Buckeye Nc502mp Review (6 Channel Amplifer)

[AdamG]

It appears that my NAD M27, which Amir reviewed in September 2019, still out performs any multichannel amplifier so far, including this Buckeye, and it has a 420 Watt output at 4 Ohms when it drives only two speakers.

Review and Measurements of NAD M27 PWR Amp

This is a review and detailed measurements of the NAD M27 7-channel surround audio amplifier. It is on kind loan from a member. Seems like the M27 came out back in 2014 and costs US $4,400. The M27 has the same design language as the excellent M17 Home Theater Processor (looks only): The...

www.audiosciencereview.com

Could not have written a better advert for the Buckeye Amp myself.

 

[JayGilb]

Regarding the upside down XLR connectors:

You'll see in any of the tear downs I use screw (solderless) XLR connectors. If I orient the connectors properly it makes it extremely difficult to insert the wires.

I have been trying to be mindful of the XLR and speaker wiring crossing over the coils but I can obviously do better.

So you can't insert the wires into the xlr connector and then rotate the connector to the correct orientation ?

 

[AdamG]

Ya, at a cost of $5000 for a newer version nad m28. You can get 3 of these 6 channel amps for a total of 12 channels for that cost

NAD Masters Series M28

7-channel power amplifier

www.crutchfield.com

Edit for a total of 18 channels.

 

[AdamG]

Full disclosure: I obviously am biased as this will be my second 6-channel Nc502mp amp build purchased from Buckeye Amps. Owner bias is a real thing. Worthy of mentioning.

 

[Jdunk54nl]

Edit for a total of 18 channels.

Simple Math is hard in the morning

 

[JayGilb]

Full disclosure: I obviously am biased as this will be my second 6-channel Nc502mp amp build purchased from Buckeye Amps. Owner bias is a real thing. Worthy of mentioning.

I had noticed.
Two 6 channel amps - How are they being implemented, if you don't mind ?

 

[Billy Budapest]

Regarding the upside down XLR connectors:

You'll see in any of the tear downs I use screw (solderless) XLR connectors. If I orient the connectors properly it makes it extremely difficult to insert the wires.

I have been trying to be mindful of the XLR and speaker wiring crossing over the coils but I can obviously do better.

I don’t think there is any “correct” orientation for XLR connectors. The cables only fit into them one way. Some manufacturers mount them sideways.

 

[Billy Budapest]

Looks like a straight up assembly job with six Hypex units in a Ghent case, and an upside down install of the XLR inputs. Easy enough to rectify. Probably won't even require a soldering iron.

Not a Ghent case, but a custom-designed case by the manufacturer.

 

[Jdunk54nl]

Full disclosure: I obviously am biased as this will be my second 6-channel Nc502mp amp build purchased from Buckeye Amps. Owner bias is a real thing. Worthy of mentioning.

Same full disclosure only I have a 6 channel 502mp coming with a 4 channel 252mp. I am cost bias

Even the new monolith hypex amps (announced on the AV Summit Monolith Talk hosted by @joentell) are going to be like $3000 for 7 channels IIRC.

 

[Walter]

RE casing, personally I prefer a plain black box. I want my amp to disappear visually as well as sonically when I'm enjoying listening to music. Different strokes for different folks of course.

Yep. The best amp I ever owned was a Chiro C-500. It sat 6 feet in front of me just below the center channel speaker and not once was I ever bothered that it was just a big plain black box. Especially when it was operating. If I decide not to go with active speakers for my next system, a stereo Buckeye NC252 is at the top of my wishlist. Even if he starts building Purifi amps, I seriously doubt I'd ever be able to hear the difference.

 

[elliott]

I recently purchased an amp from @Buckeye Amps and couldn't be more pleased. Using them to drive a pair of LX Minis and got a 6 channel for my upcoming subwoofer build.

 

[RichB]

Are all these measurements except for the frequency response at 1 kHZ?

There was this measurement of the NAD M27.

Is this measurement available for the Buckeye?

- Rich

 

[AdamG]

I had noticed.
Two 6 channel amps - How are they being implemented, if you don't mind ?

I am in the process of off-loading the internal amps on a Denon 8500h to these two amps. In the final configuration 9.2.6 setup. The Buckeye 502’s will drive the base 9 speakers that are all tower speakers and the front height that are center size speakers. The remaining 2 sets of height speakers (middle & rear heights) will remain driven by the Denon. At least that’s the plan.

 

[Jdunk54nl]

Are all these measurements except for the frequency response at 1 kHZ?

There was this measurement of the NAD M27.
View attachment 161721

Is this measurement available for the Buckeye?

- Rich

Should be similar to the above NAD and to the buckeye 252mp

Edit for reference to NAD picture in the same post:

 

[peng]

@amirm, it is a bit difficult to tell from that third chart due to the plots overlapping, at least with my eyesight, but it appears that all three modules had the same issue with about a 3-5db discrepancy in distortion level between the two channels. Is this correct? If so, I'm not an engineer, but wouldn't that indicate that the issue is in the modules themselves, not the implementation? The $1,000+ 2 channel March Audio P502 also showed the same behavior, albeit without the hump, although it actually had 3-4db worse SINAD.

EDIT: Actually the March did have a hump, especially at 8 ohm.

It looks like the hump/rise is shown in Hypex's own graphs. THD+N 0.0016% is almost -96 dB at 200 W, vs Amir's approx. -83.3 dB at 200 W.
March's P502's -94 dB (just eyeballing it) was much closer than Hypex. At low output such as at 5 W Buckeye Amp's is about 4 to 5 dB better than March Audio's. Very strange, may be the differences between all 3, Hypex, March Audio P502 and Buckeye Amp NC502MP are all due to noise, not distortions. So at higher output, the 6 channel Buckeye amp has much lower SINAD because of the increase in power supply noise? @amirm can you comment on this? The NC502MPs are total packages, hard to imagine performance between amps can vary in terms of distortions, but it may easier to understand if it is the N part of THD+N is causing the significant differences, I guess.

 

[Jdunk54nl]

I don't know what is going on with the channel in blue producing a lot more power supply noise (relatively speaking). Grounding made no difference. As a result, one channel is 3 dB better than the other. Averaging the two still lands the amp into our upper tier of all amplifiers tested to date:

We see that same issue on the March Audio channels (worse overall than buckeye)

 

[rdenney]

Here's my thinking: When Amir reviews this amp, more people will be knocking at Dylan's door to buy one.

Therefore, my strategy was to buy one and get in the queue before this review.

I predict my thinking was good on this one, for once. I had been waiting for the review, but then I thought, why? So I can take delivery in 2023, after Dylan gets his PhD and moves on to other things? Sometimes, I'm kind dumb about stuff like that and I miss out.

Some notes about the hump in distortion at higher powers: At those higher powers, there will be lots of distortion from a variety of sources, not least of which will be our ears and our speakers. To my thinking, allowing a modest increase in distortion for once-yearly demonstrations for our buddies when our wives are not home to provide abundant power to fill out every potential peak is a worthy tradeoff. And even so, the power produced by this amp into 8 ohms ~200 watts) was at 0.004% distortion (-88 dB). My B&K amp is speced at 125 wpc into 8 ohms at 0.09% distortion (meaning: -61 dB at full power). This amp's distortion performance is in the land of fantasy for amps back in the day, when 200-250 watts/channel was about as big as any mortal could afford. For any short peak that calls for more than 160 watts, this amp is cleaner than a Purifi amp.

But it doesn't reach 1% distortion until something well over 300 watts into 8 ohms, for about 2 dB of "headroom". My B&K amp specifies 1.2 dB of headroom, presumably to mean something similar--additional power that isn't at the speced distortion, perhaps, but still is not into hard clipping.

My speakers are nominally 6-ohm with 91-dB sensitivity. I cannot imagine any scenario where this amp will be pushing the boundary of its maximum power, even for that annual demonstration. At normal loud listening, this amp will be putting out 5 watts or less on average, where this amp's distortion is down around -100 dB (0.0001%), and it will still play peaks 18 dB up from there without distortion over 1%.

The B&K is a great amp; this is better.

Rick "waiting his turn" Denney

 

[peng]

As an electrician, I’d be pretty surprised if someone actually managed to trip a house breaker with one of these, but there’s firsts for everything.

As for the amplifier, these things are the bees knees. I use a 6 channel one he made for me that’s 2x500, 2x250 and 2x125 for my active 3 way fronts and it works perfectly and silently. No class AB transformer hum, no weight, much less heat, no power supply harmonics spraying across the FFT graphs, no hiss, no complaints.

Agreed, not if the amp is used to amplify music signal unless it is used with a continuous 1 kHz (just an example) sine wave at rated output then yes it would trip the breaker (15 or even 20A) but it will take time, not instantaneous. Fortunately no one would listen to a continuous 1 kHz sine wave.

 

[Doodski]

Simple Math is hard in the morning

I had a math instructor that claimed math examinations in the early morning produce higher grades. Additionally he handed out candies to suck on during the tests because as he claimed that produces 2%-4% higher marks overall.

 

[Labjr]

I wouldn't worry about distortion of Class D amps unless you're running very inefficient speakers. Gosh, I remember buying a 15w/channel receiver when I was in high school. Now 300-500 watts isn't enough for some people.