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agdr Audio sales thread

I'm collecting the sales information for my various posted projects here, going forward. :) This is mainly so folks can buy bare PC boards to DIY if you don't want to lay one out yourself and have it fabricated. The schematic, BOM, and layout of my boards are all posted at the project links below, along with build instructions for each project.

If you need a board, or want to buy an assembled unit, please visit my website: http://www.agdraudio.com/ .

Happy DIY'ing! :)


OPA1688 Super CMOY project, with the TPS3701DDCT comparator (DIP-6) adapter PC board

Project thread: http://www.diyaudio.com/forums/head...y-2x-9v-real-ground-headphone-relay-pcbs.html


Inverting Version Of The NwAvGuy O2 Headphone Amplifier project

Project thread: http://www.diyaudio.com/forums/head...avguy-o2-headphone-amp-vs-original-thd-n.html


O2 Booster Board project

Project thread: http://www.diyaudio.com/forums/headphone-systems/244473-o2-headamp-output-booster-pcb.html


O2 Desktop Amplifier

Project thread: http://www.diyaudio.com/forums/headphone-systems/229934-version-o2-desktop-amp-oda.html

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Joined 2003
Paid Member
I'm not so up-to-date on CMOY. If I get the $19.60 variant, will that make me a good HP amp? What do I need to make it play in addition to what I get for $19.60?

Or should I wait for OPA1622 Multi-Use Board?

I just want to hook up my DAC to it and use my Philips Fidelio T2 for some late night high-end music consumption.

I'm not so up-to-date on CMOY. If I get the $19.60 variant, will that make me a good HP amp? What do I need to make it play in addition to what I get for $19.60?

Hi! The CMOYs are designed to fit into a mint tin from the grocery store. I've posted a picture below. This one uses two 9V batteries of any type and does not recharge. The batteries have to be removed to replace or recharge, and would have to be recharged in the battery manufacturer's charger. If your usage is primarily desktop on AC power the Super CMOY may not be a good fit. It is primarily intended to be a portable.

The CMOY board could be mounted in a larger case by drilling those same 3 mounting holes for the volume pot and 3.5mm jacks and supplying +/-12Vdc from an external supply, but that would be a fair amount of work to build up.

The numbers on paper for the OPA1622 are a bit better and it has higher power output. It also has bipolar input which is lower noise, but that is where things might go a bit south depending on how it is is being implemeted, The 1622 has a full 1uA of input bias current - a lot as these things go - which won't matter if the input is balanced from a DAC as shown in the datasheet. But for an unbalanced input that Ib could result in high(er) DC output offset voltages. May or may not be an issue, depending on the numbers. With the OPA1688 the datasheet says 0.25mV = 250uV DC offset. I was measuring one I built up this morning and I was getting 20uV of DC offset on each channel. :)


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Hi, just PM me for the paypal address. :) I'm doing it this way to try to minimize spam. I'll send a tracking number when the package ships (US destinations).

I PM'ed you last week, but I just found the agdraudio address today so I haven't really given you a chance to reply from that one.

I'm trying to find out about getting PCBs to make this, or a kit, anything. I am looking forward to hearing from you.