Buckeye Purifi Eigentakt 1ET9040BA monoblock power amplifier Stereophile Measurements

[EdW]

I don't think the 20dB gain for XLRs is rather universal. A quick perusal of various Purifi amps from various vendors shows gains from 20dB to 29dB. The lower the gain, the better the measured SNR specs become. So there's ample opportunity for vendors to play games with "My SNR is better the yours" ads. They rarely list the gains these SNRs were measured at.

Lower gain = Higher SNR.

The latest Purifi modules have a ~14dB gain. If you have a 10Vrms source, the measured SNR will be superb. But if you measure it with a 4Vrms source (XLR), you'll get worse SNR specs. So yes, when you moved from 27dB NCore to a 20dB 9040/Weiss setup, your noise specs improved by at least 7dB and that hiss reduction is audible or noticeable, especially from sensitive speakers.

I'm curious, who built your 9040/Weiss combo? Cymax?

Have you compared SQ between the discrete Weiss module to the standard OP1612 opamp? Curious to know your thoughts on this!

I think that the sensitivity of the XLR input of the amplifier is often set such that a 0 dB max 4V RMS DAC XLR output can drive the amplifier just to the point of clipping

 

[rdenney]

Take the grilles off. I have about 12 pairs of speakers in my listening area and they all have the grills removed. Neither of our cats has attacked any of them yet...

They have these laminated cardboard scratchers to keep them happy. Best thing ever, each morning they tear into them. They last several months each.

View attachment 417320

If I see a gouge in the speaker, Button is going to become a quadruple amputee.

Rick “glad this thread worked its way to an important topic before drifting back into boring technical debate” Denney

 

[David_M]

I think that the sensitivity of the XLR input of the amplifier is often set such that a 0 dB max 4V RMS DAC XLR output can drive the amplifier just to the point of clipping

That's because there's a gain buffer on the front end that adds it gain to the 14dB of the purify module to get the full power spec at 4Vrms. If the buffer gain is low, then he amp will need more than 4Vrms to be driven to full power. And the reverse is true, if the buffer gain is high, the amp will drive full power before 4Vrms.

 

[Fidji]

I'm curious, who built your 9040/Weiss combo? Cymax?

Have you compared SQ between the discrete Weiss module to the standard OP1612 opamp? Curious to know your thoughts on this!

a) apollon audio.

b) my experience with Purifi amps - audiophonics 1et400 with opa1565, apollon 7040 dual mono sparkos and now apollon 9040 mono with weiss opamp. Used them as L-R - C duties, always on mid-gain.

regarding differences between purifis - I need to remind you, that we are not supposed to listen to amplifiers and dacs, once they clear SINAD hurdles. We spend time talking about measurements, as this is the only truth. . Because we all know, that only important thing about amp is SiNAD of 1kHz test tone at 5W.

 

[Old_School_Brad]

View attachment 419706

If I see a gouge in the speaker, Button is going to become a quadruple amputee.

Rick “glad this thread worked its way to an important topic before drifting back into boring technical debate” Denney

@ Rick "who signed up for the wrong thing" Denney:

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[David_M]

Here is a quick and dirty IMD 19+20kHz measurement of the monoblocks shipping out to JA (Stereophile) on Wednesday.

Hey, would it be possible to measure IMD at 5 Watts, instead of the crazy 50W like JA did? There's hardly any musical information at those frequencies anyways, like about -40 to -60dB down from a 100Hz reference. It seems that JA measures at 50W for one amp and another power for others. Not consistent.

5W is what Amir sets to measure amp specs and that power is more reasonable. Thanks!

 

[David_M]

I think that the sensitivity of the XLR input of the amplifier is often set such that a 0 dB max 4V RMS DAC XLR output can drive the amplifier just to the point of clipping

Yes, but only if you set it to the right gain. Set gain too low, that 4Vrms will not meet rated power. Set gain too high, you'll be clipping way beyond 1%, probably in the 10% range or worse. The point I'm saying is that the needed input voltage for 0dB output will depend on the set gain of the amplifier.

The Purifi module itself has a 14.4dB gain, so you'll need 10Vrms to meet its full power specs. I know this is an extreme example if one has no buffer to provide the extra gain, but you get the point. Full power output depends on the overall gain and input voltage into the amplifier.

 

[pma]

@David_M It is not about “musical information”, such view is pointless. 50W CCIF test is used to check HF linearity, proper module function and proper implementation. 5W tests nothing. Amplifier design is an engineering discipline, it is not about opinions and speculations on music signal content.

 

[amirm]

@David_M It is not about “musical information”, such view is pointless. 50W CCIF test is used to check HF linearity, proper module function and proper implementation. 5W tests nothing. Amplifier design is an engineering discipline, it is not about opinions and speculations on music signal content.

Why 50 watts and not another value? What if amp has 30 watts max?

 

[Salt]

So let's say 90% of spec max?
Or 95

 

[SIY]

5W tests nothing.

Really? The performance in the top octave power range where people are likely to use the product in a review made for consumers is "nothing"? Full power IMD is of interest to the designer as a benchmark (no pun intended), but of less interest to a user. Granted, I do high power IMD when I review amps, but I can see a lot of value in testing at lower powers as well, which is why I include these "nothing" data.

 

[amirm]

So let's say 90% of spec max?
Or 95

Then you can't compare one amp to another.

 

[kemmler3D]

So does this one. Hence my later post.

It's just that we are not everyone.

95dB average is absolutely super loud and if you don't think so, you've either got serious hearing loss or you haven't actually stood in a room with an SPL meter listening to it before. Speaking from experience, if there is 95dB pink noise going, most people either leave the room or cover their ears.

 

[amirm]

95dB average is absolutely super loud and if you don't think so, you've either got serious hearing loss or you haven't actually stood in a room with an SPL meter listening to it before. Speaking from experience, if there is 95dB pink noise going, most people either leave the room or cover their ears.

95 dB subwoofer output @ 20 Hz is just audible. You can't talk about loudness without frequency. A SPL meter is useless for that reason.

 

[Salt]

Then you can't compare one amp to another.

Have a look at medical science studies and their statistics: it's the relative (and not the absolute) statistical evidence that counts (for counts in sale ).
Accordingly one might go to measure at 85, 90 or 95 or even 100 (whatever is preferred) percent of announced Pmax and there we go with relative correlations ...

 

[kemmler3D]

95 dB subwoofer output @ 20 Hz is just audible. You can't talk about loudness without frequency. A SPL meter is useless for that reason.

Ok, good point. I'll still say 95dB broadband or midrange is subjectively "really loud".

 

[rdenney]

Won’t more than around 5W in the top octave fry a tweeter voice coil in a short time?

But we are supposed to test sustained output right up to 20KHz at hundreds of watts?

Rick “testing 19-20KHz IMD at full power would kill any tweeter in seconds” Denney

 

[Sokel]

Won’t more than around 5W in the top octave fry a tweeter voice coil in a short time?

But we are supposed to test sustained output right up to 30KHz at hundreds of watts?

Rick “testing 19-20KHz IMD at full power would kill any tweeter in seconds” Denney

5W for a normal tweeter yes.maybe.
There are people around though at HT madness using piezo's that can stand much,much more.
Can't narrow use cases.

 

[Buckeye Amps]

Have a look at medical science studies and their statistics: it's the relative (and not the absolute) statistical evidence that counts (for counts in sale ).
Accordingly one might go to measure at 85, 90 or 95 or even 100 (whatever is preferred) percent of announced Pmax and there we go with relative correlations ...

Can you elaborate a little? Depending on the experiment or the result one is researching, absolute values have a place in studies as well.

 

[Salt]

Piezo gives the warm smell of sound improvement