[CHRISJJ]

Worth checking. E.g. count the bursts.

This is what I have as the waveform recorded from the hardware Music 500:
02_phset_test.png

That accords with Expected.

This suggests hoglet's viewtopic.php?p=404798#p404798 "a shortened time interval between the first and second hits ... wasn't present on the recording Steve posted from real hardware" refers to a different recording.

[Coeus]

That doesn't match the recording here:
https://drive.google.com/drive/folders/ ... share_link

Something has gone wrong either exporting or uploading the file. The screenshot is the recording in the editor. Yes, the exported file I uploaded is cropped as there was no point in including near silence while I walk across the room to press <Return> on the BBC micro but what is suspicious is that the file in your screenshot starts with complete silence. This is not right as there is a tiny bit of noise even when recording a "silent" Music 500.

I have re-set the markers for the bit to export, exported it again, uploaded it, re-downloaded it and checked in audacity that it looks as expected, "it" being the file 02_phset_test.flac so it should now be correct. So that is a recording from a hardware Music 500 and does demonstrate the time-compressed first two drum hits, i.e. really a late first hit, and evenly spaced ones thereafter.

[hoglet]

I have re-set the markers for the bit to export, exported it again, uploaded it, re-downloaded it and checked in audacity that it looks as expected, "it" being the file 02_phset_test.flac so it should now be correct. So that is a recording from a hardware Music 500 and does demonstrate the time-compressed first two drum hits, i.e. really a late first hit, and evenly spaced ones thereafter.

Thanks for sorting this Steve.

[CHRISJJ]

the file in your screenshot starts with complete silence. This is not right

If needed, an improved test spec could put the under-test tone on one channel and a steady full- and known-duration tone on the other. I'm certain the stereo location won't interfere with any function under test at this stage.

[CHRISJJ]

Do you mean this one. ? http://www.retro-kit.co.uk/user/custom/ ... ematic.pdf The Kicad is very close.

Sorry to be unclear. I meant perhaps the reimplementation author has a CAD circuit of the Music 500 from which he derived that CAD circuit of his reimplementation.

[CHRISJJ]

Will do. Just thinking here not checked but "zero crossing here " should it really be "negative going zero crossing" ?

Good question.

Answer: No.

This is where we need a remastered schematic with signals hyperlinked within and to dp11's operations chart... and ideally also to charts for key cases such as this amplitude postponement. Those charts would ideally be made by a simulator. Does a tool for this yet exist?

Re the charts, I guess No.

Re the amplitude, though I'd prefer a more scientific method, instead I'll go by memory

The BCE and Studio 5000 preset waveforms are composed such that amplitude change between last and first sample would not add a discontinuity. In many but not all waveform cases, this is by having a zero crossing at that point. (I previously described it as zero-crossing unqualified because it always has that effect - but I was inaccurate. Sorry.). +ve/-ve going makes no difference. The 1MHz bus writes a channel's Target Amplitude to the synth. The synth uses Current Amplitude for channel output. Upon the channel phase+freq wrap, signified by carry from the 24-bit add, the synth copies Target Amplitude to Current Amplitude. Through postponement of amplitude changes this achieves alignment of changes to waveform cycle in a way that avoids discontinuity of amplitude*waveform at the channel output.

I hope this fits with your description at viewtopic.php?p=404489#p404489 accords.

Let's leave the word "synchronisation" out of this amplitude processing, to avoid confusion with what's called sync elsewhere e.g. in M5. Let's call the mechanism amplitude latching and this application (/purpose/effect/objective) amplitude change alignment.

I hope that helps.