Mark Levinson no:29 - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 23rd November 2007, 04:43 PM   #11
diyAudio Member
 
Stormrider's Avatar
 
Join Date: Apr 2006
Location: Connecticut
Blog Entries: 2
Send a message via AIM to Stormrider Send a message via MSN to Stormrider
PPA - could i have the schematic as well?
__________________
AJ
  Reply With Quote
Old 23rd November 2007, 04:50 PM   #12
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Dudes,
it's much easier and faster to download the schematic from Jan Dupont's homepage, aka ACD
__________________
The buck stops Here
  Reply With Quote
Old 23rd November 2007, 06:21 PM   #13
ppa is offline ppa  Italy
diyAudio Member
 
Join Date: Mar 2005
Location: Italy
Hi AJ, send me your email so I can send you the schematic
PP
__________________
PP
  Reply With Quote
Old 23rd November 2007, 06:24 PM   #14
diyAudio Member
 
zeonrider's Avatar
 
Join Date: Mar 2004
Location: Belgrade RS
Default Hi, ppa !

Send me, you know what @

Linkxp@sezampro.yu
  Reply With Quote
Old 23rd November 2007, 08:49 PM   #15
diyAudio Member
 
sparkle's Avatar
 
Join Date: Oct 2003
Location: middle of nowhere...
i believe it is Delta Audio but i can't find there any sch related Mark L.
  Reply With Quote
Old 23rd November 2007, 09:00 PM   #16
diyAudio Member
 
zeonrider's Avatar
 
Join Date: Mar 2004
Location: Belgrade RS
Default Hi to all

www.audio-circuit.dk

They have all schematic what you want.

Regards zeoN_Rider
  Reply With Quote
Old 24th November 2007, 04:33 AM   #17
diyAudio Member
 
unclejed613's Avatar
 
Join Date: Dec 2006
attach a DMM across one of the .22/5W resistors (one of them appears to be R67 or R87) and adjust R72 for about 5mV.

quickie way to adjust for proper bias: (be sure you know exactly what you are doing here before continuing)

1)put shorting plug on input
2) attach an oscilloscope to the output
3) attach a 10 ohm 20W resistor to the output hot
4) attach the other end of the resistor to another amplifier
5) input a 1khz sine wave to the other amp, and adjust the other amp for 10V p-p output
6) observe crossover spikes on the oscope with the oscope set for 1mV/division
7) adjust bias until the spikes just barely disappear

at first glance, one would think "but i'm DRIVING the output stage, and that's a no-no", but you're doing this through a 10 ohm load, very similar to bridging an amp. plus the fact that you're only applying 10V, just enough to get a bit past the crossover region. the amp's output impedance is higher in the crossover region (when underbiased), which is why you get the spikes. once the bias is adjusted properly, the output impedance becomes constant, and the spikes go away. a side benefit of this is that you now have a "direct reading" method of measuring the output impedance of an amp, since this setup reads out 1mV/milliohm on the scope, so a 5mv wave on the scope would mean that your amp has a 5 milliohm output impedance. also, before starting, you want to be sure that your amp used as the signal source also has it's bias adjusted properly

before performing this test on an ML amp, or any other high value equipment, i recommend that you learn and get used to the procedure on an amp you can afford to make your mistakes on, since ANY method of adjusting bias can go wrong, resulting in leakage of magic blue smoke out of several components
__________________
Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net
spammer trap: spammers must die
  Reply With Quote
Old 24th November 2007, 05:44 AM   #18
diyAudio Member
 
sparkle's Avatar
 
Join Date: Oct 2003
Location: middle of nowhere...

thnx
  Reply With Quote
Old 24th November 2007, 10:55 AM   #19
ppa is offline ppa  Italy
diyAudio Member
 
Join Date: Mar 2005
Location: Italy
unclejed613 is right, but mark levinson's amp often have more quiescent current in final bjt for running the amps with sonic performances similar to class A amps, moreover, the 29 power supplies is big for this.
__________________
PP
  Reply With Quote
Old 24th November 2007, 12:18 PM   #20
ppa is offline ppa  Italy
diyAudio Member
 
Join Date: Mar 2005
Location: Italy
I must say the unclejed613 is good method for looking the final stage's minimal quiscent current for running it at effective class AB.

(I hope that is a decent english)
__________________
PP
  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
Can someone help with Mark Levinson JC-2? atlantaudiophil Solid State 28 20th April 2013 07:48 PM
Mark Levinson 23 highviewvideo Solid State 6 21st December 2006 05:52 PM
Mark Levinson ML3 minorl Solid State 0 6th July 2004 04:59 PM
mark levinson karma Swap Meet 8 8th March 2003 01:42 AM
Mark Levinson ML2 arnach Solid State 7 9th April 2001 04:36 PM


New To Site? Need Help?

All times are GMT. The time now is 03:37 AM.


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