No audible noise. Amp is silent with battery or USB power. I'll get around to measuring it in a couple days to check for issues I can't hear.
I think my long test leads caused oscillation, which created the audible squeal from the chip that I reported before. Or maybe the alkaline batteries. No noise anymore when in my amp, with a lithium ion cell, and fairly short connections everywhere.
This looks excellent BDHM! Byrtt has pretty sharp eyes - is that xrk871? Doesn’t have the same ring as 971!?
It's a 9
. I reckon the image compression algorithm fuzzed it a bit
Using non rechargeable 9 Volt elements agree about the about 2 hour use, what is sensed thereafter i won't directly call a distortion but some kind of less pleasing sound stage, maybe at some stage it leads to audio able distortion but at that stage mine had been replaced, by the way think it happens for me when element reads about 7,5 volts stage and cans used were 64ohms.
I went through a box of amazon 9v because eight on amazon was the same price as two from the store and I needed one for my smoke alarm. That seems a bit low to me but maybe on the low end of the spectrum. Bear in mind my led doesn't work so maybe that helps. I never timed how long the batteries lasted because I always planned to replace them with lithium and a usb charger.
Yes mostly used alkaline but admit they cheaper than well known brands get them for discount in boxes of 10 at a time, can we say PCA needs new tin from time to time, at present have a stack of about 50-60 used and a couple of new boxes laying around : )
The li-ions have a well known issue upon startup. You may have missed it. They have a smart micro controller and power control PCB on board (yes, inside every Li rechargeable battery except RC car ones) that monitors current and shuts the battery down if it thinks you shorted the ends. In the Pocket amp, dual 2200uF caps appear as short due to in rush current at turn on. Hence battery promptly shuts down. Try clicking power switch 2-3 times on-off and it will stay on after 2-3 times. Because it partially charges caps each time.
If you run the LiPo system with cap Mx, the cap Mx ramps current up slowly so this doesn’t happen. Sounds like adding alkaline in series does same thing.
