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Why do NOS dacs sound different to oversampling designs?

MC_RME

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They used a filter with flat frequency response for the default. Also, the data that they provide in the manual is for 44.1k sample rate. A lot of people stream at much higher rates, and this filter many not be the best at higher rates. Don't know, just guessing.

It should be obvious that at higher sample rates no compensation filter is needed anymore.
 

orangejello

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Have a closer look to an 'impulse' in music or a crescendo or sudden loud noise in any editing software.
You will see that such an 'impulse' spans multiple samples.
With a NOS DAC that impulse becomes 'jagged' and has extremely poor timing characteristics because it rises and drops at the wrong moment and stepped and too steep.
.

Do you think that is also true with the RME using the Super Slow (NOS) filter?
 

solderdude

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Yes, the NOS filter is an emulation of a filterless NOS DAC so it performs as 'well' as real filterless NOS DAC (well perhaps slightly better as the 'step' voltages are more accurate)

When the samplerate is 192kHz there are much less 'problems' (aside from some very high mirror images etc) and filterless NOS operation is nearly as good as a properly filtered DAC. There are no real benefits for filterless DAC's but it is what people seem to want so manufacturers cater for it.
Such a setting would possibly be one more reason to buy such a DAC and experiment with it.

One thing is for sure the RME is a fantastic DAC and would recommend to use it on its most optimal settings unless you want some 'flavor' that the filter settings can provide.
 
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sajunky

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What is a cheap example of this this type of DAC should I be inclined to get one?
I just ordered this: Nobsound Mini HiFi Sound Card DAC TDA1387 USB 8X Audio Decoding Headphone Amplifier
My last DAC I had for years was based on heavily tuned BB PCM63, now is lost and I can't listen to delta-sigma things for long. I will see what I can get from this, maybe later modify it to accept higher sampling rates or buy a new one with better specs. It should arrive in about two months.
 

rwortman

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With the exception of Gordon Holt, who even titled his article, "Run Right Out." He liked the same aspects I did- pitch stability, neutral tonality, and low noise.
I liked that part but something about the sound bothered me. I bought one after the price came down a bit but I always thought my vinyl sounded better until I bought my second one in the late 90's.
 

solderdude

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One could ask themselves why
A: the TDA387 chips are dumped on the market and picked up by DIY and cheap Chinese DAC manufacturers.
B: These chips are/were not used in any serious DACs and CDP's.
C: Why these days paralleling is the rage.
D: Why the chip design is about 25 years old.
E: Why the specifications are mediocre at best and then are only valid at 192kHz (meaning they are worse at lower bitrates).
F: Why the datasheet specifically mentioned 2, 4 and 8 times oversampling.
G: Why this chip is designed for portable equipment and wasn't used in more expensive desktop equipment back in the days.
H: Why there are only testimonials and no measurements shown anywhere.
I: Why R2R DAC chips are normally fed via digital filters, yet cheap DAC manufacturers and DIY decided it is a good thing to leave them out.
 
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mansr

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One could ask themselves why
A: the TDA387 chips are dumped on the market and picked up by DIY and cheap Chinese DAC manufacturers.
B: These chips are/were not used in any serious DACs and CDP's.
C: Why these days paralleling is the rage.
D: Why the chip design is about 25 years old.
E: Why the specifications are mediocre at best and then are only valid at 192kHz (meaning they are worse at lower bitrates).
F: Why the datasheet specifically mentioned 2, 4 and 8 times oversampling.
G: Why this chip is designed for portable equipment and wasn't used in more expensive desktop equipment back in the days.
H: Why there are only testimonials and no measurements shown anywhere.
I: Why R2R DAC chips are normally fed via digital filters, yet cheap DAC manufacturers and DIY decided it is a good thing to leave them out.
Most of those can be answered with a single word: ignorance.
 

sajunky

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One could ask themselves why
A: the TDA387 chips are dumped on the market and picked up by DIY and cheap Chinese DAC manufacturers.
B: These chips are/were not used in any serious DACs and CDP's.
C: Why these days paralleling is the rage.
D: Why the chip design is about 25 years old.
E: Why the specifications are mediocre at best and then are only valid at 192kHz (meaning they are worse at lower bitrates).
F: Why the datasheet specifically mentioned 2, 4 and 8 times oversampling.
G: Why this chip is designed for portable equipment and wasn't used in more expensive desktop equipment back in the days.
H: Why there are only testimonials and no measurements shown anywhere.
I: Why R2R DAC chips are normally fed via digital filters, yet cheap DAC manufacturers and DIY decided it is a good thing to leave them out.
A: Possibly recycled from Sound Blaster AWE cards, they were sold in millions - I don't mind.

B: Probably the same as with TDA1541/5. Expensive to stack many chips in parallel, Denon was the only one example I know. However these chips has created many DIY projects. TDA1387 was the last design in series, it didn't create DIY interest. It probably come late, as market was taken by inexpensive four-bit delta-sigma modulators (same design as all current). From my experience single-bit delta-sigma converters sounded totaly crap, so I settled for PCM63. The current design sounds better, but is fatiguing. The another factor is that LSB portion of the current source was self-calibrating. It didn't create audiophiles confidence for true 16-bit resolution, but no-one took an effort to prove allegations.

C: There is a technical reason for this (actually two). Now we've got flood of cheap DACs (see A), so why don't use more? Not a new concept, Denon is an example (16 chips), I don't remember model number. PCM63 was paralleling too, for a cost of $xxxx

D: Pass.

E: That is for TDA1543. TDA 1387 is improved to 256kHz I think. Why no more? See D:

F: The same as my PCM63 based DAC. It it does matter to you.

G: Denon?

H: Business? R2R DACs do not meassure well, but they sound better.

I: R2R DAC chips do not have built-in digital filter, so designers have an option. I don't comment whether it is good or wrong, it is a topic for another debate. Delta-sigma modulators come with built-in digital filters and free plug-in libraries.
 

sajunky

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Evidence for that remarkable assertion?
I can listen for many hours without a fatigue. The same when playing old records.

With Delta Sigma DACs it sounds good only for the first 30 minutes. After a longer time I stop perceive details, become tired. I am getting old now, I understand my brain has a limiting processing power, but it was exactly the same 20 years ago when I decided to pay more for the PCM63 based DAC.
 

solderdude

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A: Possibly recycled from Sound Blaster AWE cards, they were sold in millions - I don't mind.

source of info ?

B: The current design sounds better, but is fatiguing.
Is there proof for this other than anecdotal and sighted listening tests ?

The another factor is that LSB portion of the current source was self-calibrating.

It's the tolerance of the MSB that is problematic, not the LSB.
It's the MSB that is monitored and adjusted.

C: There is a technical reason for this (actually two). Now we've got flood of cheap DACs (see A), so why don't use more? Not a new concept, Denon is an example (16 chips), I don't remember model number. PCM63 was paralleling too, for a cost of $xxxx

The reasons are higher output current so less noise and errors getting smaller due to averaging.
Avergaing could be beneficial because errors get smaller.
The 'hype' however is because it is supposed to sound better. Which of course is found 'sighted'.
Is there compelling evidence showing a noticeable improvement in THD ?

E: That is for TDA1543. TDA 1387 is improved to 256kHz I think.

Specs are given at 192kHz as mentioned in the sata sheet. Both TDA1543 and TDA1387 are intended to be used oversampled.
They specified it this way because 44.1 would not look great nor was it designed for that.

G: Denon?

type ?

H: Business? R2R DACs do not meassure well, but they sound better.

Why would that be the case and which research supports this ?

I don't comment whether it is good or wrong, it is a topic for another debate.

THIS debate perhaps ?
 

SIY

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I can listen for many hours without a fatigue. The same when playing old records.

With Delta Sigma DACs it sounds good only for the first 30 minutes. After a longer time I stop perceive details, become tired. I am getting old now, I understand my brain has a limiting processing power, but it was exactly the same 20 years ago when I decided to pay more for the PCM63 based DAC.

OK, so no evidence. Sighted listening and anecdote are completely unreliable for evaluation, a point that's been beaten to death.
 

THW

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i’d think the solution would be to pick less fatiguing music, not to take a step backwards and pick something that is measurably inferior.

my $0.02.
 

Jim777

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Don't know about NOS dacs sounding "better", but the RME has a NOS filter which sounds the best to me out of the five that AKM 4490 provides. According to the RME manual this is the only filter that has essentially perfect impulse response.
It's nice that we have a choice, my favorite happens to be the default SD Sharp. You get the best of both worlds, the flat frequency response, and sharp onsets that you're expecting from NOS. It's minimum phase or at least low latency, so no pre-ringing. But to be honest, I don't think I could reliably detect SD vs non-SD.
 

SIY

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This is a life. A life is an evidence.

I saw that in a fortune cookie once.

Unfortunately, fortune cookie philosophy fails as evidence for technical assertions.
 

sajunky

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i’d think the solution would be to pick less fatiguing music, not to take a step backwards and pick something that is measurably inferior.

my $0.02.
I don't mind derogatory comments. :p It shows your sucking attidude and complete lack understanding of physics.

The most fatiguing is a complex music. A single vocal, leading instruments like piano, guitar is not (but is losing details over the time). Calvyn Harris is not - there is no much to process from square waves. But complex harmonics like those created by choir or symphonic orchestra is.
 
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