Looking for the bestest UcD buffer - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

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 6th December 2004, 08:29 AM   #11
IVX is offline IVX  Russian Federation
diyAudio Member
 
IVX's Avatar
 
Join Date: Jul 2003
Location: Everywhere (Buddhist's context)
Hah! Some error in the my tube buffer setup is detected- mosfet current is too small for the 2Kohm load! I'm sorry. Probably this design is not so bad yet, simulation with the same error show 0.025% vs 0.037% achieved by me in saturday! So i hope new measurement will be close to the audigy THD limits! Coming soon..
__________________
Best regards,
E1.
  Reply With Quote
Old 6th December 2004, 08:41 AM   #12
diyAudio Member
 
Join Date: Sep 2003
Location: -
IVX,

Nice work!

Regards,

Jan-Peter
  Reply With Quote
Old 6th December 2004, 09:32 AM   #13
IVX is offline IVX  Russian Federation
diyAudio Member
 
IVX's Avatar
 
Join Date: Jul 2003
Location: Everywhere (Buddhist's context)
Well, now is much better. About 3Vp-p output voltage, but load is only ~20Kom, because mosfet current still too small (i'm delayed for my day job for 1.5 hour again :-).
Edited:
each anodes current are 2.8mA, and unbalance isn't so hard affected now, PS voltage 130V. BTW, this tube i've bought for 0.75 euro, probably it is will be equal cheap sound??? Audigy have own THD=0.002%, so i can't resist to subtract it from 0.0059%..
Attached Images
File Type: png fft_tube.png (12.5 KB, 483 views)
__________________
Best regards,
E1.
  Reply With Quote
Old 6th December 2004, 09:48 AM   #14
diyAudio Member
 
Join Date: Dec 2003
Location: hong Kong
Send a message via ICQ to ackcheng
Very nice!

Congratulations
  Reply With Quote
Old 6th December 2004, 10:07 PM   #15
IVX is offline IVX  Russian Federation
diyAudio Member
 
IVX's Avatar
 
Join Date: Jul 2003
Location: Everywhere (Buddhist's context)
Thanks guys, however i haven't tried 2Kohm load so far, and probably it's wouldn't be so lucky attempt, there is moot point because mosfet gate charge inherently nonlinear. Seems that not each of the spice model note it? When i'll have a time enough (next weekend if noone have an idea about), 2Kohm load will be checked with irf7103, bs108 and irlml2803, whatever the outcome i'll do it by complicating follower, that isn't preferable yet.
Actually any tube it's a most linear active device around, so our congratulations is rather be adressed to the tube inventors, but not for me.
__________________
Best regards,
E1.
  Reply With Quote
Old 12th December 2004, 02:59 PM   #16
IVX is offline IVX  Russian Federation
diyAudio Member
 
IVX's Avatar
 
Join Date: Jul 2003
Location: Everywhere (Buddhist's context)
As i'd promised, the new measurement is done. FFT plot captured at next conditions- 6Vp-p@2Kohm load@2.48mA each anode@16mA ir7103 source current. At the 8.2Vp-p output THD about 0.016%, IRLML2803TR (SOT23) allowed better THD performance vs bs108 or ir7103, but too hot, at least in the P2P setup. THD at >1Khz a bit less(-10%-20%). Warm settling time about 2 min, in this time from 0.008% to 0.02% can be seen.. Cathode resistors was 17k one vs 12k other!! BTW, i'd measured only one output of the circuit.. Now we can subtract 0.002%(audigy selfTHD) from the presented THD figures, and conclude that we haven't chance to obtain such figures without fine adjusting of the anode's resistors. 0.05% in the best case and if happy day, on the other hand, who of us equipped even less then i am? After all it must be listened!
edited:
BTW, Koldby has suggested servo circuit to keep close to the zero voltage at outputs.
Attached Images
File Type: png fft_tube2k.png (11.8 KB, 370 views)
__________________
Best regards,
E1.
  Reply With Quote
Old 8th March 2005, 08:50 PM   #17
IVX is offline IVX  Russian Federation
diyAudio Member
 
IVX's Avatar
 
Join Date: Jul 2003
Location: Everywhere (Buddhist's context)
Well, i know that's probably too late to being interesting, but i've done discrete opamp, measured it, and we'll listen it soon. Short form: 140V/Us, 300ns settling, 70db open loop gain with pole about 45khz so THD/Freq plot will be flat up to 45khz also.
Slowly but smoothly Tube buffer PCB is finished today too. Short form: DC servo (<4hz), delayed outputs connection (relay), onboard 150v (anode U) and +/-15V regulators.
Attached Images
File Type: png tube_buff.png (27.6 KB, 330 views)
__________________
Best regards,
E1.
  Reply With Quote
Old 9th March 2005, 11:42 AM   #18
subwo1 is offline subwo1  United States
diyAudio Member
 
subwo1's Avatar
 
Join Date: Jan 2002
Location: North American Continent
Ivan, you are the greatest.
__________________
USMPS
http://groups.yahoo.com/group/switchmode/
  Reply With Quote
Old 9th March 2005, 04:25 PM   #19
IVX is offline IVX  Russian Federation
diyAudio Member
 
IVX's Avatar
 
Join Date: Jul 2003
Location: Everywhere (Buddhist's context)
Nice joke, subwo!THX!
__________________
Best regards,
E1.
  Reply With Quote
Old 9th March 2005, 05:44 PM   #20
subwo1 is offline subwo1  United States
diyAudio Member
 
subwo1's Avatar
 
Join Date: Jan 2002
Location: North American Continent
__________________
USMPS
http://groups.yahoo.com/group/switchmode/
  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
Diamond Buffer - Super Buffer peranders Solid State 34 16th May 2010 01:46 PM
B1 buffer pmchoong Pass Labs 1 11th May 2009 05:48 AM
Near ZERO IMD buffer amp wenye Solid State 37 20th April 2009 07:50 AM
Bestest Debut album rick57 Music 75 14th August 2006 04:01 AM
Opamp + buffer, how to bypass buffer at HF for unity gain? Christer Solid State 10 29th October 2003 06:50 AM


New To Site? Need Help?

All times are GMT. The time now is 03:11 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