TSSA - The Simplest Symmetrical Amplifier - Page 111 - 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 12th September 2012, 04:05 PM   #1101
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
I think JLH argued in the original article that the 0.22 Ohm resistor somewhat helps to suppress back EMF entering the feedback chain. The lower impedance of the feedback resistors in a CFA could have a similar effect.
  Reply With Quote
Old 12th September 2012, 04:07 PM   #1102
diyAudio Member
 
Lazy Cat's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by supernet View Post
Hm...interesting question
hehe you know something I shoulda known too, please talk
  Reply With Quote
Old 12th September 2012, 04:20 PM   #1103
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Quote:
Originally Posted by Salas View Post
Meaning that amp? I got one still going strong. Using it for when everything else is under planning or cruel operations. Built on 80's L bracket modded PCBs that skip the 0.22R and speaker line fuse originals. I should add it and see what happens at a point I guess. Will reserve it for when the devil will find work for idle hands to do, and that is very British being a Morrissey lyric too.
Not that one but this one, and my moded one.
dado
Attached Images
File Type: jpg JLH80W.jpg (67.7 KB, 310 views)
File Type: jpg JLH80W-mod.jpg (117.7 KB, 305 views)
  Reply With Quote
Old 12th September 2012, 04:29 PM   #1104
diyAudio Member
 
Esperado's Avatar
 
Join Date: Jul 2011
Location: France
Quote:
Originally Posted by Joachim Gerhard View Post
A transmission line of cause does also not need a high damping factor because it has a quite flat impedance curve in the bass.
Yes, and transmission lines present a good acoustical charge to dump the speaker at the resonance too.
Transmission lines and 1/4 waves are probably the best enclosures for Bass, although not always possible (QTS of the boomer) and sooo complicated to build. :-)

On my side, I do not care too much about the influence of the serial impedance of the amp on the response curve, as my speakers are all compensated (motional and self) to present a near flat impedance on all the bandwith (6ohms +- 1 ohms).
So the influence of the damping factor of the amp is mainly on pulse response.
Having a flat impedance helps the amp, too, because it do not have to deal with disparate (word is correct ?) Voltage/Current ratios, depending on frequencies.

I will never understand why manufacturers do not care this aspect.
__________________
Ultimate Protection and more.The Only Source of Knowledge is experience, everything else is just information” ©A. Einstein
  Reply With Quote
Old 12th September 2012, 04:40 PM   #1105
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by dadod View Post
Not that one but this one, and my moded one.
dado
Which one he published last, mine or yours with the Mosfet Vas?
  Reply With Quote
Old 12th September 2012, 04:42 PM   #1106
diyAudio Member
 
Lazy Cat's Avatar
 
Join Date: Sep 2007
Lightbulb PRAT is everything

I don't know what kind of music you guys listen to, but for me Jazz is the most revealing, true "acid test", since PRAT (Pace Rhythm And Timing) is everything at Jazz. Live Jazz performances daily in summer time offers major experiences, sound absorptions, tasting and learning how live instruments and Jazz band should sound. System must be capable to reproduce near live experience and that happens only when PRAT is OK. Musicians come together playing the same tune, they're tuned together, if not, complex Jazz takes sounds like tune's falling apart, musicians not playing in the same composition. To me Y axis correlations (phase, time, frequency) are the most important ones, amplitude related distortions are much more tolerable.

I could hear Jazz band from 1 km distance and I would immediately know it is live band playing: transients (speed), phase synergy, PRAT tells me that.
  Reply With Quote
Old 12th September 2012, 04:46 PM   #1107
dadod is offline dadod  Croatia
diyAudio Member
 
dadod's Avatar
 
Join Date: Apr 2006
Location: Zagreb
Quote:
Originally Posted by Salas View Post
Which one he published last, mine or yours with the Mosfet Vas?
It was published in EW-WW 1984 July to August, later he changed it a bit, but I do not have that magazine(I think it was 1989.)
I don't know yours, I see it first time.
dado
  Reply With Quote
Old 12th September 2012, 05:17 PM   #1108
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Mine is older after all. "Wireless World August 1982"

The Class-A Amplifier Site
  Reply With Quote
Old 12th September 2012, 09:05 PM   #1109
Jay is offline Jay  Indonesia
diyAudio Member
 
Join Date: Feb 2003
Location: Jakarta
Quote:
Originally Posted by Salas View Post
Which one he published last, mine or yours with the Mosfet Vas?
Salas, the later JLH with mosfet vas has transformed into a Fetzilla

The idea of matching P and N channels (by differing the gate stopper resistance) are also still adopted in Fetzilla, not in your older version of JLH (I think mosfet was still new for him then). Even in Dadod version of JLH, JLH used a series of 2 resistors for gate stopper. In later model JLH used only one resistor, and that is lower value than yours (330R for N, 270R for P. Yours are 680R for both). Go figure
  Reply With Quote
Old 12th September 2012, 11:07 PM   #1110
diyAudio Member
 
Esperado's Avatar
 
Join Date: Jul 2011
Location: France
Quote:
Originally Posted by Jay View Post
The idea of matching P and N channels (by differing the gate stopper resistance) ...
.. look like squaring the circle, because gate capacitance are varicaps, depending on the gate voltage in a different way between the N-channel and P channel.
Paralleling a cap to reduce the C delta, playing with gate stopper to equalize the low pass filter (created with the capacitance holes) between the P & N devices ?
Never found a good enough response.
So, i believe the only thing we can really do is to allow the driver to never run out of current in the worse situation with the gate resistance little enough for keeping the desired bandwidth in the worse situation too and forget about matching... Am-i wrong ?
What are your experiences about this problem ?
__________________
Ultimate Protection and more.The Only Source of Knowledge is experience, everything else is just information” ©A. Einstein
  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
simplest amplifier possible with BJT's? rmgvs Solid State 123 10th July 2008 03:05 AM
Symmetrical Phono Amplifier seroxatmad Solid State 3 6th August 2007 04:00 PM
Simplest class B Amplifier PicancoNet Solid State 42 8th June 2005 02:55 PM
Symmetrical amplifier conundrum Kilentra Solid State 22 31st January 2003 05:06 AM
Symmetrical 400W amplifier Diogo Solid State 30 28th October 2002 11:00 AM


New To Site? Need Help?

All times are GMT. The time now is 12:28 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