Astra vs Expert Pro on paper

[mdconnelly]

Surely there will be indepth reviews that compare the Expert Pro to the equivalent Astra. That will be interesting. Hard to imagine that Devialet would release the Astra if it didn't better the Expert Pro line significantly. On the other hand, I can't imagine how the Astra can possibly justify its price tag. But hey, this is Devialet - and not the one we use to know 9 years ago.

Maybe, just maybe, Devialet managed to make our Expert Pros that much more valuable.

[Joe]

However it looks on paper, I think the new ADH is the key feature. Could be, that they have made a big step forward with it. We will see, when the first will hear it.

[hardcore]

Sadly there's no real info about the new ADH. And the specs are poorer than the Expert Pro. The photos of it also don't look promising. It looks like a smaller cut down version from what we have in the Expert Pros now.

The damping factor of the amp being so much lower is also not promising. Those are lower figures than the Purifi amps. Expert Pro was around 8000 damping factor if I recall correctly.

[Joe]

Yep, the only information about the new ADH except specs is that:

5. What is Next-Gen ADH?
For Devialet Astra, we further developed our signature SDH-implification. In detail, in-depth work was carried out on the functioning of the class D amp, so that it can feed power linearly and in real time to the class A amp, particularly at high frequencies where the class A is more demanding.

The result is inproved interaction between the two amps, and extremely efficient power efficiency. The product consumes less power while achieving even more precise, crystal-clear high frequencies.


I am sure, some can remember the discussion about the non linear power over the frequency range, which was started after measurment of an well knows asian looking guy in the HiFi scene, can't remember his name right now. Thus showing high frequencies has much less power available than low ones.
Now it seems, that Devialet had success to make the power feed linear and in real time with the new ADH. It seems from the specs, that it was not possible to keep the specs of the Expert pro, but can be, that the new ADH sounds now really right like an class A amp but with enormous power. The specs are still stellar by the way.

For me the Purifi Eigentakt amp is another great invention for using the power of class D amps, but real class A sound with class D power may be still the more promising way.

[jparvio]

...I am sure, some can remember the discussion about the non linear power over the frequency range, which was started after measurment of an well knows asian looking guy in the HiFi scene, can't remember his name right now. Thus showing high frequencies has much less power available than low ones...

This was also confirmed by Stereophile Magazine (measurements by John Atkinson), although JA did not really emphasize it in the overall measurement results.

[ada]

Of course I am biased based on what other specs are listed in the website and while everything looks like a clear step back it is very hard to believe that ADH improved but we will see when the reviews comes out but I don't think Astra is an update over Expert. Even the EVO platform based Expert didn't get any proper update, Astra will definitely be an amp of it's age and will never have room to be improved as it is not based on EVO platform which was one of the most critical success from 2010 to 2017 for Expert line.

[bernardl]

I guess all this means that the second hand price of the Expert amps such as my 1000 Pro will sky rock and will probably become more expensive that new units were.

It may remain as the best amplifier ever produced.

Cheers,
Bernard

[Confused]

Taking a look at the comparison table in the first post, it occurs to me that the Expert / Expert Pro range never achieved Devialet's claimed specifications when independently tested and measured. (this is not a criticism of the OP, who is clear in stating that this is data from Devialet's website)

Taking a couple of numbers:

Signal-to-noise ratio: 117db vs 133db
Output impedance: 0.0057Ω (1kHz) vs 0.001Ω

I can recall seeing various measurements of the Expert where the signal to noise ratio was measured somewhere in the range of 115dB to 118dB, depending on model and which input is used. Similarly, Paul Miller's (HFN) measurements of a D170 indicated an output impedance of 0.003 ohms. Both of these figures are nearer the the quoted Astra specifications, rather than for the Expert specifications specified by Devialet. I believe that the 133dB figure originally quoted by Devialet for the Expert Pro is a genuine figure, but it is achieved by measuring in a very narrow and selective way, rather than is accordance with industry norms.

This makes me wonder if the Astra is actually very similar to the Expert Pro in terms of raw measured performance, and the difference in the numbers is simply Devialet moving to providing more honest data, measured more in line with industry standard practice.

With all that said, the output impedance of 0.0057 ohms as quoted for the Astra is a theoretically "worse" figure than the 0.003 ohms figure independently measured for a D170 Expert.

Both numbers are very, very low, so I doubt this matters much in real world listening, but I am a little surprised in seeing a theoretically worse number for the Astra, when compared to a measured number for a similar product from two generations back.

There might be a good reason for this, maybe certain compromises in the new design and the Astra is actually the better performing amp overall? Or maybe the Astra is actually a step back? I think we would need a lot more data to be clear with regard to this point, and actually listening to one might also be informative.

[hardcore]

The published SNR numbers for a single Expert vs dual mono are also different. The dual mono mode has better SNR, likely because they combine both channels in bridged mode.

I think it was stated as 130dB for single 250 Pro and 133dB for dual mono 1000 Pro.

[daniel.avasilichioaei]

I think that such differences between figures have no relevance in real life, considering the fact that the amplifier signal enters speakers that have very high losses (relative to the amplifier), and the sound emitted by the speakers enters a room that usually generates high sound degradations (relative to the amplifier).