SemiSouth boiler room
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Pass Labs This forum is dedicated to Pass Labs discussion.

 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
 28th February 2013, 02:37 AM #211 kasey197 The Dastardly Dad of Three diyAudio Member   Join Date: Sep 2009 working my way thru this great writeup - meantime, two q) a) is this part of the article correct : ? "A trend line analysis performed in the Excel Chart shows good correlation to a cubic law (R2 = 1.00, where perfect correlation is R2 = 1)." .... Presumably the R2 is less than 1.00 since perfect corr is 1. b) I am probably missing the point, but why the extensive discussion/charts on the 2SC4004 BJT linearity and load-line cancellation instead of doing same on the SJEPs ? Thanks again
 28th February 2013, 03:31 AM #212 Nelson Pass   The one and only     Join Date: Mar 2001 Nice, Dr. Mike! I think it will keep the audience busy for at least a day...
 28th February 2013, 03:48 AM #213 flocchini   diyAudio Member   Join Date: Feb 2004 Location: Davis,CA Mike Really clear article You are a natural Best Bob
Semisouthfan
diyAudio Member

Join Date: Dec 2012
Location: Starkville, Mississippi, USA
Quote:
 Originally Posted by kasey197 working my way thru this great writeup - meantime, two q) a) is this part of the article correct : ? "A trend line analysis performed in the Excel Chart shows good correlation to a cubic law (R2 = 1.00, where perfect correlation is R2 = 1)." .... Presumably the R2 is less than 1.00 since perfect corr is 1. b) I am probably missing the point, but why the extensive discussion/charts on the 2SC4004 BJT linearity and load-line cancellation instead of doing same on the SJEPs ? Thanks again
Thanks for the kind comment.

(a) Good question! I figured somebody would (and should) ask. The actual R^2 is less than one, but not by much. Excel rounded 0.999... to 1.00 when I fixed the number of decimal places to report. So, to answer your question, R^2 = 1 is indeed perfect correlation. R^2 = 1.00 is simply rounding up a number very close to 1.

As for (b), great question given the thread, and worthy of an appropriate answer. I'll make two comments and then let you decide if you would like more clarification.

First, I think a "linear" transistor as a concept is worth discussing, and if one reveals itself in its transfer characteristic, like the 2SC4004, better to talk about it to see if we can understand why. Might be of use to the crowd around here. Very inventive bunch.

Second, the 2SC4004 transfer curve is an indicator of what might be done with an R100 with sufficient curvature in the output characteristics that is in series with extra drain resistance that is itself not in parallel with the load. Would a little extra power dissipation allow the drain current THD to be cleaned up without relying solely on the speaker load for canceling, which is not purely resistive? It's another means for output loop feedback than just source degeneration. I discuss this motivation at the end of that section. More analysis would be needed to answer that question than can be done with the commonly available Spice model of the SJEP120R100, which doesn't model the output curvature very well.

Hope this helps clarify my motivation.

Semisouthfan
diyAudio Member

Join Date: Dec 2012
Location: Starkville, Mississippi, USA
Quote:
 Originally Posted by Nelson Pass Nice, Dr. Mike! I think it will keep the audience busy for at least a day...

 28th February 2013, 01:34 PM #216 flg   diyAudio Member     Join Date: Jul 2005 Location: North East __________________ "It was the perfect high end audio product: Exotic, inefficient, expensive, unavailable, and toxic." N.P.
 1st March 2013, 01:41 AM #217 Nelson Pass   The one and only     Join Date: Mar 2001 I have a question about the cubic law component. Like everyone else, I assume that fets are square law devices, and this is supported by the clean second harmonics we get when we are only varying the Ids current with the Vds voltage remaining constant. When Vds is allowed to vary with signal, we start seeing some 3rd harmonic creeping in, and when the gain variation due to Drain resistance matches against variation due to transconductance, we see that "sweet spot" has clean 3rd harmonic with the second having been cancelled. Is this related to what you are talking about? Otherwise I'm somehow missing that in the distortion readings of these devices in ordinary analog use.
 1st March 2013, 02:04 AM #218 Zen Mod   Official Court Jester diyAudio Member     Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain even if I read the article in sort of skimp and end fashion ( proper read tomorrow ) , I have some objections : - there is no enough references neither to Zen Mod nor to Jimi Hendrix's work - mentioning "and other specialty SemiSouth JFETs" is not for faint-hearted , as I (by very nature ) am __________________ 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
 1st March 2013, 02:19 AM #219 buzzforb   diyAudio Member     Join Date: Oct 2010 Location: Burlington, NC I noticed that too ZM. Was trying notnto bring attention to it, but you runied it. As for the swwet spot, does it always mean second harmonic cancellation. Are we to assume this as the definition. 3rd harmonic is not what i would charcaterize as sweet. ZM, on the other hand __________________ ...Shape the sound , Man!
 1st March 2013, 02:23 AM #220 Zen Mod   Official Court Jester diyAudio Member     Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain re-read Beast ....... both article and thread then you'll be confused , for real __________________ 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

 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 Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Aussie Amplifiers         CSS         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post Zen Mod Pass Labs 271 18th October 2017 05:47 PM buzzforb Pass Labs 59 28th February 2014 07:53 AM aeronautical Multi-Way 49 22nd June 2012 09:22 PM dfidler Everything Else 5 29th March 2011 01:02 AM JinMTVT Multi-Way 4 4th September 2007 12:35 PM

 New To Site? Need Help?

All times are GMT. The time now is 03:19 PM.