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Review and Measurements of Purifi 1ET400A Amplifier

Billy Budapest

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and some noise too, it's pretty much on par with the Hypex NCore now.
How different is the Purifi circuit topology than nCore, anyway? Seems kind of like a slight tweaking and rebranding under different ownership. If I am far off base, let me know.
 

Matias

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jtgofish

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I got to hear a Purifi 1ET400A based amp today in a very good system.
It is almost really good but let down by having quite poor imaging -especially poor centre fill and image depth so it sounds very 2D .I was really surprised it sounded like that.The Accuphase amplifier in the same system had fantastic image depth /projection and height.We tried with and without active preamps and that did not make any difference.
Perhaps I need to recalibrate my expectations to fit in with modern amplifier technology ?I always used to believe that the whole point of stereo reproduction was imaging.
 

SIY

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I got to hear a Purifi 1ET400A based amp today in a very good system.
It is almost really good but let down by having quite poor imaging -especially poor centre fill and image depth so it sounds very 2D .I was really surprised it sounded like that.The Accuphase amplifier in the same system had fantastic image depth /projection and height.We tried with and without active preamps and that did not make any difference.
Perhaps I need to recalibrate my expectations to fit in with modern amplifier technology ?I always used to believe that the whole point of stereo reproduction was imaging.
Uh huh.
 

jtgofish

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What can i do for hear my purifi 2D? XD i never hear any of my speakers sounding 2D
Yes that presentation really surprised me because I have heard Class D amps from Bel Canto and Nord that had half decent imaging.Well the Bel Canto was a bit weird sounding in that it was very forward sounding but at least it did have some projection and a little bit of depth.
I have owned SS amps with that sort of sound-a cheap Kenwood KM207 which I used as a subwoofer amp and a ME550 which apparently had some sort of inverted phase arangement on one channel for some reason and which was changed in later models.I also seem to recall the NAD Power Envelope amps sounded a bit like that.
 

orangejello

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I got to hear a Purifi 1ET400A based amp today in a very good system.
It is almost really good but let down by having quite poor imaging -especially poor centre fill and image depth so it sounds very 2D .I was really surprised it sounded like that.The Accuphase amplifier in the same system had fantastic image depth /projection and height.We tried with and without active preamps and that did not make any difference.
Perhaps I need to recalibrate my expectations to fit in with modern amplifier technology ?I always used to believe that the whole point of stereo reproduction was imaging.
WTF?
 

jtgofish

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Even with a Purifi amp, one does have to wire the speakers in phase.

Rick “just sayin’” Denney

Yes that is the first thing I checked.I was convinced that had to be the case.Maybe I should have tried wiring it out of phase.Although the bass seemed fine as it was.
 

tmtomh

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I got to hear a Purifi 1ET400A based amp today in a very good system.
It is almost really good but let down by having quite poor imaging -especially poor centre fill and image depth so it sounds very 2D .I was really surprised it sounded like that.The Accuphase amplifier in the same system had fantastic image depth /projection and height.We tried with and without active preamps and that did not make any difference.
Perhaps I need to recalibrate my expectations to fit in with modern amplifier technology ?I always used to believe that the whole point of stereo reproduction was imaging.

That's interesting. When I first put my Purifi amp in my system, I noticed excellent soundstage depth in particular. It was a subjective, sighted comparison with my prior amp, but with that disclaimer, I will say that improved soundstage depth was one of the three main improvements I noticed (or thought I noticed, anyway), along with less distortion and lower (or in the case of the Purifi I should say basically non-existent) self-noise.

My first impulse would be to suggest that a higher-distortion Class AB amp might add some detectable 2nd harmonics, which can create a false sense of ambience and "air," which in turn can influence the perception of soundstage. However, my understanding is that Accuphase amps have very low distortion, so I doubt that would be the cause.

At any rate, you heard what you heard - but you'd be wise not to attribute your single experience to some objective quality of Purifi amps.
 

Billy Budapest

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Even with a Purifi amp, one does have to wire the speakers in phase.

Rick “just sayin’” Denney
If both speakers are wired out of phase, it shouldn’t matter. If the relative phase between the speakers is different (ie, one wired in phase, one wired out of phase) then it will matter big time.
 

MaxBuck

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I guarantee my NAD C298, which is a Purifi based amp, lacks nothing in the "imaging" department.

Not that that has sweet FA to do with the amplifier, but whatevs.
 

SIY

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Not that that has sweet FA to do with the amplifier...

Right there. Unless there's something pathological or deliberate DSP, the electronics has zero to do with imaging. It's a function of speakers, room, and in the case of non-ears-only evaluation, imagination.
 

jtgofish

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Right there. Unless there's something pathological or deliberate DSP, the electronics has zero to do with imaging. It's a function of speakers, room, and in the case of non-ears-only evaluation, imagination.

You have obviously never owned an ampilier with variable negative and positive feedback.Making adjustments to those can seriously alter the imaging in a system-from flat and 2D to deep and 3D.Negative feedback more so than positive feedback in my experience.Nelson Pass has extensively discussed this topic.
 

SIY

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You have obviously never owned an ampilier with variable negative and positive feedback.

I've designed and built them. Nelson does not validate his claims via ears-only testing.
 

Phorize

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Yes that presentation really surprised me because I have heard Class D amps from Bel Canto and Nord that had half decent imaging.Well the Bel Canto was a bit weird sounding in that it was very forward sounding but at least it did have some projection and a little bit of depth.
I have owned SS amps with that sort of sound-a cheap Kenwood KM207 which I used as a subwoofer amp and a ME550 which apparently had some sort of inverted phase arangement on one channel for some reason and which was changed in later models.I also seem to recall the NAD Power Envelope amps sounded a bit like that.
I went from a class a/b amplifier to the purifi-tbh if I didn’t have to press the on switch to use it I would forget it even existed, seems like the only significant difference between my system and yours is the listener…perhaps start there.
 
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jtgofish

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I went from a class a/b amplifier to the purifi-tbh if I didn’t have to press the on switch to use it I would forget it even existed, seems like the only significant between my system and yours is the listener…perhaps start there.

Yes that is possible. It does seem that not everybody hears image depth/centre fill type of imaging.Or at least not in the same way.Yamaha NS1000 speakers seem to be an especially good tool for dividing those that can from those that struggle.Some people think they image OK and others not at all.A bit like those picture puzzles in which an image appears to some people but not others.
 

SIY

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Yes that is possible. It does seem that not everybody hears image depth/centre fill type of imaging.Or at least not in the same way.Yamaha NS1000 speakers seem to be an especially good tool for dividing those that can from those that struggle.Some people think they image OK and others not at all.A bit like those picture puzzles in which an image appears to some people but not others.
Speakers matter. Amps don’t (aside from pathology). Don’t conflate the two.
 

jtgofish

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Speakers matter. Amps don’t (aside from pathology). Don’t conflate the two.
Well they do not matter if you can't hear the differences.
 
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