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.

Perplexed about M2 amplifier circuit impedance: schematic vs. user manual
Perplexed about M2 amplifier circuit impedance: schematic vs. user manual
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 13th March 2018, 11:09 PM   #11
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: Maine USA
I get notional 652.777 Ohms. As you say.

And he works the 600:15K windings pretty much spot-on the design spec.

The diff 6K versus 653 will not bother most users. Still, it "can't be right", and smacks of a lost decimal place.

Quote:
Originally Posted by Michael Rothacher View Post
...The input impedance of those source followers is very high.
But there are two 47K resistors hanging on that point. Mark's math just assumed the 23.5K and neglects Gates and Zobel (which are first-order neglectable).
  Reply With Quote
Old 13th March 2018, 11:16 PM   #12
Michael Rothacher is offline Michael Rothacher  United States
AudioMaker.Tech
diyAudio Member
 
Michael Rothacher's Avatar
 
Join Date: May 2001
Perplexed about M2 amplifier circuit impedance: schematic vs. user manual
I thought he may have been referring to the simplified schematic in the manual, speaking more generically about the system.

In any case, I think we've arrived.
__________________
Visit AudioMaker.Tech
  Reply With Quote
Old 13th March 2018, 11:20 PM   #13
Zen Mod is online now Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Perplexed about M2 amplifier circuit impedance: schematic vs. user manual
Quote:
Originally Posted by Michael Rothacher View Post
......

In any case, I think we've arrived.
let's use this thread for something really useful:

Mr. MR - is there a posibility to add Atom subscription thingie to your blog ?
__________________
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 13th March 2018, 11:36 PM   #14
Michael Rothacher is offline Michael Rothacher  United States
AudioMaker.Tech
diyAudio Member
 
Michael Rothacher's Avatar
 
Join Date: May 2001
Perplexed about M2 amplifier circuit impedance: schematic vs. user manual
I'm not sure. What is that?
__________________
Visit AudioMaker.Tech
  Reply With Quote
Old 13th March 2018, 11:44 PM   #15
Zen Mod is online now Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Perplexed about M2 amplifier circuit impedance: schematic vs. user manual
just ignore the question ..... I realized that even I didn't add Atom subscription button to my own blog

(I'm finding it most convenient way , and I didn't do it ....... )
__________________
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 13th March 2018, 11:45 PM   #16
Mark Johnson is offline Mark Johnson  United States
diyAudio Member
 
Mark Johnson's Avatar
 
Join Date: May 2011
Location: Silicon Valley
Perplexed about M2 amplifier circuit impedance: schematic vs. user manual
Reread the User Manual excerpt in post #1, and see if you agree that the dual JFET front end is only needed when driven by a tube preamp. All other preamps could easily (?) drive the 653 ohm input impedance of an M2-without-JFETs, wouldn't you say?
  Reply With Quote
Old 13th March 2018, 11:48 PM   #17
Zen Mod is online now Zen Mod  Serbia
Official Court Jester
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
Perplexed about M2 amplifier circuit impedance: schematic vs. user manual
I got that too

however .... having complete schematic and know how , somehow excludes relevancy of User Manual , especially on DIY site

or is NP somehow Bad Boy , suddenly ........
__________________
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 13th March 2018, 11:50 PM   #18
Michael Rothacher is offline Michael Rothacher  United States
AudioMaker.Tech
diyAudio Member
 
Michael Rothacher's Avatar
 
Join Date: May 2001
Perplexed about M2 amplifier circuit impedance: schematic vs. user manual
Quote:
Originally Posted by Mark Johnson View Post
Reread the User Manual excerpt in post #1, and see if you agree that the dual JFET front end is only needed when driven by a tube preamp. All other preamps could easily (?) drive the 653 ohm input impedance of an M2-without-JFETs, wouldn't you say?
No, I wouldn't say a 600 ohm input impedance is an easy load for all non-tube preamps, that's why I thought he may have been referring to the generic example in the manual, since that is the context.

We can just ask the man himself though, and save ourselves the tedium.
__________________
Visit AudioMaker.Tech
  Reply With Quote
Old 14th March 2018, 12:07 AM   #19
Nelson Pass is offline Nelson Pass  United States
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Perplexed about M2 amplifier circuit impedance: schematic vs. user manual
Probably a misplaced decimal. Stupid calculators can't get anything
rite...
  Reply With Quote
Old 14th March 2018, 12:20 AM   #20
Mark Johnson is offline Mark Johnson  United States
diyAudio Member
 
Mark Johnson's Avatar
 
Join Date: May 2011
Location: Silicon Valley
Perplexed about M2 amplifier circuit impedance: schematic vs. user manual
One of my current projects is a no-Toshiba-JFETs reimplementation of the M2, using a replacement front end that can happily drive a 50 ohm load to 5V RMS, all day long. The M2 spec of 650 ohms and 3V RMS, becomes child's play.

JFET input of course, but 2018 active production rather than Toshiba unobtanium. And a couple of other heretical deviations from First Watt dogma, which loyal fans may find disagreeable.
  Reply With Quote

Reply


Perplexed about M2 amplifier circuit impedance: schematic vs. user manualHide 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
Circuit Diagram / Schematic & Full Manual 4 Crown Ic-150 Pre Amp Wanted thermal runaway Solid State 5 1st September 2014 04:47 AM
Seek help: Leader LDM-171 user manual (Service Manual) 0451ym Parts 1 21st November 2013 03:10 PM
Crown D-60 Dual-channel Power Amplifier User Manual For Sale mv331 Swap Meet 0 21st May 2009 05:37 AM
Pioneer DV-656a or DV-655a user manual/schematic kenlow Digital Source 0 27th January 2004 08:36 AM


New To Site? Need Help?

All times are GMT. The time now is 09:02 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki