Buckeye 3 Channel Purifi Amplifier Review (2nd)

[Buckeye Amps]

The question answered itself, however. Sure it looks nice, but in terms of an measurable, let alone audible, difference...

 

[PHD]

Boxem offers nice shielded cabling with the Arthur 4215/E2 build and quality ETI binding posts.
View attachment 392692

You can't tell if it is twisted and that's doesn't look like a (gounded) shield. It looks like just a braided tubing to make it look nice.

 

[Descartes]

Boxem

Aren’t they more expensive than Buckeye?

 

[Buckeye Amps]

Definitely nicer looking options out there than our boring cases, have never argued that. And if people want to pay more money for looks (for both the case and binding posts), all the power to them.

 

[Descartes]

When I was shopping for another Purifi amp I was looking for quality binding posts like the ETI posts on my March Audio P452. I asked Buckeye if I could pay more for better binding posts. He was unable to accommodate the request so I asked Boxem if they could install ETI Kyro binding posts on their Arthur 4215/E2. Boxem was happy to help. I also wanted the higher gain options offered by Boxem on the 4215/E2. It's nice to be able to find a build with 27dB gain which matches AVR setups a bit better. I also noticed the build inside looked more professional than my Buckeye amps.

To your question, the Boxem ended up costing me $350 more than a Buckeye Purifi but the case was so much nicer, it included the ETI Kyro binding posts and support for higher gain options I wanted. The Boxem build quality is amazing. It was just what I wanted and the few extra dollars were well worth it for me. It's nice to have several sources for Purifi amps so users can get the options they desire.

True I agree especially when amplifiers are out in a living room. I personally like the design from Apollon Audio, Nord and NAD.

Of course they are more expensive!

One moment, please...

Nord Three 1ET7040SA 3CH MKII 3 Channel Power Amplifier - Nord Acoustics Ltd

The Nord Three 3CH MKII is our upgraded Purifi EIGENTAKT 1ET7040SA 3CH amplifier using 3 x power supply. Consisting of amp module, PSU, Input buffer.

nordacoustics.co.uk

M23 - NAD Electronics

Building on NAD’s long tradition of identifying and developing cutting-edge amplification technology, the M23 HybridDigital Stereo Power Amplifier features Purifi Audio’s Eigentakt™ design, a once-in-a-decade innovation that virtually eliminates harmonic and intermodulation distortion. Noise is...

nadelectronics.com

 

[PHD]

I remember that in the first review, the SINAD was lower and it turned out that it was due to bad XLR connectors. How is that even possible? The only way I can think of is added intermittent noise due to loose contact but it should only occur transiently when the cables are moved, not reflect in the steady state measurements.

Also, at the Buckeye amp FAQ it says that RCA to XLR adapters are not recommended and whole cables are preferred for the same reason. Can someone elaborate on that because it kinda contradicts what this forum claims about the fact that cables don't really matter and yet a simple connector in the signal chain could reduce SINAD by 20dB?

Thanks

 

[Buckeye Amps]

I remember that in the first review, the SINAD was lower and it turned out that it was due to bad XLR connectors. How is that even possible? The only way I can think of is added intermittent noise due to loose contact but it should only occur transiently when the cables are moved, not reflect in the steady state measurements.

Also, at the Buckeye amp FAQ it says that RCA to XLR adapters are not recommended and whole cables are preferred for the same reason. Can someone elaborate on that because it kinda contradicts what this forum claims about the fact that cables don't really matter and yet a simple connector in the signal chain could reduce SINAD by 20dB?

Thanks

It was the binding posts, not XLR connectors.
The original binding posts were ferrous, causing slightly higher distortion. That was rectified quickly. And have since switched to even higher quality binding posts.

But even then, there was no audible issue. Only measured.

 

[Buckeye Amps]

Dylan,
What is the brand and model of the new binding posts currently installed on new Buckeye amps? Is it the same binding post on all Buckeye amps sold? What material are they made of? Are they magnetic? Thank you!

They are custom manufactured so no big brand name. Same on all amps/models. Brass (non magnetic)

 

[paulcc]

I think you meant to say "Brass (non magnetic)"

 

[PHD]

It was the binding posts, not XLR connectors.
The original binding posts were ferrous, causing slightly higher distortion. That was rectified quickly. And have since switched to even higher quality binding posts.

I assume that ferrous binding posts combined with the high-frequency PWM currents of the class D amp leads to induced eddy currents which can caused added HF noise ... Interesting. So what about the fact that 90% of speaker binding posts do contain ferromagnetic materials, even high-end Focals where proven to be ferromagnetic... Don't see the point in using non-magnetic posts on the amp side...

 

[Buckeye Amps]

I think you meant to say "Brass (non magnetic)"

Thanks. Auto correct issues apparently

 

[Buckeye Amps]

@PHD

That's why I mentioned the measurement difference noticed with the original ferrous binding posts was an inaudible issue and more just something to fix so measurements were in-line with what the Purifi 1ET400A should messure as.

 

[-Matt-]

Looking at the websites of different manufacturers, it seems that Buckeye and Audiphonics both offer three channel Purifi amps with a single SMPS1200A400 power supply, whilst Nord uses three SMPS1200A400 supplies (one per channel).

Would using a single SMPS1200A400 cause any sort of bottleneck?

 

[HaveMeterWillTravel]

Looking at the websites of different manufacturers, it seems that Buckeye and Audiphonics both offer three channel Purifi amps with a single SMPS1200A400 power supply, whilst Nord uses three SMPS1200A400 supplies (one per channel).

Would using a single SMPS1200A400 cause any sort of bottleneck?

Ultimately it would depend on your use case and your electrical circuit. A single SMPS1200A400 is rated for 1200W rms.

Consider having three 1200W power supplies. Can you pull 3600W rms out of your wall socket?
Most people here in the US have 15-amp circuits, but let's say you have upgraded to a 20-amp circuit/outlet.
And it's rock steady at 120Vac under the 20A draw. That's still only 2400W rms.

Now consider having a single power supply. That power will be split between three channels.
How often will you be actually using more than 400W rms on all three channels simultaneously?

Maybe initially one may be able to hear a slight difference, but speakers with even a mediocre efficiency will still be dang loud.
So you probably wont hear a difference in short order.

(intentionally ignoring dynamics, crest factor, and efficiency to simplify)

 

[MaxwellsEq]

Looking at the websites of different manufacturers, it seems that Buckeye and Audiphonics both offer three channel Purifi amps with a single SMPS1200A400 power supply, whilst Nord uses three SMPS1200A400 supplies (one per channel).

Would using a single SMPS1200A400 cause any sort of bottleneck?

It's possibly worth comparing the sustained continuous power output of the PSU. If you think you will exceed that value divided by three, you may choose more PSUs.