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xrk971 Pocket Class A Headamp GB

Pcgab,
Those look close but make sure the overall assembly is not too tall. There is 12mm inside the tin on the bottom side of the board to the bottom of the tin. Those pins look a little tall. Also, do we have to buy female crimp pin that inserts into the body/shell?
Thanks,
X

Yes, the ones I have 2,3,7 pin need the pins purchased and crimped separately. I thought it was going to be tougher than it turned out to be.

Very good point about the height. I'll poke around a bit more later today.

I think you can get 90degree through hole headers for those connectors, that might help the height issue. Of course it might be in the way of the batteries, or something else as well.
 
Founder of XSA-Labs
Joined 2012
Paid Member
What's the deal with cost of 1% 0805 SMT resistors on Mouser? I was going to put together a nice one-stop shopping cart for everyone using Mouser including the SMT resistors but see that the pricing in ~20x higher than what Digikey charges. I can get a cut tape in qnty 100 for $0.71 total at Digikey and Mouser wants $0.14ea for qnty 100 ($14 for 100). I guess it's fine of you are ordering onesies and twosies, but that's the point of SMT - to get huge quantity of high quality parts for peanuts.
 
Founder of XSA-Labs
Joined 2012
Paid Member
Good find X!

I wonder why Mouser is so much more expensive for the smt resistors?

Of course, unless you are buying other stuff at Digikey, the $7 shipping is not worth it and you are better off buying the premade qnty 8 assemblies from Amazon with free shipping.

It's tough to be able to get all parts from one source for any project.
 
Founder of XSA-Labs
Joined 2012
Paid Member
Update on GB Status

xrk971 - 2 boards
pcgab - 2 boards - INVOICE SENT & PAYMENT RECEIVED
zman01 - 2 boards - INVOICE SENT & PAYMENT RECEIVED
stellarelephant - 2 boards - INVOICE SENT
samoloko - 1 pcb
lui04 - 2 boards

Morde - 2 board - INVOICE SENT & PAYMENT RECEIVED
cyteen - 2 boards
funch - 2 boards - INVOICE SENT
syyma - 2 boards - INVOICE SENT & PAYMENT RECEIVED
av-trouvaille - 2 boards - INVOICE SENT & PAYMENT RECEIVED
Mituisho - 2 boards - INVOICE SENT & PAYMENT RECEIVED
bogde - 2 boards
faltinsen - 2 boards - INVOICE SENT & PAYMENT RECEIVED
vanofmonks - 1 board - INVOICE SENT & PAYMENT RECEIVED
M_Balou - 2 boards - INVOICE SENT & PAYMENT RECEIVED
dwpeterson - 1 board - INVOICE SENT
agdr - 1 board
walangalam - 2 boards
gwrskien - 2 boards - INVOICE SENT & PAYMENT RECEIVED
redarc12- 2 boards - INVOICE SENT
dw1narso - 2 boards - INVOICE SENT & PAYMENT RECEIVED

A reminder to folks (in red above and anyone else not yet on the list) who want to participate in the GB to please send me your PayPal address via PM. I need to confirm firm orders from members and I plan on placing the order tomorrow.

Thanks,
X
 
Founder of XSA-Labs
Joined 2012
Paid Member
Update, typo - StellarElephant has paid.

xrk971 - 2 boards
pcgab - 2 boards - INVOICE SENT & PAYMENT RECEIVED
zman01 - 2 boards - INVOICE SENT & PAYMENT RECEIVED
stellarelephant - 2 boards - INVOICE SENT & RECEIVED
samoloko - 1 pcb
lui04 - 2 boards
Morde - 2 board - INVOICE SENT & PAYMENT RECEIVED
cyteen - 2 boards
funch - 2 boards - INVOICE SENT
syyma - 2 boards - INVOICE SENT & PAYMENT RECEIVED
av-trouvaille - 2 boards - INVOICE SENT & PAYMENT RECEIVED
Mituisho - 2 boards - INVOICE SENT & PAYMENT RECEIVED
bogde - 2 boards
faltinsen - 2 boards - INVOICE SENT & PAYMENT RECEIVED
vanofmonks - 1 board - INVOICE SENT & PAYMENT RECEIVED
M_Balou - 2 boards - INVOICE SENT & PAYMENT RECEIVED
dwpeterson - 1 board - INVOICE SENT
agdr - 1 board
walangalam - 2 boards
gwrskien - 2 boards - INVOICE SENT & PAYMENT RECEIVED
redarc12- 2 boards - INVOICE SENT
dw1narso - 2 boards - INVOICE SENT & PAYMENT RECEIVED
 
Founder of XSA-Labs
Joined 2012
Paid Member
Status update - we are getting there! Thanks to all of you who have paid so far.

xrk971 - 2 boards
pcgab - 2 boards - INVOICE SENT & PAYMENT RECEIVED
zman01 - 2 boards - INVOICE SENT & PAYMENT RECEIVED
stellarelephant - 2 boards - INVOICE SENT & RECEIVED
samoloko - 1 pcb
lui04 - 2 boards
Morde - 2 board - INVOICE SENT & PAYMENT RECEIVED
cyteen - 2 boards
funch - 2 boards - INVOICE SENT & PAYMENT RECEIVED
syyma - 2 boards - INVOICE SENT & PAYMENT RECEIVED
av-trouvaille - 2 boards - INVOICE SENT & PAYMENT RECEIVED
Mituisho - 2 boards - INVOICE SENT & PAYMENT RECEIVED
bogde - 2 boards
faltinsen - 2 boards - INVOICE SENT & PAYMENT RECEIVED
vanofmonks - 1 board - INVOICE SENT & PAYMENT RECEIVED
M_Balou - 2 boards - INVOICE SENT & PAYMENT RECEIVED
dwpeterson - 1 board - INVOICE SENT
agdr - 1 board
walangalam - 2 boards
gwrskien - 2 boards - INVOICE SENT & PAYMENT RECEIVED
redarc12- 2 boards - INVOICE SENT & PAYMENT RECEIVED
dw1narso - 2 boards - INVOICE SENT & PAYMENT RECEIVED
 
Founder of XSA-Labs
Joined 2012
Paid Member
xrk971 - 2 boards
pcgab - 2 boards - INVOICE SENT & PAYMENT RECEIVED
zman01 - 2 boards - INVOICE SENT & PAYMENT RECEIVED
stellarelephant - 2 boards - INVOICE SENT & RECEIVED
samoloko - 1 pcb
lui04 - 2 boards

Morde - 2 board - INVOICE SENT & PAYMENT RECEIVED
cyteen - 2 boards
funch - 2 boards - INVOICE SENT & PAYMENT RECEIVED
syyma - 2 boards - INVOICE SENT & PAYMENT RECEIVED
av-trouvaille - 2 boards - INVOICE SENT & PAYMENT RECEIVED
Mituisho - 2 boards - INVOICE SENT & PAYMENT RECEIVED
bogde - 2 boards
faltinsen - 2 boards - INVOICE SENT & PAYMENT RECEIVED
vanofmonks - 1 board - INVOICE SENT & PAYMENT RECEIVED
M_Balou - 2 boards - INVOICE SENT & PAYMENT RECEIVED
dwpeterson - 2 boards - INVOICE SENT & PAYMENT RECEIVED
agdr - 1 board
walangalam - 2 boards
gwrskien - 2 boards - INVOICE SENT & PAYMENT RECEIVED
redarc12- 2 boards - INVOICE SENT & PAYMENT RECEIVED
dw1narso - 2 boards - INVOICE SENT & PAYMENT RECEIVED

The folks in blue above still have not provided me their email for the invoice. We are currently at 31 boards for people who have paid and 41 if counting folks who have not yet paid.
 
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Founder of XSA-Labs
Joined 2012
Paid Member
xrk971 - 2 boards
pcgab - 2 boards - INVOICE SENT & PAYMENT RECEIVED
zman01 - 2 boards - INVOICE SENT & PAYMENT RECEIVED
stellarelephant - 2 boards - INVOICE SENT & RECEIVED
samoloko - 1 pcb
lui04 - 2 boards
Morde - 2 board - INVOICE SENT & PAYMENT RECEIVED
cyteen - 2 boards
funch - 2 boards - INVOICE SENT & PAYMENT RECEIVED
syyma - 2 boards - INVOICE SENT & PAYMENT RECEIVED
av-trouvaille - 2 boards - INVOICE SENT & PAYMENT RECEIVED
Mituisho - 2 boards - INVOICE SENT & PAYMENT RECEIVED
bogde - 2 boards - INVOICE SENT & PAYMENT RECEIVED
faltinsen - 2 boards - INVOICE SENT & PAYMENT RECEIVED
vanofmonks - 1 board - INVOICE SENT & PAYMENT RECEIVED
M_Balou - 2 boards - INVOICE SENT & PAYMENT RECEIVED
dwpeterson - 2 boards - INVOICE SENT & PAYMENT RECEIVED
agdr - 1 board
walangalam - 2 boards
gwrskien - 2 boards - INVOICE SENT & PAYMENT RECEIVED
redarc12- 2 boards - INVOICE SENT & PAYMENT RECEIVED
dw1narso - 2 boards - INVOICE SENT & PAYMENT RECEIVED
 
Founder of XSA-Labs
Joined 2012
Paid Member
xrk971 - 2 boards
pcgab - 2 boards - INVOICE SENT & PAYMENT RECEIVED
zman01 - 2 boards - INVOICE SENT & PAYMENT RECEIVED
stellarelephant - 2 boards - INVOICE SENT & RECEIVED
samoloko - 1 pcb
lui04 - 2 boards
Morde - 2 board - INVOICE SENT & PAYMENT RECEIVED
cyteen - 2 boards
funch - 2 boards - INVOICE SENT & PAYMENT RECEIVED
syyma - 2 boards - INVOICE SENT & PAYMENT RECEIVED
av-trouvaille - 2 boards - INVOICE SENT & PAYMENT RECEIVED
Mituisho - 2 boards - INVOICE SENT & PAYMENT RECEIVED
bogde - 2 boards - INVOICE SENT & PAYMENT RECEIVED
faltinsen - 2 boards - INVOICE SENT & PAYMENT RECEIVED
vanofmonks - 1 board - INVOICE SENT & PAYMENT RECEIVED
M_Balou - 2 boards - INVOICE SENT & PAYMENT RECEIVED
dwpeterson - 2 boards - INVOICE SENT & PAYMENT RECEIVED
agdr - 1 board
walangalam - 2 boards
gwrskien - 2 boards - INVOICE SENT & PAYMENT RECEIVED
redarc12- 2 boards - INVOICE SENT & PAYMENT RECEIVED
dw1narso - 2 boards - INVOICE SENT & PAYMENT RECEIVED

Bogde,
Sorry, my mistake.
X
 
Founder of XSA-Labs
Joined 2012
Paid Member
Update on status, thanks to all for the quick responses!

xrk971 - 2 boards
pcgab - 2 boards - INVOICE SENT & PAYMENT RECEIVED
zman01 - 2 boards - INVOICE SENT & PAYMENT RECEIVED
stellarelephant - 2 boards - INVOICE SENT & RECEIVED
samoloko - 1 pcb - INVOICE SENT & PAYMENT RECEIVED
lui04 - 2 boards
Morde - 2 board - INVOICE SENT & PAYMENT RECEIVED
cyteen - 2 boards - INVOICE SENT & PAYMENT RECEIVED
funch - 2 boards - INVOICE SENT & PAYMENT RECEIVED
syyma - 2 boards - INVOICE SENT & PAYMENT RECEIVED
av-trouvaille - 2 boards - INVOICE SENT & PAYMENT RECEIVED
Mituisho - 2 boards - INVOICE SENT & PAYMENT RECEIVED
bogde - 2 boards - INVOICE SENT & PAYMENT RECEIVED
faltinsen - 2 boards - INVOICE SENT & PAYMENT RECEIVED
vanofmonks - 1 board - INVOICE SENT & PAYMENT RECEIVED
M_Balou - 2 boards - INVOICE SENT & PAYMENT RECEIVED
dwpeterson - 2 boards - INVOICE SENT & PAYMENT RECEIVED
agdr - 1 board - INVOICE SENT
walangalam - 2 boards
gwrskien - 2 boards - INVOICE SENT & PAYMENT RECEIVED
redarc12- 2 boards - INVOICE SENT & PAYMENT RECEIVED
dw1narso - 2 boards - INVOICE SENT & PAYMENT RECEIVED
 
Founder of XSA-Labs
Joined 2012
Paid Member
Status update, only Lui04 and Walangalam have not responded.

xrk971 - 2 boards
pcgab - 2 boards - INVOICE SENT & PAYMENT RECEIVED
zman01 - 2 boards - INVOICE SENT & PAYMENT RECEIVED
stellarelephant - 2 boards - INVOICE SENT & RECEIVED
samoloko - 1 pcb - INVOICE SENT & PAYMENT RECEIVED
lui04 - 2 boards
Morde - 2 board - INVOICE SENT & PAYMENT RECEIVED
cyteen - 2 boards - INVOICE SENT & PAYMENT RECEIVED
funch - 2 boards - INVOICE SENT & PAYMENT RECEIVED
syyma - 2 boards - INVOICE SENT & PAYMENT RECEIVED
av-trouvaille - 2 boards - INVOICE SENT & PAYMENT RECEIVED
Mituisho - 2 boards - INVOICE SENT & PAYMENT RECEIVED
bogde - 2 boards - INVOICE SENT & PAYMENT RECEIVED
faltinsen - 2 boards - INVOICE SENT & PAYMENT RECEIVED
vanofmonks - 1 board - INVOICE SENT & PAYMENT RECEIVED
M_Balou - 2 boards - INVOICE SENT & PAYMENT RECEIVED
dwpeterson - 2 boards - INVOICE SENT & PAYMENT RECEIVED
agdr - 1 board - INVOICE SENT & PAYMENT RECEIVED
walangalam - 2 boards
gwrskien - 2 boards - INVOICE SENT & PAYMENT RECEIVED
redarc12- 2 boards - INVOICE SENT & PAYMENT RECEIVED
dw1narso - 2 boards - INVOICE SENT & PAYMENT RECEIVED
 
Founder of XSA-Labs
Joined 2012
Paid Member
Revised Board Schematic, Silkscreen, and BOM

Thanks to BDHM for revising the schematic to be easier to use with designations A and B for left and right and paralleled parts with sub-numbers. Below are the new schematic, board silkscreens on topside (through hole) and bottomside (SMT) so you can see where everything goes.

Schematic:
596768d1486181745-xrk971-pocket-class-headamp-gb-xrk971-pocket-class-headamp-schematic-v8.png


Top side Layout Silkscreen:
596769d1486181745-xrk971-pocket-class-headamp-gb-xrk971-pocket-class-headamp-board-side-top-v8.png


Bottom side Layout Silkscreen (note that 100nF C4A and C4B are mislabled 47uF - need to rework this before sending to fab):
596770d1486181745-xrk971-pocket-class-headamp-gb-xrk971-pocket-class-headamp-board-side-bottom-v8.png


BOM:
Code:
All resistors 0805 package, metal thin film, 1% on specified parts, else 5%. Yageo 1% 0805 SMT from Digikey are $0.77 for 100
R1	100k (5%)
R2	47k (1%)
R3	1k (1%)
R4	33R (1%)
R5	270R (1%)
R6	47R (5%)
R7_1	470R (1%)
R7_2	470R (1%)
R7_3	470R (1%)
R7_4	470R (1%)
RL	270R (5%) User select (optional, use for higher current draw on amp) 
RLED 15k (5%) 	Current limit for LED, 15k or value according to supply voltage 

C1	Input cap 5mm pitch up to 5.5mm wide (Wima 2.2uF MKS2B042201F00JSSD)
C2_1	Output cap 3.5mm pitch, 8 dia (390uF 20v Panasonic OSCON  20SEPF390M)
C2_2	Output cap 5mm pitch, up to 9mm wide (Wima 1uF MKS2C041001F00KSSD)
C3	Rail cap 100uF 3.5mm pitch, diameter whatever you can fit in the tin (100uF 20v Panasonic OSCON  20SEP100MX)
C4	Rail cap 100nF 1206 package (50v X7R) 
C5	Additional 100nF rail cap 1206 package  (50v X7R)

Q1	BF862  (771-BF862-T/R)
M1	ZVN4306GTA 

Switchcraft 3.5mm stereo jacks x2 (35RAPC4BV4)
Alps 10kOhm stereo pot with power switch (RK0971221Z05)
3mm round LED (red or green)
4-pin 2.54mm pitch power connector (see post #44)
 

Attachments

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Yee-haw! Thanks for all the effort. :)

Question:
A gentleman on Head-Fi with 16 Ohm IEMs expressed interest in this amp. I used the formula provided by Andrew in post #25 and found F-3dB to be at ~26Hz.
(Also found this handy calculator: -3dB Cutoff Frequency Calculator)

This seems like it could present audible roll-off??

I'm planning to use the recommended 390uF Panasonic poly caps in the amp I'm building for myself to pair with my HD 598 headphones. But let's say I want to build my second amp to play well with ANY headphone. I've not quite mastered Mouser yet, but it looks like 390 is the largest value available for that type of cap... Would it be worthwhile to sub a regular electrolytic of a higher value, and what would be the sonic tradeoffs, if any? Any specific brand recommendations? Worth it?
 
Founder of XSA-Labs
Joined 2012
Paid Member
We just need to get the silkscreen fixed for C4A and C5B to show 10nF rather than 47uF then we are ready to get the boards made.

Update:

xrk971 - 2 boards
pcgab - 2 boards - INVOICE SENT & PAYMENT RECEIVED
zman01 - 2 boards - INVOICE SENT & PAYMENT RECEIVED
stellarelephant - 2 boards - INVOICE SENT & RECEIVED
samoloko - 1 pcb - INVOICE SENT & PAYMENT RECEIVED
lui04 - 2 boards
Morde - 2 board - INVOICE SENT & PAYMENT RECEIVED
cyteen - 2 boards - INVOICE SENT & PAYMENT RECEIVED
funch - 2 boards - INVOICE SENT & PAYMENT RECEIVED
syyma - 2 boards - INVOICE SENT & PAYMENT RECEIVED
av-trouvaille - 2 boards - INVOICE SENT & PAYMENT RECEIVED
Mituisho - 2 boards - INVOICE SENT & PAYMENT RECEIVED
bogde - 2 boards - INVOICE SENT & PAYMENT RECEIVED
faltinsen - 2 boards - INVOICE SENT & PAYMENT RECEIVED
vanofmonks - 1 board - INVOICE SENT & PAYMENT RECEIVED
M_Balou - 2 boards - INVOICE SENT & PAYMENT RECEIVED
dwpeterson - 2 boards - INVOICE SENT & PAYMENT RECEIVED
agdr - 1 board - INVOICE SENT & PAYMENT RECEIVED
walangalam - 2 boards
gwrskien - 2 boards - INVOICE SENT & PAYMENT RECEIVED
redarc12- 2 boards - INVOICE SENT & PAYMENT RECEIVED
dw1narso - 2 boards - INVOICE SENT & PAYMENT RECEIVED
zimmer64 - 2 boards - INVOICE SENT & PAYMENT RECEIVED

About 40 boards total
 
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