phase splitter issue - Page 105 - diyAudio
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 13th January 2013, 07:46 PM   #1041
piano3 is offline piano3  United Kingdom
diyAudio Member
 
Join Date: Aug 2010
Location: London,UK
The inputs are a balanced switched attenuator followed by balanced cathode followers. There is 22k series resistance in each leg of the attenuator with the adjustable element 4k7 at maximum attenuation. Each leg is referenced to ground via the usual 1 Meg grid leak
  Reply With Quote
Old 13th January 2013, 08:19 PM   #1042
diyAudio Member
 
Join Date: Nov 2011
Usually the value of a differential system is that noise appearing identically on both legs is subtracted out by the receiver. Using the Concertina as a driver defeats this in two ways.

First, the Concertina’s power supply noise is present virtually unattenuated at the plate, but is attenuated by more than the triode’s mu at the cathode. This means that the differential receiver cannot cancel it out.

Second, stray magnetic fields (power lines, etc.) can induce voltages along signal lines. If the lines are routed similarly, and the line impedances are identical, the induced voltages will be similar and will be mostly canceled out by the differential receiver. But you can prove to yourself that this won’t happen with the Concertina by inserting identical high impedance signals into both legs. The different signals occur because the plate and cathode impedances are quite different.

I think that there are simple and better alternatives, but we discuss those, let’s see if you agree with what I wrote above.
__________________
"It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
  Reply With Quote
Old 13th January 2013, 09:15 PM   #1043
piano3 is offline piano3  United Kingdom
diyAudio Member
 
Join Date: Aug 2010
Location: London,UK
Naturally, I agree with all this. I had considered it as an after the fact modification for CD input only-98% of my listening is LP/78's which my main system is totally dedicated to, and as I said, fully differential from cartridge to output. Space is tight, so I was attempting to keep the component count low and additionally, I do not need any significant gain so I was trying to avoid another 2 differentials pairs with their usual CCS's. It may be a better solution to build a separate amplifier for the CD as was my original intention.
  Reply With Quote
Old 13th January 2013, 10:30 PM   #1044
diyAudio Member
 
Join Date: Nov 2011
I guess it depends on how far you want to go. I'd be a little concerned about the moderate amount of distortion that any triode I know would present when its P and K were loaded with a resistance as low as 1.5K and it were driven to line levels. But if you're OK with that and you're not concerned with power supply noise or stray magnetic fields, go for it!
__________________
"It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
  Reply With Quote
Old 13th January 2013, 11:12 PM   #1045
piano3 is offline piano3  United Kingdom
diyAudio Member
 
Join Date: Aug 2010
Location: London,UK
Then we are in total agreement; 1k5 would be a stupidly low load feedback or nay; an input cap would be the better option using cathode bias and the available HT shared more or less equally. I am confident that I can get the HT sufficiently quiet, hum in the microvolt range. As for stray fields.........

Many thanks for your input!
  Reply With Quote
Old 13th January 2013, 11:17 PM   #1046
diyAudio Member
 
Join Date: Nov 2011
My pleasure!
__________________
"It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
  Reply With Quote
Old 31st May 2013, 01:58 PM   #1047
diyAudio Member
 
Join Date: Nov 2011
Nothing new, just testing how some posts look.

21CenMaida_1.GIF

21CenMaida_2.GIF
__________________
"It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
  Reply With Quote
Old 31st May 2013, 02:00 PM   #1048
diyAudio Member
 
Join Date: Nov 2011
Click the image to open in full size.

Nothing new, just testing how some posts look.
__________________
"It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
  Reply With Quote
Old 31st May 2013, 02:38 PM   #1049
diyAudio Member
 
Mosquito's Avatar
 
Join Date: Sep 2009
Location: Santa Fe, Argentina
Hi, hope this question is on topic,
what to do when constraints forced You to use sub optimal tubes for the function? I'm thinking specifically in a direct coupled concertina/input stage, made solely of *AX7 tubes. (HT limited to < 320V but very easy output tubes to drive)
__________________
If I only had a dollar for every song I've sung...
  Reply With Quote
Old 31st May 2013, 02:53 PM   #1050
diyAudio Member
 
Join Date: Nov 2011
What constraints are you dealing with? Can you be more specific about what you mean by "what to do"?
__________________
"It is error only, and not truth, that shrinks from inquiry." - Thomas Paine
  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 11:36 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