Go Back   Home > Forums > >

Pass Labs This forum is dedicated to Pass Labs discussion.

F5X -- the EUVL Approach - The Build Thread
F5X -- the EUVL Approach - The Build Thread
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 19th May 2020, 02:33 AM   #1311
soldersober is offline soldersober  Hong Kong
diyAudio Member
 
Join Date: May 2016
Quote:
Originally Posted by EUVL View Post
Yes.


Patrick
  Reply With Quote
Old 23rd May 2020, 06:26 PM   #1312
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
There were some questions about the X connection.
I guess the best is to use the one published by Nelson :
http://www.firstwatt.com/pdf/art_f5_turbo.pdf
(page 15)

You can call it X with a dot in the middle, or an H.
Either can be done on the PCB easily.




Patrick
__________________
xen-audio.com
  Reply With Quote
Old 24th May 2020, 08:44 PM   #1313
Morde is offline Morde  Finland
diyAudio Member
 
Join Date: Oct 2014
F5X -- the EUVL Approach - The Build Thread
Due to some confusion in my measurements that gave me the wrong assumption that something was damaged in my build, I had to do some extensive measurements for the JFETs and MOSFETs only to find out that there was no fault.

Here’s some report what you are able to measure if you boubt a faulty device.

JFETs can be measured even when they are soldered to the pcb. Note that the MOSFETs must not be installed. The X point of the JFETs needs to be floating and then you connect 1k (R3/R8)and 100k (R4/R9) resistors and scope channels according to the picture 1 attached. The dc offset part (R1,2,6,7) can be omitted if your signal source has dc offset functionality. You should then be able to plot in X-Y mode of the scope a curve that should correspond to the JFETs Vgs/Id curve. See pic 2 for example.

The MOSFETs Vgs at targeted rail voltage and bias current can be measured according to pic 3. This is presented somewhere in the UDNeSS thread as well. For the F5X you want to have 16V and 2 A. Remember to change the connection for N channel device.

Thanks to Patrick for the measuring guidelines and ideas. I couldn’t have done it by myself.

After successful measurement results I was confident that my circuitry was intact and I could proceed with re-soldering once again the output devices into place. After checking bias currents and dc offsets I went on measuring some distortions.

My distortion measurement setup is simply a Focusrite Scarlet 2i connected to a laptop that is running REW software. Loopback measurement using balanced in => balanced out connections is presented in pic 4.

Pic 5 is my F5X in floating X configuration and pic 6 the same with floating H config. Measurements were done in balanced mode with 1W/8ohm load. Very similar results, but the H is a tiny bit better with second harmonic. Amazingly low distortion from a class A diy amp.
__________________
Head amps: SE84, Salas DCG3, UTHAiM, PassDIY HPA, Pioneer Super Linear, XEN JLH
Power amps: M2x, UDNeSS, F7 clone, F5X
  Reply With Quote
Old 24th May 2020, 08:54 PM   #1314
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
> but the H is a tiny bit better with second harmonic

As it should.
And the even lower H2 than H3 is the evidence of the level of device matching.




Patrick
__________________
xen-audio.com
  Reply With Quote
Old 24th May 2020, 09:49 PM   #1315
CeeVee is offline CeeVee  Portugal
diyAudio Member
 
CeeVee's Avatar
 
Join Date: Dec 2006
F5X -- the EUVL Approach - The Build Thread
Congrats Martti.

Great work and reference for the other builds.
  Reply With Quote
Old 27th May 2020, 12:14 PM   #1316
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
For those who want to do the testing step by step, you can test the entire front end as in the attached Spice file.
The only thing not installed are the MPC74's and the Toshiba MOSFETs.
You will need to add a 390R resistor to the cross member of the "H".
And you need a balanced signal source of 0.3V (per phase) 1kHz.

Then check V1,2,3,4 and compare with the spice file results.
Once that is done, you only need to put in the MOSFETs and adjust bias / DC offset.


Patrick

.
Attached Files
File Type: asc F5X JFET Test.asc (5.6 KB, 46 views)
__________________
xen-audio.com
  Reply With Quote
Old 29th May 2020, 02:28 PM   #1317
druidaudio is offline druidaudio  Wales
diyAudio Member
 
Join Date: Feb 2009
Location: Wales UK
Does anyone have the BoM for the protection board in spreadsheet format please?
It's a pain trying to do it from a pdf!
  Reply With Quote
Old 11th July 2020, 08:50 AM   #1318
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
I showed you my LM4780's in post #1272.

A team member in HK wants to have a summer amp to go with his F5X Pre.
(HK summer is 35C. You need air con, and the F5X adds to the air-con load.)
So I propose to use the same LM4780 inverted.

Here is the result (photo is from earlier, unfunished state).
Case is adapted from the F5X Pre.




Patrick

.
Attached Images
File Type: jpg 200711 LM4780 Top.jpg (246.9 KB, 325 views)
__________________
xen-audio.com
  Reply With Quote
Old 31st October 2020, 09:01 AM   #1319
Morde is offline Morde  Finland
diyAudio Member
 
Join Date: Oct 2014
F5X -- the EUVL Approach - The Build Thread
The First music track (Tool - Pneuma) has been played with my F5X! Dead silent background without any noise.

Still need to measure and adjust bias currents since it seems to be running a bit hot now @~1.9A.

I attached a couple of quick and dirty photos.

Thanks a lot Patrick and Carlos for making this happen!
Attached Images
File Type: jpeg 0EA4FBFF-8730-43ED-A80B-F7B7FC6BFFA9.jpeg (204.7 KB, 297 views)
File Type: jpeg BFA6CCBF-3B57-46D0-84B1-5070506DDD09.jpeg (212.3 KB, 222 views)
File Type: jpeg 92768406-B984-417E-B8B3-8B61974713DC.jpeg (252.6 KB, 253 views)
File Type: jpg 72CD1656-FFF8-47BF-AB56-DCBD81EBE23E.jpg (782.8 KB, 294 views)
__________________
Head amps: SE84, Salas DCG3, UTHAiM, PassDIY HPA, Pioneer Super Linear, XEN JLH
Power amps: M2x, UDNeSS, F7 clone, F5X
  Reply With Quote
Old 31st October 2020, 10:11 AM   #1320
CeeVee is offline CeeVee  Portugal
diyAudio Member
 
CeeVee's Avatar
 
Join Date: Dec 2006
F5X -- the EUVL Approach - The Build Thread


Fantastic Job....Enjoy.
  Reply With Quote

Reply


F5X -- the EUVL Approach - The Build ThreadHide 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
F5X -- the EUVL Approach EUVL Pass Labs 900 4th November 2020 10:16 PM
Potential EUVL F5X designed case user distribution check pchw Group Buys 1004 27th February 2013 04:32 PM
GB 2SK3497/2SJ618 for EUVL F5X or other projects pchw Group Buys 266 8th April 2012 07:05 PM
[B]PRP resistor group buy for the EUVL F5X build[/B] NicMac Group Buys 70 4th February 2012 05:20 PM
New Saburo Build thread Wha' DIYa know? Full Range 94 17th October 2010 05:49 PM


New To Site? Need Help?

All times are GMT. The time now is 04:40 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki