Selecting transistors (grade)

[Centurion53]

I am currently finishing up my ACA build, kit purchased from the diyaudio store. I am planning on building an Aleph J as my next project and have decided to start collecting parts. The input jfets are back in stock so I thought I would acquire these now, however there are grades "A" through "D" listed and I'm not sure which to select. I did do a search of threads to see if this has been answered before but could not find anything.
Thanks

 

[Zen Mod]

look for these declared having Idss range of 6-12mA

higher range will work also, lower not

 

[JSA1971]

Depending on how much of a hurry you’re in you could wait for the matched pair they sell in the DIY Store to come back in stock.

https://diyaudiostore.com/products/j74-j74-stereo-differential-kit

 

[Dennis Hui]

Grade B is in the 6mA to 12mA Idss range. Just buying 8 may not give you
very good matched pairs (At least with the Toshiba originals, the Idss of the parts
are quite spread out within each grade.) So it may be worth it to wait for prematched
sets.

Dennis

 

[Centurion53]

Thanks guys for the quick response, I'm not in a big hurry since I have the ACA to play around with for a bit so I will just wait for the matched pairs to restock.

 

[Zen Mod]

sorry for blatant jump in ... or it isn't if you make your own - look in Babelfish J thread , for slightly easier and simpler approach - easier obtainable input JFets and no need for mosfets matching

or , even better - combine , regular JFets but just a pair of IRFP150 in output

 

[Centurion53]

Thanks ZM! I went to your blog and started going through the “Babelfish” info, sounds like a winner! Do you still have the boards, semiconductor kits available?
Thanks

 

[Zen Mod]

you can contact me via PM

of course - I'm encouraging if you have any other , closer , faster solution

it's always sweetest if you make your own from scratch and - when you need semis for matching - whatever is left of quantity you bought- you can always use for further projects

I didn't chime in to advertise B. J , but to tell that there are some simpler solutions , no need to blindly follow

 

[Centurion53]

ZM, no worries, I hadn't come across the Babelfish before you mentioned it. I am just looking for a good sounding amp with just a little more power than the ACA. I'm getting kinda old, 66, 😱 so my hearing is not good enough to get the full benefit of some of the really high quality amps that are being produced here. I would like to build the Nutube pre next so I am just patiently awaiting the Pass pcb. 🙂
Thanks for your advice

 

[Zen Mod]

of course that you can buy Babelfish J package from me , if that suits you and that is probably easiest way of all , for making any of J iterations

However , as always , point is that fun is in learning what can be changed and for what reasons , and still being on target

read here : About possible Babelfish J interest

plenty of details , if I remember correctly ..... so - if you grasp at least half of them , it'll lead you to more fun - understanding more and being able to ask right questions, to increase both fun and knowledge

Papa did show us long ago that Aleph is an Aleph is an Aleph - what's important - it's concept , and you can stretch it for your own needs