Buckeye 6 Channel Amplifier Review

[Venture4663]

If comparing between those two and your budget is within the range of the 3ch Purifi, I would recommend the Purifi.

Do you have any thoughts or predictions to share on the Purify vs the new ncorex modules?

 

[Buckeye Amps]

My prediction is similar performance (maybe even "exact") but with the Hypex being a little cheaper.

 

[xaxxon]

Swapping just 2 channels instead of all of a home theater system is not that straight forward. You would need matching gain on the power amp section, you would need measurments. Plus there is no reason movie lovers would want less fidelity. If anything, the Dynamic range on most movie soundtracks is quite a bit greater than for most recorded music. also, notice that the top measuring amp here contain amplification topology developped by a company mainly involved in movie theater/home theater audio, and bloomed with this use case in mind.

you just run the correction software and you're done. you don't need to manually match anything.

 

[cardsdoc]

Hoping to get some input on my amp choice from the experienced folks here. My AVR is a Marantz SR8015. LCR are revel F36x3 which are 6ohm, 91db. I sit ~9ft from the front sound stage. Other speakers include front wides Revel M16 x 2, surrounds Revel S16 x 4, Atmos Revel C763L x 4. Subs SVS PC-4000x2. I needed an additional 2 channel amp when adding the wides and figured I might as well just offload the LCR. I wound up purchasing the Buckeye 4 channel NC252MP which I have now. I don't listen at reference however would like the headroom to hit 105db peaks if needed. What I didn't realize was that Hypex reports max power and not RMS. My SPL calculations were based on the max power and I had estimated 200 watts for 6ohm speakers. Dylan is confident that I shouldn't have any issues hitting those peaks in my HT setup given that they do not need to be continuous and also assuming the amp is kept cool. What power numbers should I use for the SPL calculation at MLP and do you think the NC252MP is sufficient based on Amir's measurments? Thanks.

 

[mdsimon2]

Hoping to get some input on my amp choice from the experienced folks here. My AVR is a Marantz SR8015. LCR are revel F36x3 which are 6ohm, 91db. I sit ~9ft from the front sound stage. Other speakers include front wides Revel M16 x 2, surrounds Revel S16 x 4, Atmos Revel C763L x 4. Subs SVS PC-4000x2. I needed an additional 2 channel amp when adding the wides and figured I might as well just offload the LCR. I wound up purchasing the Buckeye 4 channel NC252MP which I have now. I don't listen at reference however would like the headroom to hit 105db peaks if needed. What I didn't realize was that Hypex reports max power and not RMS. My SPL calculations were based on the max power and I had estimated 200 watts for 6ohm speakers. Dylan is confident that I shouldn't have any issues hitting those peaks in my HT setup given that they do not need to be continuous and also assuming the amp is kept cool. What power numbers should I use for the SPL calculation at MLP and do you think the NC252MP is sufficient based on Amir's measurments? Thanks.

The Hypex datasheet reports average power for a continuous 1 kHz sine wave input at 1% THD. RMS power really isn't a term but is unfortunately commonly used as average power is calculated by multiplying RMS voltage by RMS current.

How long a NC252MP will be able to produce ~200 W in to 6 ohm depends on how much cooling it has. For typical operation playing music a NC252MP in a simple aluminum enclosure will have sufficient cooling, if you are playing full power test tones for minutes at time you will need more substantial cooling.

Assuming that 91 dB sensitivity at 2.83V / 6 ohm is even remotely accurate you will have no issue hitting 105 dB with a NC252MP, even with a single speaker. In fact Hypex says that a bare module with no additional cooling in 25 degC ambient air can produce 50 W indefinitely. 50 W in to 6 ohm is a voltage of sqrt(50 x 6) = 17.32 V which is 15.7 dB greater than the 2.83 V the sensitivity is quoted at it, so 91 dB + 15.7 dB = 106.7 dB.

I should say I find calculating theoretical SPLs a bit of a wasted exercise. If you don't see the clipping indicators going off at your highest levels you have nothing to worry about.

Michael

 

[cardsdoc]

The Hypex datasheet reports average power for a continuous 1 kHz sine wave input at 1% THD. RMS power really isn't a term but is unfortunately commonly used as average power is calculated by multiplying RMS voltage by RMS current.

How long a NC252MP will be able to produce ~200 W in to 6 ohm depends on how much cooling it has. For typical operation playing music a NC252MP in a simple aluminum enclosure will have sufficient cooling, if you are playing full power test tones for minutes at time you will need more substantial cooling.

Assuming that 91 dB sensitivity at 2.83V / 6 ohm is even remotely accurate you will have no issue hitting 105 dB with a NC252MP, even with a single speaker. In fact Hypex says that a bare module with no additional cooling in 25 degC ambient air can produce 50 W indefinitely. 50 W in to 6 ohm is a voltage of sqrt(50 x 6) = 17.32 V which is 15.7 dB greater than the 2.83 V the sensitivity is quoted at it, so 91 dB + 15.7 dB = 106.7 dB.

I should say I find calculating theoretical SPLs a bit of a wasted exercise. If you don't see the clipping indicators going off at your highest levels you have nothing to worry about.

Michael

Thanks appreciate it.

 

[Stinga]

Hello from New Zealand people! Can @Buckeye Amps or one of you other knowledgeable lads help me out a bit pls as my mis-bent youth has obviously affected my brain capacity in regards to amp power.....

I want to upgrade my system and it ranges from AVR upgrade say MRX740 / 6800 vs AVM70 plus MC amp, depending on if the finance minister finds out or not second option appeals to me for end game solution.

The difficulty I have is comparing amp specs as everyone seems to have a different way of stating their power capacity re THD and freq.

My current Denon (I need more power as when running Zone 2 outside hard, I trip the amp..) has the following specs:
125w x 2 @8ohms 20-20khz at 0.05%THD
165w x 2 @6ohms 1khz at 0.7%THD
Dynamic power 130w@ 8ohms and 190w@ 4 ohms whatever this is?

What is the correlation between the above and say Dylans 252 or 502 ie how much power does the Denon give me in the same terms as what the 252 or 502 does?

Likewise say the Anthem 740 vs 252/502:
140w @ 8ohms at 1%THD
170w @ 6ohms at 1%THD

Happy to be schooled!!
Thanks a heap
Al

 

[anarchist]

This is a review and detailed measurements of the Buckeye Hypex NC252MP based, 6-channel amplifier. It costs US $1149 as of this writing. The owner/builder is @Buckeye Amps on our forum.

The looks are fine for a well-priced build:

View attachment 100354

The unit is quite light courtesy of rather thin sheet metal. I am not as worried about the top being thin but the bottom is as well and that is where heat is generated. You won't likely push all three modules to max but if you did, I would put taller feet under it and maybe even some temperature controlled fans. In my testing the bottom just got a bit warm so not a major concern.

Back panel shows standard connectors plus the trigger input:
View attachment 100355

I stopped using my Mogami Gold XLR cables because I wanted to have colored ones. I bought a batch from Amazon that is nice and flexible cabling but some kind of generic XLR connectors. I have found them to be a hair worse than my Mogami cables as far as fit. On the Buckeye amp though, I could barely get them into the XLR connectors and then back out. I tried other XLR cables and my other generic ones were also stiff. The Mogami cable however, was a bit tight but nothing as bad as my generic ones. I know tolerances very but I had not seen this level of compatibility before with any other gear I have tested. Anyway, it is a one-shot deal so not a big deal even if the problem exists.

Buckeye NC252MP Measurements
Internally we have three stereo amplifier modules. So I decided to drive the unit in stereo using first and last channels. This way we have some variation in modules and their placements. Here are the results:


Frequency response is pretty good for a class D amplifier:

View attachment 100360



I am happy to recommend the Buckeye 6 channel, NC252MP based amplifier.

-----
As always, questions, comments, recommendations, etc. are welcome.

Nice amp for a high end PA system, due to the drop in FR starting already from 5 KHz this is not really an audiophile amplifier.

 

[Jdunk54nl]

Nice amp for a high end PA system, due to the drop in FR starting already from 5 KHz this is not really an audiophile amplifier.

That drop is 0.5dB by 20khz…not something to worry about.

 

[anarchist]

That drop is 0.5dB by 20khz…not something to worry about.

Well, many $500 AB amps don't have such issue, this is one is twice the price. If 0.5 dB drop is fine, then why make a big deal out of SINAD values? Noise is not detectable by human ear over 80 SINAD...

I think the reason major HiFi vendors, even high end like Rotel, don't use class D for anything than subwoofers is exactly this issue of problematic FR.

 

[Everett T]

Well, many $500 AB amps don't have such issue, this is one is twice the price. If 0.5 dB drop is fine, then why make a big deal out of SINAD values? Noise is not detectable by human ear over 80 SINAD...

I think the reason major HiFi vendors, even high end like Rotel, don't use class D for anything than subwoofers is exactly this issue of problematic FR.

Down .5db at 20hz isn't audible to 99.9% of humans (at 2kh, maybe) and the percentage that it is audible to is age related and they're buying GI Joe toys. Also what do you think Kii audio uses in their 3s, Dutch and Dutch, RTM, and many others?

 

[iraweiss]

Down .5db at 20hz isn't audible to 99.9% of humans (at 2kh, maybe) and the percentage that it is audible to is age related and they're buying GI Joe toys. Also what do you think Kii audio uses in their 3s, Dutch and Dutch, RTM, and many others?

Ain't that the truth. Just think of the money I could have saved on hearing aids if I still had my 20-year old hearing out to 20 KHz and beyond. And yes, my Outlaw 2220s measure flatter, down 0.5 dB out to 50 KHz. I can't hear it. My dogs, on the other hand...

 

[anarchist]

Down .5db at 20hz isn't audible to 99.9% of humans (at 2kh, maybe)

That's a baseless statement.
besides, it's not even about audibility - such FR doesn't have place in $1K+ segment, under $300 it's OK.

 

[anarchist]

Ain't that the truth. Just think of the money I could have saved on hearing aids if I still had my 20-year old hearing out to 20 KHz

I'm 50+, and can hear quite well up to 18K still (and down to 10 Hz), tested via signal generator sent through my own AV receiver.

 

[rvsixer]

I think the reason major HiFi vendors, even high end like Rotel, don't use class D for anything than subwoofers is exactly this issue of problematic FR.

You think? Problematic FR? It is KNOWN that major hifi vendors, including Rotel, have been and still use Class D across their entire product lines (not just subs). Notably Hypex modules.

 

[anarchist]

Ain't that the truth. Just think of the money I could have saved on hearing aids if I still had my 20-year old hearing out to 20 KHz

I'm 50+, and can hear quite well up to 18K still (and down to 10 Hz), tested via signal generator sent through my own AV receiver.

 

[PeteL]

I'm 50+, and can hear quite well up to 18K still (and down to 10 Hz), tested via signal generator sent through my own AV receiver.

Great, but in this case can you hear that the sparse harmonics still present at 20K are 0.5 dB less loud than they should have been?

 

[anarchist]

You think? Problematic FR? It is KNOWN that major hifi vendors, including Rotel, have been and still use Class D across their entire product lines (not just subs). Notably Hypex modules.

Rotel? Not really, they used to have some Class D offerings, but they pretty much stopped sales of those, most US dealers not carrying them any more.

 

[anome]

such FR doesn't have place in $1K+ segment, under $300 it's OK

For 6 channels, where is this to be had.

 

[Buckeye Amps]

So NAD and ATI are not high end? Nor McIntosh?