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Review and Measurements of Purifi 1ET400A Amplifier

Rottmannash

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I guess I'm trying to decide whether the extra 1,000 is worth it. I can swallow that if there's a noticeable audible improvement. It just being better on paper makes it much harder for me to just eat that cost.
There's a $1000 difference between an NCore 252 amp and a Purifi?? If so hell no it isn't worth the difference. I have a Buckeye 252 and a VTV Purifi and they sound VERY close in SQ. The Purifi appears to have a bit more power but the 252 gets quite loud without distortion. Either would work for most.
 

phoenixdogfan

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There's a $1000 difference between an NCore 252 amp and a Purifi?? If so hell no it isn't worth the difference. I have a Buckeye 252 and a VTV Purifi and they sound VERY close in SQ. The Purifi appears to have a bit more power but the 252 gets quite loud without distortion. Either would work for most.
Even more mind blowing are the versions of the Eigentact by other manufacturers costing $3-4k which include their own buffers and op amps and actually degrade the performance of the Purifi modules to the point where they measure around the same as the $500 NC 252.
 

Rottmannash

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Even more mind blowing are the versions of the Eigentact by other manufacturers costing $3-4k which include their own buffers and op amps and actually degrade the performance of the Purifi modules to the point where they measure around the same as the $500 NC 252.
Yes, I've seen those and read many glowing reviews of those inferior (measurement-wise) versions on other forums.
 

goryu

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If you want a real laugh check out the discussions on audiogon about the GaN class d amps coming out and the nonsense being spread by the tweaker cult.
 

peng

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There’s nothing wrong with your instinct, and the 32 tone test is perfectly sensible. Keith Johnson already used a cluster of 8 tones in the 90’s. He said that for AD/DA this was an excellent indicator of sonic transparency. To my ears his HDCD encoder box is still the gold standard in sonically transparent AD/DA so I’m not about to disagree.

The more complex the test signal, the more likely you are to separate out the different nonlinearities that together make up amplifier distortion. On the other hand, it becomes harder to read the graphs. Once you use more than 2 sine waves the plots become quite hard to interpret. You have to do some calculations to work out what particular combination of tones underlies a particular spur.

Bruno (and Lars, from a sunny campsite in Sweden)

I realize this is from a very old post but I thought I would try my luck, that you may still follow this forum once in a blue moon.

There is an article on the Elliot Sound website that casually touch on the topic about the often touted claim that testing with a pure sine wave may not be too meaningful because music waveforms are inherently much more complex, and suggested the 32 tone test may be at least better.


Under the heading "Measurements Versus Subjectivity" it says:

"If I never hear of someone complaining that "distortion measurements are invalid, and a waste of time" again, it will be too soon. I am so fed up with so-called experts (where "x" is an unknown quantity, and a "spurt" is a drip under pressure) claiming that "real world" signals are so much more complicated than a sinewave, and that static distortion measurements are completely meaningless."

They are not meaningless, and real world signals are sinewaves! The only difference is that with music, there is usually a large number of sinewaves, all added together. There is not a myriad of simultaneous signals passing through an amp, just one (for a single channel, naturally).

Since physics tells us that no two masses can occupy the same physical space at the same time, so it is with voltages and currents. There can only ever be one value of voltage and one value of current flowing through a single circuit element at any instant of time - if it were any different, the concept of digital recording could never exist, since in a digital recording the instantaneous voltage is sampled and digitised at the sampling rate. This would clearly be impossible if there were say 3 different voltages all present simultaneously."

and then under the heading "Slew Rate and Intermodulation", it says:

"That a typical audio signal is a complex mixture of signals is of no real consequence, because an amp has no inherent concept of "complex" any more than it has an opinion about the date. At any given point in time, there is an instantaneous value of input voltage that must be increased in amplitude and current to drive the loudspeaker. As long as this input voltage does not change faster than the amplifier is capable of doing, then no degradation is should occur."

That sounded logical to me, just wonder if you have a different take.
 

rdenney

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The multitone test is intended for viewing in the frequency domain using spectrum analysis, using a fast Fourier transform. That analyzes those the multiple tones, but it also shows any products of mixing between those tones, which would be spurious (meaning: unintended and not part of the input signal). Those mixing products comprise intermodulation distortion. A perfect display is a sharp peak at every tone with nothing but noise floor in between. Spurious mixing products would be shorter peaks in between the multitone peaks that comprise difference tones, etc.

But taking the single signal waveform that produces those tones in the time domain instead of the frequency domain, it is indeed a superposition of 32 separate sine waves that all create a single waveform that is the sum of sine waves at a variety of frequencies. Slew rate is just the ability to increase the signal as steeply (in time) as would be the case for the highest frequency in the mix of frequencies.

So, I agree with what you quoted.

Rick "even a square wave is the sum of sine waves" Denney
 

mocenigo

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Chill out, dude! I’ve looked at the configurations on their websites and have seen the boutique discrete opamps. It is certainly not “false information” and I am not “spreading” anything. For sure regarding the Nord. As for the Audiophonics, I had remembered seeing an implementation where they used discrete opamps. Maybe their design has changed since then. In any event, I find the entire discrete opamp industry rather silly.

Do not worry, I was using more of a paternalistic tone, than a harsh one, but it does not come off easily with written text. I apologise if it sounded harsh, and it is never too late to do that (some other user liking my reply made me notice this reply of yours only now).
 

Billy Budapest

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Do not worry, I was using more of a paternalistic tone, than a harsh one, but it does not come off easily with written text. I apologise if it sounded harsh, and it is never too late to do that (some other user liking my reply made me notice this reply of yours only now).
It’s all good—I didn’t even remember this exchange!
 

Kelims

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Dobrý den, mám dotaz ohledně kombinace purifi a Topping D 90 SE .Jaká je ideální kombinace nastavení Vrms? Purifi má 11+ Vrms a D90 SE pouze 5Vrms. Nebo je možné udělat Bypass na purifi a D90 SE Nastavit na 4 Vrms. Chci to zároveň použít jako předzesilovač
 

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David_M

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Hello, I have a question about the combination of purifi and Topping D 90 SE .What is the ideal combination of Vrms settings? Purifi has 11+ Vrms and D90 SE Only 5Vrms. Or is it possible to do a Bypass on purifi and D90 SE Set to 4 Vrms. I want to use it as a preamp at the same time
Purifi amps have an option for having a preamp stage which can easily take the D90's 4v or 5v to drive the Purifi to full power (and then some). Many, if not all, vendors include their own custom-designed or 3rd party preamps boards. An example would be ...

https://www.audiosciencereview.com/...ith-sil-994enh-ticha-pro-buffer-review.24855/
 

Kelims

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Dobrý den, mám dotaz ohledně kombinace purifi a Topping D 90 SE .Jaká je ideální kombinace nastavení Vrms? Purifi má 11+ Vrms a D90 SE pouze 5Vrms. Nebo je možné udělat Bypass na purifi a D90 SE Nastavit na 4 Vrms. Chci to zároveň použít jako předzesilovač
Zesilovače Purifi mají možnost mít předzesilovač, který může snadno vzít 4V nebo 5V D90, aby rozptýlil Purifi na plný výkon (a pak ještě nějaké). Mnoho, ne-li všichni, prodejci zahrnují své desky předzesilovačů jiných navržených na zakázku nebo od výrobců. Příkladem by bylo...

https://www.audiosciencereview.com/...ith-sil-994enh-ticha-pro-buffer-review.24855/
I know about these option but I wanted to use the complete Purifi.(to save some money) Do you think the 5.2 Vrms is insufficient? Any idea what happens if I use Bypass?
 

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David_M

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Sorry I know about these option but I wanted to use the complete Purifi.(to save some money) Do you think the 5.2 Vrms is insufficient? Any idea what happens if I use Bypass?
You want to engage the pre-gain option to further boost your 5.2vrms volt input to bring up its gain to a total of 27dB as they claim in their datasheet. If you bypass the pre-gain stage, then you'll not be able to drive the Purifi to full power as it requires 11vrms (w/o gain stage) to run at full power. So, do not use bypass but engage or use the pre-gain stage.
 

phoenixdogfan

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You want to engage the pre-gain option to further boost your 5.2vrms volt input to bring up its gain to a total of 27dB as they claim in their datasheet. If you bypass the pre-gain stage, then you'll not be able to drive the Purifi to full power as it requires 11vrms (w/o gain stage) to run at full power. So, do not use bypass but engage or use the pre-gain stage.
Actually, I think it's more like 10 volts. I have my Octo Dac 8 Pro configured to output 10 VRMS for outputs 1-2 and run mine with the pre-gain bypassed.
 

David_M

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Nice ... but his D90SE can only output 4 or 5Vrms. I recommend the 4V option with gain engaged to take advantage of the full dynamic of the D90SE.
 

Kelims

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Nice ... but his D90SE can only output 4 or 5Vrms. I recommend the 4V option with gain engaged to take advantage of the full dynamic of the D90SE.
Would you be so kind as to advise me how to do this? Set it up according to the picture?
 

David_M

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It's really simple. Set the jumpers as shown in the picture for enabling the gain stage. Have jumper shorts across all 4 terminals horizontally as shown in the picture.
 

Kelims

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Can you explain why it is better on ...... 4V and not 5,2V I mean the input and output sensitivity should be comparable
 
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