Most exotic 3.5kOhms Output Transformers - Page 4 - diyAudio
Go Back   Home > Forums > Commercial Sector > Vendor Forums > Vendor's Bazaar

Vendor's Bazaar Commercial Vendors large & small hawking their wares

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 1st December 2012, 04:04 PM   #31
diyAudio Member
 
Join Date: Mar 2003
Location: NYC
Quote:
Originally Posted by petavgeris View Post
I have a graph somewhere.
With a gap and DC bias there is an initial substantial increase in mu, then mu is almost dead flat and then it starts to go down due to saturation.
I would like to see that graph.

Quote:
That's one of the main virtues of SET amps. Push Pull gives terrible sound compared to Single Ended because there is no DC bias and initial effective permeability of iron is quite low, so low level detail gets lost.
or it could just be the airgap required for DC linearizes the inductance.

Quote:
It is this low level detail where magic of music lies! This has nothing to do with the amplitude of the signal, it is purely a function of DC bias. Gap and DC is all the magic of SET amps!
I agree with the concept that music lies in the low level details but have yet to witness DC current increase the perm. As an experiment I measured a choke I had on hand. 49% nickel core with 0 DC current I measured 144hy's with a 0.5V 50hz signal applied. (this represents an AC flux of 3.5 gauss) Applying 1ma of DC current (Bdc of 236 gauss) did not alter the inductance at all. Granted this device had a substantial airgap which could hide a slight change of perm so I placed a minimal gap (0.0005") and remeasured.

This time I measured 810hy's and interestingly enough 1ma of DC did bump the inductance a bit. This was simply the DC current pulling the core together which has the effect of shrinking the gap. A few large clamps secured everything in place and the inductance now measured 950hy's. I then applied DC in .1ma increments and it wans't until 1.8ma that a change was noticed and that was the slight reduction of Q that predicts the onset of saturation. 2.5ma of current dropped the inductance to 890hy.

Finally I changed the excitation frequency to 120hz to reduce the net flux to 1.4 gauss and the inductance dropped to 900hy but I was unable to get an increase in inductance by applying DC. To close up this experiment I did the calculations based on the selected airgap and a 25% increase in perm translates to a 1.5% increase in inductance which should be observable if it existed.

dave
  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
Looking for a decent pair of 807(output tube) output transformers hatrack71 Swap Meet 4 5th April 2012 07:43 PM
exotic product ... exotic price Pocoyo Swap Meet 73 20th June 2010 01:44 AM
Difference between SE output transformer and push-pull output transformers hilbert_mostert Tubes / Valves 12 8th March 2009 05:10 PM
Help identifying a pair of output transformers and power transformers mjk130 Parts 3 30th January 2009 10:44 AM
Which is the best for output transformers AD1865 Tubes / Valves 32 28th October 2003 09:17 PM


New To Site? Need Help?

All times are GMT. The time now is 02:26 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