CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS

Lobby => Speakers => Topic started by: takato14 on May 31, 2015, 10:50:30 PM

Title: Stereo to Mono?
Post by: takato14 on May 31, 2015, 10:50:30 PM
I bought a cheapie 20W Class T amp to use with my K1000 a while ago, but I never got around to that so it's been sitting around. I found a 6 ohm subwoofer for like $2 at Goodwill today, so I decided to put the amp to use and used the two outputs of the Geek Out -- one to my monitor's speakers and one to the speaker amp -- to add it into my sound system.

I had the wires of both channels from the amp spliced together at first, but the amp started shutting itself off randomly after a while. Switched it to one channel and now it works fine... what can I do to get stereo to mono if I can't just splice the channels? Google is useless.

Thanks.
Title: Re: Stereo to Mono?
Post by: thune on May 31, 2015, 11:22:27 PM
You should just need some resistance in each leg before summing together, 1kohm should do it for headphone outputs, higher (5-15k) would be more appropriate for line level type outputs.

     1kohm
L---^v^v^v----|_______0 amp in
R---^v^v^v----|       |
     1kohm            |
gnd-------------------
     
Title: Re: Stereo to Mono?
Post by: Armaegis on May 31, 2015, 11:50:33 PM
Wait... were you splicing at the input or the output of the amp? Trying to do that at the output is just going to fry your amp.

Splice the input like Thune showed you, and use just one half of the amp. You can't bridge the amp outputs without extra shenanigans.
Title: Re: Stereo to Mono?
Post by: takato14 on May 31, 2015, 11:54:45 PM
Wait... were you splicing at the input or the output of the amp? Trying to do that at the output is just going to fry your amp.

Splice the input like Thune showed you, and use just one half of the amp. You can't bridge the amp outputs without extra shenanigans.
Output. Lol. Can you tell I'm new with this?

I just decided to put the sub with the TV in the living room, it didn't sound very good with this setup anyways and my dad will appreciate the thump.
Title: Re: Stereo to Mono?
Post by: Armaegis on June 01, 2015, 12:10:57 AM
Yeah... basically you were shorting the outputs together. Think of it this way, the signals always want to move towards ground. Yeah some of it will go through the sub, but it will ALSO try to shove its way through the other speaker terminal. So both sides fight into each other. All that voltage that generates sound going through the sub? Well you've also got that voltage going across the output impedance of the other output (which is typically very small, so you get a ton of current rushing through). Best case, the amp detects the faults or has a heat-safety and shuts off. Worse case... fire and other badness.
Title: Re: Stereo to Mono?
Post by: takato14 on June 01, 2015, 02:19:02 AM
Yeah... basically you were shorting the outputs together. Think of it this way, the signals always want to move towards ground. Yeah some of it will go through the sub, but it will ALSO try to shove its way through the other speaker terminal. So both sides fight into each other. All that voltage that generates sound going through the sub? Well you've also got that voltage going across the output impedance of the other output (which is typically very small, so you get a ton of current rushing through). Best case, the amp detects the faults or has a heat-safety and shuts off. Worse case... fire and other badness.
Huh. Could I solve the issue with a high volt/amp rated diode?
Title: Re: Stereo to Mono?
Post by: anetode on June 01, 2015, 04:49:53 AM
Are you talking about summing the inputs for the subwoofer? Why?
Title: Re: Stereo to Mono?
Post by: Armaegis on June 01, 2015, 05:23:20 AM
Huh. Could I solve the issue with a high volt/amp rated diode?
Nope. That's not how they work.

Please don't try to juryrig a solution here when you have no idea what's going on... you're going to damage either your equipment or yourself.
Title: Re: Stereo to Mono?
Post by: joeexp on June 01, 2015, 10:00:02 AM
https://www.gearslutz.com/board/attachments/geekslutz-forum/246857d1311841872-mono-stereo-passively-help-sought-stereo-mono-passive.jpg


Or you can by a readymade product i.e.:
https://www.audiomate.co.uk/proddetail.php?prod=Monacor-SMC-1-Stereo-Mono-Converter&gclid=CImkzrWe7sUCFSEYwwodHD0Afg