Review and Measurements of Purifi 1ET400A Amplifier

[sdo_riga]

I think certain people tend to forget there are a lot of real analog sources out there. Wild variations in output levels and impedances. Reel to Reel, Cassette decks, tuners, turntable preamplifiers, various line outputs ranging from CD players to iPods, computers and laptops. Not everyone is out there is predictably boring with a measly single input, or a USB interfaced D/A converter.

That's where a proper preamplifier comes into its own. This minimalist, simplistic, one input deal is painfully boring. Phono 1, 2 (MC/MM), Tuner, Aux 1 and Aux 2 along with a few tape loops and a processor and I am mostly happy. I have three CD players, an open reel and another few analog sources currently hooked up to a few power amplifiers right now.

And as to why I'd be listening to a cassette source? Because I can. And because I have recordings that are so good, so rare and so indistinguishable from the source, they are amazing. Recordings carefully made on the same deck they are played back on 40 years later.

Maybe also Living Stereo recordings https://www.amazon.com/Living-Stereo-60-Collection-Box/dp/B003UCPEJ2 ?

 

[MediumRare]

I haven't read through the 78 pages - is there a completed commercial product similar to this I can buy?

 

[Matias]

I haven't read through the 78 pages - is there a completed commercial product similar to this I can buy?

https://www.apollonaudio.com/apollon-1et400a-mini-stereo-amplifier/
https://www.nordacoustics.co.uk/product-page/nord-three-1et400a-stereo-amplifier-1
https://www.audiophonics.fr/en/powe...eo-amplifier-purifi-2x400w-4-ohm-p-14557.html
https://vtvamplifier.com/product/vtv-amplifier-stereo-purifi-audio-1et400a-amplifier/

 

[jae]

I haven't read through the 78 pages - is there a completed commercial product similar to this I can buy?

NAD M33
Audiophonics HPA-S400ET
Audiophonics LPA-S400ET
March audio P451 (mono, P452 coming soon)

Big list here: https://www.audiosciencereview.com/...mplifier-sonic-shootout-€820-to-€8-344.14048/

 

[MediumRare]

Thanks - the prices are out of reach for me - I need to buy three zones (6 channels) worth. At this point looking at the Behringer and Monoprice amps at around $250 each and about 150 WPC into 8 ohms. Not SOTA but perhaps the differences are (close to) inaudible in a real-world environment. Any other suggestions are most welcome!

 

[Matias]

Thanks - the prices are out of reach for me - I need to buy three zones (6 channels) worth. At this point looking at the Behringer and Monoprice amps at around $250 each and about 150 WPC into 8 ohms. Not SOTA but perhaps the differences are (close to) inaudible in a real-world environment. Any other suggestions are most welcome!

NAD M28 - 5k usd. It's the best, hence the price.
https://nadelectronics.com/product/m28-seven-channel-power-amplifier/

 

[echopraxia]

NAD M28 - 5k usd. It's the best, hence the price.
https://nadelectronics.com/product/m28-seven-channel-power-amplifier/

It’s worth mentioning that the price is high also due to having seven channels. If you need that many channels, it may actually be the best price per channel out there for Purifi amps.

 

[Labjr]

Has there been any mention of new Purifi modules?

 

[echopraxia]

For those (like myself) who might be unsure whether the Purifi 1ET400A is enough power for you, here is a data point that might be useful:

Powering my Revel Salon2’s (86dB/2.83V sensitivity = ~83dB/1Watt sensitivity between 20-200hz where impedance is ~4 ohms) via March Audio P451 (Purifi 1ET400A) mono-blocks, I ran several test sweeps from 20-200hz gradually increasing SPL while keeping an eye on distortion.

Even at 110db SPL at 25hz, measured from 20 foot listening distance, there was never any sign of distortion (e.g. definitely no clipping):

More measurements here if you're interested. (The bass distortion shown here is actually lower than my Rythmik F18’s, though much of this is probably from room effects like rattling walls since the Rythmik’s are against them.)

At this point, the woofer excursion was quite large so I stopped increasing the volume here. That said, there was probably some headroom left, but I didn't want to push it too far. Here is a GIF:

 

[phoenixdogfan]

For those (like myself) who might be unsure whether the Purifi 1ET400A is enough power for you, here is a data point that might be useful:

Powering my Revel Salon2’s (86dB/2.83V sensitivity = ~83dB/1Watt sensitivity between 20-200hz where impedance is ~4 ohms) via March Audio P451 (Purifi 1ET400A) mono-blocks, I ran several test sweeps from 20-200hz gradually increasing SPL while keeping an eye on distortion.

Even at 110db SPL at 25hz, measured from 20 foot listening distance, there was never any sign of distortion (e.g. definitely no clipping):

View attachment 80113

More measurements here if you're interested. (The bass distortion shown here is actually lower than my Rythmik F18’s, though much of this is probably from room effects like rattling walls since the Rythmik’s are against them.)

At this point, the woofer excursion was quite large so I stopped increasing the volume here. That said, there was probably some headroom left, but I didn't want to push it too far. Here is a GIF:

View attachment 80114

So the Eval1 with SMPS can legitimately be considered endgame.

 

[Matias]

SoundStage! Hi-Fi also measured this amplifier with an APx555. They are starting to do measurements in house too (before Bascom's BHK Labs did it for them). Nice, @Doug Schneider , congrats!

https://www.soundstagehifi.com/inde...asured-performance-of-the-eigentakt-amplifier

 

[echopraxia]

So the Eval1 with SMPS can legitimately be considered endgame.

I think it’s hard to define how much power in an amp is truly “endgame”. ~200 watts at 8 ohms and ~400 watts at 4 ohms seems to be enough for most people and speakers, but this is relative, and I think more headroom is always appreciated.

I’m actually quite curious as to whether the improved SINAD and IMD of Purifi 1ET400A is actually audible vs the Hypex NC1200 (which is twice as powerful, at ~400 watts into 8 ohms and ~700 watts into 4 ohms).

While it’s nice to know your amp has ultra-low distortion/noise/etc, once you’re already at the level of performance as the Hypex NC1200 (for example), it’s hard for me to imagine how any further improvements would be audible. When you look at speaker distortion measurements, it’s clear that the amount of distortion from either of these amplifiers is going to be completely overpowered by the distortion caused by the speakers themselves.

Don’t get me wrong — the improved quality performance from the Purifi is very welcome. It’s really beautiful engineering. But if the difference isn’t audible, then the Hypex NC1200’s greater power capability (twice as powerful as the Purifi 1ET400A) would make it the better “endgame” amplifier.

It turns out I own both Hypex NC1200 amps, and Purifi 1ET400A amps... almost as if I planned to try a blind ABX test between them at some point

 

[retro]

Well then, how about bi-amping with both NC1200 and Purifi..you get the best of both..?!?

Actually really interested in your comparsions, since I'm planning to get a pair of Salon2 in the near future..

 

[Matias]

After this test I did with 2x500W at 4 ohms into my 2.7 ohms current hungry speakers, playing loud and bass heavy music, it really had me rethinking how much power I really need. The 1ET400A could be all I really need. But how much is it of an audible improvement over my current NC500OEM based main amplifier? That is the question.

 

[Labjr]

SoundStage! Hi-Fi also measured this amplifier with an APx555. They are starting to do measurements in house too (before Bascom's BHK Labs did it for them). Nice, @Doug Schneider , congrats!

https://www.soundstagehifi.com/inde...asured-performance-of-the-eigentakt-amplifier

ASR may not be the first with AP measurements but they've certainly been influential in making others rethink their review methodology. Or at least try harder to fake it.

 

[Matias]

ASR may not be the first with AP measurements but they've certainly been influential in making others rethink their review methodology. Or at least try harder to fake it.

To be fair SoundStage! Hi-Fi has been publishing amplifier measurements for a long time, way before ASR. The difference is that before they had this outsourced to BHK Labs and his Audio Precision unit, and now they do it in house.

https://www.soundstagenetwork.com/index.php?option=com_content&view=article&id=17&Itemid=141

 

[carlob]

After this test I did with 2x500W at 4 ohms into my 2.7 ohms current hungry speakers, playing loud and bass heavy music, it really had me rethinking how much power I really need. The 1ET400A could be all I really need. But how much is it of an audible improvement over my current NC500OEM based main amplifier? That is the question.

How much power do I really need? Interesting video.

 

[Willem]

A lot. And that may be more important than the reduction of the last residual bit of distortion.

 

[Labjr]

To be fair SoundStage! Hi-Fi has been publishing amplifier measurements for a long time, way before ASR. The difference is that before they had this outsourced to BHK Labs and his Audio Precision unit, and now they do it in house.

https://www.soundstagenetwork.com/index.php?option=com_content&view=article&id=17&Itemid=141

Stereophile has been doing it longer too. But they seem to publish some of the measurements which support their opinions and not the other way around. I've noticed other reviewers scrambling to do some of what ASR is doing. I know, I rarely read other reviews anymore and recently gave up my Stereophile subscription after 30 years.

 

[Matias]

How much power do I really need? Interesting video.

That was VERY interesting. Thank you very much for sharing!