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To Dig or not to dig, that is the question

DonH56

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Where are the spurs coming from in the analog (analogue) implementation? Noise, clock, power, ???
 

solderdude

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I guessed wrong too :confused:
The pot picked up some noise, possibly due to longer wires or slightly different connection on the PCB.

In either case... I am not worried about anything at -90dB :cool:
 

Krunok

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Funny enough my analogue pot seem quitest when on full volume . You can hear a reduction Of hiss at the tweeter. With ear right up to it nothing audible at MLP.

Well implemented digital attenuation to me would be preferable. On my to-do list.

Nah.. if it ain't broken, don't fix it. Better buy some good booze with that money instead. :D
 

DonH56

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At -140dB it could as well be a Super Nova at the far end of our galaxy. :D

Fortunately my current job does not need such huge dynamic range. However, most of my career focused on systems ultimately achieving SFDR from 120 to 180 dB or so, thus I am always curious when I see discrete spurs like that. Do I think it matters? No, just curious as to the source. Don't appear to directly correlate to IMD or image folding but I did not try to figure out exactly where they lie.
 

Krunok

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Fortunately my current job does not need such huge dynamic range. However, most of my career focused on systems ultimately achieving SFDR from 120 to 180 dB or so, thus I am always curious when I see discrete spurs like that. Do I think it matters? No, just curious as to the source. Don't appear to directly correlate to IMD or image folding but I did not try to figure out exactly where they lie.

As it sings on 8 and 16khz I would put my money it is USB packet noise. I wouldn't put a lot of money on it, though.. :)
 

RayDunzl

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A is digital and B is analogue.

I guessed right - the little noise spike in there made me pick (guess) it. More parts/cables more (not much) noise.

I tried overlaying the A and B graphs looking for inconsistencies in the levels, but drew no conclusion there.

Two overlays of each:

1546190341405.png
 

RayDunzl

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At -140dB it could as well be a Super Nova at the far end of our galaxy.

No no no...

The Shoutometer lists -140db someplace between someone shouting at you from 1 meter from a little closer than Chicago to Perth.

Light years start at -318dB, other side of the galaxy is about -400dB, on my personal extended version (-520dB to the edge of the visible universe)
 

Krunok

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No no no...

The Shoutometer lists -140db someplace between someone shouting at you from 1 meter from a little closer than Chicago to Perth.

Light years start at -318dB, other side of the galaxy is about -400dB, on my personal extended version (-520dB to the edge of the visible universe)

LOOL :D :D :D

This Shoutometer thing is so cool&fun to me! :D
 

rebbiputzmaker

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This is just a excise in curiosity, no claim here it would prove definitive in fact the opposite has been expressed from the start.

And it seems you guessed wrong, don't worry you will recover.
People do recover from laughter.
 

JustMe

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I realize this is old, but its interesting since i'm doing some experimenting here right now. The ALPS POT is clear. But what is the alternative?

Is it digital control as the words say (manipulation of a digital stream, with or without premature truncation)?

Or a chip-based digitally controlled stepped attenuator (which is dicey, but in fact very analog)? e.g.: MAXIM/Dallas etc.?

For the record I've done a number of both measurements and semi-controlled listening tests with various subjects -- and have some very definite opinions (that's I'll keep to myself until I'm done or asked about specifics....).

And yes, of course, tacking is MUCH better with the chips.

TIA,

JustMe
 
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