Audiophonics HPA-S400ET Review (Stereo Amplifier)

[TheBatsEar]

On top of that, it is quite common to consider having LCR being the same for the homogeneity of the front scene.

Doesn't matter, these amps have no sound of their own, you can mix as you like to.

If you find the NC252MP doesn't have enough powder for a center you are either too far away, not hearing right, or you didn't know that you can bridge them ;-).

 

[Vincentponcet]

Doesn't matter, these amps have no sound of their own, you can mix as you like to.

If you find the NC252MP doesn't have enough powder for a center you are either too far away, not hearing right, or you didn't know that you can bridge them ;-).

Then it will be the same for right and left

 

[TheBatsEar]

For that reason you cannot will or shoo your perception biases away, or override them. You cannot even look inside to see what they are or how they came to be. They could be part of your genetic setup, they could be the result of some experiences you had earlier today or 10 years ago, something you read or heard, or a combination of several factors. The perception biases can only be controlled through the design of the experiment.

• And so you buy this nice amp, that, objectively, has no sound. But you perceive one. One day, with a particularly dark mood, you decide to sell the amp to get something more organic, warm, since this amp sounds cold. You order the new one right away.
• The new amp arrives. A veil is lifted. You feel good.
• A week later you read about that amp that widens the soundstage. Since you are full of energy from that Bagel you just had, you order right away.
• The new amp arrives. The soundstage widens. You feel good.
• A week later you see that diamond encrusted amp that has ethereal qualities. After a glas of wine too much, you order right away.
• The new amp arrives. Sparkly sounds appear. You feel good.

And so on, and so on.
Is this what you want?

 

[Daka]

Center channel is the one being the most solicited one in multi-channel movie soundtracks.
On top of that, it is quite common to consider having LCR being the same for the homogeneity of the front scene.

IMHO I doubt anyone could hear difference between two great digital amps in a movie. I have AB class on center channel and it doesn’t stand out. Speaker matching is much more important. I would dare to say it’s more to do with OCD to have same power amps for Center as for LR.

 

[VintageFlanker]

IMHO I doubt anyone could hear difference between two great digital amps in a movie.

Class D is still not digital...

 

[JSmith]

After a glass of wine too much

... the soundstage becomes so wide one falls into it.


JSmith

 

[CRKebschull]

Honestly, I don't understand this post.

Apples and oranges, really.

"Complexity" or engineering-speaking, Benchmark wins hands down. It is an in-house (and non-Class D, BTW) design that proved to be unparalleled for the last 7 years. Audiophonics assembled an amp with Purifi modules and Hypex PSU, that you may basically find from any tiers-assemblers. Credit is on @Bruno Putzeys here, Audiophonics just did a great job making a competitive finished product (yet, there is even cheaper. See post #13) and that's it.

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

Then you need the SMPS1200A400 PSU for 229 EU:

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.

 

[MBI]

Re: that last line about bypass mode. The Pre90 I'm using seems capable of this. Does anyone make one without an input buffer?

Do you expect input buffer suppression to be cheaper or better or both?

The Audiophonics HPA-S400ET in bypass mode is presented as admitting 2 to 4 kΩ impedance outputs. Does that mean the lower limit is 2 Ω or 2 kΩ?

 

[theREALdotnet]

And so on, and so on.
Is this what you want?

Is this what I want? I don’t follow, are you sure you’ve replied to the right post?

I was merely pointing out that this optical illusion illustrates nicely how futile it is to try and control/override one’s subconscious perception bias.

 

[TheBatsEar]

I was merely pointing out that this optical illusion illustrates nicely how futile it is to try and control/override one’s subconscious perception bias.

You will base future decisions/avaluations on the knowledge that the rings are static, thus overriding your subconscious perception.

Rational mind 1.
Subconscious perception 0.

 

[Bouteille]

Re: that last line about bypass mode. The Pre90 I'm using seems capable of this. Does anyone make one without an input buffer?

Good catch !
I knew I read something like this but could not remember where...
That's why I'm not 100% confident with my current config in "low-gain" mode.

My minidsp-SHD has following characteristics:
Balanced analog audio (4 channels) on XLR connectors
- Full-scale output: 4V RMS
- Output impedance: 200 Ω
- THD+N: 0.0003% (USB to RCA)
- Dynamic range: 120 dB
- Frequency response linearity, 20 Hz to 20 kHz, –1 dBFS: +/-0.5dB

I don't care about the lower voltage, I actually use "low-gain" mode to limit max output for speakers protection.
Can the "output impedance" value allow me to conclude that I'm in the safe zone for using this amp's "bypass/low-gain" mode coupled with the minidsp SHD ?

 

[Haskil]

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.

+ one box + 2 XLR + 2 RCA + 4 HP + on-off + IEC = the price of this Audiophonics

 

[theREALdotnet]

You will base future decisions/avaluations on the knowledge that the rings are static, thus overriding your subconscious perception.

Yes, if you are allowing yourself to be guided by rational thought rather than subjective impression. A lot of people unfortunately are not, and believe their perception to be of higher validity because they can supposedly “switch off“ the biases they bring to a listening session.

Basing an equipment choice on rational throught is obviously not an option for people who cannot rationalise the choice because they lack knowledge of the subject matter. But even people who understand the principles of electrical engineering (or whatever field is relevant) regularly fall into the trap of thinking they can evaluate by sighted listening, because they think their knowledge makes them immune to bias. Then you hear things like “I know how it works, I know there can’t possibly be a difference, but by golly – there is!”…

 

[CRKebschull]

Whatever you heard in those shops, listening to different amps, could better be explained by blood pressure, caffeine intake or glucose level. Your ear is not a reliable instrument, it's prone to misinterpretation of reality, just like your eyes:
View attachment 194553
Only through measurement (put your mouse pointer on one of the rings) will you be able to get a glimpse of reality (the rings don't move about).

There is no scenario where you are able to reliably detect a difference between NAD C298 or HPA S400ET by ear. Anyone telling you differently, is likely talking out of their butt.

Pick your purchase based on a few key performance indicators, like power and SINAD, then looks, features and price, because these almost state of the art devices have objectively no sound of their own. Acting as if they had will just cost money and annoy a lot of ASR people.

+ one box + 2 XLR + 2 RCA + 4 HP + on-off + IEC = the price of this Audiophonics

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 case and connecting parts and wiring locally, or, maybe you're like me and already 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.

 

[PeteL]

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.

Don't forget connectors, switch... Time... Some tools, and enclosures are not cheap neither. It is Indeed a nice project and I am not discouraging anybody to do it, but isn't your comment about "for just 1028 EU" somehow a bit misleading?

 

[JohnnyNG]

Do you expect input buffer suppression to be cheaper or better or both?

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.

The Audiophonics HPA-S400ET in bypass mode is presented as admitting 2 to 4 kΩ impedance outputs. Does that mean the lower limit is 2 Ω or 2 kΩ?

From the 1ET400A – Data Sheet

 

[MBI]

Can't remember why, but a buffer seemed necessary to someone on this forum for some reason. Not sure what part is bypassed exactly in low gain.

From the 1ET400A – Data Sheet

View attachment 194922View attachment 194922

Not sure it matters much, but unless I misunderstood Topping Pre90 specs, the output impedance is rated either as 20Ω or 40Ω (balanced or unbalanced respectively), which doesn't reach the theoretical 2kΩ indicated minimum in Audiophonics amp specs for low gain (nor the 2.2kΩ in the 1ET400A datasheet, if that's the same but with more precision). Voltage probably is close enough (to 10) though. Can this still work, I'd quite like to know for a secondary system?

 

[KMO]

Not sure it matters much, but unless I misunderstood Topping Pre90 specs, the output impedance is rated either as 20Ω or 40Ω (balanced or unbalanced respectively), which doesn't reach the theoretical 2kΩ indicated minimum in Audiophonics amp specs for low gain (nor the 2.2kΩ in the 1ET400A datasheet, if that's the same but with more precision). Voltage probably is close enough (to 10) though. Can this still work, I'd quite like to know for a secondary system?

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

The source's output impedence has to be sufficiently lower than the amp's input impedence to not screw up the transmission.

40Ω would be absolutely fine - that's headphone-capable, right? The 200Ω of the miniDSP SHD mentioned above should also be okay, but you wouldn't want to be much higher than that, I think.

 

[JohnnyNG]

Can't remember why, but a buffer seemed necessary to someone on this forum for some reason. Not sure what part is bypassed exactly in low gain.

That's what I was wondering.

 

[KMO]

Can't remember why, but a buffer seemed necessary to someone on this forum for some reason. Not sure what part is bypassed exactly in low gain.

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.