Pads are provided to wire an external +5V supply if you don't want to use the onboard one.

I've built one of this guy's kits. No idea what it does for audio, but it works fine for my non-audio-related purposes: ADuM4160 USB Isolator board, bare PCB and kits « Circuits@Home

I designed a PGA2320 board quite a while ago as well: MiniVol PGA2320 Volume Control - error404's Audio DIY Endeavours Nobody was interested

Quote: Originally Posted by Juaquin I2C is two pins. It could be done with the existing board (breakout pins) but I wanted to simplify. Honestly I haven't done a lot of research on the communication aspect yet (I had to have something to do during the 3 week wait for boards) and I'm...

Looks fine to me. My only concern is how you're going to address it on the bus, adding some jumpers/DIP switches is probably prudent since you don't have a hardware 64-bit unique ID and programming it manually for each device is a pain if you ever plan to build more than one. I'm curious...

Sorry guys, I've been totally AWOL for months, my personal life has become a bit too insane to keep up these projects, and probably will be for a while. Anyone is welcome to take up the reigns though, if you want the current Altium files or anything just send me a PM and I'll get them to you...

I finally received the rest of my parts from Mouser last week, and today I got around to building up the Carrie board. I used the posted BOM in the 2nd post and pretty much ordered what was on there. I haven't had a chance to hook it up and test it yet, but I did have a few build notes. I...

Just wanted to say thanks for giving me this idea. I've been using the ALIX boards as pfSense firewalls at my clients' for a year or so now, and they're great. Never thought to set them up as mpd boxes though, that's really genius, and I'm going to build one up this afternoon. Cheers...

Quote: I agree with TzeYang that w/o FET isolation it technically isn't a PPAS. I think that may be the last 1% or something like that. I think this is a great sounding amp in small package. There really is a need for an amp like this. Exactly my dilemma. I haven't found a way to...

Does anyone have any input on the proposal to remove the JFET isolation? Any prototypers willing to try jumpering the JFETs and reporting on sound quality changes if any?

Both the Arduino boards I linked are pretty small. The Boarduino DC is about half the price, much smaller, but doesn't include the USB->RS232 IC. The USB Boarduino is still quite a bit cheaper and smaller than the 'official' one and does include it. Both have bare boards available, and so are...

Quote: Originally Posted by jcx how about a $20 development system in a usb key fob MSP430 USB Stick Development Tool - EZ430-F2013 - TI Tool Folder also 16 bit is too cheap today to waste the time with 8 bit processor limitations Or get 16 bits extra for only $5...

PIC is awful. The architecture is strange, inconsistent across uCs, it's difficult to learn if you come from a 'normal' architecture. The IDE might be the same (AFAIK it is for AVR too), but almost any bit of code requires effort to port to a different uC when I last looked at the architecture...

It'd be nice if you broke out the data lines.

Removing the JFETs isn't an issue, in fact I think that'd be preferable really. But to keep the original PPAS design I'd have to keep the JFETs and use them only for the opamp supplies. That's where I'm having layout difficulties. But if everyone is in favour I'd rather just rip them out. The...

I've been very swamped with work the past few weeks, but the bug that TzeYang noticed has so far been defeating me. It seriously complicates the layout since the (now) two sets of power rails cross in several places. I'm not sure I have the motivation to completely ripup the board and redo it...

Quote: Originally Posted by joneeboi I also read on this thread that power will be readily available from the USB regardless of enumeration. I hope that that's true. diyAudio Forums - USB powered HIFI headphone amp/DAC - Page 1 Yea, you can pretty much assume at least 1A will be...

Quote: Originally Posted by tcpoint One quick note. Shouldn't the power to the buffers be Vdd and Vee instead of Vp and Vn, respectively? The Q3, Q4, Q6, Q7 Jfets are supposed to isolate the rails for the opamps, not the buffers. The original PPAS does this. I think you're right...

Quote: Originally Posted by joneeboi 2) Would it be worthwhile connecting two ground wires between the boards? Should work either way, though you should probably use a separate ground for each signal if possible, plus it's hard to get a really consistent connection without solder...

How can you parallel a BUF634 with a TLE2426? They have different functions and that notion doesn't really make sense.

Yes! It's done! http://audio.gotroot.ca/ppas/PPAS_placement.pdf Most labels are directly over the part in question. If anything is unclear, suck it up and read the schematic :P Oh, do note that the layout is already updated for the pot bug, so that area looks little different, but the...

Don't be so afraid of smd! It's really not as hard as it looks; if you need an ultra-fine-point soldering iron for success, you're probably doing it wrong. Once you get the hang of it 1206 and 0805 sized passives are dead easy, and it's a lot more efficient than through-hole parts because...

I'm not totally sure what that warning is about, but I'm sure you don't need to worry about it.

Quote: Originally Posted by wolf18t Since when Digikey carry RN55D resistors? At least a year or so, when I noticed them available. I've ordered them many times now. They are technically not RN55 series as CMF55 is the commercial variant, but physically they're identical. As far...

Sometimes I wish I didn't have e-mail notifications on :P Quote: Originally Posted by Datasheet summary The LME49720 is unity gain stable.