Tone 2 Maker - Popping Noise

Dear all,
In my setup, I connected the Tone2 Maker to a Raspberry Pi4 via USB and the RCA outputs (unbalanced mode) are connected directly to an ICEPOWER module. Everything works perfectly and the sound is wonderful, really top notch, but I have a very annoying problem that I can’t solve. Every time I start a track or stop it it produces a pop (the noise is very similar to when you place the needle on a vinyl record).
It’s like you turn muting on and off and for some reason it makes this pop, but that’s just my guess.
What do you think the problem could be?
Thanks in advance

I solved the problem myself……
I’m sharing my experience so that it can help others if they encounter the same problem as me. It’s simply an impedance problem, now everything works great!

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Accord to the schematic of tone2 maker, you can see that we consider the Popping Noise at different scenes by means of setting POP_MUTE low. POP_MUTE is equal to POP_MUTE1 and POP_MUTE2, POP_MUTE1 is controlled by MCU, it can eliminate popping noise when power up and power off, POP_MUTE2 is controlled by XMOS, it can eliminate popping noise when start a track or stop. But we can not solve it completely, and just weaken it.

Could you share your methods about it? :grinning:

Hi Eric68,

Thanks for your comprehensive answer!
Yes, I saw the diagram, that’s why I had a doubt about the mute, now thanks to your explanation I understand how it works correctly. Can your solution be done with a firmware update, or is this already in its best condition?

In my case it was enough to put two 2K resistors in parallel on the +R/GND, +L/GND amplifier inputs. However, by doing a more in-depth check this did not completely eliminate the problem but reduced it to an acceptable value, now the pop noise is very low. I would like to try with a 2:1 transformer to connect the balanced outputs of the TONE2 with the unbalanced input of the amplifier, but I’m waiting for it to arrive and it will take some time…


Yes, it is already the best condition by firmware scheme. And about your method, you mean you change the value of R264/R265 to 2K. Right?

I didn’t change any resistors on the PBC, the resistors were put in parallel on the amplifier input. Theoretically they are parallel to the resistances you mentioned, mine is an empirical condition that works in my case, but I can’t say with certainty that it will work for everyone.

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