cinema amps - Page 5 - 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 8th December 2012, 02:07 AM   #41
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
The DCR != (is not equal to) the output Z.

You want to determine the voltage ratio first, then plug it into the formula and get the actual impedance ratio.

Likely with all the secondaries together you have more like 16ohms or 32 ohms.

It's unclear to me if you said there are two primaries - each pair of tubes go to their own windings - OR if the tubes are in push-pull parallel. That would be two tubes going to a single winding, and then the other two tubes go to the other end of the winding, with a CT in the middle.

It seems you are a bit confused about things like "magnetization". It's not a factor.

There should be no DC offset between each side of the tubes, if properly biased and balanced.

Oh yes, the different DCR of the halves of the secondaries. Usually this will happen if one half the secondary is wound close to the center of the windings, and the other outside. It's the same number of turns, but the turns on the outside are longer than the ones on the inside, so the DCR is different.

There are ways to overcome this, but not all output transformers are built to do this.

Use a small AC source, like a an AC wall supply (12vac, 10vac, 5vac, etc) to provide a signal to use for determining the turns ratio. Use a DVM and calculator and you can figure out the ratio, and knowing the target plate Z for the tubes, know the output Z...

_-_-bear
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 12th December 2012, 10:54 AM   #42
diyAudio Member
 
Join Date: Nov 2012
Thanks for the reply
PP two valves in each side of the CT primary
I am having fun so far deciphering them
Any input is well received
Will not be around for a few weeks traveling overseas
Project has come to a standstill at this point in time
Back into it as soon as I get back
Cheers
  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
Active cinema speakers Thims Multi-Way 1 9th November 2008 09:31 AM
Crossover Advice for Home Cinema DIY RedCoat23 Multi-Way 10 7th July 2008 01:29 AM
home cinema speakers skogs Multi-Way 6 7th September 2007 06:15 PM
Sound in the Cinema planet10 Everything Else 17 25th March 2004 10:07 PM
TV/home cinema speakers Hay Introductions 1 6th January 2002 05:50 PM


New To Site? Need Help?

All times are GMT. The time now is 02:07 AM.


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