Why most $3000 and lower DAC’s sound almost identical

@cundare2 

Holo May KTE measures superbly

https://www.stereophile.com/content/holoaudio-may-level-3-da-processor-measurements

But then again, almost every DAC does because every designer or chip designer uses Precision Analyzers. Listeners seem to rate this DAC very highly and there seems to be a growing community of R2R proponents  since 10 years or more.
 

The sad truth is that Precision Analyzers rely on frequency analysis and large windows of analysis to achieve their precision. And a pre or post-echo will not be detected at all because it’s just time domain distortion - it’s the exact audio signal at much lower level delayed or earlier than the main signal. (A true echo and a completely different animal from pre- or post-ringing at the Gibbs single frequency tone)
 

It is NOT so much the shape of the upsampling filter (smooth etc) that affects what we hear but the equiripple added to pass-band. Anyone who thinks a very slight roll off at 15-18 KHz on a smooth filter is going to change much is mistaken. It doesn’t. What changes is the equiripple which is well audible as a pre or post echo that our hearing detects as fatiguing digital glare and makes stereoscopic interpretation (imaging/soundstage) more laborious and tiring (it’s why we tire of digital more quickly than analog)

@cundare2 

T+A, one of Europe’s ’s most highly regarded manufacturers of high-end DACs (well-known on the continent and now starting to establish a rep in the US) sells sophisticated $5-9000 dual-path DACs that process PCM with Delta-Sigma circuitry, but run DSD through an independent bespoke R2R DAC. 

T+A D200 DAC is incredible. I was wildly lucky to get one. It does have separate PCM (using a Burr Brown chip) and a discrete DS DAC that accepts DSD up to 1024. The DSD side of the DAC runs without upsampling and is the best aspect of this DAC, although PCM sounds pretty good. 
 

Another, similarly priced DAC is the Holo May KTE - this one supports DSD and NOS via an R2R DAC. It is equally highly regarded as the T+A D200. 
 

Both overcome the upsampling limitations of the short tap filters of a typical chip-based DS DAC.

As mentioned, elsewhere in this thread, not all filters in DAC chips are optimized by Parks-Mcllelan - yet this approach yields the best specs - so it’s been almost a standard approach for years. However even those filters without this design will suffer from equiripple. Even “smooth” filters have equiripple. Only NOS R2R or 1 million+ taps upsampling  (like Chord Dave) or super high precision conversion of PCM to high rate DSD on a computer (also using high number of taps) can sufficiently reduce pass-band equiripple and the echoes it generates. Only R2R can do so and not introduce latency.

@dsnyder0cnn 

Unfortunately, the ESS chips all have pass-band equiripple just like other DS upsampling chips. This results in echoes (exact copy of entire audio at lower level just like a reflection)

Ringing is not the same as echo.

Ringing is a Gibbs phenomenon and mathematically it occurs at the corner frequency of the filter - unless you can hear 21KHz (typical corner) then pre or post ringing will be inaudible anyway. In truth it should not be on any digital audio mastered file/CD because those frequencies above 20 KHz should have been filtered out prior to A to D.

The problem with any filter other than a sharp linear phase at 21KHz is that 

1) It changes the phase of high frequencies compared to low frequencies which changes the timbre.

2) any smooth filter with slow roll off can be leaky and frequencies above nyquist can get through, resulting in intermodulation distortion.

This is just from a technical perspective. Of course what sounds better to the listener trumps everything else.

@macg19 

The Burr Brown chip is my preferred Delta Sigma chip - smooth and detailed. That said it still doesn’t image quite as well as a NOS DAC. 

@kofibaffour 

Totally agree $3000 is arbitrary. What I really mean is to draw a line between chip-based DS DACs (typically under $3K and as cheap at $50) and that of R2R ladder, ring and other discrete designs (anything typically $3K and up)

@ghdprentice 

Yes - exactly what you said 100%. ‘Tend not to sound as natural” - exactly what I meant

@jrareform 

Absolutely agree the T+A D200 is outstanding, especially when fed DSD256. However it’s like $5K so although $3000 is my arbitrary price point it’s well above. The Gustard R26 is an R2R DAC and it should definitely sound more natural than the Topping D90. The D90 is the typical ESS chip-based DAC - great spec, low latency but “digital glare” or unnatural sound from the upsampling pre and post-echos.

@hilde45 

True - it’s a generalization but it is also true that upsampling Delta Sigma DACs totally dominate under $3000.

The mathematical link is a fact. The audibility is indeed system dependent and probably listener dependent. That said - there is a huge amount of anecdotal evidence for R2R sounding smoother and for files upsampled to DSD on a PC to image better.
 

Take for example rectangular box speakers with a wide 12 inch baffle. These will have post-echos arriving at the listener from the baffle edge diffraction - so this might dominate soundstage and reduce the imaging quality more than the post and pre-echos from the upsampling algorithms used on every DS-chip DAC.

And yes your comments are valid, accepted and appreciated! 

@mahler123 

Indeed there are differences due to the upsampling filters used and other designer tweaks - that said there is usually no way around the upsampling function built into these Delta Sigma chip DACs where EVERYTHING ultimately ends up converted to high rate DSD in the final stage. However, the difference between these Delta-Sigma upsampling chip DACs and a modern R2R ladder DAC or PC upsampled audio to DSD256 to a discrete DSD DAC (no chip) is in my experience much more dramatic.

 

Isn’t eliminating the “pre echo” exactly what Meridian’s apodising filters (circa 2008) were designed to eliminate? Not mitigate, eliminate - at the expense of higher artifacts on the post side. I also thought that has been largely replicated now as “minimum phase” filters in other DACs.

The Meridian apodising DACs do sound quite good to me, but then so does its old 566 - Delta Sigma chips, and way before the apodising filters. 

I’ve heard the sterile, etchy nature you cite in other DACs, and certainly, I do not like it at all! 
 

@mulveling 

Excellent point - especially about sterile etchy sound - and yes an MQA style apodizing filter might improve things but it is what I would call a Band-Aid and this is why:

The ringing you refer to above is in the time domain. It happens at the cut off frequency. It only occurs on signals that exceed the Nyquist frequency. Properly produced music should not have transients above 21 KHz. It’s actually a non issue and unnecessary. 

However, an apodizing filter will change the sound and energy distribution - so it will sound less accurate but may be arbitrarily preferred by the listener - especially on poorly produced material that has many non-musical transients at 22.05 KHz (which will ring).

$3000 is arbitrary to be the cost at which ladder-R2R and discrete DACs become available. Obviously older DACs with TDA 1461 may be found used for less than that but I am generalizing with respect to current DACs being manufactured.