Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Pass Labs This forum is dedicated to Pass Labs discussion.

Sony VFET Amplifier Part 2
Sony VFET Amplifier Part 2
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 26th August 2016, 08:27 PM   #1791
Rodeodave is offline Rodeodave  Austria
hates ground loops
diyAudio Member
 
Rodeodave's Avatar
 
Join Date: Dec 2004
Location: in the alps
Sony VFET Amplifier Part 2
Sweet. The link I tried to provide pointed to page 30 of Bob Pease' s book Troubleshooting Analog Circuits on Google Books. Well worth the read.
__________________
Gravity - Making the G since 13.7 billion B.C.
  Reply With Quote
Old 26th August 2016, 09:43 PM   #1792
wdecho is offline wdecho  United States
diyAudio Member
 
Join Date: Oct 2014
Halfway there. I have one channel up and running. The problem I was having was not being able to follow the directions precisely. After Nelson's comments I decided to reinstall the J313 and K2013 and give them another try. The build itself is straight forward, it is the setup that is more complicated, at least for me. I disagree on one thing Nelson said. He said it could be done with one meter. Do not even try it. He can and a few other talented persons may but it is and was impossible for me to do. It was much easier attaching one meter to T18 and ground and using another to test and set the pots. The one difference I found is when you start biasing up the frontend and have the DC offset low a slight turn of P3 or P4 will make the offset go possible 20V's quickly. Using two meters made it much easier. The other 4 FW builds I have had to set the offset on a small turn of a pot changed in mv's not V's.

Variac has been asking about multiturn or single turn pots. Definitely single turn is what one wants. I first had 12 turn multi's and changed them out for single turn. Much better, at least for me. I will probably wait till tomorrow to work on the other channel.

And yes I cover the power supply while adjusting the pots. You do not want to drop a screwdriver on top of those caps. I built the PS shown at the BAF F6 build where the PS is split at the final cap. I added an additional cap for each section along with a motor run cap for each channel. I build for function not looks. If this was my only amp I would definately go with a Deluxe 4U. From a brief use the amp does not run hot at all.
Attached Images
File Type: jpg P1030648.JPG (515.4 KB, 692 views)
File Type: jpg P1030649.JPG (527.3 KB, 676 views)

Last edited by wdecho; 26th August 2016 at 09:52 PM.
  Reply With Quote
Old 27th August 2016, 06:52 AM   #1793
Variac is offline Variac  Costa Rica
diyAudio Editor
 
Variac's Avatar
 
Join Date: Dec 2001
Location: San Francisco, USA & San José, Costa Rica
Sony VFET Amplifier Part 2
So could you tell us the 2 cap voltages you're using and whether the distance between the leads (pitch) is the same as the boards? And whatever else you want to add?


Quote:
Originally Posted by wdecho View Post
Looking at the schematic a 25V should be adequate. Test point T19 shows +14. Using a larger cap is no problem for me. Caps have long leads to suspend the cap away from everything and from what I have read it is not a good idea to put a cap directly on a board because of contracting and expansion pulling the leads of a cap. Probably never happen but.
__________________
"The geek shall inherit the earth"
2019 Burning Amp is Nov. 9 & 10 in S.F. Thread here on diyAudio:
Burning Amp 2019!!!
  Reply With Quote
Old 27th August 2016, 09:23 AM   #1794
noelectrix is offline noelectrix  Europe
diyAudio Member
 
noelectrix's Avatar
 
Join Date: Dec 2006
Location: leipzig germany
Quote:
Originally Posted by wdecho View Post
a slight turn of P3 or P4 will make the offset go possible 20V's quickly
mmmhm, but thatīs why i donīt understand the preference for singleturn pot.
anyway, both are ok for me, itīs not a critical part to purchase locally.

ah, and hey wdecho, how does it sound : ) your first channel, and all best for the other one,
stefan
  Reply With Quote
Old 27th August 2016, 10:12 AM   #1795
wdecho is offline wdecho  United States
diyAudio Member
 
Join Date: Oct 2014
Quote:
Originally Posted by Variac View Post
So could you tell us the 2 cap voltages you're using and whether the distance between the leads (pitch) is the same as the boards? And whatever else you want to add?
I used the Elna 35V and the only only place the size did not fit perfectly was the spot in question. George Anderson of Tubelab was where I first heard not to place the caps directly on the boards but leave a little space. He adds a tiny bit of foam under his caps. Has anyone ever seen black lines on your LCD-LED TV that went away after warming up? I have heard this is caused by cap leads too tight on board, no experience only heard. I ordered the pots listed on the BOM and the 500 ohm fits perfectly, the 5K pot leads are not spaced to fit board, I made them fit by bending the leads. Just thought to add this fact, no problem really.
  Reply With Quote
Old 27th August 2016, 10:17 AM   #1796
wdecho is offline wdecho  United States
diyAudio Member
 
Join Date: Oct 2014
Quote:
Originally Posted by noelectrix View Post
mmmhm, but thatīs why i donīt understand the preference for singleturn pot.
anyway, both are ok for me, itīs not a critical part to purchase locally.

ah, and hey wdecho, how does it sound : ) your first channel, and all best for the other one,
stefan
My thoughts exactly when I first ordered the multipots. I found out it was too much unnecessary turning. Both will work but the multiturn ones I ordered worked in reverse of what Nelson used. The single turn did exactly as described in instructions. All Bournes. I did not listen too long on my test speakers being satisfied that I finally got one channel to work. Wish me luck on the next one. On cheap test speaker without even using a pre, just computer mp3 it did sound really good.
  Reply With Quote
Old 27th August 2016, 02:48 PM   #1797
wdecho is offline wdecho  United States
diyAudio Member
 
Join Date: Oct 2014
Success. If you follow the explesive instructions on biasing seasoned builders should have no problem with this build. I had one other hitch with the other channel that caused some frustration and anxiety because of builder error. Let's just say be careful with grease and getting a good solder joint. Biasing the 2nd channel was no problem after understanding what it was I was trying to do. Do use 2 meters, one attached to ground and T18 and another to set up the bias.

Many thanks again for Nelson making this project available to diyer's as myself. As for sound I only listened for one side of a LP. The bass is as good or better than anything I have heard with my horns. The jump in you chair drum roll when you hear it unexpected.

I include a picture of my F6 build to show I do know how to make a pretty amp. The store 4U is plenty good enough for this build. With the prescribed bias my amp is extremely cool.

I do need to tidy up the wires and ground all the metal parts. I lived on the edge and could not wait to hear what it sound like.
Attached Images
File Type: jpg P1030650.JPG (535.5 KB, 591 views)
File Type: jpg P1030651.JPG (538.2 KB, 577 views)

Last edited by wdecho; 27th August 2016 at 02:54 PM.
  Reply With Quote
Old 27th August 2016, 06:15 PM   #1798
grimberg is offline grimberg  United States
diyAudio Member
 
grimberg's Avatar
 
Join Date: Oct 2002
Location: California, USA
Quote:
Originally Posted by wdecho View Post
... George Anderson of Tubelab was where I first heard not to place the caps directly on the boards but leave a little space. He adds a tiny bit of foam under his caps. ...
Do you remember in which post, or at least which thread, he said that? I am curious if the reason behind that advice is related to high-voltage operation.
  Reply With Quote
Old 27th August 2016, 06:17 PM   #1799
WalterW is offline WalterW  Netherlands
diyAudio Member
 
Join Date: Oct 2012
Location: Utrecht
Sony VFET Amplifier Part 2
Are those Austerlitz Electronic KS-300 - 100mm heatsinks?
__________________
Pass F5, F5Tv3, ACA, Aleph J, DDDAC1794, DCB1, BA3-preamp, VFET CSX1, Pass F6, Pass M2-HPA, VFET-X balanced, Pass J2
'If you see me talking to myself, don't worry. I'm getting expert advice'
  Reply With Quote
Old 27th August 2016, 06:22 PM   #1800
Nelson Pass is offline Nelson Pass  United States
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Sony VFET Amplifier Part 2
Quote:
Originally Posted by wdecho View Post
Success.
I suppose this makes you the index case.

  Reply With Quote

Reply


Sony VFET Amplifier Part 2Hide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Sony VFET Amps Nelson Pass Pass Labs 229 2nd January 2019 10:02 AM
PCBPCBs for Nelson Pass‘ CSX1 SONY VFET amplifier permaneder Group Buys 430 25th August 2018 11:09 AM
Sony Vfet housing Solid State 26 26th January 2014 03:38 AM
Sony TA-N7B VFET Help!! gpdavis2 Solid State 16 24th October 2009 01:20 PM
Sony VFET...tragic... EchoWars Solid State 21 11th November 2006 11:40 AM


New To Site? Need Help?

All times are GMT. The time now is 09:46 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki