Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

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 20th January 2014, 11:11 PM   #1
diyAudio Member
 
Join Date: Jan 2014
Default Class D Stereo Amp in Mono?

Hello,
I am new to this so please excuse my ignorance. I have a two channel Class D amplifier but only need to run one channel. Will it damage the amp to leave one channel unused? The amp is a Sure Electronics TDA7498 2x100 watt. Thank you in advance for any feedback.
Jeff
  Reply With Quote
Old 20th January 2014, 11:49 PM   #2
diyAudio Member
 
doctormord's Avatar
 
Join Date: Oct 2007
You should ground the input of the unused channel and check the filter components for geneated heat. If they get hot after some minutes i suppose to not leave the output open. (If the output filter components are getting hot, it might help to put a 4ohms resistor with a 33uh coil in series at the output)

There shouldnt be any problems, as this amp has an output filter. More care has to be taken when running in a filterless configuration.
__________________
http://www.360customs.de
  Reply With Quote
Old 20th January 2014, 11:53 PM   #3
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
if you don't connect a speaker to the second channel the output filter choke will ring at very high voltages and possibly fry the output filter capacitor.
Depending on how conservative the voltage of the capacitor is will decide if it fries or not.
__________________
http://www.murtonpikesystems.co.uk PCBCAD50 pcb design software.
  Reply With Quote
Old 21st January 2014, 08:49 AM   #4
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
Parallel the amp. Split the signal and use it as input on both channels and then parallel the output, plus to plus, minus to minus.
  Reply With Quote
Old 22nd January 2014, 04:49 PM   #5
diyAudio Member
 
doctormord's Avatar
 
Join Date: Oct 2007
Do you think, its a good idea to put output filters in parallel without changing their values? I guess not. Wouldnt this invoke eddi currents and a misconfigured reconstruction filter?
__________________
http://www.360customs.de
  Reply With Quote
Old 22nd January 2014, 05:26 PM   #6
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
Quote:
Originally Posted by doctormord View Post
Do you think, its a good idea to put output filters in parallel without changing their values?
Yes.

You should either parallel the outputs before the filter and change the values, or parallel after the filter and leave the values as they are.

In most cases there will be no negative effect of paralleling outputs after the filter on relatively low output amps such as is discussed here.

And in any case, leaving a channel unused will have far greater negative effects than tying the inputs and outputs together.

Last edited by Saturnus; 22nd January 2014 at 05:29 PM.
  Reply With Quote
Old 22nd January 2014, 09:32 PM   #7
diyAudio Member
 
doctormord's Avatar
 
Join Date: Oct 2007
According to ST Semi and the datasheet of the TDA7498E, bridging to mono has to be done before the filter without changing the values. So you say, parts changes are needed then?

That confuses me. Beside this, the TDA7498E has a dedicated mono mode.

So, who right?

Regards,

doc
__________________
http://www.360customs.de
  Reply With Quote
Old 22nd January 2014, 09:52 PM   #8
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
Quote:
Originally Posted by doctormord View Post
That confuses me. Beside this, the TDA7498E has a dedicated mono mode.
What are you talking about? Space weather?

Quote:
The amp is a Sure Electronics TDA7498
I'm replying to this question.

Please also refer to this excellent guide that describes those output filter components that needs changing if you want anything resembling the promised performance.

http://www.trevormarshall.com/class-d-tutorial/

Last edited by Saturnus; 22nd January 2014 at 10:02 PM.
  Reply With Quote
Old 23rd January 2014, 12:52 AM   #9
diyAudio Member
 
doctormord's Avatar
 
Join Date: Oct 2007
Quote:
Originally Posted by Saturnus View Post
What are you talking about? Space weather?


That's replying to this question.

Please also refer to this excellent guide that describes those output filter components that needs changing if you want anything resembling the promised performance.

Trevor Marshall - Class D Audio Amplifier Design - TDA7498 Output filters
Output
Are you trying to be funny?

The 7498E is, compared to the 7498, designed to be run in mono mode. Thats why you parallel the outputs before the filter. The 7498 is not.

There also shouldn't be a problem with shorting one input and leave the output open. With no signal the arithmetic middle belongs to zero.

Anyway, Trevor's essay don't belong to the things discussed here.
__________________
http://www.360customs.de

Last edited by doctormord; 23rd January 2014 at 12:54 AM.
  Reply With Quote
Old 23rd January 2014, 06:31 AM   #10
diyAudio Member
 
Saturnus's Avatar
 
Join Date: Jun 2005
Location: Copenhagen, Denmark
Quote:
Originally Posted by doctormord View Post
Anyway, Trevor's essay don't belong to the things discussed here.
It does because as it mentions the output filter on the Sure amp is less than optimal so if you're going to do the trouble of tying the outputs together before the output filter, you change the values of that to the correct ones for your implementation. That is why I mentioned it at all.

If you just want it to run as a mono amp, you can tie both the input and the outputs together without changing anything. Simple.

I'm not sure why you mention the tda7498e at all. It's irrelevant to this discussion here.
  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
Cannibalize a Class AB Stereo to Class A Mono block. owenhamburg Solid State 8 13th September 2010 08:55 PM
Class-T amp with subwoofer - impedance? mono or stereo? pdvrog Subwoofers 6 14th July 2008 05:04 PM


New To Site? Need Help?

All times are GMT. The time now is 07:11 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