Can ya help a Brother out?... Opinions on five Class D amp options

[fatoldgit]

Background

- I am 65, have good even hearing response until 13.5k then it drops off like a stone
- Have been a audiophile since 1980
- Last 25 years my amp time has been evenly split between firstly Bryston (SS) and currently Rogue Audio (Toobs)
- I don't roll over equipment much... way more gains to be had in room treatments, room correction and speaker positioning
- Am science based so look at numbers as well as aesthetics (for example, no black boxes and controls must be symmetric)
- Source material is all two channel but I "pipe" that out into four speakers so need four channels of amplification
- Need at least 150w per channel (maybe I don't but bad habits due hard)
- Music is Jazz and Blues with a tiny bit of Blues tinged rock (Roy Buchanan, Rory Gallagher etc)
- Have been digital rips for the last ~20 years... don't spin any black or sliver discs anymore.. they are from a bygone era.

What's important

- Lets assume that the contenders are all of similar resolution, THD etc (or the numbers are below the threshold of my hearing)
- I live at the bottom of the world and so whatever I buy will be shipped from the top of the world or Asia
- Thus vendor reputation , vendor support (esp with regard to warranty) and hardware reliability are the paramount consideration
- Stuff is expensive down here... take any €, £ or $US value and times it by 2.5x to 3x as the landed cost in my local dollars so what might by a throw away price elsewhere isnt down here


Contenders

So having spent lots of time with "classic" SS and Toobs it's time to try out Class D.

Again I am not wanting opinions on whether you think, for example, that the GAN 1's (due to a no feedback design) might have an issue with high frequency roll off.

Below are the contenders (noting rather than use a dollar value I am using a relative price index where the GAN 1's are the most expensive so have a value of 100):


View attachment 465513

From a purely measurements perspective, the topping and the vtv ncx500 are best but as noted, can I hear that extra resolution...no.

I am really intrigued by the GAN 1's no DAC, PCM direct to PWM architecture so from a techie, left field standpoint these really grab my interest.


Thanks

Peter

 

[JSmith]

Not that it matters much, but the B200 isn't Class D... it'c Class B, or A/B depending on how one defines the quiescent current level.

The Peachtree's didn't measure up great, but acceptable;

'Peachtree GAN400 Amplifier Review'

Mar 14, 2023

This is a review and detailed measurements of the Peachtree GAN400 stereo balanced (input) amplifier. It is on kind loan from a member and costs US $2,499.

I am not generally a fan of peachtree audio product looks but this one in coffee stain looks pretty good. Other than a power switch, not much else is there. Ditto on the back side:

The claim to fame of this amplifier is use of GaN transistors which in theory simplify the design of a class D amplifier (a bit) and improve its efficiency (a bit). And in theory, it can also produce lower distortion (in open loop...

• amirm
• Replies: 118
• Forum: Stereo and Multichannel Amplifier Reviews

• 

'Peachtree amp500 Amplifier Review'

Dec 21, 2022

This is a review and detailed measurements of the Peachtree amp500 stereo amplifier. It is on kind loan from a member and costs US $1,499.

The amp500 comes in the same packaging of many previous Peachtree products. I wish company would innovate here as the design looks kind of dated. Then again it is very unique. This amplifier comes with balanced inputs which I very much like:

When I pushed the amp, the protection circuit naturally kicked it but unlike many other amps, recovered automatically without the need for a power cycle.

The back half of the box is...

• amirm
• Replies: 129
• Forum: Stereo and Multichannel Amplifier Reviews

• 

JSmith

 

[pollock0424]

Here are a few things that you should know about class D.
1. Most class D can't pump full power at 20khz for as much time as a class AB can (not that you would listen to sweeps but consumer must know)

2. Bus pumping can be an issue with class D. Basically, bus voltage spikes potentially damaging the amp if not addressed or protected.

3. They're pretty lite weight.

4. If the low pass isn't designed well then you could have rising treble or load dependent FR.. just like a crappy tube amp.

I use Purifi 1ET7040SA based class D btw!

 

[fatoldgit]

Not that it matters much, but the B200 isn't Class D... it'c Class B, or A/B depending on how one defines the quiescent current level.

The Peachtree's didn't measure up great, but acceptable;



JSmith

Yes you are correct... it was a last minute addition so it slipped by my class D focus...it's my status quo option.

The difference between the GAN 1 and say the other peachtree GAN amps is no DAC conversion is involved ..the GAN 400 etc are all analog input, have feedback etc, and not "direct" digital like the GAN1 (i.e. the GAN 400 etc have lots of "stuff" between the input and the speaker terminals).

I am not sure if the GAN 400 etc use the a gan module from Elegant Audio Solutions (as the GAN 1 does) but they have two versions: one for an analogue front end and one for a digital only front end so there is enough difference between the GAN 400 etc and the GAN 1 to make the GAN 400 etc measurements not applicable/relevant.

But... it's a valid concern... if the GAN 400 etc are border line good does that flow into the GAN 1.

While not a scientific method, but I have read many very long threads re the GAN 1 on various forums and any one who owned one liked the sound (which is probably around 30 opinions)... and typically you find that the people who own something they don't like and are on a forum will make it very clear that they don't like the device.

Thanks,

Peter

 

[fatoldgit]

Here are a few things that you should know about class D.
1. Most class D can't pump full power at 20khz for as much time as a class AB can (not that you would listen to sweeps but consumer must know)

2. Bus pumping can be an issue with class D. Basically, bus voltage spikes potentially damaging the amp if not addressed or protected.

3. They're pretty lite weight.

4. If the low pass isn't designed well then you could have rising treble or load dependent FR.. just like a crappy tube amp.

I use Purifi 1ET7040SA based class D btw!

I looked at purifi....will look again..

So based on my power needs, the 400A is what I need.

Thanks

Peter

 

[JSmith]

I'd be looking at @boXem for a premium build, Audiophonics for more vanilla options and 3e Audio for the more budget conscious. Nothing wrong with those B200's either...


JSmith

 

[fatoldgit]

I use Purifi 1ET7040SA based class D btw!

Added a purifi option from VTV...the options from Apollon Audio seem an outlier in terms of pricing so not included

Thanks for pushing me to revisit that.

 

[fatoldgit]

I'd be looking at @boXem for a premium build, Audiophonics for more vanilla options and 3e Audio for the more budget conscious. Nothing wrong with those B200's either...


JSmith

The mental health "issue" I have is the offering MUST have a silver face plate and the controls (which on a power amp amount to the on/off) must be centerally located.

Yes I am an idiot but I can't live with a device that doesn't have the above.

So the above vendors (while I have looked at them many times) can't get past this hurdle (from memory)

Thanks for proposing them though.

Peter

 

[fatoldgit]

So in terms of pure quality, is the ranking (with respect to class d):

(1) purifi xxx
(2) hypex ncx500
(3) hypex nc252
(4) peach tree GAN 1 (given it's an unknown)

If the consensus is that purifi is best sound quality wise and there modules are very reliable then they are the winner (which only leaves the amp builder as the final decision point)

Thanks

Peter

 

[fatoldgit]

And of course, if I am considering a US builder I need to pull the trigger before 1 Aug to beat the tariffs (assuming they stick to 1 Aug)

 

[MaxwellsEq]

If you are concerned about longevity, you might want to look at Vera.

As others have pointed out, many Class D amplifiers are unable to sustain 20kHz peak rated power with sine waves for more than a few seconds before shutting down.

The "standard" cases and heatsinking are fine for normal music use, but if you want something that can play sine waves for long periods at peak power 20kHz, then you need more mass, more airflow (including fans) etc. All of which adds to cost.

I have a Nord Purifi 1ET400A amplifier and after hours of use, it's barely warm to the touch. So for me, anecdotally, I've not encountered a need for large heatsinks and forced air cooling.

Edit: I should add for completeness that the SMPS are often limited in how long they can sustain peak power before reducing to lower power.

 

[mike70]

Find a guy over 40 years old and capable to listen to 20 khz ... is like to find a white fly.
I know we like science, but sometimes the "measurements fever" goes too much

 

[Multicore]

So having spent lots of time with "classic" SS and Toobs it's time to try out Class D.

Why?

View attachment 465513

ASR said attachment not found.

 

[Matias]

This in black.

'Apollon NCx500ST Stereo Amplifier Review'

Sep 7, 2023

This is a review and detailed measurements of the Apollon NCx500ST stereo class D amplifier based on Hypex NCOREx NCx500 modules. It was kindly drop shipped from the member and costs 1,090.00€ (US $1,168) with standard opamp.

While the case is stamped aluminum, it is a heavily customized one with attractive side vents. You get to select your color of choice. The back panel is where you notice the high value add:

You have no less than four gain settings and even an LED brightness switch! FYI, I will have to confirm which op-amp is included with this...

• amirm
• Replies: 981
• Forum: Stereo and Multichannel Amplifier Reviews

• 

 

[Gorgonzola]

"Classic" solid state amps from the '60s, '70s and even '80s were typically had quite low THD but that low THD was comprised mostly of high-order harmonics, (harmonics above 3rd order). What is better understood today is that high-order harmonics sound bad -- strange because this fact was recognized by the the ancient Greeks, (seem to recall it was Pythagoras).

I remember my Phase Linear 400 amp which I used for years. I finally realized it was a truly ghastly sound amp.

By contrast to these old solid state, tube amps are relatively lower in high-order harmonics but higher in low-order, (2nd, 3rd), harmonics that sound pleasant, (also understood by the ancient Greeks). Perhaps not yet scientifically proven, but it is likely the 2nd/3rd order harmonics also MASK the higher-order harmonics; this is why many older hi-fi folks like a tube preamp ahead of a solid state power amp.

However the best current class D amps, (and some AB), are much lower in distortion over all distortion than typical '60s and '70s amps. Also, what minimal distortion they have is likely to be 2nd/3rd order.