This is a second review of the Buckeye 3-Channel Purifi based balanced class D amplifier. First sample had an issue with its binding posts increasing distortion. It costs US US $1,595.
Typical of Buckeye amplifiers, focus on what is inside rather the case which is utilitarian. An indicator nicely shows status of the amplifier (on, fault or overload). Back panel sports a 3-way switch for setting the gain which is very nice to have:
Let's get right into the measurements to see if the issue with distortion is resolved (I ran full suite of tests).
Buckeye Purifi 3 Channel Amplifier Measurements
Let's start with our low gain dashboard:
Looking at the spectrum of the FFT we see a large reduction in harmonic distortion compared to the first sample. SINAD as a result improves a bit although it is mostly noise limited. Still, we match the reference design, landing the amp solidly in our top 20 best amplifiers ever measured (out of over 200):
You need pro type interface to drive the low gain to full power (as much as 7 volts for 4 ohm). Fortunately high gain hardly brings any penalty:
Request was made to show power with reactive loads as opposed to just resistive as is the norm in my reviews (and industry). Using my new PowerCube loadbox, I can do that:
Capacitive load doesn't change things but inductive loads it down a bit more. SINAD remains more or less the same so really, nothing of worry.
SNR is the same as before and excellent:
Frequency response is flat as always: (should say "NO load impedance dependency"
Oh, forgot to mention that I am testing channels 1 and 3. Due to larger distance, crosstalk is even better now (and was incredible before):
Multitone shows an improvement of 2 bits:
Let's dig into power measurement where we saw the rising distortion before:
Performance is far improved. No longer do we have a large hump in mid-power region. There is a small increase that exists but we can ignore it:
Power remains as before:
Here is the warm up behavior:
I didn't re-run the on/off pop test. Should be the same as before (which was very good).
Reactive Load Amplifier Power Testing
Let's use our fancy Powercube loadbox to simulate both capacitive and inductive loads ranging from 8 down to 2 ohms (amplifier goes into protection with 1 ohm):
(ignore the color differences.) Response is perfect. Regardless of load impedance down to 2 ohm reactive, the amplifier maintains the same output voltage. Can't ask for more.
Conclusions
It is great to see such responsive companies such as Buckeye that take the results of a review and instantly jump on the issue identified to resolve it. And resolve they have. Performance is essentially identical to Purifi reference design. Value added is provided in the form of a 3-gain buffer stage and powerful power supply that allows all three channels to produce near full power when driven simultaneously. Results is one of the cleanest/most transparent multichannel amplifiers you can buy.
I am happy to add the Buckeye Purifi 3-Channel amplifier to my recommended list.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Typical of Buckeye amplifiers, focus on what is inside rather the case which is utilitarian. An indicator nicely shows status of the amplifier (on, fault or overload). Back panel sports a 3-way switch for setting the gain which is very nice to have:
Let's get right into the measurements to see if the issue with distortion is resolved (I ran full suite of tests).
Buckeye Purifi 3 Channel Amplifier Measurements
Let's start with our low gain dashboard:
Looking at the spectrum of the FFT we see a large reduction in harmonic distortion compared to the first sample. SINAD as a result improves a bit although it is mostly noise limited. Still, we match the reference design, landing the amp solidly in our top 20 best amplifiers ever measured (out of over 200):
You need pro type interface to drive the low gain to full power (as much as 7 volts for 4 ohm). Fortunately high gain hardly brings any penalty:
Request was made to show power with reactive loads as opposed to just resistive as is the norm in my reviews (and industry). Using my new PowerCube loadbox, I can do that:
Capacitive load doesn't change things but inductive loads it down a bit more. SINAD remains more or less the same so really, nothing of worry.
SNR is the same as before and excellent:
Frequency response is flat as always: (should say "NO load impedance dependency"
Oh, forgot to mention that I am testing channels 1 and 3. Due to larger distance, crosstalk is even better now (and was incredible before):
Multitone shows an improvement of 2 bits:
Let's dig into power measurement where we saw the rising distortion before:
Performance is far improved. No longer do we have a large hump in mid-power region. There is a small increase that exists but we can ignore it:
Power remains as before:
Here is the warm up behavior:
I didn't re-run the on/off pop test. Should be the same as before (which was very good).
Reactive Load Amplifier Power Testing
Let's use our fancy Powercube loadbox to simulate both capacitive and inductive loads ranging from 8 down to 2 ohms (amplifier goes into protection with 1 ohm):
(ignore the color differences.) Response is perfect. Regardless of load impedance down to 2 ohm reactive, the amplifier maintains the same output voltage. Can't ask for more.
Conclusions
It is great to see such responsive companies such as Buckeye that take the results of a review and instantly jump on the issue identified to resolve it. And resolve they have. Performance is essentially identical to Purifi reference design. Value added is provided in the form of a 3-gain buffer stage and powerful power supply that allows all three channels to produce near full power when driven simultaneously. Results is one of the cleanest/most transparent multichannel amplifiers you can buy.
I am happy to add the Buckeye Purifi 3-Channel amplifier to my recommended list.
------------
As always, questions, comments, recommendations, etc. are welcome.
Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Last edited:
