Go Back   Home > Forums > Amplifiers > Tubes / Valves

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
Reply
 
Thread Tools Search this Thread
Old 18th September 2012, 12:59 PM   #861
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Quote:
Originally Posted by CPaul View Post

Your circuit which purportedly tests P & K to ground impedances by simultaneously shorting plate and cathode to ground draws no ground current. So there can be no current through ground referenced impedances. So they can't possibly be tested by your circuit.
I can't answer a nonsequitur.
__________________
"The way to deal with superstition is not to be polite to it, but to tackle it with all arms, and so rout it, cripple it, and make it forever infamous and ridiculous."- H. L. Mencken
  Reply With Quote
Old 18th September 2012, 01:07 PM   #862
diyAudio Member
 
Join Date: Nov 2011
Please don't. Just respond to my comment.
__________________
"It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
  Reply With Quote
Old 18th September 2012, 01:13 PM   #863
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
That's even stranger. "Don't answer me, but answer me."
__________________
"The way to deal with superstition is not to be polite to it, but to tackle it with all arms, and so rout it, cripple it, and make it forever infamous and ridiculous."- H. L. Mencken
  Reply With Quote
Old 18th September 2012, 01:51 PM   #864
diyAudio Member
 
Join Date: Nov 2011
Quote:
Originally Posted by dave slagle View Post
Every test you have proposed to prove unequal plate and cathode impedances has unbalanced the loads. I do not accept braking the model to prove it wrong acceptable.
To test an impedance, you run a current through it, observe the resulting change in voltage across it, and divide. Since the impedances in question are connected to ground, as you test each one individually, the current must go into ground from one path and out through another. There simply is no other way to test the impedance. If that's all it takes to break the model, it's a pretty brittle model. But I think you find your way through this a little later on in this post.

Quote:
Originally Posted by dave slagle View Post
In the case of the dual LCR's the only correct answer is ~5800 ohms in both the plate and cathode...

I agree in this case there will be no current flowing through the ground node. I will also accept that we need to call this the differential output impedance.
The problem was the demand, per SY's grounded two source model, that each load be driven by a separate source of impedance 6K rather than a single differential source of impedance 12K.

Quote:
Originally Posted by dave slagle View Post
I think the key here is to draw the current loops and treat each loop impedance as it should. Currents common to the plate and cathode must have the differential output impedance. Currents common to just the plate or cathode loop (through ground) will have the respective plate or cathode impedance.
Dave, I agree completely. Not sure I could have said it better myself. (SY, take note!) Consensus is nice!
__________________
"It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
  Reply With Quote
Old 18th September 2012, 01:53 PM   #865
diyAudio Member
 
Join Date: Nov 2011
I'm sure you're chortling about what you consider to be a non-sequitur. Perhaps you'd care to explain yourself so the rest of us can have something to laugh about.
__________________
"It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
  Reply With Quote
Old 18th September 2012, 02:19 PM   #866
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Consider symmetry and current cancellation under the specified constraint. You might call it "brittle," but it was successfully applied in some of the most popular and high performing tube amps ever made (Williamson, Dynaco, Heathkit, Eico...).
__________________
"The way to deal with superstition is not to be polite to it, but to tackle it with all arms, and so rout it, cripple it, and make it forever infamous and ridiculous."- H. L. Mencken
  Reply With Quote
Old 18th September 2012, 02:27 PM   #867
diyAudio Member
 
Join Date: Nov 2011
?
__________________
"It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
  Reply With Quote
Old 18th September 2012, 04:38 PM   #868
diyAudio Member
 
Join Date: Mar 2003
Location: NYC
Quote:
The problem was the demand, per SY's grounded two source model, that each load be driven by a separate source of impedance 6K rather than a single differential source of impedance 12K.
here is where I have a problem. The only way for the circuit to provide the proper results is with 5800 ohms in the plate side and 5800 ohms in the cathode side. This suggests that the differential output impedance of the cathodyne is 200 ohms to make up the needed 12K impedance.

If it were just the differential output impedance that we care about, you should be able to divide up that 11K8 series resistance any way you want and still get the 12K differential output impedance, when you do this the low frequency behavior tells us we are not providing the proper source impedance.

dave
  Reply With Quote
Old 18th September 2012, 05:03 PM   #869
diyAudio Member
 
Join Date: Nov 2011
I understand why this bothers you.

The best simple answer I can think of is that the Cathodyne is a bit more complex than either a single floating differential source or certainly a pair of ground-referenced opposing sources. Thatís one good reason not to think of it in terms of either of these models, because doing so is sure to trip you up.

To get an understanding of a circuit, I always recommend doing a full circuit analysis rather than assuming shortcut models. Short of that, you could play around with a lot of simulations, but I still prefer the former approach.
__________________
"It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
  Reply With Quote
Old 19th September 2012, 12:16 AM   #870
diyAudio Member
 
Join Date: Jun 2011
Quote:
Originally Posted by grungeman91 View Post
Has anyone ever built a concertina phase splitter and have the signal be perfectly split but they differed in amplitude?

I had that happen is when I used too small of a grid stop resistor on the input of the splitter.

And another time I tied too many output tubes in parallel. I increased the grid stoppers on the output which did fix it however, I went back and added a 6sn7 as a buffer between the outputs and phase splitter to provide a better drive signal.
  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
Phase Splitter Help famousmockingbird Tubes / Valves 16 10th May 2011 09:40 PM
Phase splitter Hojvaelde Tubes / Valves 9 6th May 2011 07:32 PM
phase splitter grungeman91 Tubes / Valves 2 5th May 2011 01:58 AM
Need help on phase splitter guwakzhai Power Supplies 7 23rd December 2010 05:51 PM
Phase Splitter Name Gold_xyz Tubes / Valves 17 21st February 2008 09:48 AM


New To Site? Need Help?

All times are GMT. The time now is 03:02 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