phase splitter issue
 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

 Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

 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
 11th December 2011, 10:20 PM #501 CPaul diyAudio Member   Join Date: Nov 2011 Well, then, are you going to reveal it to me? I'm not a mind reader (my mother's favorite expression.) And let's not forget I'm going down your chosen path. When are you going to respond to what the current mirror circuit tells you about your flawed rise time analysis? __________________ "It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
 12th December 2011, 12:54 AM #502 SY   On Hiatus     Join Date: Oct 2002 Location: Chicagoland Equal loads. Balance is a consequence of boundary conditions, not a "given." __________________ "You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
 12th December 2011, 10:36 AM #503 DF96   diyAudio Member   Join Date: May 2007 Q1: How do you measure output impedance of a balanced cathodyne? Subsidiary question Q1a: How do you measure output impedance? A1a: By changing the load impedance and seeing how the voltage varies. Subsidiary question Q1b: How do you maintain a balanced cathodyne? A1b: By ensuring the same load at both output ports. A1: By changing both load impedances at the same time and seeing how the voltage varies. Q2: What do I mean by the output impedance of a balanced cathodyne? A2: The impedance I would use as the upper part of a potential divider or RC low pass filter in order to calculate the gain or frequency response of a balanced loaded cathodyne. Q3: Isn't this just half the differential output impedance of a balanced cathodyne? A3: You might choose to call it that - if you place twice the load on twice the impedance you get the same gain and frequency response. Balance means that the centre-point of the doubled impedance can be grounded, as it is already at ground potential anyway.
 12th December 2011, 12:30 PM #504 CPaul diyAudio Member   Join Date: Nov 2011 Your mission, should you accept it Jim, is to apply your boundary conditions without violating Thevenin's theorem. Take me through it, step by step. When are you going to respond to what the current mirror circuit tells you about your flawed rise time analysis? __________________ "It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
 12th December 2011, 12:35 PM #505 Alfred Centauri   diyAudio Member     Join Date: Jul 2007 Location: Metro Atlanta, Georgia DF96: Q1c: Can the individual output impedances be measured by changing both load impedances at the same time? A1c: No, unequivocally no. Thevenin's Theorem is clear on this and Chris' LTE circuit unambiguously demonstrates this. There is no rational doubt possible. Whatever it is you measure, it is not the individual output Thevenin impedances. The outputs of Chris' circuit, by inspection, have vastly different Thevenin impedances and yet, by "ensuring the same load at both output ports", you might incorrectly infer that the outputs have equal Thevenin impedances. To maintain that it is possible to measure the individual output Thevenin impedances while varying both loads is to dispute one of the most elementary, fundamental results in circuit theory. Guys, stop trying to fit square pegs into round holes. All the word play in the world isn't going to change reality.
 12th December 2011, 12:38 PM #506 CPaul diyAudio Member   Join Date: Nov 2011 You can measure the impedance between the p-k by varying a load connected between p&k, the center point of which is ground. This is why the identical grounded loads in a Cathodyne look like a single (differential) load between the p&k. I believe I agree with what you say, as long as you are talking about the impedance between the p & k (the differential output impedance of the balanced Cathodyne) and not the impedance from p to gnd or k to gnd. Your treatment is different from what SY says - that the p to gnd and k to gnd impedances are 1/gm. __________________ "It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
 12th December 2011, 12:50 PM #507 DF96   diyAudio Member   Join Date: May 2007 I have always been careful to accept that if you measure the output impedances individually then you get different results. That is not in dispute. As far as I remember, SY's main practical point is that it is incorrect to include a cathode build-out resistor. I think you accept that? If so, we probably are arguing about the meanings of words rather than the design of circuits.
Merlinb
diyAudio Member

Join Date: May 2006
Location: Lancashire
Quote:
 Originally Posted by DF96 we probably are arguing about the meanings of words rather than the design of circuits.
This was my feeling all along...

jan.didden
diyAudio Member

Join Date: May 2002
Location: The great city of Turnhout, BE
Quote:
 Originally Posted by CPaul janneman, I agree that you can use 5K and 10K loads to test impedanaces - you don't have to use open and short circuits. But look at Thevenin's theorem. Wikipedia actually has a good presentation. The test is about two nodes and two nodes only. There is no room in the theorem for tests involving three nodes. Thevenin doesn't know and doesn't care about SY's "boundary conditions." Thevenin's theorem applies to any two nodes in any linear circuit. No special cases; no special pleading. Whenever SY does a test with three nodes, he automatically violates Thevenin.
He doesn´t do a test with three nodes. He tests two nodes. But why can't he just test two Thevenin sources at the same time? You short TWO thevenin sources, and you MUST do that because the claim says: 'IF the two loads are the same...' so you need to test the two sources at the same time in the same way, infinite load or short circuit.
So you short the two nodes of one source, and the two nodes of the other source. Then you see that two nodes actually are the same so you end up with several nodes (three) connected all together. Well, that may look curious at first sight but it doesn't change anything, thevenin still holds. Why wouldn't it?

OTOH, Chris´ current source circuit in his last LTE does bother me....

jan
__________________
Cable: a potential source of trouble interconnecting two other potential sources of trouble - Erik Margan
Linear Audio pubs and articles . The SilentSwitcher now at diyaudio store SilentSwitcher. Keeping in touch with SY.

Last edited by jan.didden; 12th December 2011 at 04:16 PM.

 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         Holton Precision Audio         CSS         Dx Classic Amplifiers         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 famousmockingbird Tubes / Valves 16 10th May 2011 09:40 PM Hojvaelde Tubes / Valves 9 6th May 2011 07:32 PM grungeman91 Tubes / Valves 2 5th May 2011 01:58 AM guwakzhai Power Supplies 7 23rd December 2010 05:51 PM Gold_xyz Tubes / Valves 17 21st February 2008 09:48 AM

 New To Site? Need Help?

All times are GMT. The time now is 06:08 AM.