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How do you know if a CMoy amp works properly?

post #1 of 19
Thread Starter 

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.

 

310172_10150409577535709_557900708_10659457_360473763_n.jpg

 

297647_10150409692805709_557900708_10659980_717870489_n.jpg

 

322763_10150409598905709_557900708_10659619_930507252_o.jpg

 

312528_10150409598570709_557900708_10659612_2112309343_n.jpg

 

291072_10150409599555709_557900708_10659627_442208847_o.jpg

 

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.


Edited by miceblue - 10/14/11 at 12:57am
post #2 of 19

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.

post #3 of 19
Thread Starter 
Quote:
Originally Posted by Lurkumaural View Post

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.

 

post #4 of 19
Quote:
Originally Posted by miceblue View Post
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.


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.

post #5 of 19
Thread Starter 
Quote:
Originally Posted by DingoSmuggler View Post

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. :(

 

post #6 of 19
Quote:
Originally Posted by miceblue View Post

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

 


I treated your original statement about operating without 9V as a typo or misstatement.  Our friend Smuggler is absolutely correct.

 

post #7 of 19

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.

post #8 of 19
Thread Starter 
Quote:
Originally Posted by Pars View Post

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:

 

Quote:
Hook the other ends of the jumpers to the board: the left and right channel jumpers go to the end of C2 nearest the board edge, and the ground can be hooked onto the R2 leads going to ground.
 
Next, do something similar with the remaining 3 alligator jumpers to tie a pair of cheap headphones to the amp’s output.

 

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

mini-cmoy--0150-test-outside-case.jpg

 

 

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).

post #9 of 19

Yeah, you should not be able to hear anything if its not on.

 

As far as sound quality goes, I really don't notice my cmoy to make any difference other than being able to turn the volume up much higher than my Zune is capable of doing.

 

If you have to sit for days or hours on end trying to hear the slightest difference, then what the hell is the point.

post #10 of 19

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.

post #11 of 19
Thread Starter 
Quote:
Originally Posted by Pars View Post

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.

 


Edited by miceblue - 10/14/11 at 9:51pm
post #12 of 19
Thread Starter 

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?


Edited by miceblue - 10/17/11 at 3:33pm
post #13 of 19

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

post #14 of 19
Thread Starter 
Quote:
Originally Posted by Lurkumaural View Post

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.

 


Edited by miceblue - 10/17/11 at 4:02pm
post #15 of 19

Most grocery stores and drug stores (Walgreens, CVS, etc.) carry 91% isopropyl, which is good enough (what I use).

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