Looks like Class D is the only option for ultra clean, high power amplification

[Galliardist]

Oh yeah? I’ve been running my steam engine (B&K 202) for over 30 years now. How long did those quadruple zero Topping amps last, 30 hours? I hear of Hypex NC amps crapping out alot as well.

I guess those “Ferraris” are about as reliable as a Ferrari.

I've not seen a lot of reports of NAD and Marantz Hypex amps crapping out. In fact I don't know of any such. I don't see hate of Buckeye amps for crapping out on here, there are a lot of owners so pretty sure we;d hear quickly. Some of those NAD and Marantz products have been available for seven years now and are still fine.

We'll have to wait to see what lasts for 30 years, obviously. Build quality comes into it though. A lot of Class AB amps don't make it to 30 years, either: there are probably a lot more failed class AB amps out there. Should we decry them all because some fail, or some are poorly designed? Of course not.

These things all do what they do. If you have good solid evidence to berate them, let's see it.

 

[Galliardist]

The tests and specs show that 2 Ohms and below for the majority of class D stuff is not yet ready for prime time like a hearty low impedance drive class A/AB amp is. The Purify has been 2 Ohm rated and the newer Hypex is too but I don't see them at less than 2 Ohms rated.

But do you have evidence of a Hypex not working with a two Ohm load? Or with a speaker with a measured minimum impedance of two Ohms, which is what most people mean by working with two Ohms?

 

[Doodski]

But do you have evidence of a Hypex not working with a two Ohm load? Or with a speaker with a measured minimum impedance of two Ohms, which is what most people mean by working with two Ohms?

I have what you have. Manufacturer specs for most of them and not actual test results.

 

[Galliardist]

I say it again,that's for cheap.
Cause if price is not of concern here's an example:

View attachment 300277

View attachment 300278

Of course it's 40K$.

I believe you are supposed to link to or clarify the source of these measurements, and name the product, when posting them, according to site policy. Some uncredited graphs from Stereophile were removed from posts recently for that reason. I presume they come from this:

Halcro Eclipse Stereo Power Amplifier Lab Report

Lab Report Much about the Eclipse is truly exceptional, but it is not breaking any audiophile records for power output. Rated at 2x180W/8ohm and 2x350W/4ohm, it achieves 2x210W and 2x370W, respectively, though its clipping behaviour is very abrupt indeed. Class D and high-feedback Class AB...

www.hifinews.com

 

[Positivevibrations]

Very low impedance drive is still the domain of the class A/AB designs. Class D is just starting to become 2 Ohms capable in tests.

All the Ncore and Purifi amps can handle any load. Even 1/4 ohm. If too much current is being drawn, the current limiter kicks in before anything bad happens.

 

[Doodski]

All the Ncore and Purifi amps can handle any load. Even 1/4 ohm. If too much current is being drawn, the current limiter kicks in before anything bad happens.

Yes, the current limiter is good for some stuff although it is limiting the current and therefore the voltage too and that means reduced power output when a low Z class A/AB would keep on pushing the power into even a direct short sometimes. Even exceeding the power into 4 Ohms would cause a class D current limiting situation. The power supplies in the class D stuff is impressive to say the least but there is still room for improvement with the worst of the worst case speakers.

 

[Galliardist]

I have what you have. Manufacturer specs for most of them and not actual test results.

OK. Here are some numbers for the Marantz KI Ruby. Dynamic load measured.

The review included the matching CD player, and remember that the Ruby amp is integrated.

So, yes, the Halcro amp is better on paper. But there are few speakers it will drive that the Marantz can't,

That should apply to most nCore500 amps and variants, if properly built.

Do you want to argue audible differences?

 

[ahofer]

I have what you have. Manufacturer specs for most of them and not actual test results.

Somewhere on here March audio showed some low impedance/constant power tests with his Hypex amps (on YouTube). No problem. The case temperature didn’t even rise that much.

 

[Doodski]

OK. Here are some numbers for the Marantz KI Ruby. Dynamic load measured.

View attachment 300340

View attachment 300341
The review included the matching CD player, and remember that the Ruby amp is integrated.

So, yes, the Halcro amp is better on paper. But there are few speakers it will drive that the Marantz can't,

That should apply to most nCore500 amps and variants, if properly built.

Do you want to argue audible differences?

The 2 Ohm test graph estimated at ~630 W RMS would require if true to Ohm's Law ~50.2 V DC +/- and ~25.1 A peak. So the test at 2 Ohms is derated due to the protection circuitry engaging.

At the specifications rating below the graph of 280 W @ 4 Ohms requires 11.8 A peak so that is within spec of the current limiting circuitry.

For 370 W dynamic into 1 Ohms requires 27.2 A peak. That by far exceeds the max 19.2 A rating for the power supply. Hence the reduction in power output.

Frankly I'm, veryyy surprised it took a 1 Ohm load. Impressive stuff. Those thermal compound goo'd heat sinks no doubt played a part as well as the peak current output of the power supply for a fraction of a ~second.

I estimate the numbers as I played with them a bit and found that ~553 W RMS into 3 Ohms with +/- 57.6 V DC that the amp goes into current limiting.

It appears to be a nice Hypex design.

 

[MAB]

Bryston is one (among many) options:

I would argue that this is ultra-clean. And offers warranty, serviceability that I don't see in the 'class D' options. I have Class D amps as well and love them, they sound just as good as the Bryston gear! I'm not sure if they are going to be as durable.

 

[CleanSound]

Bryston is one (among many) options:
View attachment 300347

I would argue that this is ultra-clean. And offers warranty, serviceability that I don't see in the 'class D' options. I have Class D amps as well and love them, they sound just as good as the Bryston gear! I'm not sure if they are going to be as durable.

Bryston are very nice, also very expensive. . .but two zeros, not 3 nor 4. But even so, I be happy with it.

 

[Positivevibrations]

Yes, the current limiter is good for some stuff although it is limiting the current and therefore the voltage too and that means reduced power output when a low Z class A/AB would keep on pushing the power into even a direct short sometimes. Even exceeding the power into 4 Ohms would cause a class D current limiting situation. The power supplies in the class D stuff is impressive to say the least but there is still room for improvement with the worst of the worst case speakers.

There’s not a speaker on the planet that any Ncore or Purifi amp can’t drive with ease. Sure if you want to parallel 4+ 4 ohm woofers there might be better choices.

 

[jomo]

I've not seen a lot of reports of NAD and Marantz Hypex amps crapping out. In fact I don't know of any such. I don't see hate of Buckeye amps for crapping out on here, there are a lot of owners so pretty sure we;d hear quickly. Some of those NAD and Marantz products have been available for seven years now and are still fine.

We'll have to wait to see what lasts for 30 years, obviously. Build quality comes into it though. A lot of Class AB amps don't make it to 30 years, either: there are probably a lot more failed class AB amps out there. Should we decry them all because some fail, or some are poorly designed? Of course not.

These things all do what they do. If you have good solid evidence to berate them, let's see it.

I don't have issue with Hypex. I just remember the thread below on the Hypex NC252. I think Marantz uses the Hypex NC500 which folks also suggest in the thread. NAD uses Purifi and Hypex UdC modules......which I own (Rythmik sub).

Hypex NC252 failed (twice) -- suggestions for replacement?

Bryston are very nice, also very expensive. . .but two zeros, not 3 nor 4. But even so, I be happy with it.

I would not count out A/B amps. One thing I would suggest is that you compare peak power when comparing amps because class D amp power supplies are commonly regulated which mean little, if any, headroom beyond the continuous rating.

If low, "two zeros" is in the cards, you may want to look at the Schiit Vidar 2. It's quieter than the previous version, the little distortion is primarily 2nd harmonic (the "sweet distortion" tube guys like) , built with top quality parts, 5 year warranty, US made and $799. The measured data below.

https://www.schiit.com/public/upload/PDF/Schiit%20Amp%20APx555%20Standard%20Test%20Suite_%20Vidar%202.pdf

 

[Doodski]

There’s not a speaker on the planet that any Ncore or Purifi amp can’t drive with ease. Sure if you want to parallel 4+ 4 ohm woofers there might be better choices.

Mostly factual but not 100%. There have been speakers and still are that push into the 1.x Ohms range for Z specs.

 

[Positivevibrations]

Mostly factual but not 100%. There have been speakers and still are that push into the 1.x Ohms range for Z specs.

And any Purifi or Ncore amp won’t have a problem with them. I’ve never heard of anyone triggering the current limiter on any Ncore or Purifi amp. Even with Martin Logan’s or Maggie’s

 

[Doodski]

And any Purifi or Ncore amp won’t have a problem with them. I’ve never heard of anyone triggering the current limiter on any Ncore or Purifi amp. Even with Martin Logan’s or Maggie’s

The issue is not that that class D will operate with the low Z speakers but if the power supply in the class D amp rolls back the current output causing the voltage to droop and that reduces the output power. That become a linearity issue if the Z setting is too high for rollback. Refer to Post #69 for calculations and results.

 

[Positivevibrations]

The issue is not that that class D will operate with the low Z speakers but if the power supply in the class D amp rolls back the current output causing the voltage to droop and that reduces the output power. That become a linearity issue if the Z setting is too high for rollback. Refer to Post #69 for calculations and results.

It’s the amp modules that have the limiters. In a proper Ncore or Purifi amp build you use power supply’s at least 200w more powerful than what the amp modules draw.

 

[Doodski]

It’s the amp modules that have the limiters. In a proper Ncore or Purifi amp build you use power supply’s at least 200w more powerful than what the amp modules draw.

Is it? I never know if it's the amp module or the power supply rolling back.

 

[Positivevibrations]

Is it? I never know if it's the amp module or the power supply rolling back.

Ya the current limiters are located in the amp modules.

 

[Doodski]

Ya the current limiters are located in the amp modules.

Thanks. I never knew that.