[tangent]

Quote:

I took the 3rd hole on the power switch and grounded it.

Don't do that. Think about what you've done: in one position the switch connects the battery's V+ to the V+ point on the board, and in the other position it connects V+ on the battery to virtual ground. Does the latter make sense?

You want the second position on the switch to simply break the V+ wire, not connect it somewhere different.

Quote:

There is a noticable white noise when I use my cmoy..

The amp is probably showing you the noise inherent in your system. You wouldn't be the first person in the world to hook an amp up to your system and discover that it's noisy.

It may be that you need to add R5, but certainly not for the AKGs. I have no idea if the Sony's need R5. If it's with the AKGs that you're hearing the noise, it's probably coming from the source, and the amp is doing what it's supposed to: letting you hear what the source is putting out. Unplug the source to see if the noise goes away to be sure.

Quote:

I must eliminate it

Get a better source?

 

[tangent]

Quote:

I think I'm going to attempt to build an amp, but as an electronics noob I'm afraid to bite off more than I can chew. So maybe CMoy first to get experience, then a Meta 42.

There are a couple of ways to look at that tradeoff:

1. The META42 has more parts, which means it's harder to chase them down and it's more expensive

2. If you blow up a CMoy, it's cheaper to build another one than to build a second META42

3. Because it's easier to build it right the first time on PCB, you're less likely to blow up a META42 than a CMoy, assuming you pay equal attention to both tasks

4. The CMoy will probably be more educational since you're making it from scratch

5. The CMoy is more flexible, since you choose the layout to use

6. The META42 sounds and works a whole lot better.

I'd say, build the CMoy first if you're in this for the knowledge and the fun of tinkering, then maybe later do a META42. If you just want to make a good, inexpensive amp the first time out, go with the META42.

 

[chrono]

Quote:

Originally posted by tangent The amp is probably showing you the noise inherent in your system. You wouldn't be the first person in the world to hook an amp up to your system and discover that it's noisy.

I think that white noise is my amp.. because my sound card directly is fine, and for some reason my CD player stoped producing the white noise too (without me changing anything

)

Quote:

You want the second position on the switch to simply break the V+ wire, not connect it somewhere different.

I still dont perfectly understand the power switch. It confuses me.

I had it set up like this originally:

these are the three prongs on the power switch

- (connect to + battery wire)
-
- (connect to + battery hole on PCD)

Nothing happend when I fliped the switch when it was hooked up like this,, so I tried:

- (connect to + battery wire)
- (ground)
- (connect to + battery hole on PCD)

This way gave power to the board.. but not the full power it was supposed to.

If you could tell me what I have to connect to the prongs specifically, in what order, I'll be able to go and instal the power switch.

Thanks!

 

[Voodoochile]

Connect the battery + to the center pin on the switch. Then, take a wire from the board's + and run it to the lower pin. Connect the battery's neg to the board's neg.

It will actually work with the positive on either pin, but on the lower pin, the amp will then be 'on' with the bat up, instead of 'on' with the bat in the downward position.

 

[tangent]

The way an SPDT toggle switch works is, the center lug is connected to either outside lug, depending on the position of the bat. The bat moves a contactor inside the switch body, connecting the center lug with the lug opposite the direction the bat is pointing. If you think about it, you can visualize this lever action inside the switch body. It's like a see-saw, with the fulcrum being just inside the switch body from the opening.

An SPST is the same thing, just with internal one contact and one lug removed. That's why SPDTs are so much more common -- it's almost the same cost to make an SPDT as an SPST, and since SPDTs are more useful, the volume advantage means it's actually cheaper to just make SPDTs and use them for both roles.

 

[chrono]

Perfect, the power switch works now.

I just made a nice custom wood case, with a classic oak finish.
Just got to wood-glue it together, and slip in all the components, and it's finished.

Thanks again for all the help

 

[psyco1]

Did you put the R5 output resistors in it? If so, what did you use?

I'm putting a Cmoy together now and am wondering about what would work best with a pair of sr-125's(32ohm) & hd-590's(120ohm).