Noisy Analog Section

Forum for the JD-XA.

Noisy Analog Section

Postby Jedi_mastaa » 08:00, 4 February 2018

There’s a rather large amount of noise before the filter section that ruins just about any patch that isn’t very full of harmonic content. It doesn’t occur using digital parts, and it isn’t a 60hz hum (covers my entire spectrograph) and I’ve tried multiple power supplies at multiple locations, which I hoped it would be.

While it does get boosted with mixer and drive, it doesn’t disappear all the way even with oscillators totally mixed out, which totally ruins even using just the self-resonating filter as a sine.

I bought it second hand without original proof of purchase and after many emails back and forth with rather painful support, they told me to take it in for diagnostic at their authorized shop nearby because they were stumped. They first said they couldn’t hear it and wouldn’t believe the scope images were from the JD-XA, so I had to record a video and edit in the example’s audio being run through a spectrograph side by side; to which they finally conceded something was wrong but wouldn’t provide any warranty information.

Is this noise something you folks have? There aren’t any demo units or folks in possession of one near me to do an A/B with, so I’d rather know if it’s normal, and it’s just a noisy synth. I love this buddy and have been incredibly inspired by it, so it’s a pity.

Is it possible to get schematics for any of the newer gear? It’s doubly frustrating because I’m comfortable with schematics and SMT rework and I just don’t have the information to go off of.

Thanks a bunch,
Michael
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Re: Noisy Analog Section

Postby pelican » 13:34, 4 February 2018

no noise here at all
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Re: Noisy Analog Section

Postby mimoid » 11:57, 10 February 2018

Funny you should write this as I just recently noticed the exact same thing.

Especially with It sounds like a really crusty digital aliasing. It can make it difficult to play bass arpeggios with smooth filter settings. Also bass-rich high resonance sounds like analog kick drums are easily ruined by this aliasing noise. Here is an example of how it sounds:

https://soundcloud.com/lunarstructures/ ... alog-noise
https://soundcloud.com/lunarstructures/ ... og-noise-1

(Disregard the compression related degradation with SoundCloud).

TBH, I don't think there is any point in sending the unit back to Roland, it will just come back as "according to spec". Personally I just write it down to a slightly dirty analog filter.
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