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DIY cmoy is too loud. Help please

post #1 of 13
Thread Starter 

Firstly, sorry if there are already threads like this, i can't find them.

 

I've just finished a cMoy BB DIY kit

http://www.ebay.com/itm/190742044923?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

But the sound is too loud for my low impedance headphones. How can I reduce this loudness while preserving the same sound quality?

Will increasing the potentiometer halp?

 

Thanks

post #2 of 13
Quote:
How can I reduce this loudness while preserving the same sound quality?

Changing a couple of resistors will lower the gain but telling you which resistors to change is rather difficult without a schematic or close up pics of the PCB.

Ask the seller.... 

 

 

Quote:

Will increasing the potentiometer halp?

No.

post #3 of 13
Thread Starter 

Here you are...

700

post #4 of 13
Thread Starter 

If i'm not wrong, I should change R11 and R15, shouldn't I? If yes, how much R should I use?

post #5 of 13

You can change either R12/R16 or R11/R15.

 

http://tangentsoft.net/audio/calc.html

 

R13/R16 translate to R4 on Tangent's gain calculator.

R11/R15 translate to R3 on Tangent's gain calculator.

 

Here's a calculator to give you an idea how changing the gain effects the bass boost:

 

http://tangentsoft.net/audio/ppa/amp/calc.html

 

(R7 = 33K, C7 = .068uF)

post #6 of 13
Thread Starter 

Thanks a lot. I will check it out
 

post #7 of 13
Thread Starter 

Do you mean "R12/R16 translate to R4 on Tangent's gain calculator."?

post #8 of 13

Yep. Some day will have to fix that short circuit between the brain and the fingers. tongue.gif

post #9 of 13
Thread Starter 

hahahaha.....

 

I think I understand the circuit now.

So, now, my gain is G = R4/R3 + 1 = 10K/1.5K +1 = 7.67
with fc = 255 Hz, fs = 76 Hz, Boost 3.9x (12dB)

 

If I want gain = 4, I choose R3 = 3.4K and R4 = 10K(the same).

Then I can preserve fc, fs, and boost to be roughly the same. Am I wrong???

 

Do you think gain = 4 good for 16 or 32ohm headphone?

Are those fc, fs, boost good for listening to music pleasantly?

post #10 of 13
Quote:
Do you think gain = 4 good for 16 or 32ohm headphone?

I would go even lower.

2?

 

 

 

Quote:
Are those fc, fs, boost good for listening to music pleasantly?

 

It's a little  "fat" for my taste but it's what the seller chose so.....

post #11 of 13
Thread Starter 

Oh.. Thanks

 

I've just ordered some resistors for gain = 4 ,and am gonna order some more soon for gain = 2.

But... ah... why is shipping of small electronics parts so expensive? I wish there was an electronics store next to my apartment. - * -
 

post #12 of 13

Hi

Why didn't you ask me?

 

I have no problem sending you a couple of resistors :-)

 

trust me I have spares

 

cheers

FRED

post #13 of 13
Thread Starter 

Sorry for late reply.

 

That will be greatest service ever. :)
Next time I'll ask you then

 

Thanks

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