[]|[ GorE]

Hi,
i am not able to hear sine tones below 40Hz at an appreciably volume on my cmoy with gain of 3.
I can hear them without the cmoy.

Currently using 0.1uF polypropylene capacitors for the cmoy input.
What other values do you suggest ?

Thanks,
Sushant Gore.

 

[ericj]

0.22 should be plenty. 0.33 or 0.47 are popular

 

[morsel]

ƒ = 1/2πRC will tell you the -3dB point for your amp. If you are serious about bass response, then either a large input cap of 1µF or more, or no input cap at all is your best bet.

 

[rickcr42]

Always remember folks,the low cut point of the R/C high-pass filter formula is not where the slope will be flat but where it will be -3dB below the overall signal.
That is why the formulas all us F3 as the operative word so if you choose a cap for an F3 of 20 hz it will have a response 3dB down at 20hz,1.5 dB down at 40hz and 0.75 db down at 80hz !!!!!!!!

I try to shoot for an F3 in the 5-15 hz range which still has an effect in the low bass but not one you will actually hear using headphones and that is the important part.not the graph but what is or is not audible

 

[]|[ GorE]

Hey,
Just attached a 0.47uF polypropylene cap. to teh inputs and the bass has reduced evern more in extension and volume.

Whats up ? Shoukd i use the 0.22uf cap now ?

 

[ericj]

This doesn't make any sense.

What value is R2?

 

[]|[ GorE]

R2 is 100K.R5 is 100 Ohms.

 

[ericj]

Quote:

Originally Posted by ]|[ GorE R2 is 100K.R5 is 100 Ohms.

Well, here's the thing. Unless you've got the wrong resistor in R2, or something is just plain hooked up wrong, you should have plenty of bass.

The a47 i use at work has a 110k R2 and .33uf input caps, and i can actually hear subsonic noise sometimes. Which is rather deafening through the DT-770 Pro's.

Maybe you should double check your resistors.

 

[guzzler]

Do remember you're trying to compare two different sounds in a subjective manner with a long gap in between listening. Regardless of your R value, you shouldn't have measured a low frequency drop with a larger capacitor. As eric says, something is wrong here!

 

[rickcr42]

Sounds like a mis-wired pot where instead of the capacitor seeing a stable resistance it is seeing a varying resistance as a the classic R/C tone control but with all cut instead of a boost/cut mode which makes sense considering the single capacitor

 

[]|[ GorE]

thanks for the replies.Will recheck everything