Not to worry - I’m in the buyers club 🙂 I’ve succumbed to temptation. I bought mine a while back with Sissysit in mind, but the decision on what to build just got harder... Good problems to have 😀
I've got a couple of pairs coming, one for a sissysit, and another for something else I haven't decided yet
Very exciting
Very exciting
Can anyone share how the Tokin sound like vs the Sony (or others?). I know the Sony ones were purpose built for audio use so it's a given that good results will come using them. However, the Tokin may be a different can of beans in terms of sound? THF-51S on paper seems to have better specs but it's sound?
I congrats that you've built and will continue the SIT venture as I will (and no qualms if you hold a couple of spares for future backups). Also it's fair to say this level of hype would not come without Mr watanabetomoaki selling his stash - there may be others but he's quite reputable and that speaks a lot in this day of online buying & selling.
The SIT are in a special category because of unobtanium while all the other projects can simply be put on the shelf without consequences of out of supply of parts / substitution parts. I would expect everyone that has bought SITs to have the full intention of building because there would be many that will build, but can not do so once these parts have long gone and sold out.
I congrats that you've built and will continue the SIT venture as I will (and no qualms if you hold a couple of spares for future backups). Also it's fair to say this level of hype would not come without Mr watanabetomoaki selling his stash - there may be others but he's quite reputable and that speaks a lot in this day of online buying & selling.
The SIT are in a special category because of unobtanium while all the other projects can simply be put on the shelf without consequences of out of supply of parts / substitution parts. I would expect everyone that has bought SITs to have the full intention of building because there would be many that will build, but can not do so once these parts have long gone and sold out.
For the obvious reason that Tokins only come as N channel parts, the
comparison would naturally be with the Sony parts in single-ended
operation.
As the very shortly-to-be-released DIY Sony Vfets are just that, I have
some data on the differences.
We see that the 2SK82/2SJ28 parts (which look to be dual die versions
of 2SK60/2SJ18) have a balance of transconductance, Drain impedance
and dissipation that appears to to favor about 8 ohm loads. In this case
the optimal bias arrangement seems to be close to a constant current
source, which is what I ended up using.
The 2SK/60/2SJ18 favor a higher impedance. They might want a little
help or a higher impedance load.
The 2SK180 THF51s are not all that different from the bigger Sony parts,
but they have the advantage of much higher dissipation capability, so
you get a more flexibility in setting the load lines, and of course the
potential for much more power.
The performance you get depends a lot on load line selection. In the
end, SITs in linear operation are prima donnas. If you want the
best performance out of them you tend to have to do it their way, but
of course that depends on what you call best performance. They are
pretty flexible that way - just adjust the voltage, bias current and load.
It you want wide band performance with the big SITs you also have
to be prepared to drive them with a low source impedance. Common
Drain Mode, 100 ohms is good. Common Source mode, more like 10
ohms.
comparison would naturally be with the Sony parts in single-ended
operation.
As the very shortly-to-be-released DIY Sony Vfets are just that, I have
some data on the differences.
We see that the 2SK82/2SJ28 parts (which look to be dual die versions
of 2SK60/2SJ18) have a balance of transconductance, Drain impedance
and dissipation that appears to to favor about 8 ohm loads. In this case
the optimal bias arrangement seems to be close to a constant current
source, which is what I ended up using.
The 2SK/60/2SJ18 favor a higher impedance. They might want a little
help or a higher impedance load.
The 2SK180 THF51s are not all that different from the bigger Sony parts,
but they have the advantage of much higher dissipation capability, so
you get a more flexibility in setting the load lines, and of course the
potential for much more power.
The performance you get depends a lot on load line selection. In the
end, SITs in linear operation are prima donnas. If you want the
best performance out of them you tend to have to do it their way, but
of course that depends on what you call best performance. They are
pretty flexible that way - just adjust the voltage, bias current and load.
It you want wide band performance with the big SITs you also have
to be prepared to drive them with a low source impedance. Common
Drain Mode, 100 ohms is good. Common Source mode, more like 10
ohms.
Nelson am I missing something I thought the ciss of a 2sk180 was
only about 1,600 PF and having a rather low MU why would it be hard
to drive ? By the way glad you got the jab I get my second one next
monday.
only about 1,600 PF and having a rather low MU why would it be hard
to drive ? By the way glad you got the jab I get my second one next
monday.
I am driving my 2SK180 and THF-51s single ended common source amps with my 75R output impedance Luminaria preamp with no perceived loss of high frequencies. I do not have an input buffer on the amps either.
Look at a rail-to-rail 10kHz square wave driven by your preamp. You will likely see slewing when the driving impedance is not low enough. You may not hear the slewing but someone else may hear it. Your mileage may vary.
For the obvious reason that Tokins only come as N channel parts, the
comparison would naturally be with the Sony parts in single-ended
operation.
As the very shortly-to-be-released DIY Sony Vfets are just that, I have
some data on the differences.
We see that the 2SK82/2SJ28 parts (which look to be dual die versions
of 2SK60/2SJ18) have a balance of transconductance, Drain impedance
and dissipation that appears to to favor about 8 ohm loads. In this case
the optimal bias arrangement seems to be close to a constant current
source, which is what I ended up using.
The 2SK/60/2SJ18 favor a higher impedance. They might want a little
help or a higher impedance load.
The 2SK180 THF51s are not all that different from the bigger Sony parts,
but they have the advantage of much higher dissipation capability, so
you get a more flexibility in setting the load lines, and of course the
potential for much more power.
The performance you get depends a lot on load line selection. In the
end, SITs in linear operation are prima donnas. If you want the
best performance out of them you tend to have to do it their way, but
of course that depends on what you call best performance. They are
pretty flexible that way - just adjust the voltage, bias current and load.
It you want wide band performance with the big SITs you also have
to be prepared to drive them with a low source impedance. Common
Drain Mode, 100 ohms is good. Common Source mode, more like 10
ohms.
I may ask, you are saying that the Sony sk82/sj28 (and Tokin by virtue) differs from the SS Pass-SIT (Sit-1 having 40 load and presenting more like sk60), sk82 would not benefit from a similar 40 ohm load, but a much lower load.
would you please share where put the volume potentiometer? input or output.from the Mike's document.if we put the output it will be impact the output impedance.
Dear Mr.Pass,do you think the ACP+ as the preamp is the best choice for the 2SK77/2SK180 50W SE amp?It you want wide band performance with the big SITs you also have
to be prepared to drive them with a low source impedance. Common
Drain Mode, 100 ohms is good. Common Source mode, more like 10
ohms.
Thanks.
Leo
Leo, Mr Pass sells preamps that cost 10s of thousands of dollars; is it possible that the ACP+ is going to be better than those?
A better question, in the ACP+ thread might be:
What would be necessary to modify an ACP+ to drive a 2SK77/2SK180 50W SE amp?
And a good place to start to answer that question yourself, would be to read the ACP+ thread and pay attention to impedance matching.
Cheers,
Scott
Can I ask , for the members who have received the THF-51 and 2SK182ES SITS from watanabe in Japan, did he include the insulating pad and mounting screw insulating bushes, with the transistors?
If not, where do we get these from?
If not, where do we get these from?
As I understand he only sell transistors.
No mounting kits and so on.
Info of what everyone use scattered through SissySit and HockeyPuck threads.
THF-51/2SK182E mounting holes are 5.2mm and 2.5mm deep.
Right now i found this for insulation bushing:
Screw Nylon Transistor Gasket The step T Type Plastic Washer Insulation Spacer Screw Thread Protector M3 M4 M5 M6 M8 M10 M12|Washers| - AliExpress
(TW-10 model) But it's lenght still need to cut.
May be I will find something beter later.
Mounting bolts or screws M4.
Edit: Fixed link to ".com"
Attachments
Last edited:
