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Buckeye Amps: New US based Hypex multichannel amplifier builder, line-up announcement!

Walter

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While not a true functional test, if the speaker outputs are not connected to the amp, the LEDs will flash during power up and down. This is one way to be sure the circuit is operational without trying to drive the amp to clipping.

Ofc, the other way would be to use a dummy load. While a dummy load will save your hearing, it needs to be done carefully too. Running dummy loads has other potential dangers and should not be done casually.

Rick
Yes, but that does nothing to answer the burning question of "just how loud can this go without clipping?" Inquiring minds want to know!
 

Jdunk54nl

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Yes, but that does nothing to answer the burning question of "just how loud can this go without clipping?" Inquiring minds want to know!
I am pretty sure it isn't a question of how loud the 502mp's will go without clipping, but when will your speakers stop working. Pretty sure that is gonna happen before the 502mp clips for the majority of speakers out there.
 

TrevorLJ

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Dylan built me two 8-channel NC252MP's for my new 9.3.6 theater and they've been rock solid since install a month ago. Zero noise (super clean) and crazy dynamic. Totally worth the wait!
 

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sweetchaos

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Dylan built me two 8-channel NC252MP's for my new 9.3.6 theater and they've been rock solid since install a month ago. Zero noise (super clean) and crazy dynamic. Totally worth the wait!
Looks awesome!
You can't just leave a cliffhanger like that...we need specs of your build!
 

TrevorLJ

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Looks awesome!
You can't just leave a cliffhanger like that...we need specs of your build!
OK, OK, OK...LOL!

Sooo...let see:
Sony 75" Z8H
Oppo 203 UHD Player
Nvidia Shield TV Pro (2019)
Emotiva RMC-1L Processor cal'd w/Dirac Live
ELAC Debut 2.0 C6.2 Center Speaker
ELAC Debut 2.0 B6.2's Everywhere Else :p
JTR Captivator 4000ULF-ST Sub nearfield in the center
2 ea HSU Research VTF-15H MK2 Subs on either side
miniDSP 2x4 HD and REW to align and EQ the subs

All the audio is on a dedicated 20A circuit. The room's normal 15A feeds all the video/source components.

I really wanted a Monoprice HTP-1 but they were out of stock when I was ready to pull the trigger (and have been since). So far the Emotiva RMC-1L is surprisingly decent. :rolleyes:

Pros:
- Sound quality has been remarkable
- Stability has been great
- Dirac cal was easy (once Emotiva sent me the Dirac kit that should have shipped w/the processor)
- Cool display on the unit

Cons:
- No eARC and ARC functionality blows. Like damn near unusable if you don't know the tricks. My previous receiver was a Yamaha w/eARC (3070) and it felt like I went back to the stone age.
- On screen interface comically lags behind the display on the unit. You're better off looking at the processor itself
- No ability to choose your upmixer on non Atmos/DTS-X sources (Dolby encodes=Dolby Surround Upmixer / DTS encodes=Neural-X) (PCM sources are still unlocked though)
- The RMC-1Ls Dolby Surround Upmixer is an older version from back when the wides were locked-out at Dolby's direction. I guess Dolby changed their mind and there's an update on other processors/receivers that brings the wides online.

I'm digging the 9.X.6 deal but it's not revelatory. You're not missing much at 7.X.4 with Atmos and (normal/Non-Pro) DTS-X doesn't use wides and center tops at all.
 

rdenney

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I installed my NC502MP Buckeye this evening (at least provisionally--need to rearrange things to take advantage of the change in box size). I used the Monoprice RCA-to-XLR cables.

And I measured REW sweeps before and after. Centering on 85 dB, the volume on my preamp is about the same as it was with my two B&K amps. The difference is that the distortion coming out of the speakers is significantly lower--by 5-10 dB. Given that the speakers vary around -40 dB distortion levels with respect to the sweep tone during the sweep, and the amp is probably 50 dB below that, I'm rather surprised.

There was very little change in frequency response, but my Revel F12's are not particularly troublesome to drive for a good amp. I had no need to change my EQ.

I also did some sweeps with the preamp in passive mode and with the processor loop (wherein resides the PEQ) switched out. That makes the preamp a passive volume control only. The volume knob moved from about 10 o'clock to maybe 2 o'clock.

The real test of dynamics will have to come another time, when I'm alone in the house. I did crank up one of my favorite piano recordings, and ran that up a bit. I was able to easily make it louder than my grand piano in the same room, but that was just a quickie test. Much more to come on that, especially after my ears open up.

Rick "ears still clogged from Covid recovery, so nothing really sounds good at the moment" Denney
 
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Buckeye Amps

Buckeye Amps

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I installed my NC502MP Buckeye this evening (at least provisionally--need to rearrange things to take advantage of the change in box size). I used the Monoprice RCA-to-XLR cables.

And I measured REW sweeps before and after. Centering on 85 dB, the volume on my preamp is about the same as it was with my two B&K amps. The difference is that the distortion coming out of the speakers is significantly lower--by 5-10 dB. Given that the speakers vary around -40 dB distortion levels with respect to the sweep tone during the sweep, and the amp is probably 50 dB below that, I'm rather surprised.

There was very little change in frequency response, but my Revel F12's are not particularly troublesome to drive for a good amp. I had no need to change my EQ.

I also did some sweeps with the preamp in passive mode and with the processor loop (wherein resides the PEQ) switched out. That makes the preamp a passive volume control only. The volume knob moved from about 10 o'clock to maybe 2 o'clock.

The real test of dynamics will have to come another time, when I'm alone in the house. I did crank up one of my favorite piano recordings, and ran that up a bit. I was able to easily make it louder than my grand piano in the same room, but that was just a quickie test. Much more to come on that, especially after my ears open up.

Rick "ears still clogged from Covid recovery, so nothing really sounds good at the moment" Denney
OK, but when will you make the clipping indicators light up? That's what everyone wants to know.

Just kidding
 

rdenney

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OK, but when will you make the clipping indicators light up? That's what everyone wants to know.

Just kidding
Yes, I made them light up. They light up for about half a second during the power-on self test. Very bright!

Rick "hoping to see those lights only in that situation" Denney
 

Jdunk54nl

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Yes, I made them light up. They light up for about half a second during the power-on self test. Very bright!

Rick "hoping to see those lights only in that situation" Denney

Just use a passive sub to make them like light ;)
 

AdamG247

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@Rick Sykora hooked up my 3 module/6 channel 502 with the test clip mod. His first one, so finally a virgin in the house! I have watched the new Dune UHD twice. Once alone and again with the Wife. The first time I had the MV at -10 and UMIK peaks of about 115 dbs. About the loudest I have ever pushed my system (Have Dual 6ch 502’s, but only one with the clip light mods). The lights work during power cycle. During the demo of Dune my internal limits kicked in before any sign of Amp clipping. The Amps never got any warmer than 84 degrees Fahrenheit. The movie is over two hours and has demo worthy dynamics. I think I now have more horsepower than I have the cojones to ever use. :D
 

rdenney

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The Redhead went to the store and I was released from duty owing to a bout with food poisoning or something last night (I do not believe Covid-related, based on my gluttonous attack yesterday of a cookie care package sent to us by a friend).

So, I suggested that the cat go to another part of the house, put the Chesky demonstration disk into the CD player, and cranked it up.

Question: how does the amp determine when to light the clip indicators?

Because I sure as heck made them flash at me playing the “loud” drum solo track at the end of the CD. Peaks at 105 dBA (measured) at my sitting position and not the slightest hint of audible clipping. The track of the organ and church choir also peaked at that level but did not light the indicators, so my SPL meter app is certainly not catching the points of the peaks. It certainly sounded louder—easily in comparison well over 110 dB, but I’d need a better meter to know by how much.

If the speakers compress at all at these levels, I can’t tell it. I wouldn’t play test tones that loud but with music it’s awesome. The B&K preamp puts out 12 VRMS maximum, and the volume pot was at 12 o’clock. Testing was done with EQ, of course.

After I judged my free time was up, I shut it down and moved back to the back bedroom, to which the cat had retreated. She shot the bird at me. :cool:

The amp is dead silent with no input, but I do hear the components hissing slightly when turned on.

At similar levels, the B&K amps were showing signs of compression (damping of drums) and strain. That additional 3 dB makes a difference. I’ll move them back to driving a pair of my stacked Advents as soon as I find the right place for that. (We just built a shop/garage and I want to turn the old garage into an exercise room.)

Rick “the clip indicators work” Denney
 

Matias

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@rdenney if you want even more power there is always the option to bi-amp your speakers: 1 NC502MP for each speaker, with 1 channel for the mid+tweeter and 1 channel for the woofer. Maybe 1.200W peaks at 4 ohms will destroy the speakers before the clipping LED turns on. :D
 

Rick Sykora

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The Redhead went to the store and I was released from duty owing to a bout with food poisoning or something last night (I do not believe Covid-related, based on my gluttonous attack yesterday of a cookie care package sent to us by a friend).

So, I suggested that the cat go to another part of the house, put the Chesky demonstration disk into the CD player, and cranked it up.

Question: how does the amp determine when to light the clip indicators?

Because I sure as heck made them flash at me playing the “loud” drum solo track at the end of the CD. Peaks at 105 dBA (measured) at my sitting position and not the slightest hint of audible clipping. The track of the organ and church choir also peaked at that level but did not light the indicators, so my SPL meter app is certainly not catching the points of the peaks. It certainly sounded louder—easily in comparison well over 110 dB, but I’d need a better meter to know by how much.

If the speakers compress at all at these levels, I can’t tell it. I wouldn’t play test tones that loud but with music it’s awesome. The B&K preamp puts out 12 VRMS maximum, and the volume pot was at 12 o’clock. Testing was done with EQ, of course.

After I judged my free time was up, I shut it down and moved back to the back bedroom, to which the cat had retreated. She shot the bird at me. :cool:

The amp is dead silent with no input, but I do hear the components hissing slightly when turned on.

At similar levels, the B&K amps were showing signs of compression (damping of drums) and strain. That additional 3 dB makes a difference. I’ll move them back to driving a pair of my stacked Advents as soon as I find the right place for that. (We just built a shop/garage and I want to turn the old garage into an exercise room.)

Rick “the clip indicators work” Denney

Cool, made me realize I can add another possible functional test for the clipping LEDs. A high excursion subwoofer driven hard enough will likely drive amp to clipping without sacrificing your hearing.

May scare your family and the pets, but if you need to know for sure, have them take a walk outside for some exercise! ;)
 
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rdenney

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@rdenney if you want even more power there is always the option to bi-amp your speakers: 1 NC502MP for each speaker, with 1 channel for the mid+tweeter and 1 channel for the woofer. Maybe 1.200W peaks at 4 ohms will destroy the speakers before the clipping LED turns on. :D
I was doing that with two B&K amps. But it’s deceptive—the speaker crossovers are passive and cannot be bypassed, so biamping doesn’t really add power. The B&K amps aren’t particularly happy with low impedance, and can’t be bridged.

But the NC502MP amps can be bridged. :p

Rick “kilowatt monoblocks, anyone?” Denney
 

rdenney

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Cool, made me realize I can add another possible functional test for the clipping LEDs. A high excursion subwoofer driven hard enough will likely drive amp to clipping without sacrificing your hearing.

May scare your family and the pets, but if you need to know for sure, have him take a walk outside for some exercise! ;)
At my next opportunity, I might try to figure out a way to measure speaker outputs when the clip lights are flickering. I don’t have expensive analysis stuff and scope isn’t a storage scope. I could either measure the amp in isolation by attenuating test leads connected the speaker terminals down to a couple of volts and feeding the attenuated signal into a recording. Easier would be to just put a microphone in the room and look at the waveforms making it out of the speakers.

REW probably has a feature I haven’t discovered yet.

That said, I usually hear more distortion than is there simply because of my hearing, and I wasn’t hearing any.

Rick “not seeing any description of detected clipping in the data sheet” Denney
 

rdenney

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Hypex tells me the same thing they told Rick Sykora when I asked them how they detected clipping—when output is different from input. They told me they can detect very small differences, which I take to mean at the very knee of the distortion curve, not where rising distortion passes rating thresholds. Thus, for 8-ohm loads, the curve first points up at around 200 W, where distortion is about 0.002%, versus rated maximum power output at 1%, which is well over 300 W.

My F12’s are rated at 6 ohms, but dip below 4 ohms only in the mid-bass, so probably still voltage-limited rather than current-limited for the (snare) drum transients that lighted the indicators.

My initial read of this is that a flashing indicator on sharp transients is probably no issue if distortion isn’t audible. The indicator appears to be quite conservative, which is good.

Rick “may hear more from Hypex” Denney
 

HammerSandwich

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Bruno made some relevant comments about exactly that. Excerpt:
First conclusion: Nelson Pass is a Dire Straits fan.
Second conclusion: clipping often goes unnoticed. It pays to build a clip detector into an amp just to get an idea of whether it happens. You'd be surprised how some kinds of material can sustain a lot of clipping before anyone notices. You can slice almost 10dB off the top of a snare hit with not much more than some fattening of the sound.
The whole post deserves a look.
 
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