Go Back   Home > Forums > >

Pass Labs This forum is dedicated to Pass Labs discussion.

VFET amp Bourns trimmer exchange
VFET amp Bourns trimmer exchange
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
Old 23rd June 2021, 07:38 AM   #61
Zen Mod is offline Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
VFET amp Bourns trimmer exchange
no need to be sorry
Pa did his best every time; it's just that this time he had just half number of parts at disposal
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
  Reply With Quote
Old 28th June 2021, 08:14 PM   #62
MEPER is offline MEPER  Denmark
diyAudio Member
 
MEPER's Avatar
 
Join Date: Nov 2017
Location: Copenhagen
I was able to use my lab-supply as PSU for the VFET amp by using some mini-clips just for a test at 30 VDC. The lab-supply is a regulated linear supply. Using this supply both channels seems to behave well. Therefor I think the stange noise I see/hear comes from the SMPS. Why it seems only to be audile/visible in R-channel I can't explain but SMPS has some very high frequency noise (in MHz area....according to scope) and that it also makes some strange random spikes ("mV area").

The lab-supply has some 50 Hz ripple (20 mSec period) and this ripple is very visible at VFET output (with grounded input). I think this is expected for a SE-output stage. Before exchanging any components I need to try out a "clean" PSU. I wonder if my SMPS is inside specs. I could get another SMPS and see if this will fix it.
  Reply With Quote
Old 29th June 2021, 06:58 PM   #63
MEPER is offline MEPER  Denmark
diyAudio Member
 
MEPER's Avatar
 
Join Date: Nov 2017
Location: Copenhagen
I ordered a new 36 VDC PSU for the VFET amp:

CONNEX SMPS2000RS Switching Mode Power Supply Module 2000W +36V - Audiophonics

I expect it to be reasonable quiet when it is only loaded about 5% of max. power. Then we will see if it makes a difference. Under all circumstances it should be an upgrade from the small Meanwell. I need to find a chassis for it and install some fuses to avoid the large amount of energy if something goes wrong.
  Reply With Quote
Old 29th June 2021, 06:59 PM   #64
egellings is offline egellings  United States
diyAudio Member
 
Join Date: Aug 2010
Location: CA
I call it nervous little puddle *******.
  Reply With Quote
Old 29th June 2021, 07:38 PM   #65
MEPER is offline MEPER  Denmark
diyAudio Member
 
MEPER's Avatar
 
Join Date: Nov 2017
Location: Copenhagen
Yes, but the physical size is still on par with the "smaller" units and the data looked quite good and the price not that high.....so why not :-)
  Reply With Quote
Old 29th June 2021, 08:15 PM   #66
Super_BQ is offline Super_BQ  New Zealand
diyAudio Member
 
Super_BQ's Avatar
 
Join Date: Sep 2001
Location: New Zealand from Canada
Send a message via ICQ to Super_BQ Send a message via Yahoo to Super_BQ
Quote:
Originally Posted by MEPER View Post
I ordered a new 36 VDC PSU for the VFET amp:

CONNEX SMPS2000RS Switching Mode Power Supply Module 2000W +36V - Audiophonics

I expect it to be reasonable quiet when it is only loaded about 5% of max. power. Then we will see if it makes a difference. Under all circumstances it should be an upgrade from the small Meanwell. I need to find a chassis for it and install some fuses to avoid the large amount of energy if something goes wrong.
I suppose if one was serious in the market for a new power supply, you can't go wrong by spending more than the rest of the amplifier components.

That's a bold move and as mentioned before, there are ways to narrow down this minimal noise problem. But at over Ä200? What if this does not solve the problem?
  Reply With Quote
Old 29th June 2021, 08:32 PM   #67
MEPER is offline MEPER  Denmark
diyAudio Member
 
MEPER's Avatar
 
Join Date: Nov 2017
Location: Copenhagen
If it does not solve the problem I have a more quiet PSU when problem is solved. It seems that with lap-supply which is a cheap one from China (2 x 30 VDC, 5A with current limiter etc.) problem seems solved. But this supply has some ripple even that it is regulated so not much sense using it for a test with music. But on scope I did not see anything unusual other than ripple at amp speaker out with grounded input. So now I go for a PSU with almost no ripple and very little noise.

I have ordered a chassis for it and I got the special 4-pole connectors so I can make a wire from PSU to amp. These male connectors has really many parts....8 parts. I need an instruction manual to assemble it......
  Reply With Quote
Old 29th June 2021, 11:26 PM   #68
Eric is offline Eric  United States
Knows enough to be dangerous
diyAudio Member
 
Eric's Avatar
 
Join Date: Nov 2000
Location: Central PA, USA
VFET amp Bourns trimmer exchange
Quote:
Originally Posted by MEPER View Post
OCD = Obsessive-Compulsive Disorder?
I think this is "spot-on" :-)
But I don't feel alone with this in this forum :-)
I'm a bit late to this part of the conversation, but I thought you guys might appreciate the T-shirt that my wife got for me a while ago...
Attached Images
File Type: jpg CDO t-shirt.jpg (142.7 KB, 126 views)
__________________
DIY Theater, Aleph-X Amps, LDR based BA-3 pre, B1 Korg, Pearl II, modified SL-1200 TT, F4, M2, Aleph-J, MoFo, a40, VFet-2, ACAs, FHXL & TB 1772 speakers
  Reply With Quote
Old 30th June 2021, 05:50 AM   #69
MEPER is offline MEPER  Denmark
diyAudio Member
 
MEPER's Avatar
 
Join Date: Nov 2017
Location: Copenhagen
Maybe diyAudio Store should have this on the program?
  Reply With Quote
Old 5th July 2021, 12:00 PM   #70
Soundhappy is offline Soundhappy  France
diyAudio Member
 
Soundhappy's Avatar
 
Join Date: Oct 2012
Location: Montpellier near Mediterranean Sea France
@ Meper

Are you sure one Vfet is not the small noise source ?
__________________
class A amplifiers with full range speakers
sings like angels in heaven
  Reply With Quote

Reply


VFET amp Bourns trimmer exchangeHide this!Advertise here!
Thread Tools

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
Looking for 1 genuine Sony 2SJ18 vfet for my Sony TA 5650 vfet amp VFET747 Pass Labs 7 17th April 2021 06:21 PM
VFET-X (or my 1/3 40th Anniversary Sony VFET Clone) WalterW Pass Labs 191 2nd April 2021 08:02 PM
WTB 1 channel of VFET from Diyaudio's Sony Vfet kit fishball79 Swap Meet 3 10th July 2020 03:11 AM
IC: 2x sony vfet essentia kits, PSU PCB's, vfet part 2 PCBs and other acessories MASantos Swap Meet 7 15th April 2018 04:34 PM
WTB dual "modular" pots from Clarostat, Bourns ETC mihow Parts 0 15th September 2005 06:40 AM


New To Site? Need Help?

All times are GMT. The time now is 12:07 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki