A New Take on the Classic Pass Labs D1 with an ESS Dac

[pmchoong]

Hi Owen,

I send you a pm.

[maravedis]

Qusp, Could you advise me about FET matching?
I have found a bag of 25 IRF540N in my stash...
What method do you use? I'm happy to build a matching Jig for the future
thanks!

[qusp]

if you look in the parts forum i started a thread search for threads containing 'mosfet matching D1' in the parts sub-forum with thread starter as me. the pass articles are a good source of info too. its too much info to make a whole new post here, sorry i dont have time, but my matching rig pics of it, the schematic etc are all in there. if i was to do it again i would actively control the temp of the heatsink with a mosfet and thermistor to allow contant use of the device rather than watching for temp spikes and stopping. i got very good results all the same as all 3 sets i have installed have ended up with the pots to adjust bias on the D1 have all been pretty much identical setting to get the same 1.65v once up to temp. this isnt a great indicator due to the tolerance on the pots being not fantastic, but nice reinforcement

a word of warning, i matched for transconductance in a replica of one arm of the D1 at the exact operating point we are using, its not a normal mosfet vgs matching rig and 25 isnt really enough to get excellent matches, you'll get decent matches though.

[opc]

Hi Guys,

I'm going to do another run of these boards, but this time it'll be PCB only.

If you're interested, post it here and I'll compile a list. The price will likely be $25 plus $5 flat rate for shipping. I need to confirm the price after checking with the PCB fab guys though.

Once the number hits 25 boards, I'll give it one week and then place the order. If you miss it this time, you're probably out of luck as it's unlikely that I'll ever run another.

Regards,
Owen

[cersepn]

Sweet! Would it be possible to have the SMD stuff pre-soldered like in the first run? I wouldn't mind paying extra for that

D1 PCB Interest List
1. cersepn x 1

[icewall]

Sweet!
I'm in for 2 boards!

[merlin el mago]

D1 PCB Interest List
1. cersepn x 1
2. icewall x 2

[pmchoong]

How many boards do we actually need? Thanks.

D1 PCB Interest List
1. cersepn x 1
2. icewall x 2
3. pmchoong x 1

[opc]

The list begins! Good work guys, and keep it coming.

cersepn:

I've got too much on the go to put kits together for this. There is a good BOM in the build thread if you want to get a kit together for the others who order this board. Generally speaking, if you get enough people interested then everyone can save a little money by buying parts together.

Soldering the SMD is a piece of cake. There are several videos on youtube that show just how easy it is.

Regards,
Owen

[qusp]

D1 PCB Interest List
1. cersepn x 1
2. icewall x 2
3. pmchoong x 1
4. qusp x 1 this is tentative mate, but wanted to make sure my name was down