F2J parts. - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th January 2012, 06:01 AM   #1
diyAudio Member
 
oon_the_kid's Avatar
 
Join Date: May 2008
Location: Singapore
Default F2J parts.

Hi,

I am looking to build the F2J. I would just like some information on some parts which I view as being the critical parts, which may affect sound.

1) Is this transistor by semisouth a good replacement for the original one (which has become unobtainium).

SEMISOUTH|SJEP120R100A|JFET, SIC, AUDIO, 1200V, 17A, | element14 Singapore Products

2) The output capacitors, which type/suitablity part number etc would useful too. Or any 15,000 uF capacitor will do?

3) Capacitor for power supply, can I use a 33,000uF cap instead of 2 pcs of 15,000uF.

4) Is it advisable to switch to a lower current (bias if speakers are 8ohm)? by changing R16 and R1 to 1 ohm.

5) What size of transformer do I need? 200VA (18V X 2) sufficient?

Thanking all in advance.

Oon
  Reply With Quote
Old 19th January 2012, 09:49 AM   #2
ianc13 is offline ianc13  United Kingdom
diyAudio Member
 
Join Date: Oct 2005
Hi,

I am currently collecting parts for a F2J at the moment also. Here are a few bits that you might find useful:

Peter Daniel (on this forum) has F2 boards that can be used for the F2J. I have a pair waiting to be stuffed with components and they are really good quality.

The SJEP120R100A is equivalent (for our purposes anyway) to the SJEP120R100 (the A denotes 'Audio' apparently). It is possible that these are JFETs that didn't quite make the grade as far as power switching applications are concerned so they are a bit cheaper.

Another forum member - Tea-Bag - was providing a matching service for these parts at a modest additional cost, you can PM him through the forum. Not sure if there are any left, see:

R100A JFET Group buy

Of your questions that I can answer:

2) This is in the signal path, I am sure that you could spend mega $ buying some esoteric capacitor. Depends on taste - I will go for something snap in with low ESR (most likely Panasonic as that is what usually comes up when I look on Farnell - same company as element14 BTW).

3) Yes.

4) I can't really comment on that one I'm afraid - you can always build as per the spec and then change after and let your ears decide.

5) Maybe a touch low running at ~2.5A at 25V each side will draw 62.5W for 125W total. Most people like to overrate by double so 250VA is maybe more appropriate for cool running, but 200VA would work.

Ian
  Reply With Quote
Old 20th January 2012, 12:53 AM   #3
diyAudio Member
 
oon_the_kid's Avatar
 
Join Date: May 2008
Location: Singapore
Hi,

Thanks for all the tip... will contact tea bag. Alternatively might just get it from element14/farnell who is just down the road, (yup I know the name change, been buyibng from them for the last 15 years). I think the matching o the transitor may not be so critcal in this one, since this is left and right. It would probably be more critical in those cases where they are in parallel

1) How much did you have to pay for the F2 board? I suppose the circuit is so simple a veroboard with point to point wiring would be about the same.

2) Well that's the ironic thing about currents, they are the same in series circuit. So putting on an esoteric capacitor may not make any difference... in which case I might as well save the money and pay for a plain old vanilla capacitor..

Oon
  Reply With Quote
Old 20th January 2012, 07:59 AM   #4
ianc13 is offline ianc13  United Kingdom
diyAudio Member
 
Join Date: Oct 2005
The F2 boards came to $22 US for the pair delivered to the UK IIRC - which I thought was pretty good value.

Ian
  Reply With Quote
Old 26th January 2012, 11:30 AM   #5
diyAudio Member
 
oon_the_kid's Avatar
 
Join Date: May 2008
Location: Singapore
Thanks for the tip again. I think the price is pretty fair...thanks for the tip again.

Oon
Sent from my MB860 using Tapatalk
  Reply With Quote
Old 26th January 2012, 12:22 PM   #6
Anchan is offline Anchan  United States
diyAudio Member
 
Join Date: Jul 2009
If you guys are both building the f2j at roughly the same time, I'd like to suggest that perhaps you use this thread as a dedicated build thread. I'm also interested in the f2j, and the original f2 thread has gotten very long, and also not "J" specific which is the main problem I think. I'm still a few months from getting into the project, but as always I look forward to seeing these amps develop.
  Reply With Quote
Old 14th February 2012, 08:48 AM   #7
ianc13 is offline ianc13  United Kingdom
diyAudio Member
 
Join Date: Oct 2005
OK so the case for my F5 has been canabalised for the F2J which is now 99% complete (just need to wire up the LEDs on the front panel and check the bias later this week). I feel sorry for the F5 but as I listen to the F2J I am getting over it really fast. The F5 could make a reappearance sometime in the future if I ever have the option to bi-amp a pair of speakers.

So how does it sound - really, really good. My F5 was fast but a touch dry in the bass. The F2J is just as fast, sweeter through the midrange and the bass has much more weight (if very slightly less control - but not much). I may play around with the output resistance a little see what it does to the sound. It is worth noting that it only has a couple of (long) evenings play on it so far - so I expect it to get even better as it breaks in.

I have a tiny bit of hum on the left channel, but that is due to the power wiring running down that side of the bank of capacitors in the middle. I can't hear it more than a couple of feet away from the speaker. I may rewire this bit so that the incoming power comes straight down the middle of the PSU caps.

I am running it with a pair TB W8-1772 in 45 litre BR cabinets and in my smallish room; it provides plenty of volume.

I will post some photos a little later in the week when I open it up again to wire the afore mentioned LEDs.

I'd just like to take a second to thank NP for a fabulous design (and being so generous opening them up to the public), and also Peter Daniel for the boards and Tea-Bag for the JFETs (starting to sound like an Oscars acceptance speech so I'll stop now!).

Ian
  Reply With Quote
Old 14th February 2012, 10:32 AM   #8
diyAudio Member
 
oon_the_kid's Avatar
 
Join Date: May 2008
Location: Singapore
Hey Ian, congratulations on almost completing the journey. I am in the midst of looking for the most difficult part of this project- time ... which becomes unobtanium when you have a 4 month old baby...

Oon



Sent from my MB860 using Tapatalk
  Reply With Quote
Old 15th February 2012, 12:35 AM   #9
zany is offline zany  Australia
diyAudio Member
 
Join Date: Oct 2010
Fantastic Ian! Looking forward to more info and pics of your build. Will be building one very soon I hope... cheers.
  Reply With Quote
Old 18th February 2012, 01:51 AM   #10
diyAudio Member
 
oon_the_kid's Avatar
 
Join Date: May 2008
Location: Singapore
Hey Ian,

Just checking. Did you have any problem stuffing the transistor from semisouth into peter Daniel's board?

Oon

Sent from my MB860 using Tapatalk
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
F2J schematic needed neazoi Solid State 1 6th November 2011 04:35 PM
F2J PCB: a question on ground layout Lazybutt Pass Labs 11 5th October 2011 11:04 AM
F2J power supply voltage?? holminator Pass Labs 6 15th September 2011 04:14 PM
nelson pass f2j f2 pcb psu board. bjcwolters Pass Labs 2 5th August 2011 07:32 AM
PARTS PARTS PARTS!!! Infocus Powerview 820, triplet, ballast, light, power supply!!! marioinla Swap Meet 1 31st August 2004 04:22 PM


New To Site? Need Help?

All times are GMT. The time now is 12:47 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2