2SJ109 and 2SJ74 in GR version???

carlomar · 12th February 2010, 10:12 PM

Hi,
I m planing to build my first NP project, Aleph J.

I have some 2SJ109 GR and 2SJ74 GR.
I cant find BL version.

I know GR have less Idss.

My question is, can i use GR version in single or in paralel, at front end of Aleph J?

Blues · 12th February 2010, 11:42 PM

Carlo, check this thread...scroll down for the P-P only matched 2SJ74BLs.

Pass DIYers

cviller · 13th February 2010, 05:34 AM

You could try to parallel the GR's and get sufficient bias, but you also increase transconductance - probably not a problem though.
If this is your first NP project, you might what to start with something where you don't need to tweak as much, but if you are used to adjusting circuits, you should be able to make it work.
What is the idss of the parts you have?

carlomar · 13th February 2010, 07:43 AM

Quote:

Originally Posted by Blues

Carlo, check this thread...scroll down for the P-P only matched 2SJ74BLs.

Pass DIYers

Tanks

carlomar · 13th February 2010, 07:53 AM

Quote:

Originally Posted by cviller

...If this is your first NP project, ...
...What is the idss of the parts you have?

For a first NP project do you recomend me other project?(Aleph30,F4, F5,??)
My speakers are not high efficiency.

Idss of my GRs are 2,5 - 6,5mA
I think the corrent in front end is about 8,5mA???

bobodioulasso · 13th February 2010, 10:48 AM

F5 is simpler and you can adjust the bias to fit your heatsinks size. It works well even leaving class A, which is not the case for an aleph which has to stay into class A.
F5 does not need transistor matching...

cviller · 13th February 2010, 02:23 PM

Quote:

Originally Posted by carlomar

1. For a first NP project do you recomend me other project?(Aleph30,F4, F5,??)
My speakers are not high efficiency.

2. Idss of my GRs are 2,5 - 6,5mA
I think the corrent in front end is about 8,5mA???

1. I would recommend a project where you do not need to diverge from the original schematics, so the alephj is just as good as many of the other projects.

2. The idss is a bit low for most power amps - a phono stage or a preamp would better utilize your grs. For BA-1/2 it might actually work since it has an additional stage before driving the output devices.

Alternatively you could save your GR parts for a GR project and get some BLs for the amp you would like to build the most.

carlomar · 13th February 2010, 11:55 PM

Thanks,

I think i go for F5.

carlomar · 11:38 PM

What is the (volt) input for full power in F5?
Can i use it whith a passive pré for 2Volts CD output?

Tanks

EUVL · 25th February 2010, 03:55 AM

F5 has a gain of 6. So 2V RMS output (standard for CD) will give you 34V peak to peak at full volume. The standard F5 should do 40V peak to peak without clipping.

Patrick

12th February 2010, 10:12 PM	#1
carlomar diyAudio Member Join Date: Dec 2004 Location: lisbon	2SJ109 and 2SJ74 in GR version??? Hi, I m planing to build my first NP project, Aleph J. I have some 2SJ109 GR and 2SJ74 GR. I cant find BL version. I know GR have less Idss. My question is, can i use GR version in single or in paralel, at front end of Aleph J?

12th February 2010, 11:42 PM	#2
Blues Lightning In A Bottle diyAudio Member Join Date: Sep 2003 Location: Bremerton, WA	Carlo, check this thread...scroll down for the P-P only matched 2SJ74BLs. Pass DIYers __________________ Quad Matched Toshiba 2SK1530/2SJ201 MOSFETs http://www.diyaudio.com/forums/swap-...ml#post2086375

24th February 2010, 11:36 PM	#9
carlomar diyAudio Member Join Date: Dec 2004 Location: lisbon	What is the (volt) input for full power in F5? Can i use it whith a passive pré for 2Volts CD output? Tanks Last edited by carlomar; 24th February 2010 at 11:38 PM.

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13th February 2010, 05:34 AM	#3
cviller diyAudio Member Join Date: Dec 2005 Location: Copenhagen Blog Entries: 2	You could try to parallel the GR's and get sufficient bias, but you also increase transconductance - probably not a problem though. If this is your first NP project, you might what to start with something where you don't need to tweak as much, but if you are used to adjusting circuits, you should be able to make it work. What is the idss of the parts you have?

13th February 2010, 10:48 AM	#6
bobodioulasso diyAudio Member Join Date: May 2008	F5 is simpler and you can adjust the bias to fit your heatsinks size. It works well even leaving class A, which is not the case for an aleph which has to stay into class A. F5 does not need transistor matching...

13th February 2010, 11:55 PM	#8
carlomar diyAudio Member Join Date: Dec 2004 Location: lisbon	Thanks, I think i go for F5.

25th February 2010, 03:55 AM	#10
EUVL diyAudio Member Join Date: Oct 2003	F5 has a gain of 6. So 2V RMS output (standard for CD) will give you 34V peak to peak at full volume. The standard F5 should do 40V peak to peak without clipping. Patrick

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