Noise in Bassdrum decay

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Noise in Bassdrum decay

Postby flomo » Nov 12th, '22, 17:34

My Nava has a noise floor in the decay phase of the bassdrum. I've recorded a .wav file here: https://florianmoser.ch/909-noise-decay.wav

It is recorded right out of the BD-output, but the noise is also there on the mix-output.

Does anyone else have this issue?
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Re: Noise in Bassdrum decay

Postby gihaume » Nov 19th, '22, 13:37

Could it be this ?
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Re: Noise in Bassdrum decay

Postby flomo » Nov 19th, '22, 15:24

gihaume wrote:Could it be this ?


Thanks, Gihaume. I'm currently unable to check my power supply (it is installed somewhere deep behind a rack). But I recall reading this thread, when I was building the Nava. So I'm pretty sure I took a power supply with >= 1A. But I indeed have a little bit of distortion on the mix out (only visible on the sine wave, almost impossible to hear). And I have installed the Extra9 Kit. However, the noise I recorded is on the individual BD out.

So you don't have this noise in the decay phase of your unit? When recording the linked .wav file, the BD-decay was set pretty high (pot around 3 o'clock).
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Re: Noise in Bassdrum decay

Postby gihaume » Nov 19th, '22, 16:48

Finally I recall I had this. I probed the + and - 15v and found they had the small oscillation we hear on the bass drum. I could also hear it on the steiner parker filter.
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Re: Noise in Bassdrum decay

Postby flomo » Nov 20th, '22, 12:36

gihaume wrote:Finally I recall I had this. I probed the + and - 15v and found they had the small oscillation we hear on the bass drum. I could also hear it on the steiner parker filter.


Thanks Gihaume. I guess I'll have to play with another power supply. Maybe simply use a toroidal transformer instead of a wall plug.
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Re: Noise in Bassdrum decay

Postby flomo » Nov 27th, '22, 10:53

I just tried out a toroidal transformer, 15VAC 2.667A. On load (Nava on and playing a pattern) I measure 18VAC @ 970mA.

But still the same hissing on the BD decay. Gonna have to find something else.
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Re: Noise in Bassdrum decay

Postby flomo » Nov 27th, '22, 18:11

I finally found the issue. This post helped me.

In the Bassdrum section, cable 1 and 2 (noise decay in/out) leading from the Nava to the Extra 9 board, must not be bundled with the other cables. There's indeed a crosstalk from noise to audio.

Simply separating these two cables and keeping them 2cm apart from the rest of the cables solves the problem!
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