[Hifihedgehog]

Here are the latest PIMETA V1, PPA V1 and PPA V2 Gerber files. Note that that PIMETA V1 files do not have an outline file because of a minor incompatibility in PDF2GERB with non-rectangular board shapes. Related to this, the PPA V1 and PPA V2 now have outline files. Let me know how they work. I will probably get some PIMETA V1 boards fabricated in the next few weeks.

See attached:

 

[3l3tric]

 
So at this point, we would have to organize a group buy to pull off getting more PIMETA V2 boards.

I'd be up for this.
Assuming you are too, 8 to go. Lol.
But reading the rest of what you stated, the price point is a tad bit meh. 
I thought about it a bit, and maybe (with tangent's blessing) we could get another DIYer with a storefront to carry the boards?
Ti Kan (AMB) has a pretty robust storefront already with multiple boards and other products for sale. Although I'm not sure how keen he'd be on selling a second 3-channel board (his M^3 design is also 3 channel).

 

[Hifihedgehog]

  I'd be up for this.
Assuming you are too, 8 to go. Lol.
But reading the rest of what you stated, the price point is a tad bit meh. 
I thought about it a bit, and maybe (with tangent's blessing) we could get another DIYer with a storefront to carry the boards?
Ti Kan (AMB) has a pretty robust storefront already with multiple boards and other products for sale. Although I'm not sure how keen he'd be on selling a second 3-channel board (his M^3 design is also 3 channel).

I would definitely be in on this. I would probably want a couple at least for op-amp swapping, gifting to friends and family and such.
 
The storefront idea would actually be quite simple for me to pull off. I own a URL ( theheadphonehub.com ) that I have wanted to get off the ground for some time--originally for an ad-based headphone review site but listen here, I have an even better idea. Instead, I could set up a non-profit circuit board group buying and non-profit headphone information site. I would first have to get permission from the higher ups here and possibly apply for MoT status to post anything about it. I mean, I could buy the batches, sell them on a slightly above for-cost basis, use the excess money to pay for renewing the site subscription and lowering the costs on future board runs, and finally donating whatever extra is left after all is said and done to a non-profit charity like The Red Cross.

 

[3l3tric]

I would definitely be in on this. I would probably want a couple at least for op-amp swapping, gifting to friends and family and such.

The storefront idea would actually be quite simple for me to pull off. I own a URL ( theheadphonehub.com ) that I have wanted to get off the ground for some time--originally for an ad-based headphone review site but listen here, I have an even better idea. Instead, I could set up a non-profit circuit board group buying and non-profit headphone information site. I would first have to get permission from the higher ups here and possibly apply for MoT status to post anything about it. I mean, I could buy the batches, sell them on a slightly above for-cost basis, use the excess money to pay for renewing the site subscription and lowering the costs on future board runs, and finally donating whatever extra is left after all is said and done to a non-profit charity like The Red Cross.

That's an excellent idea!
I wouldn't necessarily count out the reviewing part of the site, though. We could put comprehensive reviews of different DIY equipment and articles about different DIY related stuff like cable braiding, DIY cable building, soldering techniques, opamp reviews, and the like.

 

[tangent]

Okay, this time for sure. I dug the design files out of the email archive, so they have to be correct now.

 

[Hifihedgehog]

I just ordered what appears to be the greatest deal in PCB fabrication history. I will post the pictures when my PIMETA V1 boards arrive. I ordered from Maker Studio which charges only $10 plus about $6 shipping and handling for ten 10x10cm boards. Insanely cheap but it is 100% legil. They seem to be the new benchmark for this price point. The only noted problem is just a very minor ~1mm offset in the silkscreens which is nothing big at all to worry about in projects like these. See examples of the quality of the boards here:
http://www.edn.com/electronics-blogs/all-aboard-/4437745/Quick-Turn-PCB-shop-review-project--Maker-Studio
http://www.protonbasic.co.uk/showthread.php/72429-Anyone-used-PCB-Maker-Studio
 
Also, a quick question for Tangent: Are we authorized to resell any boards (for profit and/or non-profit) we have made from your designs? (The boards will have the original, unaltered attributions and design layout that you provided. One exception: On the PIMETA V1, I had to remove several silkscreen lines that went off the board of the ALPS pot that resulted from the import of the original Express PCB diagram.) If so, I may sell off a few of the extra boards on eBay if they all pass my probing tests. 

 

[tangent]

I have not formally released any of my hardware designs under an open hardware license, which means they're still under copyright.
 
I put the files up there for people to riff off of, not to copy wholesale.
 
I don't care if make a few for yourself or friends.
 
But if you're going to involve money, I'd ask you to create your own design. Go do something interesting.  Add something different to the world.

 

[Hifihedgehog]

I have not formally released any of my hardware designs under an open hardware license, which means they're still under copyright.

I put the files up there for people to riff off of, not to copy wholesale.

I don't care if make a few for yourself or friends.

But if you're going to involve money, I'd ask you to create your own design. Go do something interesting.  Add something different to the world.

Understood. If even a group buy ever happens, it will happen under your go ahead to respect your hard work for the community these many years. Speaking of creating something new and interesting on someone's own, I do have an idea of a more advanced DIY device I have been wanting to make for some time: a digital ADC-DAC interface and headphone amplfier combo with a digital crossfeed filter. I think the merits of crossfeed have been getting pushed under the rug lately because of the flagship price battles that been a-waging the last decade. And many people have long forgotten that one limitation, the superstereo effect, can only really be overcome by advanced channel filtering and mixing that crossfeed and other virtualization techniques provide. As for implementing this, I will have to do some heavy reading and mega prototyping this summer if it is ever going to see the light of day.

 

[3l3tric]

Question for you guys:
I want to integrate a battery charge indicator board to my amplifier. I want it to have 4-5 LEDs and a push button that, when pushed, lights up the LEDs to indicate the charge. 5 LEDs would be 100-81%, 4 80-61%, so on.
I found the link below, but it looks like this board is for 5V batteries, instead of the 9.6V setup I have.
Any suggestions?
 
http://ru.aliexpress.com/store/product/Single-section-lithium-battery-LED-power-indicator-display-voltage-lithium-battery-voltage-indicator/914980_955703587.html

 

[MisterX]

A LM3914 would be an easy way to add a voltage level indicator.
http://www.ti.com/product/lm3914

 

[3l3tric]

A LM3914 would be an easy way to add a voltage level indicator.
http://www.ti.com/product/lm3914

How easy would it be to both power the chip and measure battery charge with it?
I coud be reading wrong, but it sounds like the source is only measurable between 0-5V, not 9.6.
EDIT: Nevermind, I was looking at an example diagram.
My question about the input measuring battery charge and the whole chip being powered by the same battery still stands, though

 

[MisterX]

Put a voltage divider between V+ and the signal input.
(trimmers are frequently used so the "scale" can be calibrated)
IIRC there was a schematic posted somewhere in this thread.
 
 
Edit: check page 30.

 

[3l3tric]

Thanks!
One question, though: How would I go about running the indicator with only 5 LEDs? I don't have room for and really don't want all 10.

 

[MisterX]

You don't have to use all 10 LED positions.
Put it all together on a breadboard and then pick which terminal (on the LM3914) best suits the desired behavior for each LED.

 

[3l3tric]

  You don't have to use all 10 LED positions.
Put it all together on a breadboard and then pick which terminal (on the LM3914) best suits the desired behavior for each LED.

Alright, thanks.
After further research, I found a design that uses Zenerdiodes in combination with resistors and LEDs to conduct the indication.
Each zenerdiode's tolerance voltage goes up, from the battery-nearly-dead voltage to the battery-nearly-full voltage.
I looked on digikey, and they seem to have all the necessary parts in a good accuracy space (I found 9.0V, 9.1V, 9.6V, 9.3V, 9.4V, and others).
Is there something I'm missing that would result in this circuit not working?