summing channels - diyAudio
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 23rd February 2005, 04:39 PM   #1
diyAudio Member
 
Join Date: Nov 2004
Location: sk
Send a message via AIM to ocool_15 Send a message via Yahoo to ocool_15
Default summing channels

I have been looking for a while on how to sum the left and right channels for use on a mono subwoofer and havent found the appropriate information.
I remember reading somewhere a long time ago about having to use a 10k? resistor somewhere in order to not"short" the right channel. It seems to sound fine to use the left and right connected together in parallel ie: just a y-adapter.
  Reply With Quote
Old 23rd February 2005, 04:54 PM   #2
diyAudio Member
 
Join Date: Sep 2004
Location: Central California
You do need a resistor in series with each channel. This will keep each channel from loading the other. A 1k will probably work fine. Most equipment makers put a series resistor on the output of line level products just as a safety measure, in case someone uses a 'Y' adapter. If your is working OK, thats probably the case.
  Reply With Quote
Old 23rd February 2005, 08:46 PM   #3
diyAudio Member
 
Join Date: Nov 2004
Location: sk
Send a message via AIM to ocool_15 Send a message via Yahoo to ocool_15
Default resistors

So for building a sub amp I should do this for the inputs if i want to use both channels? Is the value of the resistor important or will change the sound signifigantly? The periods are just there as place holder for the diagram.
...............1k
L+ ------\/\/\/\/\--------\
.....................................|
.....................................|-------------+amp input
.....................................|
R+-------\/\/\/\/\--------/
.................1K


Im just using a discman right now because of funds but eventually it will run off of normal CD/DVD source
  Reply With Quote
Old 23rd February 2005, 09:08 PM   #4
Duo is offline Duo  Canada
diyAudio Member
 
Duo's Avatar
 
Join Date: Jun 2002
Location: Victoria, BC, Canada
Send a message via ICQ to Duo
Hi there, that looks good. The resistances define how much you'll load your source equipment. You'll notice an attenuate(quiet)output if the resistors are too big, but you'll have crossloading (as defined earlier) if they are too small.

For something like a discman, the output is designed to handle a lower resistance load because of headphones. In this case, 1K resistors are good.

In most audio equipment I use between 6.8K and 10K for my summation resistances; unless there's a special case like high voltage in tubes.

Hope this helps.
__________________
-- Duo, W1ngs, VA7MON, and lesser known handles. --
-- http://www.w1ngselectronics.com -- My Work and Projects --
  Reply With Quote
Old 23rd February 2005, 09:09 PM   #5
diyAudio Member
 
Join Date: Sep 2004
Location: Central California
No, the value isnt real critical. It just provides isolation between the two channels. 1K is probably fine. Different values may cause a slight level difference, but thats all.
  Reply With Quote
Old 24th February 2005, 07:23 AM   #6
diyAudio Member
 
Join Date: Nov 2004
Location: Florida
I've been using a parallelled stereo amp running mono to drive a sub for over a year now.

It has an STK 4231-2 IC amp that's rated at 100W/ch at 8 ohms.

The Transformer measures 40/0/40 and is fairly big and heavy.

The inputs are connected together, and the outputs have a 0.1 ohm resistor at each output which connect together at the speaker.

This is running a single 12" 4 ohm speaker, at over 200W.

This sub gets slammed by this amp, but the bass sounds clear, controlled, and sounds good way down low, even at low volumes.

My original idea was to use a dual coil sub, but I couldn't find a good cheap one with dual 8 ohm coils, so paralleling 2 8ohm amps to make a mono 4 ohm amp worked better.
  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
DIY summing ? jayjaybee Analogue Source 16 25th July 2010 09:27 AM
Summing at the LTPI memphissound Tubes / Valves 2 11th January 2008 05:36 PM
Xtreme Noob - Summing Channels For Mono 3875 CarlosT Chip Amps 37 30th November 2006 01:36 AM
Summing two channels to one (line level signals) jarros Class D 5 19th September 2005 12:39 AM
Summing Channels with opamps hacknet Solid State 20 7th June 2004 02:09 PM


New To Site? Need Help?

All times are GMT. The time now is 02:53 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