Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 11th November 2011, 05:52 PM   #1
diyAudio Member
 
Join Date: Jul 2010
Default output transformer for on solid state dual channel for THD reduction

Just wondering that can we use output transformer 1:1 to convert a dual channel amplifer (each channel 180 deg out of phase) like in a bridge mode to drive on singe channel for noise cancellation, and noise reduction,


I have dual Focal 2.150 amplifiers with 150 w per channel on each , i need two channels only and was wondering that whether i could use a custom made transofrmer to get less distortion like Mcintosh does in in car and tube amplifier. would i be getting 150 w or 300 w from each channel.

Seems interesting avenue for diy. Regards
  Reply With Quote
Old 11th November 2011, 08:49 PM   #2
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
You can only bridge two amplifiers IF the load presented to the output stage given the increased voltage swing does not result in the amp exceeding the power/current capability of the output stages.

In the case of a 1:1 output transformer connected to the two HOT (+) terminals, one each channel, you would have to invert the input to ONE of the two channels. Then connecting the outputs each to one side of a transformer would have no difference in terms of power then connecting the speaker to the same terminals.

Of course there is a difference, since the transformer looks like an inductance between the two terminals, and the load is then has galvanic isolation from the amps. But the impedance remains the same.

The classic McIntosh output stage does not use a simple 1:1 transformer.

You would be getting 600 watts with the bridged pair.

E = I * R and P = I * E so P = I^2 * R OR P = E^2 * R.

This last one is the key. You are going to see the square of the doubled voltage swing divided by the load as the resulting power.

example:

P = 10v^2 /10 = 10 watts
P = 20v^2 /10 = 40 watts

So your output stage has to be able to handle the extra current. Or <poof>.

You will NOT get THD reduction, except to the extent that you run the amp at a lower average level (not significant, in all likelyhood) and there will be no noise reduction, unless there is a signal that can be inverted and cancelled, but it would have to be a common mode signal entering equally at both inputs to the amp, since you would FIRST have to invert the input signal.

If you do NOT invert the input signal then you need a DUAL primary on the transformer, and you are running in parallel, not in P-P.

Either way the transformer will likely introduce some distortion and the cost will not be inconsiderable for one that can handle the power.

Buy another amp if you want more power, or bridge this one with care. (check the manual, it may NOT be bridgable).

_-_-
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 12th November 2011, 08:26 AM   #3
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Bear, does a 1:1 transformer not result in an impedance transformation of 1:4 as well? I am speaking under correction.
__________________
Kindest regards
Nico
  Reply With Quote
Old 12th November 2011, 09:05 AM   #4
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
Quote:
Originally Posted by muddasirwaheedmalik View Post
Just wondering that can we use output transformer 1:1 to convert a dual channel amplifer (each channel 180 deg out of phase) like in a bridge mode to drive on singe channel for noise cancellation, and noise reduction,
You can use the transformer to invert one of the outputs, allowing you to bridge it.

Because you can doesn't mean you should: inversion is best made at the signal stage, for both economical and technical reasons.

The best of the transformers is still worst than the worst amplifier, and you will get none of the expected benefits: noise reduction could only happen if both channels have a large, correlated noise like a buzz, and although some even-order distortion cancellation is in theory possible, any effect will be swamped by the transformer's own distortion.

And don't forget the transformer will also degrade the frequency response and the efficiency. Better use it as a paperweight, that's the optimum use for any audio transformer.
__________________
. .Circlophone your life !!!! . .
♫♪ My little cheap Circlophone© ♫♪
  Reply With Quote
Old 12th November 2011, 10:36 AM   #5
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Maybe use the redundant audio transformer as a choke/inductor.
__________________
regards Andrew T.
  Reply With Quote
Old 13th November 2011, 02:58 AM   #6
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Quote:
Originally Posted by Nico Ras View Post
Bear, does a 1:1 transformer not result in an impedance transformation of 1:4 as well? I am speaking under correction.

Nico, I dunno... I took the OP's spec of 1:1 to mean that somehow the result is the same as a simple isolation transformer, no change in ratio... Vin = Vout, no impedance change then?

_-_-bear
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 13th November 2011, 05:37 AM   #7
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally Posted by muddasirwaheedmalik View Post
Just wondering that can we use output transformer 1:1 to convert a dual channel amplifer (each channel 180 deg out of phase) like in a bridge mode to drive on singe channel for noise cancellation, and noise reduction,


I have dual Focal 2.150 amplifiers with 150 w per channel on each , i need two channels only and was wondering that whether i could use a custom made transofrmer to get less distortion like Mcintosh does in in car and tube amplifier. would i be getting 150 w or 300 w from each channel.

Seems interesting avenue for diy. Regards
If you can drive one channel of each amp in opposite phase, you can just connect the speaker between the two outputs. Gives the effect you want without needing a xformer.

jan didden
__________________
Never explain - your friends don't need it and your enemies won't believe you anyway - E. Hubbart
Check out Linear Audio Vol 7
!
  Reply With Quote
Old 13th November 2011, 11:14 PM   #8
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
Assuming the outputs can handle the extra current...

In which case the place for a transformer would be at the input, so that one can invert the phase without doing much work...

Hi Jan. I see from ur avatar you are doing "blind testing"?

_-_-bear
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  Reply With Quote
Old 14th November 2011, 07:05 AM   #9
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally Posted by bear View Post
Hi Jan. I see from ur avatar you are doing "blind testing"?

_-_-bear
I'm one of the few here that actually trust their ears enough to base my judgements on what I hear only
__________________
Never explain - your friends don't need it and your enemies won't believe you anyway - E. Hubbart
Check out Linear Audio Vol 7
!
  Reply With Quote
Old 22nd May 2012, 07:13 PM   #10
diyAudio Member
 
Join Date: Jul 2010
then how mcintosh uses its output transformer ??
  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
What Solid State Amps with Output Transformer do you know of? Onvinyl Solid State 27 27th April 2010 10:41 PM
Solid State Replacement of Ribbon Transformer? tmblack Pass Labs 5 31st January 2010 04:49 PM
Solid State amp with output transformers vizion Solid State 31 10th November 2007 03:23 PM
Transformer output solid state lumanauw Solid State 34 3rd April 2007 02:14 PM
Anyone have adivce on a good two channel solid state amplifier or CD player? Corn-Picker Everything Else 2 14th January 2003 09:19 AM


New To Site? Need Help?

All times are GMT. The time now is 04:46 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