Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

transformer based phase splitter
transformer based phase splitter
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 February 2018, 04:39 PM   #1
DAK808 is offline DAK808  United States
diyAudio Member
 
Join Date: May 2012
transformer based phase splitter
Default transformer based phase splitter

I have this UTC O-6 which has primary 15K into 95K CT secondary. Is this an appropriate trans for phase splitting. If so what kind of tubes would be best suited for this ? I have mostly pentodes and beam pentodes, el84 to kt120 in terms of power output. I also have output trannys to match. Thank you for your suggestions. cheers, 808
  Reply With Quote
Old 12th February 2018, 04:57 PM   #2
Eli Duttman is offline Eli Duttman  United States
diyAudio Member
 
Join Date: Apr 2004
Location: Monroe Township, NJ
The "iron" has a 1/2.5 step up ratio. Take that into account, when working the small signal circuitry out.

Drive the trafo from a low impedance source, for best performance. You may have to resistively load the secondary legs, in order to stop ringing.
__________________
Eli D.
  Reply With Quote
Old 12th February 2018, 05:24 PM   #3
artosalo is offline artosalo  Finland
diyAudio Member
 
artosalo's Avatar
 
Join Date: Feb 2010
I just tested quite similar high impedance audio transformers and noticed that good frequency response require some amount of testing, impedance matching and testing again....
I could not get satisfactory results. Especially transient response was a mess with a lot of ringing.
  Reply With Quote
Old 12th February 2018, 05:52 PM   #4
DAK808 is offline DAK808  United States
diyAudio Member
 
Join Date: May 2012
transformer based phase splitter
Would it be better to have this between the input voltage amp tube then to 2 driver tubes then to the finals? I have no experience with this type of circuit and there seems to be little information about any schematics with this IT.
  Reply With Quote
Old 12th February 2018, 06:04 PM   #5
kodabmx is offline kodabmx  Canada
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
This is how I did it. It sounded pretty good, but lots of ringing on square waves even with gNFB. By the time I increased the cap in the gNFB network to 7500pf the ringing had stopped, along with high frequency response. I gave up and ended up using a split load phase splitter instead.
Attached Images
File Type: jpg 25790897_10155785305716006_1226196334886724409_o.jpg (51.8 KB, 332 views)
  Reply With Quote
Old 13th February 2018, 12:29 AM   #6
DAK808 is offline DAK808  United States
diyAudio Member
 
Join Date: May 2012
transformer based phase splitter
Quote:
Originally Posted by kodabmx View Post
This is how I did it. It sounded pretty good, but lots of ringing on square waves even with gNFB. By the time I increased the cap in the gNFB network to 7500pf the ringing had stopped, along with high frequency response. I gave up and ended up using a split load phase splitter instead.
thanks for the schematic. What kind of IT did you use?
  Reply With Quote
Old 13th February 2018, 12:31 AM   #7
danFrank is offline danFrank  United States
diyAudio Member
 
Join Date: May 2005
Location: California
Quote:
Originally Posted by kodabmx View Post
This is how I did it. It sounded pretty good, but lots of ringing on square waves even with gNFB. By the time I increased the cap in the gNFB network to 7500pf the ringing had stopped, along with high frequency response. I gave up and ended up using a split load phase splitter instead.
Why? Make it simpler and put the bias voltage on the secondary CT. Remove the coupling caps to the power tubes. Remove both 100K resistors to power tube grids.
  Reply With Quote
Old 13th February 2018, 12:43 AM   #8
trobbins is offline trobbins  Australia
diyAudio Member
 
trobbins's Avatar
 
Join Date: Feb 2009
Location: Melbourne, Oz
Quote:
Originally Posted by danFrank View Post
Why? Make it simpler and put the bias voltage on the secondary CT. Remove the coupling caps to the power tubes. Remove both 100K resistors to power tube grids.
Agree. That is the vintage technique that also allowed operating in to AB2 if the bias supply and IT secondary DCR suits.
  Reply With Quote
Old 13th February 2018, 12:58 AM   #9
kodabmx is offline kodabmx  Canada
diyAudio Member
 
Join Date: Oct 2011
Location: Toronto
I used Hammond 124B, and I biased it this way because I used individual bias controls for each tube since the OPT was a power toroidal. Using a single voltage for both tubes results in too much imbalance.


I was using one of these for biasing. Electron Tube Amp Negative Grid Bias Power Supply Adjustable 4channel for PP SE | eBay
  Reply With Quote
Old 13th February 2018, 01:28 AM   #10
Eli Duttman is offline Eli Duttman  United States
diyAudio Member
 
Join Date: Apr 2004
Location: Monroe Township, NJ
A cautionary note, we barely get away with putting O/P "iron" inside NFB loops. An interstage trafo inside a NFB loop can be problematic.
__________________
Eli D.
  Reply With Quote

Reply


transformer based phase splitterHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Tribute Line Input Transformer / Phase splitter transformer chrismercurio Swap Meet 3 3rd September 2017 12:25 AM
Fet based phase splitter? danielwritesbac Solid State 94 9th July 2014 03:34 PM
Transformer phase splitter Jaime Tubes / Valves 10 31st May 2010 07:40 PM
K & K Audio Transformer phase splitter? wttaylor Tubes / Valves 0 5th March 2010 09:55 PM
Stereo 7O with transformer phase splitter? wttaylor Tubes / Valves 2 26th February 2010 11:55 PM


New To Site? Need Help?

All times are GMT. The time now is 12:07 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki