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gradier

Does a DAC need a pre-amp

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9 hours ago, Ralf11 said:

I'm not understanding how mechanical speed variation in reading bits off a CD would affect SQ.  Shouldn't the buffers handle this?

Of course they should, and they do. Every CD player has to have at least a small buffer for the CIRC decoding. The decoded bits are clocked out using a crystal oscillator. Feedback from the buffering system regulates the CLV servo that spins the disc. The portable CD players that used to be popular would buffer several seconds of audio, allowing them to recover even if shaken badly enough that tracking was lost.

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9 hours ago, esldude said:

From your usage, I don't think dither means what you think it means.  Jittered maybe is what you have in mind?

hmm, perhaps not. Dither = "white noise" is not what I was intending to describe. Jitter is probably an inexact term also in that superimposed vibrations aren't random, have 1 or more component frequencies. 


Regards,

Dave

 

Audio system

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Except quality toslink cables sound better than cheap ones. I can validate that phenomena right now with my Supra vs Monoprice cable.

 

Wether its because of jitter induced by internal reflections or self-noise generated by the reciever cleaning it up, quality of transmission even over toslink still matters.

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8 hours ago, GUTB said:

 

You say that with a complete lack of irony, don’t you?

 

He says it because it's true. You seem to misunderstand almost all the technical underpinnings of this hobby. I shudder as to what your setup sounds like. 

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7 hours ago, GUTB said:

 

I think the Mytek uses digital volume control of the Sabre and doesn’t have an analog mode.

 

I rest my case....

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11 minutes ago, plissken said:

 

He says it because it's true. You seem to misunderstand almost all the technical underpinnings of this hobby. I shudder as to what your setup sounds like. 

 

I understand them to a greater degree than you at least who seems more interested in class warfare.

 

You have more limited means...or you don’t place a high priority on sound. Either way, you’ve chosen to spread misinformation about audio. You have an audience for that amongst the non-audiophiles here but don’t be put out if I show up every once in a while to hit it with reality.

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10 minutes ago, GUTB said:

 

I understand them to a greater degree than you at least who seems more interested in class warfare.

 

You have more limited means...or you don’t place a high priority on sound. Either way, you’ve chosen to spread misinformation about audio. You have an audience for that amongst the non-audiophiles here but don’t be put out if I show up every once in a while to hit it with reality.

 

You couldn't keep up with me on your best day...

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3 hours ago, davide256 said:

hmm, perhaps not. Dither = "white noise" is not what I was intending to describe. Jitter is probably an inexact term also in that superimposed vibrations aren't random, have 1 or more component frequencies. 

Dither in terms of digital audio has a specific meaning. So it doesn't help to use the term in some other poorly defined way. Jitter applies to timing errors which may or may not be random. So what did you mean?


And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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21 hours ago, GUTB said:

 

Have you tried a preamp that costs more than $50?

My last preamp (still owned, and gets occasional use) was a Pass Aleph P. It did cost (ahem...) more than $50. Chosen at the time based on listening comparisons with other top preamps, using a pair of Rowland Ones (ditto), with a Wadia DAC that let me by pass a preamp altogether. It was the most transparent, and added the gain necessary for that system. 

 

Current Dac is a Buffalo, with heavily modded Legato output. I feed a pair of The Wire amps, with the gain structure built to give me a volume I want with quiet recordings (i.e., plenty loud with most). The difference between having a preamp in line v. Going straight from DAC to amps is not subtle. 

 

This is is not a yes or no question—it's going to depend on the specific DAC, the specific amp, and possibly the speakers. For many, a preamp will improve the sound, but for some, it just adds additional veiling and noise.

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2 hours ago, pooger said:

My last preamp (still owned, and gets occasional use) was a Pass Aleph P. It did cost (ahem...) more than $50. Chosen at the time based on listening comparisons with other top preamps, using a pair of Rowland Ones (ditto), with a Wadia DAC that let me by pass a preamp altogether. It was the most transparent, and added the gain necessary for that system. 

 

Current Dac is a Buffalo, with heavily modded Legato output. I feed a pair of The Wire amps, with the gain structure built to give me a volume I want with quiet recordings (i.e., plenty loud with most). The difference between having a preamp in line v. Going straight from DAC to amps is not subtle. 

 

This is is not a yes or no question—it's going to depend on the specific DAC, the specific amp, and possibly the speakers. For many, a preamp will improve the sound, but for some, it just adds additional veiling and noise.

 

Agreed, as everything in life....it depends....

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20 minutes ago, beerandmusic said:

 

Agreed, as everything in life....it depends....

 

No it doesn't depend. There's certain things that should be matched correctly. But generally speaking, better speakers are better speakers, better amps are just better amps, and so on.

 

For example, Magicos are better than Magnepans. 

 

Pass is better then Adcom.

 

Ayre is better than Logitech.

 

Nordost is better than Blue Jeans.

 

Etc and so on.

 

If a VAC Reference stack was dropped in beside your NuPrimes, Adcoms, Onkyos, Yamahas, etc, 10 out 10 of you guys world prefer the VACs.

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7 hours ago, mansr said:

That's not what a digital potentiometer is. A digital potentiometer is simply a digitally controlled variable resistor. Here's an example of one: http://www.analog.com/en/products/digital-to-analog-converters/digital-potentiometers/ad5142a.html

 

Indeed? Never thought of that! Never mind my criticism. The only digital volume control of which I've ever heard uses an ADC and then a multi step volume control which works in the digital domain, and then requires the digital signal to be returned to the analog mode via a DAC. Not a great high-end audio solution in my estimation. However the one you describe should be fine.


George

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Just now, gmgraves said:

Indeed? Never thought of that! Never mind my criticism. The only digital volume control of which I've ever heard uses an ADC and then a multi step volume control which works in the digital domain, and then requires the digital signal to be returned to the analog mode via a DAC. Not a great high-end audio solution in my estimation. However the one you describe should be fine.

There are also devices like this one: http://www.ti.com/product/pga2311

That's basically a variable resistor combined with an opamp to produce a variable-gain device with fixed input and output impedance.

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11 hours ago, Speed Racer said:

 

You start out with one argument and then pivot to one we weren't even having. You must be trying to fit angels on the head of a pin..... 

 

My good friend. I didn't start out with any argument at all! I merely stated that adding more active stages (as in a pre-amp) to an audio system adds distortion because no active electronics are distortion free. There is no such thing as Stewart Hegeman's mythical "straight wire with gain"*. I never stated nor intimated. that a system couldn't still sound better with a preamp than without one. Several times, I recall agreeing with you that I'd rather have a system with a preamp than without one. But you kept arguing with me anyway.

 

*That's not actually 100% accurate. There is a British "pre-amp" that uses a pair of  auto-transformers to provide gain, and the transformers are tapped to provide a stepped volume control. I don't remember the brand, but this device offers gain without adding noise or distortion because that's the nature of transformers. So technically, such a device could be considered a "wire with gain" if not actually a "straight" wire! Because the inputs are isolated from the output, the load to the power amp is constant. I don't really know if this theoretical advantage translates into a practical sonic advantage or not, but harmonic and IM distortion added by such a device should be , essentially, nonexistent. 


George

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Just now, mansr said:

There are also devices like this one: http://www.ti.com/product/pga2311

That's basically a variable resistor combined with an opamp to produce a variable-gain device with fixed input and output impedance.

 

Of those, I am aware. I am also aware of Voltage Controlled Amplifiers or VCAs where a DC variable control voltage is applied to an op-amp-like component which varies the "gain" of the device from passing no signal all the way to unity gain output depending on the amplitude of the voltage applied. These are used in lots of consumer grade appliances such as televisions that offer remote volume control. Performance, again, is not what I would consider worthy of a high-end audio system.


George

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36 minutes ago, GUTB said:

No it doesn't depend.

WOW, I guess everything really is debatable, when it comes to some people....but it's not my desire to debate something so obvious.

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42 minutes ago, GUTB said:

 

No it doesn't depend. There's certain things that should be matched correctly. But generally speaking, better speakers are better speakers, better amps are just better amps, and so on.

 

For example, Magicos are better than Magnepans. 

 

Pass is better then Adcom.

 

Ayre is better than Logitech.

 

Nordost is better than Blue Jeans.

 

Etc and so on.

 

If a VAC Reference stack was dropped in beside your NuPrimes, Adcoms, Onkyos, Yamahas, etc, 10 out 10 of you guys world prefer the VACs.

 

I would say that whether Magico's are better than Magnepan's would depend on which Magicos and which Magnepans. For instance, a pair of Magnepan MG-20.7s will easily outperform a pair of Magico Q1s even though the latter cost ten grand a pair more than the Magnepans. 

 

Also I would argue that Nordost and Blue Jeans are sonically and measurably equivalent. The Nordosts, being audio bling, just cost more, that's all. 

 

The notion that the level of cost = the level of quality, either aesthetically or sonically is simply not applicable when it comes to high-end audio. 

 

I wouldn't bet money on your last assertion, either! :)


George

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13 minutes ago, gmgraves said:

 

My good friend. I didn't start out with any argument at all! I merely stated that adding more active stages (as in a pre-amp) to an audio system adds distortion because no active electronics are distortion free. There is no such thing as Stewart Hegeman's mythical "straight wire with gain"*. I never stated nor intimated. that a system couldn't still sound better with a preamp than without one. Several times, I recall agreeing with you that I'd rather have a system with a preamp than without one. But you kept arguing with me anyway.

 

*That's not actually 100% accurate. There is a British "pre-amp" that uses a pair of  auto-transformers to provide gain, and the transformers are tapped to provide a stepped volume control. I don't remember the brand, but this device offers gain without adding noise or distortion because that's the nature of transformers. So technically, such a device could be considered a "wire with gain" if not actually a "straight" wire! Because the inputs are isolated from the output, the load to the power amp is constant. I don't really know if this theoretical advantage translates into a practical sonic advantage or not, but harmonic and IM distortion added by such a device should be , essentially, nonexistent. 

 

That is not accurate. I said (complete quote):

 

"My experience is that a quality active preamp sounds better than no preamp or a passive preamp."

 

You came back with:

 

"You are misinterpreting what you have experienced*." 

 

An then you went on with this:

 

"Every active stage adds distortion."

 

So you did not "merely state" that active preamps add distortion. You said I was misinterpreting what I have experienced. Since my interpretation said that "a quality active preamp sounds better than no preamp or a passive preamp", you must be saying that is not the case. That a quality active preamp does NOT sound better than no preamp or a passive preamp.

 

Own up to what you write......

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2 hours ago, mansr said:

There are also devices like this one: http://www.ti.com/product/pga2311

That's basically a variable resistor combined with an opamp to produce a variable-gain device with fixed input and output impedance.

 

I mentioned the PGA2310PA back on the previous page.

Attached is a simplified diagram from Silicon Chip magazine.
However, this device is a little different in that the gain of it's opamp is also digitally programmable.

Digitally controlled analogue attenuator..jpg


How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 28-06-2020

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2 minutes ago, sandyk said:

 

I mentioned the PGA2310PA back on the previous page.

Attached is a simplified diagram from Silicon Chip magazine.
However, this device is a little different in that the gain of it's opamp is also digitally programmable.

Digitally controlled analogue attenuator..jpg

So Alex, is that an analog control or a digital control in that context?

 

Or do we call that analogical?


And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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Just now, esldude said:

Or do we call that analogical?

 

Sounds like a good description provided that when you say it, you have a small pause between the "a" and the "l" at the beginning. :)


How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 28-06-2020

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