[Sidnicious]

I'm super curious…

a. What in these files triggers the explosion of noise (and whether other people have run into this or the author would mind sharing a representative problem file).

b. Whether an output attenuator (or "resistor") would work to quiet the noise (edit: the hiss, not the explosion) without a powered circuit.

[xylon]

Hi, author here, I can't send you a sample because of copyright but get "scare force one" by Lordi on CD and rip it into any format.

[PascLeRasc]

Hi, this isn't related to the parent comment, but I'm wondering why you went through all this effort, which you don't seem to have enjoyed, just to be able to listen to music at home but not at your desk. Isn't all the stuff you have pretty bulky to be carrying around? Not to mention the portable CD player probably skips if you're walking around with it somehow in a pocket.

It seems like all of this could be solved with some bookshelf speakers. You can hook up your portable CD player or browse Craigslist/Goodwill for an older HDCD player that'll run higher sampling rates and queue up multiple CDs, have music for cooking/cleaning/exercising. Maybe even get a Chromecast Audio and have effortless streaming.

[squarefoot]

a: I had a similar issue on my Sandisk player and it was due to corrupt data on the SD. Formatting it then copying back the files from a backup solved the problem. the author's problem is different though; it seems his player doesn't like some files although they appear to be undamaged. I agree it's probably a bug in the decoder.

b: a voltage divider would attenuate everything so the listener would end up raising the volume and the noise explosions would be unaffected. In my experience those noises are much louder than the music even at its louder peak, so a limiter would work better. A limiter is a circuit which let the audio signal unaffected up to a given level, then if necessary it starts limiting it to keep it to maximum that level. The limiter should be set up to trigger only with levels above the maximum original audio signal, so that although the noises wouldn't disappear, they would be confined to a lower level with the original signal left untouched.

[Sidnicious]

a: Interesting!

b: Good point, but I just meant quieting the hiss that the author ended up solving with the op-amp circuit, not the 'explosions'.

[squarefoot]

Ah, I missed the hissing part. Apparently he gets that noise only from a CD player, and that noise is constant through all song and unaffected by volume settings. That would mean the audio section of that player is really noisy and/or possibly the volume control has been put in the wrong place, for example too far (circuit wise, not distance) from the power amplifier section. When connecting multiple stages together care must be taken to minimize noise. Besides careful design and choosing low noise parts, some practices can at least reduce the perceived noise even on noisy devices, for example by putting the volume control just before the power amplifier. This ensures that when the user lowers the volume the noise generated by previous stages gets also lowered along the signal.

[dcminter]

I don't have this issue on my Android phone (G5+) but I did have a very similar issue on my laptop (XPS 9350) where there was lots of line noise whenever the power management turned off the audio chipset.

So I wonder if it's something with this specific phone?