I've searched extensively but I can't seem to find the k170 FET's for sale ANYWHERE except the matched pairs from the diyaudio store, which sell for 20 dollars per pair and limits to 2 pairs / person. Seeing as the design needs 6 unmatched JFET's, does anyone know where I can get them?
Are there more available alternatives for the k170?
Are there more available alternatives for the k170?
I bought the matched pairs only for the buffer JFETs, and used octopart.com to buy "cheap" parts for the ones used in the shunt PSU.
Just did an octoparts.com search again for LSK170, and found several offers, like at $2.90 a piece, which is a similar price to what I paid. I'm no expert in this though, and was worried about fakes, but I'm very happy with my built!
Just did an octoparts.com search again for LSK170, and found several offers, like at $2.90 a piece, which is a similar price to what I paid. I'm no expert in this though, and was worried about fakes, but I'm very happy with my built!
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For those six you can also use currently available Toshiba surface mount JFETs. To solder them on little adapter boards for through hole and then to the main board. You can cheaply find such mini pcb interface as "SOT23-3 to DIP SIP3 Adapter".
2SK209GR have good enough IDSS and low noise for the job in the PSU section. They also seem consistent for close sample spec straight out of the reel. I wouldn't recommend them in BL option though because tiny smd 150mW and maybe they will be getting too hot for longevity in DCB1 application that runs them full IDSS on.
Mouser no: 757-2SK209GRTE85LF
Digi-Key no: 2SK209-GR(TE85LF)CT-ND
2SK209GR have good enough IDSS and low noise for the job in the PSU section. They also seem consistent for close sample spec straight out of the reel. I wouldn't recommend them in BL option though because tiny smd 150mW and maybe they will be getting too hot for longevity in DCB1 application that runs them full IDSS on.
Mouser no: 757-2SK209GRTE85LF
Digi-Key no: 2SK209-GR(TE85LF)CT-ND
Here‘s an earlier hint from Salas for getting genuine parts...
https://www.diyaudio.com/forums/pass-labs/176723-mezmerize-dcb1-building-thread-227.html#post6211006
I feel BF862 is an appropriate replacement for DCB1 and pretty cheap too, but you would need converters since its a SOT-23 package
They are also obsoleted but more recently and you gotta watch their Idss because usually about 16mA which means 160mW each in DCB1's matched quartet. They are 300mW max smd parts and that can be a stress. If you got any BF862 their yfs and noise are fine for the quartet but it takes a special spring loaded test socket to match them. Or a component tester with auxiliary smd surface to press them on with finger or something. They aren't much consistent out of the reel.
For the six PSU JFETs I would still recommend 2SK209GR over BF862 because they run cooler and consistent out of the reel so that you wouldn't look twice.
There have also been fake BF862 from ebay reported after they went obsolete. In my opinion most carefree full TO-92 first scenario is matched quartet LSK170B from the DIYA store and six random LSK170A or LSK170B at $3.1 each from NACsemi St. Petersburg Florida.
Second TO-92+SMD more complex mixed scenario is LSK170B quad from DIYA store and six 2SK209GR at $0.46 each from Mouser/Digi-Key. Plus a bunch of SOT23-3 to DIP SIP3 Adapters from ebay or alike source.
For the six PSU JFETs I would still recommend 2SK209GR over BF862 because they run cooler and consistent out of the reel so that you wouldn't look twice.
There have also been fake BF862 from ebay reported after they went obsolete. In my opinion most carefree full TO-92 first scenario is matched quartet LSK170B from the DIYA store and six random LSK170A or LSK170B at $3.1 each from NACsemi St. Petersburg Florida.
Second TO-92+SMD more complex mixed scenario is LSK170B quad from DIYA store and six 2SK209GR at $0.46 each from Mouser/Digi-Key. Plus a bunch of SOT23-3 to DIP SIP3 Adapters from ebay or alike source.
I must say I feel tempted to just buy a few dozen 2SK209GR for 32 cents/ piece. I have a buddy who works at an electronics equipment facility and can match them for me.
And to avoid burning them I could mount them to a piece of aluminium or copper strip after soldering them to the adapters.
It will certainly not be easy to heatsink the ones in the power supply section, but I think it might be worth a shot.
No need to sink those SMD when 2SK209GR. Usually about 3mA IDSS only. 45mW dissipation at most. A member measured them very close for IDSS when coming out of the reel. Maybe he lucked out on a very consistent batch though. Your friend may confirm if that consistency is repeatable or not. Not that it matters much in PSUs section. OK avoid gross mismatches when able and that's enough.
cathing up on forgotten projects
Here is a Mezmerize, that i completely forgot about, in a temporary home untilI can order or construct a chassis for it. I recentley constructed a "de-lite" amp and found my korg B1 a little to "flavored" for it. Then I remembered I had a Mezmerize, board fully built, laying around untested. Long story short I powered it up and WOAH! This preamp is GREAT! It sounds very clear and perhaps a tiny bit dry but with the "de-lite" it really shines. Voices are so well represented you can tell when the singer moves away from the michrophone. Instruments are sharp and vivid. Strings are so clear the bowing is audible, Guitars are fast and punchy and drums are full!
I also tried it out with my Aleph J, I have read complaints about the Aleph with a B1. Not the case in my system. I am finally able to drive my Aleph and it sounds amazing! I do have fairly sensetive speakers so perhaps this is why. I do have an impedance mismatch with my phono stage, which does not sound good - but I'm finishing up a FSP so hopefully that is better matched.
Overall I HIGHLY recomend this preamp!
Jeffrey
Here is a Mezmerize, that i completely forgot about, in a temporary home untilI can order or construct a chassis for it. I recentley constructed a "de-lite" amp and found my korg B1 a little to "flavored" for it. Then I remembered I had a Mezmerize, board fully built, laying around untested. Long story short I powered it up and WOAH! This preamp is GREAT! It sounds very clear and perhaps a tiny bit dry but with the "de-lite" it really shines. Voices are so well represented you can tell when the singer moves away from the michrophone. Instruments are sharp and vivid. Strings are so clear the bowing is audible, Guitars are fast and punchy and drums are full!
I also tried it out with my Aleph J, I have read complaints about the Aleph with a B1. Not the case in my system. I am finally able to drive my Aleph and it sounds amazing! I do have fairly sensetive speakers so perhaps this is why. I do have an impedance mismatch with my phono stage, which does not sound good - but I'm finishing up a FSP so hopefully that is better matched.
Overall I HIGHLY recomend this preamp!
Jeffrey
Attachments
Nice, congrats. Looks so cheerful in a clear case showing off its shiny LEDs. 
*Some of the tonality traits are down to the pot. And to some run-in time needed for the electrolytics.
The ALPS works fine and sits directly on the PCB but if you ever feel like investing more try a TKD pot.
2CP-2511 or 2CP-601. Ladder like. Hi-Fi Collective in the U.K. offers them in 20k Log as used in DCB1.
*Some of the tonality traits are down to the pot. And to some run-in time needed for the electrolytics.
The ALPS works fine and sits directly on the PCB but if you ever feel like investing more try a TKD pot.
2CP-2511 or 2CP-601. Ladder like. Hi-Fi Collective in the U.K. offers them in 20k Log as used in DCB1.
input impedance
Hi.When using 2sk209gr paralleled increase or decrease input impedance of DCB1?Should we use lower value potentiometer or higher value potentiometer?
Hi.When using 2sk209gr paralleled increase or decrease input impedance of DCB1?Should we use lower value potentiometer or higher value potentiometer?
OK later on I will graph you an about same 7mA IDSS 2SK170 on same interface and scales to compare
