Differences in sound: DAC vs. DAC + Pre-amplifier

[sandyk]

1 hour ago, barrows said:

Class A/B amplifiers have been equalling or outperforming class A for a long time now.  

 

  A better than average Class A/B amplifier may sometimes equal a typical Class A amplifier in performance, but a well designed Class A amplifier  will still outperform it.

 

A quote from Douglas Self in Audio Power Amplifier Design Handbook 5th ed - D. Self (Focal, 2009)

Quote

Class-AB
This is not really a separate class of its own, but a combination of A and B. If an amplifier is biased
into Class-B, and then the bias further increased, it will enter AB. For outputs below a certain level
both output devices conduct, and operation is Class-A. At higher levels, one device will be turned
completely off as the other provides more current, and the distortion jumps upward at this point as
AB action begins. Each device will conduct between 50% and 100% of the time, depending on the
degree of excess bias and the output level.
Class-AB is less linear than either A or B, and in my view its only legitimate use is as a fallback
mode to allow Class-A amplifiers to continue working reasonably when faced with a low-load
impedance.
Class-B
Class-B is by far the most popular mode of operation, and probably more than 99% of the amplifi ers
currently made are of this type. Most of this book is devoted to it. My definition of Class-B is that
unique amount of bias voltage which causes the conduction of the two output devices to overlap
with the greatest smoothness and so generate the minimum possible amount of crossover distortion.

 

[sandyk]

1 hour ago, Audiophile Neuroscience said:

sandyk how many watts is your class A amp?

 Hi David

 My Class A Amplifier is 15W/Ch into 8 ohms, and >30W Channel in Class B,(which is better than Class AB) into 4 ohms, in which case it remains in pure Class A until around 7.5W.

 It dissipates around 80W of heat at a Bias of 1Amp, and due to the size of the 2 side heatsinks it doesn't get too hot for my cat to sleep on top of in Winter.

 I have never been able to use it at full power in a typical sized room of a modest sized house,( e.g. a converted double bedroom)  but it would obviously be too low a power for high level sound output use in much larger dwellings.

 With TV Audio for example, a typical output level is around 1W

 

Regards

Alex

 

[sandyk]

1 hour ago, Audiophile Neuroscience said:

I do like the Nelson Pass but for me they have a slightly warm signature overall, unlike for example Gryphon.

 

 I noticed that too.

They probably use MOS FET output stages, or FET input stages.

Perhaps both ?

[sandyk]

14 minutes ago, kennyb123 said:

I previously owned a Spectral DMC-30S preamp, which retailed for about $6.5K back in the day.  Bypassing it to run my previous Chord Hugo TT directly into my Spectral amp brought a significant improvement - particularly in the area of transparency.  I mentioned the preamp's price only to indicate that it wasn't a slouch.  Despite that, the simpler path was the better path for sure.  I think Rob Watts' design plays a big part in that as there isn't a separate gain stage - the output voltage is coming directly off the DAC.  Such details will have a lot to do with whether one prefers using a preamp or not. 

 

 

In all fairness, don't forget that your Chord Hugo TT retailed at around 3,000 Quid back in 2015 . Your Spectral DMC-30S was from way back in 2003, and there would have been many advances since then.

[sandyk]

1 hour ago, TAS said:

Has anyone used the Uptone Audio Iso Regen to "condition" their USB-to-DAC signal?  If so, how did it sound?  Thanks in advance.

 

 

[sandyk]

3 hours ago, GUTB said:

If you want best sound, you're putting a tube pre in front, THE END.

 Sorry, but to put it bluntly :

B******T !!!

 

 Both WELL ENGINEERED SS and Hollow State can sound almost identical in most respects, however the vast majority of Tube Preamps are chosen mainly for one reason, which is to "improve"  cold and clinical sounding Digital sources, which these days do not have to sound that way.

 It's poorly implemented Digital technology that causes this.

 

It's laughable that so many will spend 10 or more times on the Vinyl side than on the digital side and then  rave about how much better analogue sounds .

[sandyk]

18 minutes ago, Allan F said:

 

The equivalent can be said of those who extol the virtues of digital with their high-end five figure DACs and music servers.

Perhaps, but most don't boast about how much better they sound than Vinyl.

[sandyk]

1 hour ago, ecwl said:

So you can imagine as you reduce the digital volume, even if mathematically your digital audio signal is accurately reduced, the DAC simply cannot accurately recreate the low-level analog signals because of the poor linearity. Of course, playing the DAC at full power and then using a good analog preamp to lower the volume level would mask the low-level nonlinearity issue.

Nevertheless, it still comes down to how electrically quiet the source device is, and this will also apply  with conversions to DSD.

If you doubt this, and are using a Desktop PC try doing what one and a half (Gary) is recommending here.

https://audiophilestyle.com/forums/topic/60381-hdd-to-case-bonding-uptick-in-sq/?tab=comments#comment-1084599

 It won't cost much at all to at least try it.😉

 

[sandyk]

27 minutes ago, ecwl said:

But I don’t think introducing a high-end desktop PC with no noise injected into the DAC is going to suddenly make a DAC hardware with low poor low-level linearity into a DAC with great low-level linearity.

 That is not what I said, or inferred  !

It doesn't matter which type of output you use, especially USB, but crap from the front end will still go along with the Binary Data signal.

How much affect it has depends on the noise rejection of the DAC itself. NO affordable DACs are perfect in this respect, or we wouldn't still need ISO Regens with low noise external power , or expensive aftermarket boutique USB cables, even though we may be converting to DSD .

John Swenson has even reported that motherboard PWM controlled fans cause a degree of SQ degradation, which is why he designed the linear controller for the Mac Mini