Buckeye 3 Channel Purifi Amp Review

[EJ3]

I like that too. @Buckeye Amps, Dylan you really should get a voltage divider made from precision resistors and a good ADC so you can test gear yourself. It's next level stuff and you need them. I am pretty sure one of the peeps here @ ASR with a setup can help you out in getting setup. I would assist but I don't have a ADC with probe setup and so I'm not 100% familiar with the stuff.

EDIT: You could even include a test screenshot printout with each amp that you sell. It's a nice touch.

Yes, like some engine builders provide a DYNO sheet of the actual engine you ordered.

 

[DWPress]

I own a Buckeye 4ch Hypex NC252 amp, serial number 02. Have been happy with it from day one, even happier now that I see Dylan going to such lengths to keep his customers content and his own integrity intact.

 

[pma]

The speaker outs on the input board use FastONs

We actually did modify a board yesterday to move the FastON's off/away from the board but no change in distortion during testing.

I asked because I could see the distortion rise above 10W in almost all of your amplifiers, even in NC252MP based amp. I also have a NC252MP based amp and cannot see it:

PMA-NC252MP power amplifier

Not necessarily surprising given we already have THD+N measurements as a function of power for various frequencies (obviously Amir used 45 kHz bandwidth instead of 24 kHz) which show the high and low frequencies giving out first, but the log scale makes the difference less obvious at first...

www.audiosciencereview.com

I found this, that’s why I asked.

 

[Doodski]

I asked because I could see the distortion rise above 10W in almost all of your amplifiers, even in NC252MP based amp. I also have a NC252MP based amp and cannot see it:

PMA-NC252MP power amplifier

Not necessarily surprising given we already have THD+N measurements as a function of power for various frequencies (obviously Amir used 45 kHz bandwidth instead of 24 kHz) which show the high and low frequencies giving out first, but the log scale makes the difference less obvious at first...

www.audiosciencereview.com

I found this, that’s why I asked.

View attachment 252071

When was this pic taken? Was it at the beginning of production or middle or closer to the now. I was going to critique it but if it is a old production unit then there's no sense in critiquing the assembly.

 

[pma]

I suspect something with steel. In the post #1, we can see H3 much higher than is normal for Purifi module. It is 5W/4 ohm measurement. I also think about the sheet metal case. @Buckeye Amps , have you tried to measure a module out-of-the box?

 

[mdsimon2]

I asked because I could see the distortion rise above 10W in almost all of your amplifiers, even in NC252MP based amp. I also have a NC252MP based amp and cannot see it:

PMA-NC252MP power amplifier

Not necessarily surprising given we already have THD+N measurements as a function of power for various frequencies (obviously Amir used 45 kHz bandwidth instead of 24 kHz) which show the high and low frequencies giving out first, but the log scale makes the difference less obvious at first...

www.audiosciencereview.com

I found this, that’s why I asked.

View attachment 252071

Link below has internal pictures of the Buckeye Purifi amp. Setup is a bit different as there is a dedicated input buffer board as mentioned elsewhere in this thread.

Buckeye Amps: Purifi 1ET6525SA (the successor to the 1ET400A)

Not looking for any pats on the back. But I know my lead times have probably lost me some customers and/or had others question just how serious my business is. I don't blame those thoughts. I definitely get it. And I know I've said a few times "things will speed up, just a little longer and...

www.audiosciencereview.com

Also thread below has prelim testing of the Buckeye Purifi amp that shows the same elevated distortion at higher power output as Amir's review. It initially appears like the higher distortion onset starts at higher power output than Amir's review but I think that is because the measurement rig is higher noise.

Measuring 2-channel Buckeye Purifi Amplifier Performance

With Amir busy with house repairs, @Buckeye Amps and I discussed whether I might share some of my efforts to measure his Purifi amplifier as a stop gap until Amir can do so. A couple of disclaimers here as I am NOT an experienced electrical engineer and my QuantAsylum test rig is NOT as capable...

www.audiosciencereview.com

Michael

 

[Buckeye Amps]

I suspect something with steel. In the post #1, we can see H3 much higher than is normal for Purifi module. It is 5W/4 ohm measurement. I also think about the sheet metal case. @Buckeye Amps , have you tried to measure a module out-of-the box?

Regarding the case: it is aluminum (just an fyi).

The picture posted of the XLR with the FastON tab is from my very first iteration of my Hypex build back in 2020.

The Purifi build buffer board uses board-mounted XLRs (same with the input board I use on my Hypex builds now).

Internal pictures can be found on my website.

 

[dscottj]

You wait three month for a Buckeye Purifi. Next, the ASR review is released...

That's literally me. I got mine a little more than a month ago after placing the order in late August. That said, while I'm concerned I'm not mad or even disappointed. OEM has promised a fix and has been extremely responsive almost from the moment this came out. In a weird way I'll be looking forward to a board fix if it comes to that because it'll give me an excuse to take a screwdriver to it.

I'm quite sympathetic to Dylan. This must've been one hell of an unwelcome Christmas present. Not as unwelcome as that Michigan game of course, but still!

 

[Bruce Morgen]

I suspect something with steel. In the post #1, we can see H3 much higher than is normal for Purifi module. It is 5W/4 ohm measurement. I also think about the sheet metal case. @Buckeye Amps , have you tried to measure a module out-of-the box?

In my experience, even the cheapest imaginable Fastons aren't ferromagnetic at all and therefore not made of "steel." That even goes for the ones found in "home handyman" assortments from Harbor Freight, a very "bargain basement" chain of tool emporiums here in the U.S. -- even a neodymium magnet can't attract them. Moreover, when you start blaming tiny bits of steel in an amplifier's output circuit for measurable distortion at the relatively low frequencies involved in audio, you're pretty much in Danny Richie audiophool woo-woo territory.

 

[Fahzz]

Asking for a friend: How much for one of these with this inaudible defect?

 

[pma]

In my experience, even the cheapest imaginable Fastons aren't ferromagnetic at all and therefore not made of "steel." That even goes for the ones found in "home handyman" assortments from Harbor Freight, a very "bargain basement" chain of tool emporiums here in the U.S. -- even a neodymium magnet can't attract them. Moreover, when you start blaming tiny bits of steel in an amplifier's output circuit for measurable distortion at the relatively low frequencies involved in audio, you're pretty much in Danny Richie audiophool woo-woo territory.

Base material of faston terminals is either brass, or phosphor bronze, or steel. Depends what you purchase.

https://www.farnell.com/datasheets/1658358.pdf

 

[DSJR]

I owned NAIMs since serial nr 002 on some models and I have no idea what you are saying? What on earth is a “banana shaped rectangular sleeve?”

Post 1980, the construction was a U shaped tray slid into a cast rectangulart sleeve (CB and Olive versions). Said sleeve rang like a bell, so Nail fitted a little plastic 'strip' over the rear edge of the inner tray which on completion, was pushed into contact with the sleeve to reduce the clanky rining noise it made. Most of these castings weren't fully 'straight' and 'true' either, hence the 'banana' remark. I had a now deceased pal with six NAP135's and a NAP250 from a previous system (he didn't sell anything) and four of the seven cases weren't properly straight! The current cosmetic style post 2000 is rather better but the matt finish can hide a multitude of case flaws apparently.

 

[don'ttrustauthority]

For an 'objective' site, the decisions about recommended gear seems rather catch as catch can.

 

[pseudoid]

Thank you, Amirm,
1kHz test tone for THD measurements seem so arcane.
Wouldn't an automated sweep be more representative of the EUT performance?
Your 2nd to last graph comes close...

 

[Urvile]

Sigh...
"While probably not an audible concern, it is nevertheless a blemish on the otherwise near perfect performance of the Purifi modules."

I believe Dylan when he says that it's not audible, otherwise I can't imagine he would have shipped even one out. He's been incredibly transparent and helpful.
I respect that Amir found a bug, didn't hide it, and reached out to Dylan. I wish he could have tested if it was audible, and if not, made it a caveat, instead of not recommending it. And worked with Dylan to test whatever fix that is needed.

I ordered one and it's shipping on Monday, my expectation is that it's not audible , and that Dylan will have a fix. (Consider there are many that are in the hands of customers already, and if audible would have posted something)

I have no regrets other than the grief this may give Dylan.

 

[sarumbear]

Post 1980, the construction was a U shaped tray slid into a cast rectangulart sleeve (CB and Olive versions). Said sleeve rang like a bell, so Nail fitted a little plastic 'strip' over the rear edge of the inner tray which on completion, was pushed into contact with the sleeve to reduce the clanky rining noise it made. Most of these castings weren't fully 'straight' and 'true' either, hence the 'banana' remark. I had a now deceased pal with six NAP135's and a NAP250 from a previous system (he didn't sell anything) and four of the seven cases weren't properly straight! The current cosmetic style post 2000 is rather better but the matt finish can hide a multitude of case flaws apparently.

It’s interesting how you explain a case like this to “ring like a bell” or looks like a “banana.”

 

[_thelaughingman]

I’m glad that the community here is sensible with their responses and approach to this review. We obviously hold a standard for transparency at ASR and to see Dylan from @Buckeye Amps provide a transparent response to the minor shortcoming of this amp is refreshing and endearing. Glad to see that Amir and Dylan have a good working relationship, which benefits the majority of the ASR community. @Buckeye Amps I do feel bad that this minor blip will be a source of pain for now, but there’s nothing but success from here on out for you.

 

[Buckeye Amps]

I also want to make sure no one mistakes me saying the problem is likely inaudible as me trying to say "this is not an issue"

A mixture of objective reasoning and subjective listening (as I use the same amp and am very familiar with how my setup should sound) points to this not causing an audible or noticeable impact to the consumer. I would be very surprised if someone A/B'ed their amp pre and post fix and heard a real change/improvement.

BUT that does not mean this is not an issue that shouldn't be addressed. I know sometimes people can use the scapegoat of "you won't hear it" to defend measurement shortcomings. Definitely not what I am trying to do (I think that is obvious).

 

[Fahzz]

I also want to make sure no one mistakes me saying the problem is likely inaudible as me trying to say "this is not an issue"

A mixture of objective reasoning and subjective listening (as I use the same amp and am very familiar with how my setup should sound) points to this not causing an audible or noticeable impact to the consumer. I would be very surprised if someone A/B'ed their amp pre and post fix and heard a real change/improvement.

BUT that does not mean this is not an issue that shouldn't be addressed. I know sometimes people can use the scapegoat of "you won't hear it" to defend measurement shortcomings. Definitely not what I am trying to do (I think that is obvious).

Your commitment to your product is obvious, and you have a lot of supporters and "helpers" here apparently. This will get sorted. Enjoy your holidays, and congratulations on your degree.

 

[Urvile]

I also want to make sure no one mistakes me saying the problem is likely inaudible as me trying to say "this is not an issue"

I for one did not interpret your comment that way, to paraphrase you:
Oh damn we tested the best we could, both objectively and subjectively, and we missed something, and we are investigating a fix.

Even Amir said it's probably not audible. And in no way have I inferred, that you thought it was not an issue, nor that you won't address it.