Audiophonics HPA-S400ET Review (Stereo Amplifier)

[Bouteille]

Don't know. Just figured there's no reason to buy that board just to bypass it. And the input buffer seems to be a big variable in quality between these various Purifi implementations so maybe best left out if possible.



From the 1ET400A – Data Sheet

View attachment 194922View attachment 194922

Thank you for digging in the documentation. I thought the Audiophonics sentence was not clear whether this 2.2/4.4kΩ values are actually the specified input impedance of the purifi module.

The minidsp SHD has output impedance of 100Ω for unbalanced and 200Ω for balanced outputs (=1/22 ratio compared to corresponding 2.2kΩ and 4.4kΩ input impedance of purifi module).

 

[JohnnyNG]

The entire input buffer circuit is bypassed in this system's low-gain mode, so the input connectors get routed straight to the 1ET400A's inputs.

Which is why the input impedance changes from the easy-to-drive 47/94kΩ of the buffer to the harder-to-drive 2/4kΩ of the 1ET400A.

Some sources will struggle to drive the lower impedance, and it can impact frequency response.

I'm assuming Amir's test rig was basically impervious to that effect, so he only saw SINAD upside to using low gain. I believe a real source could have potential FR/SINAD downsides.

Other Purifi amps, such as the Apollon or Vera Audio ones, may keep the buffer in circuit but disable the gain, avoiding that issue.

Got it! In addition to Amir's measurements, Stereophile measured the Pre90 as barely breaking a sweat @ 10V into 600 ohms so was curious.

 

[MBI]

The 2.2kΩ isn't "required output impedence for attached source", it's the 1ET400's own input impedance.

Many thanks for explaining! That's very useful thank you.

40Ω would be absolutely fine - that's headphone-capable, right?

Topping Pre90 is a high SINAD (>120) preamp which I don't think is designed or even applicable to headphones, but I could be wrong so please feel free to check Amir's review here.

 

[KMO]

It should be noted that conventionally, line inputs in consumer gear usually have impedance somewhere in the 10kΩ to 100kΩ range, and outputs are usually fine for anything 10kΩ or higher.

So the buffered 47-94kΩ would be fine for anything, and the unbuffered 2.2-4.4kΩ is a bit low, but not that low.

 

[DSS]

In Germany for example you can buy the ET400 modules including the FE02-Front-End-Module with two OPA1612-Opamps for 799 EU:

View attachment 194873

Then you need the SMPS1200A400 PSU for 229 EU:

View attachment 194875

And put that in any enclosure of your choosing, in any orientation of your choosing, with any wiring of your choosing, and you can have your own optimized to taste Purifi Stereo Amp for just 1028 EU.

Looks like Soundimports online store of the Netherlands.

Plus this case and cabling: https://www.ghentaudio.com/kit/purifi-eval1-se.html
and you're close to Audiophonics compact version price.

 

[CRKebschull]

Indeed, but if you are going to send these parts to the US, and you do or don't have to pay duty and tax, then it's much easier to source the case and connecting parts locally, or, maybe you're like me and I have a box of Neutrik XLR and Speakon parts and all the cables you can shake a stick at (since this is my hoby), so maybe you'd rather build the Purifi modules to your taste anyway.

Looks like Soundimports online store of the Netherlands.

Plus this case and cabling: https://www.ghentaudio.com/kit/purifi-eval1-se.html
and you're close to Audiophonics compact version price.

Yes, it would seem then that Audiophonics is selling at the sum of the component retail pricing, which is fair. They ofcourse buy the components as a reseller at some discount, and that then is their profit. Since the reference Hypex and Purifi implementations are superb, and as the case with the Sparko buffer boards show not easily bested in quality, and unless you want to build your own, it's totally OK to have Audiophonics or some other such retailer do it for you.

 

[BlackTalon]

Yes, it would seem then that Audiophonics is selling at the sum of the component retail pricing, which is fair. They ofcourse buy the components as a reseller at some discount, and that then is their profit.

You are leaving off their labor and overhead costs. There will be very little profit on these once you take those costs into account.

 

[amarsicola]

... you can have your own optimized to taste Purifi Stereo Amp for just 1028 EU.

What Audiophonics or many other implementation with an input buffer can give you is the possibility to drive your amplifier with a 4volt dac.
The standard Eval1 implementation unfortunately has a maximum input voltage of 1.6volts. After that, the amplifier starts clipping and your speakers might be damaged.
And even if this does not happen because you don't have kids at home that enjoy turning knobs, you still induce the dac to worsen the overall signal to noise floor level of the system.
I had the same doubts as yours and then opted for the cheaper version of the Audiophonics purifi, which is also giving a good aftersales

 

[PeteL]

What Audiophonics or many other implementation with an input buffer can give you is the possibility to drive your amplifier with a 4volt dac.
The standard Eval1 implementation unfortunately has a maximum input voltage of 1.6volts. After that, the amplifier starts clipping and your speakers might be damaged.
And even if this does not happen because you don't have kids at home that enjoy turning knobs, you still induce the dac to worsen the overall signal to noise floor level of the system.
I had the same doubts as yours and then opted for the cheaper version of the Audiophonics purifi, which is also giving a good aftersales

The Eval 1 Kit has a buffer, and you can have different gain settings trough jumpers. I am a bit lazy to do the maths right now but how did you get the 1.6V Clipping?

 

[amarsicola]

The Eval 1 Kit has a buffer, and you can have different gain settings trough jumpers. I am a bit lazy to do the maths right now but how did you get the 1.6V Clipping?

There is a >100 pages thread on building the Purifi as a DIY...
I'm too lazy to give you the exact page, you try
Or just have a look at the official specs

 

[mike70]

no they don`t correct ..but tube amps for better or for worse do add to the signal. that is what`s stated in the post. and if you can`t hear metal cones sound harsher and brighter then say paper/wood based cones, you need your ears checked

No, I don't. The Kef R3 have metal tweeters but i saw the spinorama and at higher frequencies is very flat. I have them since 2 years and sometimes I wanted to pump up the treble

That kind of generalization ... doesn't work.

 

[PeteL]

There is a >100 pages thread on building the Purifi as a DIY...
I'm too lazy to give you the exact page, you try
Or just have a look at the official specs

Well, you wont clip at 4V with the pre gain buffer disabled (see excerp) , but yes it's nice that this version here has a midle value of 20 dB. On the eval you have to solder a resistor or 2 resistor for that. That said 27 dB gain is not very high even at full gain. The fact that it can't take the full output of a 4V Dac, would apply to any amp with a 150ish Watts in 8 ohms, 27 dB is closer to standard than 20. This buffer really don't do anything special really. Gain switching is a nice feature for sure but it's the exception more than the norm for power amps. Most commercial implementations that you'll find of 1-ET400A should be set at 27 dB or 29 dB, which are, at least to me, much more useful than lower. Many of us have many sources and have analog volume control anyway. 20 dB Gain will only be useful for this very specific use case where you have no preamp and want to use strictly digital attenuation. For a balanced DAC. At it's core it's not a limitation of the Eval Kit, but yes, it's an eval Kit, if you want 20 dB gain you'll need a soldering Iron. But still they document how to set it so no guess work here.

 

[MeMe]

Thanks for the review Amir.
As an owner of one of these, I can confirm that it sounds and behaves great.
I have mine linked to a Schiit Freya+.
Incredible value for money.
+ Audiophonics people provide quick and friendly answers to questions.

 

[Aerith Gainsborough]

Definitely a very sexy looking amp. Too bad that subwoofer integration is a pain in the rear end with non AVR components. :'D

 

[PeteL]

Definitely a very sexy looking amp. Too bad that subwoofer integration is a pain in the rear end with non AVR components. :'D

Do you know any power amp that offers subwoofer integration? I don't think it's the job of them.
To your point tough I am surprised there aren't more DACs that offer that in a simple manner with all these that are now designed to be able to feed power amps directly, I find that all we see is a race to crunch that extra inaudible dB of SINAD but not a lot of advance on features like a subwoofer Channel.
Now of course you can have subwoofer integration without AVR components. There are DSP units that do that very well, Many preamps in the traditional sense of the term has that too.

How would you have suggested that a power Amp, designed to drive speakers would have included that. In all cases you will have something upstream, this is the very last electronics in the chain, I don't see why it would be at that stage that this sort of signal routing would be done. It does one thing, taking a small signal and deliver a larger signal.

 

[Vacceo]

a stereotype ? Why is that ? no, certainly for certain positions (jobs in mass distribution in particular) it has unfortunately become very different over the last 20-30 years but it is still far from being generalized. For the majority, the French actually have a very comfortable lunch break, and fortunately!



but that, yes, is indeed a good stereotype! The food can be excellent (but you will be disappointed by the contents of the bowls of many of us, especially at noon), the wine too, and the women more complex than you can imagine. But it is a challenge that may be worth taking up. (or not...)

As for Audiophonics, I have had nothing but good experiences with them as a regular customer. And precisely I was eyeing these amps for some time. Thank you Amir for this review!

Just for the creation of mi cuit, France deserves culinary credit.

 

[Aerith Gainsborough]

I am surprised there aren't more DACs that offer that in a simple manner with all these that are now designed to be able to feed power amps directly, I find that all we see is a race to crunch that extra inaudible dB of SINAD but not a lot of advance on features like a subwoofer Channel.

Agreed. Would be nice of them to offer such filters. Routing the entire signal through the sub for xover and filtering before feeding it the power amp kinda defeats the whole "overkill SINAD stats" bit.

How would you have suggested that a power Amp, designed to drive speakers would have included that.

I never did suggest anything of the sort, that is entirely your interpretation.
Merely pointed out that sub integration is annoying with all of these high end 2.0 stereo components.

I think the ideal place for the crossover filtering would be at the DAC stage, so all of it can be done digitally before the D/A conversion happens.

 

[tonapo]

I have been keeping an eye on class d, as I have been wondering about building my own amp, as a fun project which I have not done before, although I never seem to have the time. I was wondering about building another system in my house possibly using the home built amp. I was also thinking it would be fun to test against my main amp, a class A Musical Fidelity M6SI. Not sure what I would hear, maybe I could do it blind somehow. Anyway, I have a Topping D90 and an RME ADI-2 DACs, so I could use either, probably the RME for volume control, feeding my Kef reference 1's. Given the quality on show here though with the Audiophonics unit, I can feel an ebay splurge coming on, selling some stuff and then picking one up.

 

[garbz]

in short.. metal drivers are stiff and light providing sensitivity, power handling and strong transient response, though not well damped as organic cone materials so resonances quickly rears its ugly head

Ding ding ding. We have a winner. That is objectively correct. Stiffer lighter materials present more resonance. Just the other day I was listening to music with my best friend and he said "woof woof woof grrr" which loosely translated to "screw this damn resonance at 35kHz, can't you hear it sounds like shit?" So I threw a ball at him. I love him to bits but he should be content with doggy treats, I'm not building a hifi system for his enjoyment.

Resonance is something very easy to measure. Tweeter resonance also shows up very clearly on any speaker measurement which goes beyond the audio band. Woofers resonate too, that is something to consider when designing crossovers, ports, and enclosures.

In short, attributing any audible quality to an individual driver is stupid, attributing it to the material of said driver doubly so. This isn't your kid's first art project. Speakers are "designed", not "tossed together" and designers consider how all aspects of their designs interact.

.... Or at least they should.

Is this what you want?

I want this. That's why I only listen to music after breaking up with a girl eating a bagel and drinking wine.
I've always been of the opinion that people should go get a massage rather than upgrade their amp. It's cheaper and has a great effect on the perceived quality of sound.

 

[gsp1971]

Definitely a very sexy looking amp. Too bad that subwoofer integration is a pain in the rear end with non AVR components. :'D

From my B&W AS2 subwoofer manual:

"For 2-channel operation, use speaker level rather than line level connections. The subwoofer presents a high impedance load to the stereo power amplifier and takes very little current, so may be connected in parallel with the main speakers with no adverse effects."

So you can connect a subwoofer using speaker wire from the speaker terminals of the subwoofer to the speaker terminals of your amp, in parallel with your speakers. A powerful amp like this one from Audiophonics should have no problem supplying power to both the speakers and the subwoofer.