How do you know if a CMoy amp works properly?

So I finished soldering the amp and power parts of the Tangent CMoy amp, I'm using alligator clips to connect a male-male cable from my source to a pair of headphones and it seems to work just fine.

My only question is, how do I know if the amp actually works as an amp? Whether or not I have a 9V battery attached to the CMoy, I don't really notice a difference in sound. I think there MIGHT be a bass boost, but I cannot really tell.

EDIT: Maybe it's my soldering job...it gets pretty messy near the op-amp at the bottom half of the board. I need to get some 90%+ alcohol to get the rosin off of the board too.

Quote:

Originally Posted by Lurkumaural 

If a quick A/B isn't telling you enough, sit at your workbench** for a while and have a good listen to your amp.  Some people say spend a few days, but maybe just an hour or so with a very short playlist so you hear a few songs over and over again.

 

Then go unamped.  See if you're missing detail or separation or tight bass or any of the other things that amplification is known to improve.

 

** Assuming you're still relying on clips for your connections.  If you're all built up and ready to plug your cables in, by all means do it.

 

Because I haven't done this with my wife's E5, it sits in a desk.  Neither of us gave it a proper listen.

Yeah I'm not hearing a differences if there are any. The sound coming out of my headphones using an amp sounds like when I directly plug in my headphones into my source.

Quote:

Originally Posted by DingoSmuggler 

If you can pull the battery out of circuit and not notice much/any difference, then you definitely have something hooked up wrong. Without the battery, you shouldn't hear any sound at all.

Wait a sec....yeah the circuit shouldn't work without power I think. :(

Quote:

Originally Posted by Pars 

It looks like from your photos that you have both your input and output connected to the amp input. The input L+ and R+ should connect to the film caps (orange). The outputs should be coming from the "M" jumpers.

Hm, I could try that. I was connecting both of them to the input since Tangent mentioned:

And I couldn't really see where the leads were connected to on his picture:

But based on the circuit board layout, the outputs are indeed coming out from the "M" jumpers. I can try again later (I need to re-borrow the alligator clips since I don't own 6 of them).

Quote:

Originally Posted by Pars 

You basically had the input tied directly to the headphones, bypassing the amp. No wonder it didn't seem to matter whether the battery was in, amp turned on, etc. A CMoy at the stock gain is able to go quite loud.

Yup, that was stupid of me. I'll give it another try when I get back home today.

EDIT: Dang it, I picked up the wrong male-male cable...I guess I'll have to wait another day or two.

Okay, so I placed the alligator clips in the right spots this time and the amp works for the most part.

The right-side of the amp amplifies correctly (based on a higher volume output), but the left side's amplifier doesn't work. Sound comes out of the left channel at the same volume as if it were plugged into the source. I also notice that after pausing a song on my iPod Touch, the right channel has a hissing sound. Is this "noise?" If so, should I try adding in the R5 component instead of bypassing it via a short as Tangent did?

I'm going to go to Radio Shack soon to see if I can buy some soldering braid and re-do some of my solder joints. Either that or clean the rosin flux off of my board.

Would anyone happen to know what store sells 99%+ isopropyl alcohol in the US?

Quote:

Originally Posted by Lurkumaural 

Don't know, sorry.  May I ask why you need it?  And have you tried Harbor Freight, McMaster Carr, and Uline?

Oh yeah I forgot about Harbor Freight, I might look there when I get the chance. I was going to use it to clean the rosin flux off of my circuit board as recommended by Tangent.

I used a multimeter to do some measurement checks and for some reason, R4 on the left part of the circuit gives me 0.10 MOhms whereas the right side gives me the 10.9 kOhms.