luvdunhill

The obvious solution: build two PSUs and go dual mono. Then it's a all a moot point.

I Don't want to step in a minefield here The facts are in the thread if you want to do something other than follow the previous builders. I didn't.

I am leaving that Sunday for San Francisco a week so that will impact when I have to get back by. I can leave early on Friday though. Verbal approval given by spouse

It's a 4 hour drive for me. I am going to try hard to make it. I would also request a "no idiots allowed" sign for my space as I won't have at least one of my items fully cased up. Also, curious if Jacob would allow some listening on his speaker rig and if so I would bring more items.

Rather than asking for larger cores, I would ask for less temperature rise. Be the customer with requirements, not the engineer. Also you might ask someone for measurements who is using SumR so the comparison is somewhat sane. (Notice the temp rise spec in GeorgeP's post and compare to my post. Hint: I went down this road already and still wouldn't mind cooler transformers)

So, my filament transformer is spec'ed at 33C temperature rise (relative) and the other two are 31C temperature rise. At maximum current, where the load on each supply is equivalent to the current limit and similarly the heaters are loaded, I measured max temperature at 52C (absolute) after 1 hour of operation all cased up. There is 1.5" of clearance above the toroids, with lots of venting above. For what it's worth, that resulted in a max temperature of one of my loads to be around 178C, which was bolted to the same case (!). The maximum device temperature in the PSU, as measured at the bolt of the device was 78C. Again, this is definitely "worst" case. In this configuration, the noise seems to go up slightly, I think my highest rail noise was .76mV (!).

I have been considering how to heatsink toroids but havent found a strategy that works well. Be careful to avoid creating a shorted turn as well.

Sorry I wasn't clear. Replace the bad one and compare the voltage drops across the 10 ohm resistor. They will be close but not exact. You can then adjust the ballast resistor (you can do this out of circuit, since you have a board to get the voltage on top of the jfets from, also it is on the schematic) and then make the same change on the good chanel. Or just replace them with matched singles K170BL. Or negotiate a trade I might have some lying around.

I don't have fin temps, but I do have a few device temps. I have them somewhere I can post them once I shake the flu When measuring toroids it seems that the highest temp rise is between the potting compound and the side opposite from the wire leads. I finally gave up on my IR thermometers and bought a pyrometer that I can touch directly to the device I want to measure. This seems to help getting accurate measurements.

Moving to vertical finned heat sinks is enough to make the thing run a lot cooler. I worry most about my transformers, they run hotter than I would like.

I would replace the bad one first and go from there.

Is there a Headamp trade up plan?

Likely the expensive one in the right channel went bad I can verify when I can grab the schematic.

The new Airport Extreme can have a USB drive connected that can work as a Time Machine server. Probably the power savings over the G5 will cover the $200 cost.

Is reliability really that important these days? Backup to an external drive and use cloud for some stuff as well. Anyways I would make the SSD non negotiable. Same argument as above with regard to size, shouldn't need much really.

Heh. I would suspect something is wrong, yes.

I didn't ask what they were around, but what they measured. I want to see if you suck at randomness or need better matched devices. Pick a bias and compare. If you want post a min and max value across all the values.

Can you post the voltage drop across each 10 (2x20) ohm resistor for all four channels?

Sweet. Advertised 10% THD.

Anyone have the cheapie Shiit DAC for sale / trade / demo etc.?

If it is 80 mA DC then 150 mA RMS isn't overkill at all, it's a bare minmum.

Is the 150 mA specified as AC RMS? What is the DC current draw of the amp?

If one of the SK170 is bad (my guess) I can match a new one for ya.

I have the manual just can't upload it from my phone to Tapatalk and I am lazy. PM me your email addr.

Measure the voltage drop across the four 22 ohm resistors that degenerate the four input 2SK170 to start with. Also the 10 ohm near the 2SK389. Compare channels.