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PPAS Build Thread. - Page 2

post #16 of 254
A minor correction to the web site BOM for the no compromise version- I think 3 ( not 2) SST502's are "required", including one for the ground channel, although certainly the ground channel class A could be left out since it is an optional feature.
post #17 of 254
Got the boards! Man, that's really tiny. Now I'm just waiting for my mouser order (out for delivery, come on UPS guy get here) and then I can start assembly. I'll try to take pictures as I go.


Boards:


With Nano (dang they're small):


AD8620 on, pot just sitting there for reference. PLEASE tell me I got the opamp on in the right direction.


Same deal with AD8610. Is it on right?
post #18 of 254
DOH! forgot to order buffers... well I guess we'll find out soon how well it runs bufferless... shorting out pins 2 & 3 should work, right?
post #19 of 254
Got mine too and above poster is right - thats damn tiny ! I am gonna have to order a clamp on magnifying glass for this job.

Also to above poster - is it the pic, or have you solder bridged the opamp pins ?
post #20 of 254
Quote:
Originally Posted by ozshadow
Got mine too and above poster is right - thats damn tiny ! I am gonna have to order a clamp on magnifying glass for this job.

Also to above poster - is it the pic, or have you solder bridged the opamp pins ?

Angle of the pic, those are actually pads for R6R, I got a little solder on them and didn't clean it up yet.
post #21 of 254
Bottom populated with resistors, sst310s, caps:


Top with caps and resistors:



Yes, I am ugly at soldering SMD.


Questions:

1) What is the purpose of the VGND pad?

2) What is JP1 for? Buffer bandwidth?


The only thing left is to wait for the buffers to arrive. Next thursday!
post #22 of 254
Thread Starter 
Looks great so far. You probably want to take those pictures on teh macro mode on your camera, it'll turn out much nicer and you can make out the details.

The opamps are oriented in the right direction, so are the tantalums =)

VGND is for troubleshooting purposes. without that pad it makes life much much harder when something goes wrong. originally I was planning to take it out on the production run, but something told me it would be nice to keep that pad

yes, JP-1 is buffer bandwith for all buffers.. putting a resistance from 0-> open will change the bandwith, with shorted JP1 being wide bandwith mode. Apparently it makes a difference, though personallly neither I nor daniel can hear it..
post #23 of 254
Excellent, looks like I did all that right, then. So far everthing is together nicely, with some temporary 100uF caps 'till I get my panasonic FM, and still waiting on the buffer.

I'm really tempted to just temporarily wire a socket to the pads and pop in a dip8 buffer, just to get the thing running.

Edit: hmm, or jumper the buffers for now
post #24 of 254
Anyone having trouble finding TLE2426's, try Jameco. As of now, they have them in stock, but unfortunatly they don't list how much is left.
post #25 of 254
oh, and VGND would be useful in a amp-powered Alien DAC.
post #26 of 254
Quote:
Originally Posted by rsabo
oh, and VGND would be useful in a amp-powered Alien DAC.
I was thinking that, too I just wasn't sure if it served an explicit purpose in the amp.
post #27 of 254
Thread Starter 
pddjsteve - just wait for the buffers.. probably not worth it to attempt it without the buffers, the opamp rails will proably clip and it'll sound horrible.

PDDJ - if you have any high current opamps, you can put them onto the buffer pads and run them as a unity gain buffer..
post #28 of 254
Quote:
Originally Posted by ATAT
pddjsteve - just wait for the buffers.. probably not worth it to attempt it without the buffers, the opamp rails will proably clip and it'll sound horrible.

PDDJ - if you have any high current opamps, you can put them onto the buffer pads and run them as a unity gain buffer..
Well, I've got some intersil buffers (the kind in the full size ppa). I just gave it a shot without anything on the buffers and it sounded like ass (but it worked!). I don't know if I've got the patience tonight to play with wiring a dip8 socket to try out my intersils. Maybe I'll just wait for the lmh6321s and not play anymore
post #29 of 254
Thread Starter 
Its not worth it to rush and perhaps mess something else up on the circuit.. and yes, without the buffers the circuit will sound *horrible* worse than any cmoy you've ever heard.
post #30 of 254
Newark has over 600 SST310's in stock.

Part# 13C1768
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