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Buckeye Purifi Eigentakt 1ET9040BA monoblock power amplifier Stereophile Measurements

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Here is a quick and dirty IMD 19+20kHz measurement of the monoblocks shipping out to JA (Stereophile) on Wednesday.
Probably they will now not sound as nice anymore :facepalm::cool:;)
 
Are you sure about that - in crowns calculator I've found and plugged in those figures, you need 2x80W (the calculator seems to have no inputs for room gain or two speakers, so I've subtracted 3dB for each from the headroom to compensate)

But now perhaps your speakers only have 85dB sensitivity - so you need 2x160W. And if your listening distance is actually 3m (only 50cm further) - now you need 225W

Finally, what happens if every now and then when the family is out and you like to really crank it to 95dB - now you are looking at 2250W.

And we haven't had to go to anything insane for that. Individual cases need to be considered individually.

View attachment 419211
The difference seems to be in "," vs. "." when giving listening distance input. You may very well be right in using "." As a European, I'm used to use "," in such cases.

Anyway, setting listening distance to 2 meters (which is actually roughly my current listening distance) brings the calculated power to 50W.

As I mentioned in my post, I am well aware that the power needs increase sharply with distance, required SPL etc..., but I don't see why anybody would want to use very low sensitivity speakers if high SPL and distance are required. Also, I absolutely agree that the cases need to be considered individually. This individual just happens to think that 95 dB average is insanely loud ;)
 
but in home hifi needs ....
..it's very individual.
As demonstrated by various calculation examples.
Additionally, PA speakers typically have higher sensitivity than HiFi speakers, as the latter generally feature much smaller bass drivers and have less space for components like horns.
 
...though not directly comparable,specs for IMD (18.5+19.5kHz though) call for about 0.0001% (-120dB) at 1-10-200W/4 Ohm what we see here is some 20dB worst performance.
I don't think this is how is suppose to measure,even if Purifi's measurement BW is brickwalled at 20kHz.

Edit:here's Amir's NCx500's measurement at the same signal as Buckeye above at 5W for comparison:

1736236591481.png

still some 10-15dB difference.
 
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This individual just happens to think that 95 dB average is insanely loud
So does this one. Hence my later post.

It's just that we are not everyone. :)
 
The difference seems to be in "," vs. "." when giving listening distance input. You may very well be right in using "." As a European, I'm used to use "," in such cases.

Anyway, setting listening distance to 2 meters (which is actually roughly my current listening distance) brings the calculated power to 50W.

As I mentioned in my post, I am well aware that the power needs increase sharply with distance, required SPL etc..., but I don't see why anybody would want to use very low sensitivity speakers if high SPL and distance are required. Also, I absolutely agree that the cases need to be considered individually. This individual just happens to think that 95 dB average is insanely loud ;)
Well, an average of 95 dB A-weighted is indeed quite loud in my opinion. On a linear scale, this would require peak levels of at least 115 dB in the bass. At a listening distance of 2.5 meters, most speakers would likely struggle to achieve this unless they are large towers with substantial bass drivers.
You will in most cases be helped by room gain though.
Bottom line is that it is very hard to predict exactly how much power one might need.
 
Talking about amplifier necessary power - let me put some real data.

This is the data from music wav file:

1812_data_1.png


.... and this is the same signal part recorded from the amplifier output when playing music into Quadral Ascent 90 speaker:


telarc_1812_ recorded.PNG


Output voltage at flat impulse top is about 35Vp, this makes 306W/4ohm instantaneous power. The speaker sensitivity is about 89dB/2.83V/m.

1736253370784.png
 
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Here is a quick and dirty IMD 19+20kHz measurement of the monoblocks shipping out to JA (Stereophile) on Wednesday.
Appreciate the plot submission ... so it the IMD -94dB for the given test conditions? Are you able to post a 5W plot, so that we can compare with what Amir measures?
 
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Want to emphasize "quick and dirty" again. Will be following up with a more dialed in IMD and power sweep measurements after tweaking our rig a little more. Can at least confirm the amps do not shut down at half power....for instance 4ohms reaches over 700w under 1% as expected.

Quick point was just to show that, yes, the original review unit had a defective module.
 
Want to emphasize "quick and dirty" again. Will be following up with a more dialed in IMD and power sweep measurements after tweaking our rig a little more. Can at least confirm the amps do not shut down at half power....for instance 4ohms reaches over 700w under 1% as expected.

Quick point was just to show that, yes, the original review unit had a defective module.

Thanks Dylan! Yes, it would be nice if folks would acknowledge the actual point instead of just barreling into whatabout questions that your post was not intended to address. But I guess that's the internet....

At any rate, your measurement is clearly a strong indication that the original module was indeed defective. Will look forward to the full Stereophile measurements of this proper unit!
 
Want to emphasize "quick and dirty" again. Will be following up with a more dialed in IMD and power sweep measurements after tweaking our rig a little more. Can at least confirm the amps do not shut down at half power....for instance 4ohms reaches over 700w under 1% as expected.

Quick point was just to show that, yes, the original review unit had a defective module.
Yes,measuring conditions and equipment must be stated,no one would judge a single image like the above.Is just a hint.
It can very well be one at a wrong mode or,or,or...
What's important is to be comparable and repeatable across all measuring gear.
 
I can do it for you, if you do not mind. Dvorak, From the New World symphony, movement 2.
It is impossible to generalize about peak to average ratio in music, It depends, strongly depends on what you listen to. Same applies to sufficient amplifier power.

View attachment 419120
Reminds me of this YT.
Classical music is wild, poor player next to the hammer
 
supply.

Lastly, the 9040BA has a rated 4.5uV noise floor and a 14.4dB gain. A buffer's output noise scales with its gain, so to get the typical 26dB total gain, like analog amplifiers, the buffers gain stage will gain up its output noise by 12dB, not including the voltage and current noise contribution of its gain resistors and the opamp itself, etc

.

I think most of the use cases with symmetrical connection call for 20dB gains. Allows for optimal S/N through the full chain.
I have 9040/Weiss monoblocks, at 20dB, with rest of amps for MCH at 19dB. Difference to previous 27dB gain NCORE setup is quite substantial.

but I cam agree, that all not DClass amps are created equal. You cam still screw even the best module.
 
I think most of the use cases with symmetrical connection call for 20dB gains. Allows for optimal S/N through the full chain.
I have 9040/Weiss monoblocks, at 20dB, with rest of amps for MCH at 19dB. Difference to previous 27dB gain NCORE setup is quite substantial.

but I cam agree, that all not DClass amps are created equal. You cam still screw even the best module.
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 "My SNR is better the yours" games. 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!
 
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