Buckeye Amps: 2nd Generation Purifi EIGENTAKT 1ET9040BA Amplifier

[David_M]

I'll certianly let you know the 1kHz power sweep as planned.

Why the generic 1 kHz sweep and not the 20Hz I'm talking about.

 

[Buckeye Amps]

Why the generic 1 kHz sweep and not the 20Hz I'm talking about.

Maybe I'll start doing 40Hz like Amir has recently incorporated. At any rate, I believe Alan is going to be getting you the data you need before me so either way you'll have an answer.

 

[David_M]

Maybe I'll start doing 40Hz like Amir has recently incorporated. At any rate, I believe Alan is going to be getting you the data you need before me so either way you'll have an answer.

Ahhh ... I see what you just did, my friend. Peace and no worries !

 

[Full Zhou]

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

Could you please confirm if this test was conducted using the latest amplifier module provided by Purifi? There were issues with the previous version—was it a problem with the entire trial production batch, or only some individual units?

 

[Buckeye Amps]

Could you please confirm if this test was conducted using the latest amplifier module provided by Purifi? There were issues with the previous version—was it a problem with the entire trial production batch, or only some individual units?

That test was done with a recent batch from December.

The defective modules in question were all collected back to Purifi back in early Fall 2024. We unfortunately had one that did not make it back to them.

All is good for any 9040 customer from any company now.

 

[Holmz]

Why the generic 1 kHz sweep and not the 20Hz I'm talking about.

I am guessing that you are concerned with using the amp as a subwoofer amp??
Or why the 20 Hz?

 

[Full Zhou]

Judging from the pictures online, there are also multiple versions of their 1ET6525. Did the first batch have the same issues?

 

[Buckeye Amps]

Judging from the pictures online, there are also multiple versions of their 1ET6525. Did the first batch have the same issues?

Nope, just the very first batch of 9040 modules back in June

 

[Old_School_Brad]

I am guessing that you are concerned with using the amp as a subwoofer amp??
Or why the 20 Hz?

Amplifiers are generally expected to amplify the full range, aren’t they?

Testing at the extremes can provide a good indication of performance across the range.

 

[Willem]

Isn't it time to drop this discussion? This clearly is an excellent amplifier, even if there was a slight issue on some early production modules. The issue has been identified and addressed by Purifi and Buckeye, two reputable manufacturers, so we should expect it to have been solved. To be absolutely sure, all we have to do is wait for Stereophile, but I think the continued excitement is a bit overblown.

 

[Holmz]

Amplifiers are generally expected to amplify the full range, aren’t they?

Testing at the extremes can provide a good indication of performance across the range.

Maybe… Maybe not.
A lot of systems have subwoofers to do “the hard work”, and that makes the floorstanders not have to do it all, and reduces some of the distortion in the main speakers.

Obviously someone looking at 1.4 kW amps is likely wanting some significant bass capability as that is where lost of the power goes.
But it would not be unreasonable to have a 1.4kW amp mostly for headroom… while scraping the lower registers off and servicing them with a subwoofer.

 

[David_M]

I am guessing that you are concerned with using the amp as a subwoofer amp??
Or why the 20 Hz?

Because some class D amps have had issues playing low end notes (higher THDN and power than at mid range) due to the nature of their design...inadequate power supply capacitance creating bus pumping issues.

 

[Reddoc]

Amplifiers are generally expected to amplify the full range, aren’t they?

Testing at the extremes can provide a good indication of performance across the range.

I would have thought that testing across the range of interest would provide a good indication of performance across the range of interest

 

[David_M]

I would have thought that testing across the range of interest would provide a good indication of performance across the range of interest

Not true, unfortunately. Take tube amps for example. They perform well in the midrange but suffer from low bass extension due to transformers that step down the high voltage signals (hundreds of volts) to normal voltages. Transformers saturate quickly at low frequencies, increasing distortion and having a 'bandpass filter' for a frequency response.

 

[Holmz]

Because some class D amps have had issues playing low end notes (higher THDN and power than at mid range) due to the nature of their design...inadequate power supply capacitance creating bus pumping issues.

I can understand that in terms of the power supply.
And especially when the frequency gets low and gets near the AC frequency.

[edit]

At some point testing the device with some lab type of power supply seems appropriate for evaluating the amp section.
And there is often a market for “after market” power supplies that offer some real or perceived benefit.
Which would be a separate test of power supplies.

Class-D with the massive feedback would generally be more immune to power supply fluctuations than some zero-feedback class A or AB amp.
At least up until the power supply drop below the needed rail level.

 

[Reddoc]

low bass extension

Is that not in the range of interest?

 

[David_M]

Is that not in the range of interest?

You are correct. I thought by 'range of interest', you meant a custom user defined range and not the 20Hz - 20kHz standard audio range.

 

[Old_School_Brad]

Maybe… Maybe not.
A lot of systems have subwoofers to do “the hard work”, and that makes the floorstanders not have to do it all, and reduces some of the distortion in the main speakers.

Obviously someone looking at 1.4 kW amps is likely wanting some significant bass capability as that is where lost of the power goes.
But it would not be unreasonable to have a 1.4kW amp mostly for headroom… while scraping the lower registers off and servicing them with a subwoofer.

I would expect any amplifier to deliver full power across the entire human audible range.

While one might argue that full power at high frequencies isn’t always necessary, the area where full power is absolutely critical is at low frequencies. In this regard, there should be no room for compromise.

 

[Holmz]

I would expect any amplifier to deliver full power across the entire human audible range.

While one might argue that full power at high frequencies isn’t always necessary, the area where full power is absolutely critical is at low frequencies. In this regard, there should be no room for compromise.

OK I get where you are coming from.

1) However playing 20Hz tones at 1400W versus 1000W is somewhat different than
2) Playing music with a peak value of 1400W, and an RMS power at whatever the crest factor ends up at.

The test says it will not do #1.
There does not seem to be a test showing that it is doing #2

And, at home, we do not usually do scenario #1…
That is my point.
That failure to do 1400W sustained is meaningless unless you have some open area and/or huge room.
In which case one is almost certainly using multiple amps and speaker boxes… often some of them being subwoofer boxes.

Maybe you are blessed with a very large room, and it is a real concern.

... In this regard, there should be no room for compromise.

There is not a lot of compromise here… it is good performing amp by most objective standards.
And if one is even using the full 1400W, then they just get consider using a beefier power supply.

Otherwise it seems like pissing-n-moaning about loss of a dB or less, and a legal challenge towards not meeting spec.

 

[Old_School_Brad]

OK I get where you are coming from.

1) However playing 20Hz tones at 1400W versus 1000W is somewhat different than
2) Playing music with a peak value of 1400W, and an RMS power at whatever the crest factor ends up at.

The test says it will not do #1.
There does not seem to be a test showing that it is doing #2

And, at home, we do not usually do scenario #1…
That is my point.
That failure to do 1400W sustained is meaningless unless you have some open area and/or huge room.
In which case one is almost certainly using multiple amps and speaker boxes… often some of them being subwoofer boxes.

Maybe you are blessed with a very large room, and it is a real concern.


There is not a lot of compromise here… it is good performing amp by most objective standards.
And if one is even using the full 1400W, then they just get consider using a beefier power supply.

Otherwise it seems like pissing-n-moaning about loss of a dB or less, and a legal challenge towards not meeting spec.

My main point is about transparency.

While it’s true that using the full 1400 W would require a larger power supply, the lack of transparency makes it difficult to determine how large that supply should be if the ratings can’t be fully trusted.

To draw a comparison, power supplies for stationary PCs are typically designed to deliver their rated output continuously. This allows users to address issues by selecting a larger PSU based on specifications.

It’s unclear to me why this same level of design transparency isn’t consistently applied to audio power supplies. It can sometimes feel as though music-related equipment isn’t held to the same standard, which can create confusion.

The bottom line is that when rated power is required within a specific frequency band, the amplifier should reliably deliver it. This is especially important in the low frequencies, where power is essential.