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Subsequent 37 issue.

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Subsequent 37 issue.

Postby Chimera » Fri Dec 04, 2020 4:04 pm

My Subsequent 37 was playing up and they replaced the main board under warranty. The original problem is gone but I noticed something that I haven't heard on my other VCO synths. With two triangle oscillators at equal volume I get a sound as if the wave shape is sweeping towards a saw.

https://www.dropbox.com/s/retizo32nqezn ... 9.wav?dl=0

I compared it to my MKS 80 and that had a volume change as the note was held but no change in high harmonic content.

I adjusted the Subs 37 osc pitch variance and then put it back to zero and the Moog started behaving like the Roland but unfortunately after being instructed to update the firmware it reverted to how it originally was. The same effect isn't heard on a saw or pulse wave.

There is a video with the MKS 80 oscilloscope and frequency spectrum on the left and the Moog on the right.

https://www.dropbox.com/s/k4nk1zgql6e3w ... 0.MOV?dl=0

It isn't resetting with new notes either.

https://www.dropbox.com/s/wckqqmrmffzol ... 9.wav?dl=0
Any thoughts?
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Re: Subsequent 37 issue.

Postby BJG145 » Fri Dec 04, 2020 8:53 pm

The two WAVs seem silent to me...?

I'm not familiar with either of these synths but I'm surprised how similar the waveform looks in the video. (I wouldn't expect any two synths to behave exactly the same way.)

Re: the reset question, I can't hear what you're describing (because there's no sound) but P23 of the manual notes that:

KB RESET
When the Keyboard LFO Reset button is illuminated, the LFO will restart its cycle at zero each time a new note is played. With KB RESET off, the LFO will run freely, and will not reset at the start of any notes.
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Re: Subsequent 37 issue.

Postby Chimera » Sat Dec 05, 2020 8:27 am

Thanks I’ll try and work out what happened to the sound files.
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Re: Subsequent 37 issue.

Postby Chimera » Sat Dec 05, 2020 9:34 am

Right sorry about that folks. I've uploaded and checked the files.

Init patch, both oscillators levelled and on triangle, filter fully open, no LFO applied.


https://www.dropbox.com/s/stdjqrxf8sy3f ... 9.wav?dl=0

https://www.dropbox.com/s/7sgfyumq422zl ... 9.wav?dl=0
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Re: Subsequent 37 issue.

Postby Chimera » Sat Dec 05, 2020 3:36 pm

I have conducted a test on the oscillators and think there is a fault on oscillator 2.

1) I created an Expert Sleepers Usamo MIDI track with two long notes on. This guarantees the MIDI note timing is sample accurate. Test run at 44.1 Khz
2) I recorded Osc 1 on 1st note and Osc 2 on 2nd note on track 1
3) I recorded both notes with Osc 1 on track 2
4) I recorded both notes with Osc 2 on track 3

I produced mixes of

Osc 1 with 1 - stable no phasing
Osc 1 with Osc 2 A - unstable phasing
Osc 2 with Osc 1 B - unstable phasing (control)
Osc 2 with Osc 2 -more stable than 1 and 2 but less stable than 1 and 1.

If you import the audio files into a DAW then you can clearly see the effect.

https://www.dropbox.com/sh/5cw13txkazpm ... ApuXa?dl=0
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