A taste of the future: Analog sounding Digital amplifiers

Oh, thanks! So digital amp is not a mystery to me any longer :)

But analogue buffers (off topic I guess!) still is. "Parasitic" sounds like an efficiency thing: energy of one sort or another gets wasted, whereas buffering is a wait-till-I-can-handle-that thing. Maybe I have too much digital-model view of the world... repeating that I'm electronically naive (read: ignorant :eek:) but I guess capacitors do a sort of buffering?
 
whereas buffering is a wait-till-I-can-handle-that thing.

See this page. In the current context, "the interposed buffer amplifier prevents the second circuit from loading the first circuit unacceptably and interfering with its desired operation". Whatever!

If you remember the audio maxim: "Ideally, input impedance should be high and output impedance should be low", then the need for something to "match" a source to a load becomes clear. And that is exactly what a buffer does.

And this explains why load impedance (or input impedance) must be higher than source impedance
 
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A direct digital class-D which accepts PCM as input or has PWM[preconverted] straight as digital input is worst of any class-D. The best class-D is post filter feedback pure analog based PWM switched version, which accepts analog input.

Direct digital amps have ZERO Power supply ripple rejection ratio because they don't have feedback to track the output signal. Any noise/trash on power supply will degrade the response in certain way. But they are extremely easy to manufacture therefore are getting more common in consumer goods.
 
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A direct digital class-D which accepts PCM as input or has PWM[preconverted] straight as digital input is worst of any class-D. The best class-D is post filter feedback pure analog based PWM switched version, which accepts analog input.

So basically you're saying

the 600$ nuforce,
the 800$ wadia,
the 2500$ nad 390dd
the $7000 nad masters m2

are the worst class D amps...

?

Direct digital amps have ZERO Power supply ripple rejection ratio because they don't have feedback to track the output signal. Any noise/trash on power supply will degrade the response in certain way. But they are extremely easy to manufacture therefore are getting more common in consumer goods.

They come with correction...
 
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So basically you're saying

the 600$ nuforce,
the 800$ wadia,
the 2500$ nad 390dd
the $7000 nad masters m2

are all the worst class D amps...?
They come with correction...

What i highlighted is the technical difference which is there in direct digital vs analog feedback class-D and the associated flaw in them.

Can you tell us what type of correction is employed in direct digital amps? :)
 
Nuforce - Real time error correction at 400kHz

Wadia I don't know much about so I can't say

NAD also has error connection at 108mHz

Skip to 1:00

http://youtu.be/8jA9zOr-1e0

These are the only 4 really important models available right now, they're not common in the consumer goods at all, just recently launched.
 
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Nuforce - Real time error correction at 400kHz

Wadia I don't know much about so I can't say

NAD also has error connection : Skip to 1:00

Audio Advisor - NAD C 390DD Direct Digital DAC Amplifier - YouTube

Unfortunately he only says "error correction" but no reference to how and where it is carried on, because without tracking the output signal you cannot correct for any errors. Later he states around 800Khz + sampling frequency which reduces quantization error but what about PSRR problem.:eek:

This thread speaks for itself, if you can understand technical terms it will make you understand , though NAD uses Zetex DDFA chip :

Zetex DDFA - diyAudio

Another thing i have found is interesting to see in Zetex brochure itself. According to them they have analog feedback itself :D [Page 2 diagram :D ]but they feed the feedback signal back into DSP chip which again performs Analog to digital conversion to compare it with sampled PWM to carry out error correction, which NAD guy missed.

here is the link.

http://www.diodes.com/_files/free_pages/u_0_lnk_090413235508.pdf
 
Unfortunately he only says "error correction" but no reference to how and where it is carried on, because without tracking the output signal you cannot correct for any errors. Later he states around 800Khz + sampling frequency which reduces quantization error but what about PSRR problem.:eek:

This thread speaks for itself, if you can understand technical terms it will make you understand , though NAD uses Zetex DDFA chip :

Zetex DDFA - diyAudio

Another thing i have found is interesting to see in Zetex brochure itself. According to them they have analog feedback itself :D [Page 2 diagram :D ]but they feed the feedback signal back into DSP chip which again performs Analog to digital conversion to compare it with sampled PWM to carry out error correction, which NAD guy missed.

here is the link.

http://www.diodes.com/_files/free_pages/u_0_lnk_090413235508.pdf

I'm afraid this is going into a territory I can't follow, nuforce has their own designs, nad has their own, wadia probably their own as well.

My only thing is that I would not call something like the nuforce, the wadia or the m2 and 390dd the best or worst in any category, I feel what they offer at their prices was unprecedented earlier. And would otherwise cost ridiculous amounts of money in multiple components with multiple entry points for colouration.

So for value hunters such as myself, these offer immense hope regarding further innovation in the future. And based on what we heard at the delhi meet with the NAD, I'm really looking forward to even more affordable models in the future with better innovation.

-----------------------------

I just found this as well

Nuforce is probably one of the few class-D manufacturer with its own patent (US patent granted in 2007) and R&D. And we use not only our own class-d design but also other chips on the market. Since we started selling our first product in 2005, we have expanded into many categories and performance level, so I can say that our experience and road map reflects where class-D is going.

As many of you have recognized, with advance in technology, each generation of class-d gets better. When we started to win over many audiophiles with our power amp in 2005, after more than 8 years, with thousands of high-end customers worldwide, there is no question that the best class-d implementation can match the best solid state or tube amp. On the other hand, commercial reality (pricing pressure) and market requirement also resulted in many class-d power amp (mostly chips) being designed for low cost, low power requirement.

Nuforce vision is to design the best sounding audio for a consumer lifestyle, whether it is for portable, entry level home use, or high-end audio. So how do we decide what goes into high-end audio and how far can we push the performance limit for a $299 (Dia) or $549 all digital power amp (DDA-100, to be released in late June) ?

To be honest, the performance difference between high-end audio and entry level priced audio is getting smaller. For example, the soon to be released DDA-100, at $549 (USD or Euro), offers 4 digital inputs (1 USB, 1 coaxial, 2 optical) and 50W@8ohm x 2 speaker outputs with high-end audiophile-grade sound quality. On the other extreme end, our Ref 18 cost more than 15X. In any industry, extreme performance and limited market demand resulted in high price (Ferrari cost 20X the price of entry level car). I will use these two products to illustrate where we see class-d going in the coming years.

How can we offer a high-end integrated amp such as DDA-100 for so little money and how far have we pushed the performance?
I would dare to say that DDA-100 sounded better than our V1 generation power amp which retails for more than $2000 8 years ago. Today, we can achieve the same performance at about 1/4 the price 8 years ago. DDA-100 uses an all digital chip so that brings the cost down significantly. Surprisingly, the performance is incredibly good after we did some optimization to the system design. The limitation with such a design is that we don't have much room to modify it or increase the power. We have to start from the ground up again if we are going to offer a higher power DDA-100. Lower price product such as DDA-100 have to cut cost whereas Ref 18 uses big and heavier chassis, with lots of shielding inside.

The bottom line for high-end Class D is that it has to keep pushing the limit, and fewer and fewer high-end companies are able to do so (either because they lack the R&D capability or are dependent on module supplier such as icepower). Class-d implementation is a lot more complex than solid state or tube.

We have to amortize the R&D cost over a smaller number of units, that added to the cost of high-end products as well.

Jason from Nuforce
 
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See this page. In the current context, "the interposed buffer amplifier prevents the second circuit from loading the first circuit unacceptably and interfering with its desired operation". Whatever!
Thanks! It is all somewhat beyond me, but I needed a reminder that there is more than one kind of buffer in the world. Train carriages had them long before anybody thought of storing digital data in memory! :eek:
 
Enjoying Wadia 151 (for almost two years) with 170i in my third smaller room setup.

Paid almost USD 1300 (1200+tax).
It's a steal @ USD 800 (current price).
You should use with high sensitivity speakers.


Mac Mini > Musical Fidelity V link192 > Wadia 151 > Tara Labs > Paradigm SM20.

and

Wadia 170i> Wadia 151 > Tara Labs > Paradigm SM20.
 
Enjoying Wadia 151 (for almost two years) with 170i in my third smaller room setup.

Paid almost USD 1300 (1200+tax).
It's a steal @ USD 800 (current price).
You should use with high sensitivity speakers.


Mac Mini > Musical Fidelity V link192 > Wadia 151 > Tara Labs > Paradigm SM20.

and

Wadia 170i> Wadia 151 > Tara Labs > Paradigm SM20.

Hmm I'm unable to find information on the paradigm sm20, whats the specs like?
 
I think there is going to be a lot of movement in this category in the next 12 months and also in Active Wireless Hifi speaker category.

Nad just launched two more cheaper alternative at CES, the D 3020 and the D7050


check them out!
 
I think there is going to be a lot of movement in this category in the next 12 months and also in Active Wireless Hifi speaker category.

Nad just launched two more cheaper alternative at CES, the D 3020 and the D7050


check them out!

The D3020 is just a regular integrated amplifier combining a 30Wpc amp with asynchronous 24-bit/96kHz DAC in a single unit but are separates inside.

The D7050 however appears to be direct digital and outputs 50 watts.

There's not enough information on the internet saying if it fully direct digital amplified, or if it uses a direct digital dac and then sends the signal to a regular amplifier. If it is the former it qualifies, but if the latter, then it does not qualify.
 
I came across this thread, when i was searching for the Nuforce DDA Amp.
i have recently acquired a new DDA120 at a very good price, mainly to power my system in Chennai, which is a modest Pioneer BS22LR speakers.I will report back on impressions once i get my hands on them.
This is a blind buy, as i haven't heard any Nuforce/Nuprime Amp yet, but the price was too good to resist.
 
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