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Cmoy: What makes Panasonic EVJ/ ALPS so appealing for audio amps ? Why can't I use a panel mount... - Page 2

post #16 of 30
9/21/10 at 3:02pm
Thread Starter 
Quote:
Originally Posted by Avro_Arrow View Post

The trade-off is noise.

 

The volume pot attenuates noise from the source and provides a low

impedance path for noise at op amp inputs. To minimize noise you always

want your sources to be at high levels and the volume is controlled at the

last component.

You most certainly can design the amp with no volume control, I have several

examples in my design thread, but you might not always want to use the amp

with a device that has it's own volume.


Makes sense. Ah, I guess I'll just have to get a knob....=p

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post #17 of 30
9/21/10 at 3:45pm
Quote:
Originally Posted by TheLaw View Post

So my question is: Why would anyone have a separate volume control on the CMoy Amp if 95% of CMoy users will most likely be using it in an application where you can easily change the volume directly from the source?

 

What benefits, if any, does having a pot directly on the amp have? I mean, if you think about it, or atleast in my opinion, I'd just crank the volume up on my iPod and not necessarily the Cmoy because, why do that when I can control everything from one device?

 

So here's one thing I've been wondering. A scenario:

 

1.) iPod connected to headphones without Cmoy Amp. Volume is Maxed out on the iPod

 

2.) iPod connected to headphones via Cmoy Amp (one that does not use a pot). Volume is Maxed out on the iPod.

 

 

Now, 2.) should be louder just by nature, right? Even though I don't have a knob/pot, it will still be louder and/or distort less or whatever, right?

 

Am I right?

 

Thanks for all the responses.

 


You can build CMoy with different gain. From unity gain (gain x 1) to gain 10 or more. Depend on feedback resistors.

If you build CMoy with unity gain, then 2.) should be the same as 1.), maybe better quality, less distorted.

If your CMoy have gain 2, then 2.) is 2 time louder e.t.c...

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post #18 of 30
9/21/10 at 3:58pm

That is pretty much correct.

Higher gains come with the penalty of higher noise.

Most people find a gain of 5 is high enough.

Try and keep you gain resistor a few hundred ohms and

your feedback resistor in the low k ohms.

My desktop headphone amp (Szekeres VE3) has a gain of .95

but can provide 150 mA of current in pure class A

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post #19 of 30
9/21/10 at 4:40pm
Thread Starter 

This talk of "gain" confuses me. Google here I come.

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post #20 of 30
9/21/10 at 5:17pm
Thread Starter 

Again Mouser decides not to stock any one of the pots suggested.

 

I found this dual gang pot that is supposed to be "for audio".

 

 

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post #21 of 30
9/21/10 at 5:23pm

you can think of gain as just a multiplier for loudness. take your default signal. throw it through an amplifier with a gain of 2, it comes out the other end twice as loud.


 

Quote:
Originally Posted by tangent View Post


 

Knobs are nice.


best explanation ever.

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post #22 of 30
9/21/10 at 5:30pm
Thread Starter 

I understand what gain is but it gets a little bit confusing. Hehe...

 

Any ideas on that pot? I don't want a real piece of crap though I think its quite good.

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post #23 of 30
9/21/10 at 5:37pm

That pot is linear and not suitable, you need a log pot

 

cheers

FRED

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post #24 of 30
9/21/10 at 5:40pm
Thread Starter 
Quote:
Originally Posted by Fred_fred2004 View Post

That pot is linear and not suitable, you need a log pot

 

cheers

FRED


I just saw that............................dot dot dot

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post #25 of 30
9/21/10 at 5:59pm
Thread Starter 

So I guess I'll go with one of Alps after all. But just as a final question. What are anyone's opinions on slide pots? Like the ones supposed to be used for audio? I think that would make it looks a bit classy. =)

 

And the low wattage ratings doesn't affect anything?


Edited by TheLaw - 9/21/10 at 6:02pm
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post #26 of 30
9/21/10 at 6:08pm

It would be a real pig to fit into an Altoids tin

 

cheers

FRED

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post #27 of 30
9/21/10 at 6:12pm
Thread Starter 

Ah true...Okay I guess RK097 it is.

 

http://www.mouser.com/ProductDetail/ALPS/RK09712200MC/?qs=fQ8kcZGzY5Wzud3OJDlECg%3d%3d

 

This should be alright I guess.

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post #28 of 30
9/21/10 at 6:18pm

This is the pot you want...but it is out of stock.

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post #29 of 30
9/21/10 at 6:19pm


That will work too...

Quote:
Originally Posted by TheLaw View Post

Ah true...Okay I guess RK097 it is.

 

http://www.mouser.com/ProductDetail/ALPS/RK09712200MC/?qs=fQ8kcZGzY5Wzud3OJDlECg%3d%3d

 

This should be alright I guess.

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post #30 of 30
9/21/10 at 7:03pm
Thread Starter 

http://ca.mouser.com/Search/ProductDetail.aspx?R=RK0971221Z05virtualkey68800000virtualkey688-RK0971221Z05

 

Or this one I guess.

 

It has a switch on it? I don't quite understand that...Like there is a physical off position?

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