Audiophonics HPA-S400ET Review (Stereo Amplifier)

[2wheeldrift]

Thank you, Amir!!! Great review. Stunning amp!!! I have two of these and the NAD M23. Tube amps like my Manley Stingray and RA Cronus 3 are fantastic too but these are my all-time favs after over 60 years of dedicated listening and collecting....

 

[AweLoi]

Thank you, Amir!!! Great review. Stunning amp!!! I have two of these and the NAD M23. Tube amps like my Manley Stingray and RA Cronus 3 are fantastic too but these are my all-time favs after over 60 years of dedicated listening and collecting....

Just curious. Do you hear any difference between the M23 and the HPA-S400ET? I know NAD makes their own power supply and I'm curious if it is possible to hear a difference.

 

[2wheeldrift]

I did not compare them to the NAD as they all have different preamps, source and speaker combos and all needed some use before doing a comparison. This might be a good time to compare them as they have lots of use by now.

 

[AweLoi]

I did not compare them to the NAD as they all have different preamps, source and speaker combos and all needed some use before doing a comparison. This might be a good time to compare them as they have lots of use by now.

If you feel that you want to and have the time to please do, but it is of course ok if you don't.

I have already bought the Audiophonics HPA-S400ET because of price vs value, but I am still curious about how the different implementation of PSU and buffer of the M23 potentially affect the sound. My guess is that the differences, if any, are quite small since they both measure very well.

 

[Bob101]

If you feel that you want to and have the time to please do, but it is of course ok if you don't.

I have already bought the Audiophonics HPA-S400ET because of price vs value, but I am still curious about how the different implementation of PSU and buffer of the M23 potentially affect the sound. My guess is that the differences, if any, are quite small since they both measure very well.

Like with all well-designed amps operating within their linear power-range: if you're not told what you're listening to, you won't be able to tell the difference.

 

[Bleib]

Like with all well-designed amps operating within their linear power-range: if you're not told what you're listening to, you won't be able to tell the difference.

Yeah, speakers, room, recording quality have more to say about the final outcome than well-designed amps

 

[Bob101]

Yeah, speakers, room, recording quality have more to say about the final outcome than well-designed amp

Purifi, or: How I Learned to Stop Worrying and Love class D​

 

[KaMatthi]

Hi to all, I am wondering about when the amplifier starts, a cracking noise can be heard from the tweeters. Do I have to worry?

 

[amper42]

Hi to all, I am wondering about when the amplifier starts, a cracking noise can be heard from the tweeters. Do I have to worry?

If it's a quiet crackle that lasts one second that's normal when turning on a Purifi amp.

 

[nemesis.ie]

Also try bypass mode and see if it changes?

 

[tmtomh]

If it's a quiet crackle that lasts one second that's normal when turning on a Purifi amp.

Agree. Mine makes a very low-level sound that lasts maybe 1/2 a second. I would describe it as sounding like a very tiny pop, although I suppose one could say it sounds like a much, much quieter version of the single staticky pop you get if you walk across a carpet in the winter and then touch something metal. I wouldn't call it a crackle because to me a crackling sound has to be longer than just momentary like that, but I could see how someone could describe it that way.

Not long after I got the amp, I emailed Audiophonics about it, and as @amper42 notes, they confirmed it's normal. The amp is silent when being turned off.

 

[AweLoi]

Hi to all, I am wondering about when the amplifier starts, a cracking noise can be heard from the tweeters. Do I have to worry?

I never had any noise like that with mine. If I put my ear close to the driver I can hear a short pop or klick when when I turn it on but it is a very quiet pop. I remember seeing a video somewhere with a guy with this problem. It seem like some have it and others don't.
Perhaps soldering a snubber cap on the power button will solve this?

 

[Salt]

It's a common issue and (though in this review) usually tested by ASR.
It means no harm for any speaker.
For me I can't remark any annoyance, as I'm used to the PLOPP at startup of amps produced on the Island in the '80th so don't bother.

 

[KaMatthi]

It's a common issue and (though in this review) usually tested by ASR.
It means no harm for any speaker.
For me I can't remark any annoyance, as I'm used to the PLOPP at startup of amps produced on the Island in the '80th so don't bother.

Thanks for letting me know. I was just wondering and had the fear my tweeters could harmed by that.

I have another question. My pre-amp is able to achieve 8V to the balanced output (Stormaudio MK2). What (Jumper) Configuration should be the best choice for me ( I bought the previous version, before 2023, from Audiophonics)?

 

[nemesis.ie]

I use bypass with the Altitude 32. If there is enough gain for you, that should give the lowest noise floor and least chance of tweeter hiss.

 

[KaMatthi]

But that means, the gain would be 12,8 dB... ideal would be 26dB?

 

[Salt]

I'm running low gain with RME ADI flawlessly.

Thanks for letting me know. I was just wondering and had the fear my tweeters could harmed by that.

I have another question. My pre-amp is able to achieve 8V to the balanced output (Stormaudio MK2). What (Jumper) Configuration should be the best choice for me ( I bought the previous version, before 2023, from Audiophonics)?

 

[magchiel]

But that means, the gain would be 12,8 dB... ideal would be 26dB?

Ideal would be the lowest gain (yielding lowest distortion) that gives you the desired SPL at listening position, given the input level from a source.
26dB I think spawns from the average consumer equipment (1.5-2Vrms SE) the average listening position (other may be able to provide a better historical or theoretical reference for this). And there's also THX's 29dB.
However since my RME ADI 2/4 can spit out +24dBu/12.24Vrms, the 12.8dB gain of the bypass setting is plenty to drive my 88dB/W/m speakers to a desired SPL at 290cm.

 

[AweLoi]

I have another question. My pre-amp is able to achieve 8V to the balanced output (Stormaudio MK2). What (Jumper) Configuration should be the best choice for me ( I bought the previous version, before 2023, from Audiophonics)?

With 8V I would go for 20dB or bypass. See recommendations here: https://www.audiophonics.fr/en/blog...udiophonics-purifi-and-ncorex-amplifiers.html

 

[Vhond]

Thanks for letting me know. I was just wondering and had the fear my tweeters could harmed by that.

I have another question. My pre-amp is able to achieve 8V to the balanced output (Stormaudio MK2). What (Jumper) Configuration should be the best choice for me ( I bought the previous version, before 2023, from Audiophonics)?

So there are different versions of the amp (before and after 2023)?? If yes what are the differences?