Audiophonics HPA-S400ET Review (Stereo Amplifier)

[Rja4000]

24-bit is needed to reach those SOTA SINADs, and I'm not convinced that anything better that 16-bit is needed for most of us. Archimago has done some blinded tests which I found fascinating <https://archimago.blogspot.com/2023/05/results-internet-blind-test-of-24-bit.html>.

Well, probably not... If you do everything well to keep that margin all over the chain.

If you have to lower level at -20dB, then it's likely only 60dB remains.
Which may become a bit short.

 

[Bob101]

I'm sure you're right, but might -90 dB even be a bit optimistic, especially for old 'uns like me? Is there any research on just how low this needs to be, depending on age, experience, etc.?

I agree, not only on THD+N, but just SNR should be considered too. My listening space is DAED quiet, and I recently had an amp with a stated SNR of -90dB and I could hear hiss when it was not playing any material. Not much, but enough to be annoyed
With my HPA SA400ET I hear nothing, ever, with my ears to the tweeter of any speaker.

 

[AudioSceptic]

I agree, not only on THD+N, but just SNR should be considered too. My listening space is DAED quiet, and I recently had an amp with a stated SNR of -90dB and I could hear hiss when it was not playing any material. Not much, but enough to be annoyed
With my HPA SA400ET I hear nothing, ever, with my ears to the tweeter of any speaker.

That -90 dB is below full output, and doesn't tell us the absolute level. Also, doesn't it depend on the frequency distribution: I would find a "hiss" much more audible than a "rustle" at the same level, for instance.

 

[mike70]

with a stated SNR of -90dB

Stated by who? At what conditions?

We need trusty measurements to make statements.

 

[Ajaxlegends]

Does anybody have hum on their tweeters with this amp? The higher the gain the louder the hum. I had it on 26db because I use with the Wiim Ultra that is 2vmrs, I've now lowered it to 20db and the hum is less loud and thus distracting. I listen pretty nearfield so I heard it on my couch with nothing playing. Normal for the amp or something wrong with my unit?

 

[Acerun]

I bought the three channel and I had to return it because of that humming from the tweeters.

 

[Ajaxlegends]

I bought the three channel and I had to return it because of that humming from the tweeters.

Cheers, it's honestly not that bad because I usually have something playing anyway but just wanted to know if it something wrong with my specific unit or just an inherent flaw I guess.

 

[Acerun]

Yeah to be honest I just couldn't take it and I sent it back. I bought another Purifi amp from another vendor and it's been fantastic and no buzz. They thought it was from the op-amp but I didn't want to deal with doing troubleshooting on it. There's a whole thread on it somewhere on this site

 

[Acerun]

As Devo once wrote "There's a thought that keeps me thinking, like a stone inside my shoe"

 

[daniboun]

Does anybody have hum on their tweeters with this amp? The higher the gain the louder the hum. I had it on 26db because I use with the Wiim Ultra that is 2vmrs, I've now lowered it to 20db and the hum is less loud and thus distracting. I listen pretty nearfield so I heard it on my couch with nothing playing. Normal for the amp or something wrong with my unit?

Do you have any OPA1612 or 1656 Op amps with you? Try swapping them to see if the hum persists

 

[Grael]

Does anybody have hum on their tweeters with this amp? The higher the gain the louder the hum. I had it on 26db because I use with the Wiim Ultra that is 2vmrs, I've now lowered it to 20db and the hum is less loud and thus distracting. I listen pretty nearfield so I heard it on my couch with nothing playing. Normal for the amp or something wrong with my unit?

Same hum without the wiim ultra ? (unplugged and turned off)

 

[Ajaxlegends]

Do you have any OPA1612 or 1656 Op amps with you? Try swapping them to see if the hum persists

I have the Sparkos edition, I don't have other opamps.

 

[Ajaxlegends]

Same hum without the wiim ultra ? (unplugged and turned off)

It's quiet with Wiim Ultra off, does that mean it's something else?

 

[tmtomh]

It's quiet with Wiim Ultra off, does that mean it's something else?

Probably the Wiim, or a ground loop.

 

[Grael]

It's quiet with Wiim Ultra off, does that mean it's something else?

It means the hum is on the wiim side, just amplified by the gain set on the audiophonics.
It's strange as the wiim ultra was not that bad on the measurements board

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[Ajaxlegends]

Probably the Wiim, or a ground loop.

I'm guessing a ground loop if it gets louder with higher gain or does that have nothing to do with it?

 

[mike70]

I'm guessing a ground loop if it gets louder with higher gain or does that have nothing to do with it?

any source noise is amplified by the amplifier

you're using XLR connections?

 

[Ajaxlegends]

any source noise is amplified by the amplifier

you're using XLR connections?

Wiim doesn't have XLR unfortunately.

 

[MLR]

I just added an Audiophonics HPA S-400ET Sparkos Edition as an external amp for my Linn Majik DSM4, driving Linn Ninkas with Hiquphon tweeters. The unit was a bit less than 3 yrs old and I acquired it for 53% of the original selling price.
This is a massive improvement over the DSM4 internal amp. Improvements in bass control, soundstage width/depth, vocal clarity and dynamics are the major improvement areas.
My compliments to ASR for measuring and explaining what I’m hearing.