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2nd generation EIGENTAKT PURIFI 1ET6525SA (successor to the 1ET400A)

miero said:
From the Hypex SMPS1200 datasheet:
Click to expand...
I asked March about this on their forum. Reply was basically its the low variable voltage out of the hypex psu that means the module output will be limited. Around 210 watts at 63 volts.
 
pma said:
Yes, that is a common issue, especially it affects the noise. It adds: Vnoise(generator) * Gain(amplifier) = method error noise. I have the same problem.
Click to expand...
March basically measured the amp noise with inputs shorted then added the THD component from the measurement.
 
A datasheet for 1ET6525SA is now available on the Purifi website including the EVAL6 Stereo 1ET6525SA Evaluation Kit (EUR 706.00 VAT Excluded):
- https://purifi-audio.com/shop/eval6-eval6-stereo-1et6525sa-evaluation-kit-2576


1732612056665.png
 
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jamesdyson said:
March basically measured the amp noise with inputs shorted then added the THD component from the measurement.
Click to expand...
I know, but it is incorrect. At high power the noise floor rises, thus N in the THD+N rises and the THD+N is worse than THD + (Noise with the shorted input). His method would measure SNR, not THD+N. It would make the numbers to look nicer. Please see below. The green plot, noise only. The plot is in dBW, which is not usual here, but @John_Siau knows well why. If the noise was constant, the green plot would be straight.

NC252MP_thdnnoise.png
 
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miero said:
A datasheet for 1ET6525SA is now available on the Purifi website including the EVAL6 Stereo 1ET6525SA Evaluation Kit (EUR 706.00 VAT Excluded):
- https://purifi-audio.com/shop/eval6-eval6-stereo-1et6525sa-evaluation-kit-2576


View attachment 409660
Click to expand...
Measuring bandwidth not shown, as usually. So, the THD+N plot without BW mentioned is pointless. I know, somewhere in the datasheet they probably say 20Hz-20kHz. However, they should have mentioned it in the plot notes.
 
pma said:
I know, but it is incorrect. At high power the noise floor rises, thus N in the THD+N rises and the THD+N is worse than THD + (Noise with the shorted input). His method would measure SNR, not THD+N. It would make the numbers to look nicer. Please see below. The green plot, noise only. The plot is in dBW, which is not usual here, but @John_Siau knows well why. If the noise was constant, the green plot would be straight.

View attachment 409665
Click to expand...
I agree with you if we are talking about higher power output, but March was talking about a specific power point of 5 watts. Your graph shows there is less than 0.5dB difference at this point with that particular amp. I don't know, but I suspect the Purifi modules have negligeable increase in noise at this level. In which case wouldn't the difference between SNR and THD+N be insignificant? I might ask March to comment.
 
pma said:
Measuring bandwidth not shown, as usually. So, the THD+N plot without BW mentioned is pointless. I know, somewhere in the datasheet they probably say 20Hz-20kHz. However, they should have mentioned it in the plot notes.
Click to expand...
Screenshot_20241126_185339_PDFelement.jpg
 
What is its SINAD Value?
It's unbelievable. Better than Benchmark AHB2's.
Do we still hear the difference between these extreme fidelity amps?
 
DACs_Lover said:
What is its SINAD Value?
Click to expand...
Depends mainly from the input/gain stage it is hooked to. The 1ET6525SA is a part (the main one tbh) used to build an amplifier, not a finished amplifier.
The same way that the DAC chip performance doesn't tell the DAC performance since it is highly dependent from the power supply and output stage used.
 
A comment on THD+N vs. SINAD: These are usually close but not always exact because not everybody measures the same. Consider the following IME.

Audio commonly measures THD+N by measuring THD when driven by the signal, which is harmonic spurs (only) relative to the fundamental, and then noise by shorting the inputs and measuring the output noise. Combining (normally RSS -- square root of the sum of the squares) yields THD+N. Thus THD is the ratio of signal to the sum (typically RSS) of harmonic distortion terms, and noise is measured with no signal present. THD neglects other spur sources like power-supply noise, clock noise, and so forth. Noise measured this way ignores the influence of signal level on the noise, and may include power supply spurs and other "noise" in the measurement.

SINAD is meant to be all-encompassing and so includes harmonic and non-harmonic distortion terms (can include things like clock noise/spurs, power supply noise/spurs, etc.) as well as in-band noise. It uses the ratio of the signal to all other terms captured by the measurement so generally is a little worse than THD+N.

SNR is ideally the ratio of the signal to only noise, though again some include other terms in the SNR. A fairly common scheme is to apply a signal and subtract out the harmonic distortion terms, since a long FFT has narrow enough bins that the result is not significantly affected. High power or other spurs can corrupt the "pure" SNR measurement.

Both measurements include noise in the fundamental (and harmonic) bins so a high level of noise can cause errors in their level. This is usually important only at very low power levels, as harmonic spurs approach (and often fall below) the noise floor, and is one reason for the rise in THD+N at low power levels (it is dominated by noise).

A single number is often useful as a baseline metric, but a more detailed look at the frequency spectrum of the noise and distortion is normally required to make a final decision among comparable devices, and recognition of the system. Low noise may be more important for highly-sensitive speakers, for example, along with low power-supply spurs. Switching power supplies put the supply noise at very high frequency, above the audio band, so may be desirable in some applications. Etc.

Spread-spectrum communications and some other RF applications can make calculating these terms challenging on the actual "live" signals...
 
PEQuestrian said:
Couldn't agree more. My 4216/E2 stereo amp just arrived last week and I find both build- and sound quality, as well as the feature set excellent. Fred was super helpful and worked with me on customizing the low gain input setting to better match the low pre-out voltage (1.4V max) on my Denon X3800H. Good luck finding this level of engineering-first customer centrism from any larger manufacturer. So even though I'm US based, I had zero concerns ordering with Fred.

In general, the continuous power ratings and 2 Ohm stability with these new Purifi modules paired with minimal heat emission (vs older Hypex, or class A or A/B amps), low power consumption and compact form factor in a very nice implementation objectively represent an excellent HiFi value. I appreciate Purifi, Boxem, Buckeye and other smaller vendors here who are pushing Class D forward at reasonable prices for helping democratize sound quality.
Click to expand...
May I ask how this was resolved or what the best practice is? I will add a A 4216/E3 to a Marantz Cinema 40 on a KEF R(7+6) Metas setup. Just have to wait until the room is finished..
 
The way the new Purifi modules just keep pushing clean power at over 100 W and that smooth and gradual onset of distortion look so damn sleek :D

Some graphs:

THD+N Comparison_1ET6525SA.png


The usual disclaimer: I gathered this data from various sources including manufacturer spec sheets. The measurement conditions might differ. Especially the gains are likely not the same for each amp.

Sources:
 
mxmzd said:
May I ask how this was resolved or what the best practice is? I will add a A 4216/E3 to a Marantz Cinema 40 on a KEF R(7+6) Metas setup. Just have to wait until the room is finished..
Click to expand...
Are you asking about how the amp was optimized for the Denon's output voltage?

@boXem can configure the input stage of his A series amp for you during assembly.

IIRC, the standard high gain setting on mine was going to be 2V (low gain 4V) and that can be matched to extract the 3db more gain from the amp module with our AVRs. I paid a little extra to keep the low gain setting at 4v (instead of 2.8v) to have a better match with higher pre-out voltage stereo pre-amps.
 
DSPguy said:
If it was me I would start with one of these :

AMP-PDK-EVM Evaluation board | TI.com

View the TI AMP-PDK-EVM Evaluation board description, features, development resources and supporting documentation and start designing.
www.ti.com

One of these to clean up the aux power from the supply:


And a bunch of opamps. Along with an APx555. My goal would be to exceed the performance of the amp module in the input stage.
Click to expand...
Designers usually start a simulation SW before investing 35k in a measurement rig. This allows to check how realistic the requirements are...
 
DSPguy said:
Simple opamp based buffers are so trivial to implement. It a kindergarten level circuit. One would need to be severely incompetent to mess it up. However spending $35k on an APx555 or renting one is the only way to verify the final performance of the buffer+amp module when dealing with in excess of -120dB THD+N.
Click to expand...
According to it's datasheet, the typical 5W SINAD for the 1ET6525SA is 116.1 dB. If we want to keep the performance almost untouched, let's consider that we allow no more than 0.5 dB SINAD degradation. THD being far below noise with these amps, that means that the target noise for the amp would be 7.4 uV unweighted.
That means that the buffer noise must be below 2.4 0.58 uV unweighted.
To have an amplifier with 26.5 dB gain, we need 14.2 dB gain at buffer level.
Since you passed all kindergarten grades with flying colors, could you please show us preschoolers the schematic of a differential input stage with 14.2 dB gain and less than 2.4 0.58 uV unweighted noise, at least in theory.
Edit, I forgot that the buffer noise was amplified by 12.3 dB.
 
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Designing an input gain stage with the constraints of low noise and maintaining SFDR isn't trivial - given the amp's final output power requirements with a SINAD exceeding 100 dB. That too given the price of these amps in the range of $500-$800/channel.
 
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