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Ultra high spec. opamp MC/MM phono, warp "elliptic" filter, line, headphone amps.

Please remember that the layout, including the silk screen, conforms to the original schematic, which was wrong.
All that matters is that C50 should have its polarity reversed from the screened value so that, as Mike Barney states, the negative terminal goes to ground.
Check the layout for the location of C50 and go from there.
 
OK, I just want to preface this by saying that I spent an hour with Google and AK in order to find this answer and I wasn't able to (which may be a reflection on my own IT abilities):

Can someone please point me to the build guide or BOM for the v3.2 board? I recently grabbed an unused board from another AKer, after I've already built and have been enjoying the v1.3 for as long as it was the current option. I am just considering a cartridge upgrade and want a dedicated board perfectly spec'd for the current and new carts respectively.
 
If you're going to the effort to build one, I'd suggest building the latest version. It's better and similar build difficulty. There's a dedicated build thread.
 
hirscwi said:
If you're going to the effort to build one, I'd suggest building the latest version. It's better and similar build difficulty. There's a dedicated build thread.
Click to expand...
I concur. The schematic/BOM have been confirmed, and the only issue is that there are more SMDs to deal with, although it's certainly not overwhelming- I've just completed the board build for two identical units.
 
WYN! How are you?

I sent you a mail a while back to check in as I hadn't heard anything for a while.
 
j!m said:
WYN! How are you?

I sent you a mail a while back to check in as I hadn't heard anything for a while.
Click to expand...
Sorry, I don't remember getting an email from you.
I'm more or less fine, thank you for asking.
Both cancers were declared in remission a couple of weeks ago, but several months ago I messed up my knee jumping over a stream during a hike, and that's taking forever to heal.
Other than that, life is good.
 
hirscwi said:
If you're going to the effort to build one, I'd suggest building the latest version. It's better and similar build difficulty. There's a dedicated build thread.
Click to expand...
It's possible for an answer to be both true and unhelpful at the same time. I just picked up a v3.2 board on a lark, not a v4. As long as the v3.2 is an improvement over the V1.3, I guarantee I will be happy.

I think I've ascertained that this WAS the link to the files I need, but they are no longer there:
Dropbox
 
cdfac said:
It's possible for an answer to be both true and unhelpful at the same time. I just picked up a v3.2 board on a lark, not a v4. As long as the v3.2 is an improvement over the V1.3, I guarantee I will be happy.

I think I've ascertained that this WAS the link to the files I need, but they are no longer there:
Dropbox
Click to expand...
Have the files but they are too large to upload here, you need the V2 build note and the V3 addendum I think.

Athanasios
 
The difference between v3.2 & v 4 is minimal output wise. For this 73 year old those SMD's were very stressful to solder in place and if a mistake is made, good luck.
 
This 72 (73 in a few days) found the SMDs relatively easy.
However, I have a movable magnifier for work, a board holder and a hot air solder system, but no heating pad.
I mounted the board on the holder. Applied 138c solder paste not too generously to the pads, placed some of the devices (not too carefully), turned the heat to 430f with a medium sized nozzle and waved it around the devices in question until the solder flowed. As the solder flows the surface tension pulls the devices into the "ideal" position on the pads with virtually no intervention required. You can watch the process unfold, it's pretty interesting. The low air flow stops even the 0806 parts from being blown away.
Some soldering iron intervention was required to clear bridges between the pads of the OPA1656s, but that was minimal and easy.
I then checked for shorts and opens with a meter, and all was well.
Having said that, I ended up building two boards because the recipients (both younger than I) were put off by the SMDs and lacked the equipment to do the job properly.
As of this moment, I've only tested one of the two boards, but it works perfectly.
 
I used what I had, a fine tip for my iron. would a heat gun work in place of a hot air solder station? thinking out loud it would probably blow the SMD off the table.

Down the road I have to populate 2-V4's for AvFan.
 
Both new preamp boards and their associated power supply boards are functional.
However, I tried testing them using a big ass bench power supply and managed to damage the unexpected power off protection circuit due to the supplies coming up too quickly and causing too high a reverse VBE to pe produced on a protection transistor. This can cause the transistor to fail in unexpected ways.
This is not an issue with the associated power supply board used to produce the +/-15v supplies, but it potentially is if another supply source is used.
To that end I will be making a revision to the board and implementing the changes on the two boards I am constructing.
I will post the details when ready.
It should also be noted that one of the two boards had a defect so that an island was shorted to ground. I used an Exacto knife to sever the connection.
These were the purple boards.
I have had similar problems with boards from China. It's rare but does occur.
 
Thanks folks. @mkane and I working together on this project and a hot air solder station is on its way.

@mkane loaned me his V4 and it didn't take long to recognize just how good the V4 is in MC mode and MM with my best SUT. We both described it as "clarity" but even that description doesn't do it justice. Something more.... Now to figure out the BOM with any substitutions that might be required.
 
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