A weird noise is driving me mad


#1

Hello Zynthianers,
I would like to submit you a discovery that is driving me mad, all suggestions are welcome!

Ok, after some months of pure fun with my Zynth and just a stage monitor and a weighted master keyboard, these days I’m working to put it in a more complex live rig, finely setting up the whole system, built around a mixer, using headphones. Soon I started to hear something weird: it’s a faint noise, something like a click, and appears at the end of any sound played, it’s volume stays unvaried and is not influenced by the synth level, it can be heard on every engine but it seems worst when I play LinuxSampler (e.g. during a pianissimo part on the Salamander, where I can hear the same click on the note attack as well).
I can tell you that it is not related to the OS image (I tried 3 different images with 3 different SDs) neither to the closeness of the All-In-One Module cables to the HiFiBerry (nothing changes with the case open and all the encoder guts far away).

Here you can find 3 examples, recorded using ZynAddSubFX, Dexed and LinuxSampler (as you can hear there is a prominent hissing due to the low volume used to highlight the noise):



Thanks in advance!

Andrea

PS: I’m on a plain vanilla Zynthian Bundle All Alu-case Kit v2 (RPi 3B+ / HifiBerry DAC+ / OzzMaker PiScreen 3.5’ / All-In-One Module Kit with controller / Alu Case v2) and I’m powering it with a good 2A power supply (the red led on the RPi is steady on).


#2

I can’t reproduce this noise in my zynthian (also with HB DAC+). Perhaps it’s not zynthian related …
These noise seems like a noise-gate or something that switch-off when audio level is close to 0.

Could you describe your full audio chain?

Regards,


#3

Stripped-down for the recording: just Zynthian into a brand new Mackie 1202VLZ4, :worried: should I worry about the mixer?


#4

Perhaps your power-supply? Can you try to change or use a power bank?

Do you have a chance for using a ground-lift (perhaps by using a DI box)?

Regards, Holger


#5

It seems also to me a noise gate of some kind. In the third file, the click can be heard even at the beginning of each note. The “click” can be seen opening the wave with something like audacity.



Very strange…


#6

Is that the from the RCA (red and white phono) output?


#7

Hey many thanks for your help!
@C0d3man --> I tried with a power bank but the noise is still there :anguished:
@Baggypants --> Yes, the recording was made using the RCA but using jacks the result is the same.
And of course nothing changes using another mixer…

Is it likely to think that the HB DAC+ is gone?


#8

I’d try powering it from a big mobile phone battery pack to rule out the PSU first.


#9

@Baggypants --> did it with two different power banks: the noise remains :weary: (I’ve also tried with another power supply with no joy)

Any procedure to test the HB DAC+ before buying another one? (And is there any warranty on the card?)

Thanks!


#10

Have you tried with the “alsamixer” from command line? Perhaps there is some options there …

Regards,


#11

@jofemodo and @Baggypants could you post part number, version and manufacturing date of your DAC chip (better: a full READABLE picture of the chip)


#12

Sorry, I meant to tag @sadkermit


#13

This is from Daniel, the creator of HifiBerry DAC+:

Hi José,
there were no hardware changes in the DAC.
Unfortunately I can’t say anything about this specific problem. It could be a problem of the circuit that the DAC+ is connected to.
If would check what’s on the output of the DAC.
Best regards,
Daniel

Regards,


#14

My question about revisions are tied to the TI notes on the PCM512x.

There are two (three, actually) hardware revision of the chip.
The Jan. 2016 revision removed a feature called “Internal Pop-Free Control For Sample-Rate Changes Or Clock Halts”.


#15

Interesting … let see what Daniel says :wink:


#16

Hi @Axeman!
Could you post the link to the TI revision notes?


#17

http://www.ti.com/lit/ds/symlink/pcm5122.pdf


#18

Re reading the doc, maybe these are revision of DOCUMENTATION and not of the chip itself…
I never liked TI documentation since the 74XX data books :slight_smile:


#19

Ups! yes … it looks to be Documentation Revision … :wink:


#20

Your Honor, I retire my question and throw myself on the mercy of the court! :rofl: