Aleph J Schematic

[ide2003]

schultzsch, I did this mod because friends did changed their F5 clones with laterals and like the result.
quite true, on aleph j it's an improvement compared to IRF's. My friend got the SK's from zhou fang

 

[ide2003]

hi schultzsch, I did this SK's mod because friends did that on their F5 clones (SK's and SJ's) and liked the result, quite true, on aleph J it is an improvement. My friend got the SK's from Zhou Fang. Maybe some day I will try Babelfish J

 

[schultzsch]

with my speaker(3.5ohm@190hz) connected I measure below 1.5A output current at below 1% distortion but you don`t say you have only 7W when you are listening to music

 

[schultzsch]

most listenings I do are at below 2W

 

[ide2003]

ah, sorry for double post above
schultzsch, I did tried decoupling R24 (C3 in my case), difference in mids, ZM is right some like it, some not. I think with R24 in place things are more transparent, decoupled bit muddy there but sweet thanks for your tips, here is my humble AJ-2SK1530's , C3 decoupled

 

[jambul]

hi opa,
I bet the lateral are coming from bandung

 

[ide2003]

hello Jay ..so you're now in Belgie? bring some of that choco wafer back will you..
nope, SK's are from Zhoufang and belong to my JKT friend. but you're right, the origin of many poisonous components was from Bandung

 

[gadut]

hello opa, nice built and i'm waiting to have a chance to heat it where did you get those copper plate for supply caps?

 

[ide2003]

anytime welcome sir, copper bought at the usual place

 

[El_d]

Question, Pin 4 on 2SJ109 connect or not?

 

[Zen Mod]

not

 

[El_d]

thnx

 

[generg]

I think the data sheet suggests to let it open....

 

[El_d]

Yes, the data sheet suggests to let it open, but the boards from PD I have allows it to be connected to pin3 and pin5. Hence I thought there might be a reason for that..

 

[jacco vermeulen]

Pin 4 is there for a reason.
Do a search for what Mr Charles Hansen posted about the substrate connection.

 

[generg]

Thanks Jacco, interesting for me too.....

http://www.diyaudio.com/forums/solid-state/59543-need-help-j-fet-problem-print.html

The substrate is separate on the dual FETs. You have to figure out how to handle the substrate pin. (The data sheet is *not* the best resource here.)

Hi Charles,
what do you think ist the best connection when using these parts in a LTP? Connecting the substate together with the sources?

Charles Hansen 7th July 2005 03:29 AM
You will have to measure the connection from the substrate pin to the other pins with the "diode" mode of a multi-meter. A parasitic diode exists between some connections, which should not be forward biased. Once you have determined which connnections are allowable, you will need to do some listening tests (like everything else in audio!) to see what connection sounds best.

 

[schultzsch]

hello again

I have a little question for you guys...
Normally my amp stabilizes at 180Wpc consumption from wall outlet after an hour since power on and now these days he stabilizes at 220Wpc.
Do you have any ideas why he does this??
the only change was made is the room temperature wich increased these summer days...

Thanks

 

[qusp]

Pin 4 is there for a reason.
Do a search for what Mr Charles Hansen posted about the substrate connection.

Thanks Jacco, interesting for me too.....

http://www.diyaudio.com/forums/solid-state/59543-need-help-j-fet-problem-print.html

The substrate is separate on the dual FETs. You have to figure out how to handle the substrate pin. (The data sheet is *not* the best resource here.)

Hi Charles,
what do you think ist the best connection when using these parts in a LTP? Connecting the substate together with the sources?

Charles Hansen 7th July 2005 03:29 AM
You will have to measure the connection from the substrate pin to the other pins with the "diode" mode of a multi-meter. A parasitic diode exists between some connections, which should not be forward biased. Once you have determined which connnections are allowable, you will need to do some listening tests (like everything else in audio!) to see what connection sounds best.

thanks guys! I had no idea, so I guess 2 x j74 doesnt make a j109 afterall

 

[schultzsch]

ups....i was reading wrong information from my multimetter

 

[schultzsch]

Hello again
I gathered some money and i want to finish my amp.I would like to buy Rifa capacitors for the power supply.
I am referring to these ones Elettrolitici Condensatore elettrolitico 40V 47 000uF Evox-Rifa PEH200KJ5470MB2 consegna in 24 ore and to be more speciffic I would like to use 4 of these on each channel in crc(clc in future)network.They whitstand 22 amps ripple and when simulating with PSU Designer II I get 20mV ripple.Are these good enough for my Aleph J biased at 3.2Amps and my 88dB speakers ?