Audiophonics HPA-S400ET Review (Stereo Amplifier)

[sam_adams]

Balanced signal sums and cancels distortions.

Let's not attribute any magical properties to balanced connections. The harmonic distortion present in the signal is part of the frequency spectrum of the devices at both the sending and receiving ends of the connections and are not removed by balanced connections. Balanced connections impart a degree of noise rejection to the cable itself.

Also, balanced connections—in and of themselves—are not completely immune to noise. Much of their benefit comes from maintaining the impedance match on both ends of the connection. The increase in SINAD comes from the inherent higher signal-to-noise level in such connections.

 

[sam_adams]

Lol, while get the sarcasm, may really not be all that great. If is relying on the trigger mounts to hold the board, not a solid mechanical approach...

While clearly not affecting performance, there are several questionable wiring runs. The AC wire and the power switch wire should run along the board edge rather than through the middle on the SMPS.

Additionally, some of the signal input wiring seems longer than it needs to be.

In the end, seems a nice value. Just could be a bit tidier IMO.

Agree with @Rick Sykora on this. The modules could be rotated anti-clockwise 90 degrees to place the module inputs and outputs closer to the respective terminals on the case. This would reduce the loop area of the cables. However, this would cause the wiring from the power supply to be a little longer, but that could be mitigated by twisting the wires a little tighter. Also, they could have chosen to use a shielded, multi-conductor cable instead of the ribbon cable for the control connection. Harder to wire to the connectors, but there are solutions available for that.

 

[Slayer]

 

[Tks]

Wow, someone actually said to themselves: "HP4A reigning for over half a decade in performance? I guess we'll try and do something about that".

About time!

Great work Audiophonics

 

[VintageFlanker]

Adding shipping from US + import taxes, it was still a bit cheaper delivered to France than the Audiophonics option...

Hum... are you sure your calculations are correct?!

BTW, VTV build quality is extremely poor when comparing to what you get from @Apollon Audio, @Audiophonics or @boXem | audio... I really see no point to buy overseas when you have great manufacturers nearby .

 

[Kennyknetter]

I own two of the mono versions of this amp. My experience is consistent with Amir's. Sound, look, feel, power... all is stellar.

When I bought the amps I also ordered some cables. I changed my mind the following day, and changed them. The new cables came out to be like 20 cents cheaper, and I told them to keep the change. Still, they gave me a voucher for the difference. That speaks volumes for their costumer service.

Audiophonics is the real deal. I'd buy the same things again, from the same vendor.

 

[Kennyknetter]

Interesting thing is that the 2 channels of the amplifier seem to be running anti-phase to each other. The different loudspeaker connections for each channel in the teardown show this. I believe that the power supply used is the Hypex SMPS1200A400 which should be OK with both channels in phase. Nevertheless maybe that subtle change helps Audiophonics get its performance?

I believe that the amps are arranged in a push-pull fashion. IIRC, that presents a more gentle load on the SMPS. It would explain the wiring that you've noted.

 

[Matias]

Let's not attribute any magical properties to balanced connections. The harmonic distortion present in the signal is part of the frequency spectrum of the devices at both the sending and receiving ends of the connections and are not removed by balanced connections. Balanced connections impart a degree of noise rejection to the cable itself.

Also, balanced connections—in and of themselves—are not completely immune to noise. Much of their benefit comes from maintaining the impedance match on both ends of the connection. The increase in SINAD comes from the inherent higher signal-to-noise level in such connections.

If that were so you would see only reduced noise floor when using balanced outputs in DAC measurements, which by the way use a short cable to the ADC. But many times we also see distortion artifacts significantly reduced when using balanced instead of unbalanced outputs, suggesting that noise on the device output is being cancelled as well.

 

[bkdc]

Hum... are you sure your calculations are correct?!

BTW, VTV build quality is extremely poor when comparing to what you get from @Apollon Audio, @Audiophonics or @boXem | audio... I really see no point to buy overseas when you have great manufacturers nearby .

You get what you pay for. It is not a bad deal In the USA but EU residents definitely have better options. Anyone who has a screwdriver, wire strippers and pliers, a little heat shrink tubing and insulated tape can address most of the VTV shortcomings with little effort unless if there is a flaw in the buffer board manufacturing. I think Most here are choosing the Eval1 version anyway.

it is nice to have several different options from different assemblers and the consumer can choose vote with his pocketbook. It’s nice that audiophonics can put some price pressure on its competitors in the EU. For those based in the USA I wouldn’t scoff at VTV if you are handy with a soldering iron. It’ll be nice when Buckeyeamp has It’s Purifi amps in production. I’m eagerly awaiting a measurement on a new Purifi 1ET7040SA which appears only have beefier thermals for people who want to blast power through low impedance speakers but minimal benefit over the 1ET400A for most users.

 

[KMO]

I believe that the amps are arranged in a push-pull fashion. IIRC, that presents a more gentle load on the SMPS. It would explain the wiring that you've noted.

What reasons are there for not doing this? My understanding is that this is the exception rather than the norm, but why isn't it the norm?

Are there any downsides apart from just increased potential assembly confusion?

(And, to be fair, that is a significant downside. One of the basic rules of electronics prototypes seems to be that all the 32-bit or 64-bit buses are always correct, but some simple 2-way or 3-way connection always ends up swapped).

 

[EdW]

I really do not think so. If you start analysis with @22kHz BW setting, then the analysis finishes at 10-11 kHz. It would not allow you to go to 20kHz and they show 20kHz top frequency. You need at least @40kHz BW to make such measurement.

As a comparison, THD frequency plots of my re-design of vintage Kenwood amp

from

Measurements of vintage Kenwood KA-5010 amplifier clone - Now with SMPS!

I made some improvements in power supply section and in wiring. As a result, the amplifier is completely free from mains spuriae lines and other mess. High order harmonics have been also considerably reduced. More THD vs. frequency plots at 2W - 40W/4ohm and @45kHz BW

www.audiosciencereview.com

I would have hoped that Purifi would have better HF linearity than this thing, but it does not seem to be the case.

I think you have analysed this correctly. The AES17 20kHz filter would largely eliminate the harmonics of the higher frequency test sine waves. I suppose the justification is that you can’t hear above 20kHz so why would you be interested? I prefer @amirm rather more accurate and informative analysis.

 

[Billy Budapest]

Wow, someone actually said to themselves: "HP4A reigning for over half a decade in performance? I guess we'll try and do something about that".

About time!

Great work Audiophonics

Benchmark AHB2 has been out since 2014 and still hasn’t been bettered in many aspects of measured performance. Looking forward to someone knocking them off their perch!

 

[sarumbear]

Audiophonics HPA-S400ET (this one) US $1,638 for max. power 255W at 113dB SINAD with a complexity like this:

Or you pay almost double ($1,361 more) for the Benchmark AHB2 to gain 4dB SINAD at half the max. power and complexity like this:

 

[VintageFlanker]

Audiophonics HPA-S400ET (this one) US $1,638 for max. power 255W at 113dB SINAD with a complexity like this:

Or you pay almost double ($1,361 more) for the Benchmark AHB2 to gain 4dB SINAD at half the max. power and complexity like this:

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.

 

[amper42]

What did we learn from the Audiophonics HPA-S400ET Review? The Purifi design offers very comparable measurements to the Benchmark ABH2 but with twice the power and half the price when configured with a 12.7dB gain stage.

 

[bkdc]

The Benchmark is an impressive achievement. KISS design (keep it simple, stupid) as well as anticipated repair costs down the road lean heavily for Purifi even ignoring the initial pricing. It seems a no brainer when price is considered.

Maybe some people are more appreciative of complexity—- maybe they wear a complicated mechanical watch when a quartz will do. KISS is one rule I prefer for most breakable items.

 

[3125b]

European prices are always incl. (fairly high) sales tax, without VAT this amp costs 1241,67€.

 

[Billy Budapest]

The Benchmark is an impressive achievement. KISS design (keep it simple, stupid) as well as anticipated repair costs down the road lean heavily for Purifi even ignoring the initial pricing. It seems a no brainer when price is considered.

Maybe some people are more appreciative of complexity—- maybe they wear a complicated mechanical watch when a quartz will do.

Actually, the Benchmark has multiple failsafe and protection circuits due to its intended studio use so I would not expect having to bring it in for repair.

 

[sarumbear]

Honestly, I don't understand this post.

Apples and oranges, really.

We are comparing a power amplifier (an apple) to another power amplifier (also an apple).

Complexity without meaningful gain is considered bad engineering practice. In this case there is a considerable time between the two designs hence the Benchmark engineers certainly have not been bad. However, as a consumer the simplest device is always the better "engineering" choice.

You are paying twice for a power amplifier that offers half the power but 4dB more SINAD. That is the bottom line. I hope you understood what I posted now.

 

[Billy Budapest]

European prices are always incl. (fairly high) sales tax, without VAT this amp costs 1241,67€.

Yes, if purchased by an American consumer, VAT would be subtracted off the price but then import duty would be added, and who knows how much that would be!