f4 parts substitution

[slr 5000]

hi
i would like to use my 2sj109 in my diy f4 but i notice it has seven legs as oposed to six when using the normal combination of 108/ 389
what is this extra leg ?

i have not got the output devices yet are there any options here that would drop in and be an improvement on the originals ,toshiba or semisouth perhaps ?

thanks in advance for any help or advice

regards sheafer

 

[Zen Mod]

google for 2SJ109 ; pdf file

7-th ( middle ) pin is substrat ....... in fact - nothing .

btw- I don't know where in F4 you'll use 2SJ109 ?

you mean using pairs for both input Jfets , meaning on 2SJ109 and 2SK389 ?

 

[slr 5000]

hi zen mod
seems i must have buggered up as usual😕

i thought i could replace the 108 and 389 with a single j109 per channel
as i have heaps of j109 and canot find anywhere the 389 or 108
what alternatives do i have ?

regards sheafer

 

[Zen Mod]

you can't do this
2SJ109 is nothing else than 2pcs of 2SJ74 in one case

same polarity jfets ........ and you need one of each polarity

 

[slr 5000]

thanks zen mod
now i understand ,
so i need the opposite polarity to the or 2sj74

its a shame as i have 8 new 2sj109 bl here doing nothing 😕

i have an aleph 2 clone that is running on high bias 7.2 a and low voltage (25/0/25 sec) for my esl speakers ,perhaps i could convert it to jfet input using the 2sj109

cheers

 

[Zen Mod]

......

i have an aleph 2 clone that is running on high bias 7.2 a and low voltage (25/0/25 sec) for my esl speakers ,perhaps i could convert it to jfet input using the 2sj109

cheers

yes , you can ;

post exact schematic of your Aleph 2 and I'll draw needed changes for you ......

 

[slr 5000]

thank you zen mod

it is built from the kkk pcb boards
i will get the schematic tommorow and post it

many thanks
sheafer

 

[slr 5000]

hi zen mod
here you go regards sheafer

 

[Zen Mod]

will you manage with this ?

http://www.diyaudio.com/forums/pass-labs/135787-jfet-input-aleph-60-a.html#post2242371

 

[slr 5000]

hi zen mod
i think so ,i should replace the 4x 2sj74 with 2x 2sj109 yes
also does mucho mean remove ?

regards sheafer

 

[Zen Mod]

hi zen mod
i think so ,i should replace the 4x 2sj74 with 2x 2sj109 yes
....

exactly

.....
also does mucho mean remove ?
....

mucho means "plenty"

but - do not look previous schematic where mucho is written

just look at schematic in post #12 where I linked you

and - look at that Algar_emi's pdf - many things will be clearer to you

 

[slr 5000]

thanks zen mod

i will give it a try

cheers

 

[Variac]

This might work with a Burning Amp