Aleph J steers the current through the 2SJ74's... 4.3mA, and 4mA
But it was recommend to use J74`s with Idss of 8mA.
Dont know why but i believe it.
So if i get LSK Dual Jfet with 3mA is way to less and 10ma and more is way to much.
But this is only interesting to stock me some reserves.
Or make for fun a preamp with smd parts.
At the moment i dont Need any jfets or maybe...
nothing wrong with using Toshiba V grade and LSK C grade in Aleph J
they're biased through CCS
For the non-acronym savvy, I take it that by CCS, you mean "Constant Current Source", aka Simple transistor current sources, as discussed at:
Current source - Wikipedia
For the non-acronym savvy, I take it that by CCS, you mean "Constant Current Source", aka Simple transistor current sources, as discussed at:
Current source - Wikipedia
I prefer the two transistor CCS to other simple methods.
nope
you need complementary pair (matched , of course) in BL range - to keep dissipation on bay
you could use pair of V ones , after measuring their exact Ids , then deciding where (voltage wise) to cascode them .... exactly from same reasons
trivial in fact , but demands some play with any pcbs you have
..... still trivial - all you need is dremel , 0.7mm drill and some fine wire
you need complementary pair (matched , of course) in BL range - to keep dissipation on bay
you could use pair of V ones , after measuring their exact Ids , then deciding where (voltage wise) to cascode them .... exactly from same reasons
trivial in fact , but demands some play with any pcbs you have
..... still trivial - all you need is dremel , 0.7mm drill and some fine wire
V Grade max Idss is 20mA.
If you cascode at 9V Vds, dissipation is 180mW.
Those devices are rated at 400mW for 125°C junction temperature.
Which means at 180mW the junction temperature is about 70°C, which is OK.
Of course additional heat sinking will always help.
Cheers,
Patrick
If you cascode at 9V Vds, dissipation is 180mW.
Those devices are rated at 400mW for 125°C junction temperature.
Which means at 180mW the junction temperature is about 70°C, which is OK.
Of course additional heat sinking will always help.
Cheers,
Patrick
Hey Kevin,
The jfet values look fine. However, this is both good and bad news.
The good news is you have at least enough for 2 amps.
The bad news is you may find yourself going to "Amplifier Anonymous" meetings
in the future.
But until then, do consider the Aleph-J.
Dennis
The jfet values look fine. However, this is both good and bad news.
The good news is you have at least enough for 2 amps.
The bad news is you may find yourself going to "Amplifier Anonymous" meetings
in the future.
But until then, do consider the Aleph-J.
Dennis
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