Simple audio mixing

[KennyR]

I have three computers on my desk but only one set of speakers. I was wondering if there was a cheap hardware mixer that could simply mix these outputs with a minimum of amplifying?

I've been searching for weeks. There are plenty of mixers and amps out there, but they are too expensive and/or have features I don't even need. I don't need bass, treble or anything like that. In fact I don't even need volume control - my computers can do that. And I don't need a powerful amp, seeing as I have good quality speakers with their own output.

So basically what I need is - 4 inputs, 2 outputs (one for headphones), no amplifying, ABSOLUTELY NO FANS, and costing less than $70 or so.

Does anyone know a mixer like that?

[Karlos]

A pair of 741 op amps (left and right) configured as a virtual earth  and a gain of 1? You can shove as many inputs as you want into that :-)

[KennyR]

I got 20% for the engineering part of my chemistry course. This alone should tell you how good I am at electronics and soldering. ;-)

[Karlos]

Ah well.

If you know someone nearby who's handy with a soldering iron, you could knock it together for a fiver (inc case and connectors). The number of components needed really is small, the opamps plus a couple of resistors.

It doesn't quite qualify as a passive mixer (requiring a power supply) but it works.

You could just get some audio connectors and connect them all up in parallel. I wouldn't reccomend this however - especially when the different machine outputs may have different impedances etc...

[kgrach]

@kennyR
http://www.ramseyelectronics.com/cgi-bin/commerce.exe?keywords=mixer&defaction=search&y=

Ramsey makes a mixer kit $49.00 two stereo line and one phono which you can easily convert into another stereo line input, stereo mic input and headphone out and line out.
the mic input can be converted or you can simply build or buy yourself a 10:1 padded cable to convert line level to mic. Real simple even if you are inexperienced with a soldering iron should not take you no more than three hours to put together.

  All you need to construct a padded cable is a cable and four resistors two 4.7k and two 47k.
cut the cable in half put the 47k in the audio path and the 4.7k from the audio to gnd on the line side of the 47k resistor.
If you need additional help in the construction of a padded cable I can draw you a picture.

 That should give you what you need without any design headaches or big price tag.

[Cyberus]

As has already been alluded to, an audio mixer would be one of the easiest electronics projects you could ever undertake. I remember the first practical piece of work I ever had to do for my electronics class was build a dual input microphone mixer. Honestly, you could get a schematic and build one in an afternoon (even taking into account the fact you may not have soldered much in the past)

[xeron]

I have 3 computers (A1200, A1500, and AmigaONE) all routing their sound output to the repulse in my A4000. So, if you have a soundcard with a sufficient enough number of inputs, you can just use that. Of course, that computer needs to be on for any others to have sound ;-)

[Madgun68]

In some of the stores around here, you can pick up a/v switchers for people with multiple console units. I saw one recently that matched a Playstation2 look and went for roughly $20. (Has 4 or 5 inputs. Here's an example of one.)

You'd need some small patch cables for the type of audio cables used on computers, but seems to me that you should be able to use something like this for $35 - $40.

[KennyR]

Yeah, that's the problem, xeron - I don't want to have to leave a computer on to have sound, or I'd have used my Pegasos "sound card". I'm just looking for that same functionality in a small, portable device.

[KennyR]

@kgrach and cyberus

I have soldered a *lot* in the past, and have come to one conclusion - I never should be allowed to do it again. I break everything I solder. I make big dirty solder splashes everywhere. I fry chips. I singe PCBs. I melt wires. I burn myself and set fire to my carpet. There's really no way I could build even anything this simple myself. I hate electronics, I never could figure out how an op-amp worked, and I can't solder to save myself.

On the other hand, I'm good with credit cards... ;-)

[KennyR]

@madgun

A switcher is not what I'm after. It's just too inflexible. Not only do I have to operate it manually, I couldn't do the things I want - like play mods on the Amiga while using my Pegasos, while having my PC make audible reports for my UPS and other things. I really need a mixer, not a switch.

[greenboy]

There are plans all over the net to build simple passive resistor-based mixers, much the same principle as building the Y cables previously mentioned in the thread. They give you more room to work and can use pots in place of fixed resistors. Maybe a company or two sells such mixers as well; I know DOD had one.

Myself, I'd get on eBay and get a active mixer with a small number of inputs because it can be useful to have control over levels for disparate computer types, and EQ to get the best out of whatever speakers one has. These mixers can do a lot more besides and typically perform better.

Some like Behringers are cheaper than hell (considering what they are) even when not purchased used.

[Doobrey]

@ Kenny, sounds like you`re almost upto my standards   :-o

 I bought a nice new shiney soldering iron a couple of weeks back, to replace the massive thing I normally use.. and for 3 days I forgot I had left it powered up !!! Didn`t burn anything luckily, but I knackered the tip..

 A few years back I learned the hard way not to try and catch a soldering iron if you drop it...well, it was more a case of learning which end to catch  :-x

[bloodline]

Doobrey wrote:
 A few years back I learned the hard way not to try and catch a soldering iron if you drop it...well, it was more a case of learning which end to catch  :-x

That would explain your Avitar :lol:

[lorddef]

Doobrey wrote:

 A few years back I learned the hard way not to try and catch a soldering iron if you drop it...well, it was more a case of learning which end to catch  :-x

I know how you feel, I did the same when I was 7 years old.