Line stage for AMP6

[theskintman]

Hello all,

I've just got my AMP6 kit through the post. Before I dive into the amp itself, as I've never done anything like this before, I thought I'd practice my soldering skills by building a simple passive line stage.

My idea is to just connect four sets of phono inputs to a pot and a four-way source selector.

I'm just trying to put together a list of things to buy along with my new soldering iron. Because this is my first project, I'm bound to ask some daft questions below, but please stick with me as I'm here to learn!

For the internal hookup wire inside my line stage, would it be a good idea to use high grade shielded audio cable or just regular hookup wire? I'm trying to get everything from Maplin, which is kind of limiting on the quality cable front, but for a first project I don't feel the need to go overboard on expensive components.

Also with pots, I've read Rod Elliott's article, and a few threads on here, but still can't really make an educated decision over whether I want a 10/50/100k pot. Any advice would be much appreciated.

Cheers,

Gary

[!]

Originally posted by theskintman
Hello all,

I've just got my AMP6 kit through the post. Before I dive into the amp itself, as I've never done anything like this before, I thought I'd practice my soldering skills by building a simple passive line stage.

IMO, this is the wrong project first. You ought to practice on something non-critical to your desired goal, THEN build the amp and audition it from a single source, THEN your passive box.

My idea is to just connect four sets of phono inputs to a pot and a four-way source selector.

All four to a source-selector, then taking the output from that selector to the pot. However, if you want volume control, I would think about either making the selector box active with voltge gain or for the first project, perhaps better to just make the power amp with a pot and the separate box is only a simple switchbox.

I'm just trying to put together a list of things to buy along with my new soldering iron. Because this is my first project, I'm bound to ask some daft questions below, but please stick with me as I'm here to learn!

For the internal hookup wire inside my line stage, would it be a good idea to use high grade shielded audio cable or just regular hookup wire? I'm trying to get everything from Maplin, which is kind of limiting on the quality cable front, but for a first project I don't feel the need to go overboard on expensive components.

Indeed, quality cables are not necessarily a factor, only cables that are non-defective, suitable standard cable will work fine. Outside any shielded cases you want shielded cable. Inside shielded cases you don't need it. Point - if reasonably possible, use a shielded (metal) case.

Also with pots, I've read Rod Elliott's article, and a few threads on here, but still can't really make an educated decision over whether I want a 10/50/100k pot. Any advice would be much appreciated.

Lower ohm pot has lower noise but your source has to have a higher signal level. I suspect you are trying to make some kind of universal switchbox but in being universal it has to make compromises. IMO, 50K is a reasonable compromise. If you were making an active box with a voltage gain stage and JFET input, (closer to the ideal but each thing is a step along the path, if it's not time for that then wait and see if you feel it's important later) then 10K would be my first pick, or perhaps again 50K if a common source is a (battery powered) personal audio/MP3/etc player.