Buckeye Purifi Eigentakt 1ET9040BA monoblock power amplifier

Requires only, posted on December 20, 2024 at 09:19:12
E-Stat Audiophile Posts: 39933 Joined: May 12, 2000 Contributor Since: April 5, 2002	a correction factor of three billion to one for operation!

probably still less finicky than a Boeing 737 MAX, though, posted on December 20, 2024 at 12:08:48

mhardy6647
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Everything can be fixed with enough NFB followed by enough DSP.
This is the age of miracle and wonder...

;)

In all seriousness, I'd love to have a chance to hear a pair... ain't gonna shell out $2.3k for the opportunity, though.

all the best,
mrh

PS -- oh, in all seriousness, thanks for sharing the info & link, emailtim, posted on December 20, 2024 at 12:21:40

mhardy6647
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I actually am kind of rooting for Class D, even though it strikes me as the "astronaut pen" solution to a "pencil" problem, so to speak. ;)

in fairness, the anecdote above is purely apocryphal but it still makes a good point, from my perspective (and for the context in which I use it) in terms of simplicity, elegance, robustness, reliability, and economy being at least as important ;) as technological sexiness when it comes to solving a problem.

Yeah... I'm old... and it shows sometimes. ;)

Plus, I really do like Kal and always enjoy a chance to read his work (and his thoughts)!

all the best,
mrh

You can read my thoughts!?!? (NT), posted on December 21, 2024 at 11:47:36
Kal Rubinson Reviewer Posts: 12581 Location: New York Joined: June 5, 2002

ooh, caught using imprecise syntax!, posted on December 21, 2024 at 18:18:49
mhardy6647 Audiophile Posts: 16297 Location: New England Joined: October 12, 1999 Contributor Since: October 23, 2016	... or was I? heh-heh-heh ;) all the best, mrh

You would know. (NT), posted on December 21, 2024 at 19:55:31
Kal Rubinson Reviewer Posts: 12581 Location: New York Joined: June 5, 2002

Kal did your online review have more photos ?, posted on December 21, 2024 at 21:59:55
AbeCollins Audiophile Posts: 48277 Location: Maidenhead Grid Square DM79 Joined: June 22, 2001 Contributor Since: February 2, 2002	I seem to think so but I'd have to revisit my print issues to compare.

Yes. (NT), posted on December 22, 2024 at 07:01:53
Kal Rubinson Reviewer Posts: 12581 Location: New York Joined: June 5, 2002

"On the other hand, they will not "improve" source material", posted on December 22, 2024 at 09:14:50
Feanor Audiophile Posts: 10346 Location: London, Ontario Joined: June 17, 2003 Contributor Since: March 12, 2004	Yeah, for sure that's a problem with super-accurate amplification. Dmitri Shostakovich

RE: "On the other hand, they will not "improve" source material", posted on December 22, 2024 at 10:15:19
Kal Rubinson Reviewer Posts: 12581 Location: New York Joined: June 5, 2002	The reason there are quotes around improve is that no amplifier can actually improve source materials and, thus, accurate (and "super-accurate" whatever that is) amplifiers will not corrupt source materials. Certainly, there are those who will choose otherwise.

RE: "On the other hand, they will not "improve" source material", posted on December 22, 2024 at 10:41:40
ejman Audiophile Posts: 408 Location: SW Oregon Joined: October 3, 2006	True, but an amp can hide flaws in the source material and make that source material more "listenable" I have lots of 50 cent Lps picked up in the old days of folks wanting to get rid of their vinyl any way they could. A nice 1% + distortion tube amp makes those old treasures sound great - an analytical amp not so much.

RE: "On the other hand, they will not "improve" source material", posted on December 22, 2024 at 12:07:08

Kal Rubinson
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Posts: 12581
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I get that and understand its use. However, if you use an amp that hides the faults of poor source materials, it will also apply the same distortion filter to good source material corrupting it to, perhaps, sounding as bad as the unfiltered poor sources.

IMHO, a better option is an accurate amp with an accessory switched filter/eq.

RE: "On the other hand, they will not "improve" source material", posted on December 22, 2024 at 12:27:12

ejman
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Posts: 408
Location: SW Oregon
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Perhaps so but my experience (of course, very limited compared to yours) is that an amp that makes relatively poor source material sound "better" as in hiding some of its flaws will not necessarily make good quality source material sound bad - it just wont reveal all the "goodness" and detail the superior source material has. I am not really arguing against great, revealing amplification which with the right source can be amazing. I'm just saying that with some (many?) less than perfect sources an amp with some flaws in its distortion and frequency response characteristics can be preferable and that those same amp characteristics won't necessarily detract from the listener's enjoyment of better source material.

I seem to remember a number of reviews over the years where the reviewer enjoyed the amp and praised its musicality highly while the technical testing showed a deeply flawed performance. I seem to recall one in particular where the amp was "essentially broken" per its performance on the bench yet it sounded wonderful according to the reviewer (Mr. Fremer if memory serves)

Yup., posted on December 22, 2024 at 14:35:46

Kal Rubinson
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Posts: 12581
Location: New York
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[quote]....will not necessarily make good quality source material sound bad - it just wont reveal all the "goodness" and detail the superior source material has.[/quote]

Sure but whether it is regarded as bad or just less good is both subjective and situational. I can understand that having a large library that is heavy on poor, old and/or compromised recordings would give you a different perspective than I have.

RE: Yup., posted on December 22, 2024 at 18:42:31
George6 Audiophile Posts: 190 Joined: November 18, 2012	Seem to recall that you had bought a pair of the NAD C298s which, in the original review, you compared to the Benchmark. Would you consider the C298 comparable to the Buckeye?

RE: "On the other hand, they will not "improve" source material", posted on December 22, 2024 at 19:34:22
hahax@verizon.net Audiophile Posts: 4459 Location: New Jersey Joined: March 22, 2006	I for one would never want to give up the magic of a great system playing great source material. And I personally know that the same was true for Gordon Holt who was not happy with the direction audio was going in.

Updated review scheduled for April 2025, posted on December 22, 2024 at 20:24:42
emailtim Audiophile Posts: 7079 Joined: July 2, 2017	Current review supposedly had defective amp modules from Purifi causing the high frequency IMD. . 2022/03/30 Historical Records CENSORED

On a related note, awaiting Kal, posted on December 22, 2024 at 20:51:08
AbeCollins Audiophile Posts: 48277 Location: Maidenhead Grid Square DM79 Joined: June 22, 2001 Contributor Since: February 2, 2002	I owned the Benchmark AHB-2 and now the NAD C298. In my setup they are very comparable but I seem to get a little better bass out of the C298. If I recall, Kal heard the opposite in his system but I might be wrong. Neither amp 'colors' the sound so if there is such a thing a 'neutral' I would claim that to be the case for the AHB-2 and my C298.

Thanks. I just saw that in the review Comments section , posted on December 22, 2024 at 21:12:45

AbeCollins
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On a related note I found the comment below very interesting as I have been curious about the Pass INT-60. I had the INT-150 which was a Pass 1st generation integrated that used a passive preamp section. It wasn't quite to my liking as it sounded less 'alive' vs my Pass Labs separates with the X2.5 active preamp.

Now I'm wondering if it's even worth trying the pricey INT-60. I wouldn't consider buying one new given its price but even a used one is not exactly chump change.

As former owner of PassLab Int-60...
Submitted by Strat56 on December 21, 2024 - 8:22am

... I am now a happy owner and listener of (diy) monoblocks based on Purify 1ET400A driving my Monitor Audio PL200 II and Allison Ones. No regrets having sold the PassLab and I would never step back to it after having experienced these class D. I fully share the brilliant KR review report... 100%.

The INT-60 Is not an overly "neutral" amp, posted on December 23, 2024 at 06:14:45

Jack G
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Posts: 9769
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I lived with one in my main system for over 3 years. It tends to be somewhat warm and smooth with authoritative bass. How much so depends on the rest of your system. Personal preferences certainly play a part. It's still a very good amp, but system matching can be a bit trickier than usual though. I would still recommend it to anyone looking for that type of sound. I eventually replaced mine with a Coda CSiB. To my ear, it sounds more linear with faster tighter bass.
It's not for those who prefer a more neutral/lean (depending on perspective) sound.
Jack

RE: The INT-60 Is not an overly "neutral" amp, posted on December 23, 2024 at 08:42:30

AbeCollins
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Thanks Jack for the insight on the Coda CSiB and Pass INT-60. There are times that I do prefer a warmer sounding system so long as it is dynamic and not veiled or rolled off.

I've read a little about the Coda line of products and if I recall correctly they allow you to choose the level of biasing to your preference. How is yours setup? Would describe it as slightly less warm sounding but more dynamic or punchier than your INT-160?

I had a few Pass Labs products over the years including the X150, X150.5, X3, INT-150, Aleph 3, X2.5 pre and XP-10 pre. The only two that I didn't care for very much were the INT-150 and Aleph 3. The X150.5 amp was especially nice when coupled to my Cary tube preamp.

RE: Yup., posted on December 23, 2024 at 12:02:52
Kal Rubinson Reviewer Posts: 12581 Location: New York Joined: June 5, 2002	I do consider that they are "comparable." The differences I strain to hear are trivial.

RE: The INT-60 Is not an overly "neutral" amp, posted on December 23, 2024 at 12:27:27

Jack G
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I had them bias mine so the first 18 watts are class A, the rest of the 150 watts is A/B. Other options are 12/300 or 8/400 Watts. They double into 4 ohms. Since my speakers are 100 db/watt efficient, I didn't mind losing some overall power since I probably don't go out of the first 18 watts anyway, or not by much. As for sound, it is more linear to my ear and a lot more transparent. It also sounds *faster* than the Pass amp. The bass is faster and tighter and the treble is cleaner and more extended. Someone who prefers the Pass amp might think the coda was a tad lean. :-)
Jack

Or, perhaps, it is the Buckeye input amplifier to blame?, posted on December 23, 2024 at 15:02:30
13th Duke of Wymbourne Audiophile Posts: 3040 Location: Orange Co., Ca Joined: September 19, 2001	I would guess that all the Purifi modules are fully tested at the factory. I wonder how thorough is Buckeye's final test regime?

RE: Or, perhaps, it is the Buckeye input amplifier to blame?, posted on December 23, 2024 at 15:13:04

emailtim
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Purifi said an early batch made its way out of the factory with the aforementioned issues.

The HF IMD does not explain the early/half power shutdown though which might be thermal related.
.

2022/03/30 Historical Records CENSORED

RE: Buckeye Purifi Eigentakt 1ET9040BA monoblock power amplifier, posted on December 24, 2024 at 01:38:58

Alex M
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Posts: 932
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I am intrigued by reports of Class-D amps. I use a Hypex plate amp for the bass of my semi-active DIY speakers (Troels Gravesen's superb MUN-17), and this simply works as it should.

When, out of pure curiosity, I replaced the push-pull 300B amp driving the mid and treble with the other amp in the Hypex module, I was disappointed, though. It certainly sounded very good, but missed a lot of the "magic" of the DHT amplifier. I assumed that this was because I couldn't bypass the digital filter circuitry in the plate amp, which may not have been as transparent as the amplifier itself.

If I could find a compact amp that was as subjectively satisfying as my valve amplifier, I would certainly welcome the convenience and reduced power conception. Has anyone directly compared a Hypex/Purifi Class-D amplifier with a good DHT amplifier?

Alex

RE: Or, perhaps, it is the Buckeye input amplifier to blame?, posted on December 24, 2024 at 14:22:02

13th Duke of Wymbourne
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Thanks for the info and I recant my skepticism! I looked at JA's measurements again and none of them are bad though the HF IMD is way, way higher than the Purifi datasheet but still not bad in absolute terms and, as JA noted, the energy in music rolls off pretty quickly so you'd certainly never encounter 50W at those frequencies! Even dropping the power by 20dB to a still high 5W those third order IMD terms would drop by 40dB and the fifth order terms by 60dB. Out of idle curiosity, I went to ASR to look for any Purifi measurements and found a whole thread about the Stereophile Buckeye review - lot's of conjecture until someone found the announcement from Purifi about the bad modules. I would be interested to know what happened, maybe a wrong value component got loaded into the SMT machine? But, I would have hoped that Purifi would have caught it at final test, maybe they didn't routinely do a high power IMD test and their test equipment doesn't have the resolution of an AP system to catch errors in very low distortion levels? Buckeye posted to the ASR thread and, it seems, they don't do any quantitative unit testing - a 'functional' test and a listening test. Maybe Buckeye don't have the resources for test equipment but, IMO, live by not testing, die by not testing. At least Buckeye now know their listening test isn't that effective so they could drop that:)

RE: Or, perhaps, it is the Buckeye input amplifier to blame?, posted on December 24, 2024 at 14:41:44

emailtim
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Buckeye said they acquired an AP and recently posted they no longer have it.

They did not give a reason why they no longer have such a pertinent piece of test equipment. That is a bit troubling and was a validation point for a potential customer such as myself who could box and wire a DIY kit.

For the initial world-wide review, one would assume they would inspect the review sample inside and out.

I was always taught, "Expect only what you inspect", because customers have much better memories when things go wrong than when they go right. I often found that personal inspection practice to not be ubiquitous in corporate/commercial life.

I am concerned about the half power shutdown. The Hypex SMPS can not fully power the 9040, but the amp shut down at half the Hypex SMPS's spec'd max output. It missed the 9040's max output in 2 ways. I hope that issue identified and resolved as well.

.

2022/03/30 Historical Records CENSORED

RE: Or, perhaps, it is the Buckeye input amplifier to blame?, posted on December 24, 2024 at 16:32:11

13th Duke of Wymbourne
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An AP unit is expensive and while it would be a tax write off I wonder how many amps you'd have to sell to pat for it. Jason Stoddard, of Schitt, wrote about chosing test gear in his blog though I don't remember the details but I think they have less expensive alternatives for final test. The catch-22 maybe that if you are selling products with claimed super-low distortion that you need super-expensive test equipment to prove it. Maybe the upshot for both Buckeye and Purifi is to run a very high power, high frequency IMD test and if the result is good enough on reasonably priced test equipment then it is probably good enough.

I've no idea about the power shut down. My best guess, as before, is that a batch.of boards were built with the wrong value SMT components and final test does not push power to the limit.

RE: Or, perhaps, it is the Buckeye input amplifier to blame?, posted on December 24, 2024 at 16:45:26

emailtim
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My guess is that a sheet metal floor pan is no longer sufficient for passive cooling of 1.2K to 1.4K watts.

From the manual:

1) Assumes a thermal system of adequate size to keep the amplifier module well within its thermal recommended operating range.

2.4 Thermal Requirements
While the 1ET9040BA has very low idle losses and high overall efficiency, adequate cooling is essential for
sustained power delivery. Careful consideration must be given to the design of the thermal system in order to
achieve desired output power specifications. 1ET9040BA's power efficiency and power loss is illustrated in
Figure 12 and Figure 13

Noctua NH-P1 Passive heatsink for less than 100 watt loads (0.4064 C/W, @ 60 watt load, 21.5 degrees over ambient)

.

2022/03/30 Historical Records CENSORED

https://purifi-audio.com/document/share/57/f6d5c393-72c6-4ae

RE: Or, perhaps, it is the Buckeye input amplifier to blame?, posted on December 25, 2024 at 20:23:13
George6 Audiophile Posts: 190 Joined: November 18, 2012	I own a VTV purify-based amp with which I am very happy. It's one of those amps that someone here likes to classify as built in a garage. From their website: "VTV Amplifier proudly uses the latest AP5x high resolution Audio Precision test equipment to certify and ensure performance. Test results are provided with each amplifier. "

RE: Or, perhaps, it is the Buckeye input amplifier to blame?, posted on December 26, 2024 at 17:14:04
13th Duke of Wymbourne Audiophile Posts: 3040 Location: Orange Co., Ca Joined: September 19, 2001	Nice that the measurements are provided. It is obviously a well equipped garage. Jason Stoddard wrote in his blog about the humble beginnings of Schitt in his garage and didn't Hewlett Packard start life in a garage? And at this time of year we are reminded of other humble beginnings in an an out building.

RE: Buckeye Purifi Eigentakt 1ET9040BA monoblock power amplifier, posted on December 27, 2024 at 20:59:35

emailtim
Audiophile

Posts: 7079
Joined: July 2, 2017

Class D is not going to give you tube coloration unless you explicitly add it. VTV has a tube buffer, but it isn't cheap.

Designed by Andrew Sparks of Sparkos labs, the buffer features a direct coupled dual triode driving a four transistor Wilson current mirror. The output of the current mirror feeds an I to V converter stage featuring a discrete opamp (of your choice). The board is compatible with almost any dual (or two single) opamps.

There are NO capacitors in the signal path.
The VTV Tube Buffer is compatible with all NCore and Purifi models and installs just like the standard VTV Custom Buffer.
.

2022/03/30 Historical Records CENSORED

VTV Tube Buffer

RE: Buckeye Purifi Eigentakt 1ET9040BA monoblock power amplifier, posted on December 28, 2024 at 13:16:57
Alex M Audiophile Posts: 932 Location: Hampshire Joined: February 9, 2001	Thanks for the suggestion. I don't need a tube buffer, though, since I use a very low distortion differential tube preamp (Vacuum State RTP3C). Alex

That Preamp should sound...., posted on December 28, 2024 at 15:28:23
Cougar Audiophile Posts: 4687 Location: SoCal Joined: June 25, 2001	Really nice with one of the popular Class D amps. My Hypex Nilai's sound great with my Masterpiece 300b preamp.

RE: That Preamp should sound...., posted on December 30, 2024 at 10:38:02
Alex M Audiophile Posts: 932 Location: Hampshire Joined: February 9, 2001	It would only work at its best into an amp with a balanced input, though. My current 300B amp is 100% differential. I feed my Hypex plate amps through the XLR connectors too. Alex

Amp/Preamp Asylum

Buckeye Purifi Eigentakt 1ET9040BA monoblock power amplifier

23.242.178.78