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.
Added pads for an offboard inductor, gave the R7 array its own ground return line, and added bleeder resistors for the output caps 🙂.
This looks excellent BDHM! Byrtt has pretty sharp eyes - is that xrk871? Doesn’t have the same ring as 971!?
🙂
Thanks so much for making the layout.
Cheers,
X
🙂
Thanks so much for making the layout.
Cheers,
X
I've run about of batteries. How's the lithium/usb power board management system which I know nothing about going?
Needtubes said he is going to do a GB for his power management boards once he and X do some tests and the design is finalized. Apparently it is silent too 🙂
Re: the new desktop board: Locating the inductors off the board is brilliant. I am glad to have this option.
Re: the new desktop board: Locating the inductors off the board is brilliant. I am glad to have this option.
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Could anyone tell me how long their 9v batteries last before they run out of juice? I've noticed distortion after approximately 2H. Does this make sense?
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 EBL li-ions last 4hrs and (smart battery controller built in) cut out before any audible distortion sets in. I timed it last night and this was higher bias 68mA unit.
This amp sounds wonderful, but is a bit power hungry. That's why I've built a small, wall wart powered, albeit lunatic fringe version. Pix coming soon.
Thanks for your responses. I used one Alkaline and one li-ion (somehow my two li-ions don't work in this configuration). Would the 1200mAh version of EBL li-ions work?
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.
Nice work Aatto. Which case is the FH9? You can run that in a wooden case? It makes heat as I recall.
FH9 is one of my favorite amps. Very muscular and deep deep bass.
So I assume you are not getting any hum from the FH9 using the PCA as preamp?
FH9 is one of my favorite amps. Very muscular and deep deep bass.
So I assume you are not getting any hum from the FH9 using the PCA as preamp?