transformers

[Joe912]

I would like to build myself a 2 channel gainclone amp since the amp i was using for my computer just blew and the only part i dont understand is the transformer i dont understand which one to get and what the differences are?

I also would like to know how to add a volume knob?
And also how many watts they could put out?

[JazzzSpazzz]

Take a look here for some great info.

http://www.decdun.fsnet.co.uk/gaincloneindex.html

Also do a google on "gainclone" & you'll get about 6-10 hits that should get you going.

There is info on the tanny at most sites. Also look at the thread "Gainclone Cool Stuff/Treasure Hunt" thread. There is a lot of information about different types of trannies & how to hook them up. If you haven't built much before you may want to consider BrianGT's second group buy--Brian made some really nice PCBs that should help make it easy. I believe that he'll post on it sometime this month when he's ready.

With regard to the volume control--there are a lot of ways to control volume. The easiest way is to use a dual audio potentiometer to control the input to the amp. There are lots more complicated & better sounding ways (and more expensive). I believe that you could also just use your computer's volume control and not even have a knob on the amp. The power is, I believe, about 40-50 watts per channel and depending on tranny.

Cheers,
Bret Morrow

[Joe912]

thanks for the help

i was going to buy the briangt boards

and also i could just use a plain hedphone plug that gets split into two rca jacks and wire those into the amps to get stereo right

[Joe912]

does this look like an ok transformer. (i got it from an old tape deck)

Wat voltage do i have to measure to check if its ok?
and why are there 6 wires coming out?

[Joe912]

this was attached to the wall outlet to me it looks like a switch, a fuse and on the other side there is a dial that says

,,,,,,,,off
220---|----120
,,,,,,,,Off

( i just use commas to space it out)

i pluged the tape deck in before i took the transformer out and it worked so im not going to move the dial.

should i keep this intact so i already have a switch and a fuse

[Joe912]

sorry the pictures didn't work but heres 2 links

Transformer

attached part

[JazzzSpazzz]

Dude,

I think that you need to get a lot of knowledge before you build from salvaged bits. Electricity is dangerous, really, I'm not kidding. Now, the switch you are talking about looks sounds like 1 of those switches you'd use to change from 120 V to 220 V from the wall. I have no idea about the tranny--its a bit hard to guess what it is, but I highly doubt that a tranformer from a tape deck could power an amp--generally tape decks don't use that kind of power!

I'd grab a book on electronics from the library & have a good read before doing anything.

Cheers,
Bret Morrow

[Nuuk]

Like Jazzzspazzz says, if you are new to this game don't make things harder by trying to use used parts if you don't know exactly what they are!

As a rule, power amplifiers have larger (ie higher VA) ratings than other pieces of hi-fi kit like CD players, preamps and tape decks which all require less power.

So if you must save money on a transformer, you will have to look in an old power amp and even then you must be sure that you know what the spec is.

[moving_electron]

Here is an article about transformers:

Part 1:
http://sound.westhost.com/xfmr.htm

Part 2:

http://sound.westhost.com/xfmr2.htm

Other articles on electronic basics including power supply wiring can be found here:

http://sound.westhost.com/articles.htm