Headphone potentiometer
Oct 6, 2009 at 5:29 AM Thread Starter Post #1 of 19

zigo

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Hi
when my source is computer I plug directly the headphone in the analog output of an RME digi 96/8 PAD ( ~9,5V, 75 Ohm) and I use the software fader to regulate the volume.
But I read that attenuate the volume using software degrades the signal reducing the bits.

My can is 40 Ohm.

I was thinking to a passive potentiometer (attenuator) to put between the output and the headphone and use the maximum output volume of RME, because in this way the signal doesn't suffer degradation.
But I don't think that usual stereo potentiometer can work correctly, because they are kOhms impedance (20...100 or more).
Am I right?

My purpose is to have a very good signal, then I'm looking for a very good solution, not objects who downgrade the sound. And I don't want to use preamplifiers or amplifiers, because I want that the signal remains original.

What can I use?

TIA

Rob
 
Oct 6, 2009 at 11:48 AM Post #2 of 19

ford2

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Did you know that if you click in the box around the sliders that you can control volume with the scrawl wheel.
Fantastic card I use one myself,in fact I am now running my phones direct from it rather than using my amp.
Other's might jump in here,but I think that it increases the bits before throwing any away so no problems.
Very sweet sounding card,more than a match for a lot of dac/amp combinations out there.
 
Oct 7, 2009 at 4:44 AM Post #3 of 19

zigo

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Hello Ford, thanks for your reply.

Do you mean this http://www.soundonsound.com/sos/feb0...96screen.l.gif volume control?
What I know is that the software attenuatuator works on the digital signal and this usually downgrades the quality. About ALL the DACs with an attenuator work on the digital signal.
(One of the few who doesn't is the benchmark dac1 pre, not the standard).

This is the reason because I'm looking for something to attenuate the analog signal.
I think the digi pad excellent for headphones, the output is about perfect for it and doesn't need an headamp. The sound is neutral, detailed, with a flat "professional" frequency response.IMHO.
 
Oct 7, 2009 at 11:02 AM Post #5 of 19

ford2

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The article below is one of the best explanation's that I have encountered.
I think it will answer all of your concerns.


I'm tired of hearing people complain about digital volume controls stripping off bits. Of course, it happens--there's no way around the fact that with every 6dB of attenuation you lose a bit. Most players w/ digital volume controls upsample to 24 bits so you can attenuate 48dB by the time you're back down to 16 bits. Theoretically, a 6dB reduction is half as loud. So basically you can decrease the volume by 99.6% without losing any of the original information.
More importantly, don't forget that you lose a LOT of quality using a potentiometer in an analog volume control--it's just that you can't measure the loss in a nice quantifiable word like a "bit." Analog volume control is extrememly expensive to do well. Why else would good preamps be so damn expensive? All they are is a big switch box and a pot. In my opinion, the best preamp is no preamp. I'll take numerical multiplication over a wiper kissing a resistor anyday.
 
Oct 7, 2009 at 1:58 PM Post #6 of 19

zigo

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Quote:

Originally Posted by ford2 /img/forum/go_quote.gif
The article below is one of the best explanation's that I have encountered.
I think it will answer all of your concerns.



It's clear.
But who is the auctor? Do you have the link to this article?
What I know is that there are a lot of analog pots who have a pretty flat frequency response.
And exist resistive attenuators who mantain input impedance = to output imp.

Then I would like understand ... if I upscale before and then downscale, the result is like the "original"? I doubt it.
 
Oct 8, 2009 at 12:11 AM Post #7 of 19

ford2

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I suggest you post these questions over on Hydrogenaudio forums,you should end up with a heap of responses that will confuse you even more.

What matters the most is to enjoy the sound.I can pick NO variation in SQ using my amps volume control and the digi control.
The reason I went back direct to the card was I did not like the colouration that the amp was making to the signal.
All amps add there own signatures to the signal so its never going to be original anyway.
 
Oct 8, 2009 at 6:22 AM Post #8 of 19

zigo

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Quote:

Originally Posted by ford2 /img/forum/go_quote.gif
The reason I went back direct to the card was I did not like the colouration that the amp was making to the signal.
All amps add there own signatures to the signal so its never going to be original anyway.



It's exactly the reason because I'm doing the same...but it seems very difficult to find a simple passive potentiometer or rheostat who didn't change the impedance and who works 40/50 Ohm.
Btw thanks for your suggestions.
 
Oct 8, 2009 at 9:57 AM Post #9 of 19

ford2

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Quote:

Originally Posted by zigo /img/forum/go_quote.gif
It's exactly the reason because I'm doing the same...but it seems very difficult to find a simple passive potentiometer or rheostat who didn't change the impedance and who works 40/50 Ohm.
Btw thanks for your suggestions.



Do not forget that the digi is an amp,adding its own colour to the signal.
 
Oct 8, 2009 at 10:07 AM Post #10 of 19

zigo

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Quote:

Originally Posted by ford2 /img/forum/go_quote.gif
Do not forget that the digi is an amp,adding its own colour to the signal.


Really?
biggrin.gif

And it use a D to A convertor, who adds his proper color too. And then there is a cable between digi and the can, who adds his color too.
...and don't talk about capacitors, resistors, etc...
Even if you solder bad 2 components you introduce "color" and depending by what you use to solder you can introduce "color".

This is the reason because I like introduce few, simple and passive components. But ever analog components.
 
Oct 16, 2009 at 5:43 PM Post #12 of 19

zigo

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Quote:

Originally Posted by Quaddy /img/forum/go_quote.gif
smpro inano is good passive physical knob solution


Tankyou VERY much!
It seems exactly what I'm looking for.
Do you know if and how it modifies the impedance?
 
Oct 16, 2009 at 5:52 PM Post #13 of 19

Quaddy

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as far as i can tell it doesnt, its completely passive, meaning impedance characteristics arent touched.
smile_phones.gif
Quote:

Originally Posted by zigo /img/forum/go_quote.gif
Tankyou VERY much!
It seems exactly what I'm looking for.
Do you know if and how it modifies the impedance?



p.s. i have a spare one i could sell, i dont know where you are located though. i am in UK
 
Oct 17, 2009 at 11:14 AM Post #14 of 19

zigo

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Quote:

Originally Posted by Quaddy /img/forum/go_quote.gif
as far as i can tell it doesnt, its completely passive, meaning impedance characteristics arent touched.
smile_phones.gif

though. i am in UK



well, the fact that a component is totally passive doesn't mean that the impedance is not touched. To modify the impedance usually are used resistors, who are totally passives. Talking about potentiometers the Alps, the more used in preamplifiers, modify the impedance from >100 Ohms to 20,000 - 100,000 or more Ohms and they are totally passives.
I emailed to the italian importers (I'm from Italy) about that. Let's see in next days if they will reply me, or I will write directly to the producer.
If this object modify the impedance is important, because depending by that the result can be a lot different in term of audio quality.
About your offer I will contact you in PM.
thanks
 
Oct 17, 2009 at 11:33 AM Post #15 of 19

Quaddy

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in this instance, passive, and the inano means it has no impedance affectation. there are no resistors, transistors, no active circuitry, battery or PSU in the unit at all, just an A5K attenuator and mechanical mute.

but obviously, wait for the official word, for peace of mind.

regards.
 

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