Class D. Make or break

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Ok, the i35 Amp is here. I’ll be doing an A-B comparison with the Exposure 3510 shortly on another thread as this one is a bit clogged up.
I assume that people find these comparisons and user reviews useful?

A5370CA6-7561-43BA-9FA3-6EB0F62D8FD0.jpeg
After your previous (single) comment about the 3510, I thought I had missed a fuller explanation, so yes the comparison would be very interesting.
 
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Strider

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I'm currently mucking about with a pair of Extron XPA 1002 Plus class D power amps, they're predominantly used in the AV sector and as such aren't pretty and don't have any fluffy buttons or cute connectors. Inputs/Outputs are Phoenix connectors so you'll need to re-terminate your fancy cables but as I don't own any fancy cables and make my own its not an issue.

They're being run in bridged mono and kicking out 200w @ 8 Ohm apiece, I cant really offer an audiophile review littered with superlative guff but they possess good dynamic shift and excellent transient response, probably not the last word in finesse but for an experiment I'm confident they'll stick around for a while whilst I build my own passive preamp, the Nobsound passive I'm using is a great little thing but the channel separation is linear and is only really effective toward the end stop.

Ugly, mean and very powerful.
xpa1002-lg.jpg

XPA 1002 Plus - 2 x 100 watts @ 4 or 8 ohms, or 1 x 200 watts @ 8 ohms (bridged) The model shown is the 1002, the 1002 Plus is near identical but has more grunt when run in stereo.
 
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rocketiii

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I’m a recent convert to the new breed of Class D amps. I’ve long been a valve amp fan with an Atmasphere OTL amp being my favourite. I‘ve recently retired and keeping a valve amp on all day was getting costly. My speakers are very efficient at 107db/W (Avantgarde Duo Omega horns) and also very revealing of any changes in the system.

So I considered a number of amps including the excellent NAD M23/33, Atmasphere Class D monoblocks and AGD Audions GaNTube monoblocks. I went with the AGD Audions and I’m delighted with them.

Firstly they need no warm-up (valve amps tend to need 30 minutes at least before they come on-song). The sound is simply spectacular with a really wide and deep soundstage with instruments in the background much more present. The sound of a snare drums and cymbals now really has that ‘live’ sound which I find essential for enjoyment. There’s just more of everything now.

So I’d urge people to keep an open-mind on Class D amps as I’m confident they are now challenging the very best amps regardless of Class A/AB/Valve.
 

hearhere

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Atmasphere Class D monoblocks and AGD Audions GaNTube monoblocks.I’m a recent convert to the new breed of Class D amps. I’ve long been a valve amp fan with an Atmasphere OTL amp being my favourite. I‘ve recently retired and keeping a valve amp on all day was getting costly. My speakers are very efficient at 107db/W (Avantgarde Duo Omega horns) and also very revealing of any changes in the system.
When I read this, I thought I was reading one of my own posts as it exactly expressed my own situation 3 years ago. Then I was using valve amps (PX-25 and 845-based SETs) powering Avantgarde Unos.

I too had recently retired and was curtailing my listening hours because of the valve amps. I decided to switch to ss if (and only if) I could find an equally good or better sounding a ss amp. I was looking at Class A, AB and D and home auditioned a dozen amps and was expecting one of the Class A ones to win my affection. However not so, although the Accuphase A-36 is a great amp, but a little too civilised and slightly lacking in impact. The dozen included the NAD M32 and I decided upon this great amp in the end, despite it being one of the least costly.

This was upgraded to M33 when it became available and the Unos upgraded to Duos (pre-Omega) and currently Duo XDs. I'd now like to try the M33 against the Atma-Sphere Class D monos and the ADG Audion monos to see if either offered better sound than the NAD.

Did you home demo these 3 amps with your Duos, or was the decision after research, reviews and showroom demos? I did my tests at home after buying used amps, one new one and the rest were dealer demo units. But all were tested against the 845 mono SETs and other ss amps I had at home at the time.

Are you UK based? I guess not as the other amps you mention are unlikely to be available here - not yet anyway! If you are, I'd like to invite you to visit, bringing your miniscule but lovely Audions and we could do a NAD vs AGD workout with Duo XDs!

Thanks. Peter

PS- Do you leave the Audions on 24/7 or switch them off? I'm sorry they don't have a trigger option so they could be powered up from the preamp.
 
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rocketiii

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When I read this, I thought I was reading one of my own posts as it exactly expressed my own situation 3 years ago. Then I was using valve amps (PX-25 and 845-based SETs) powering Avantgarde Unos.

I too had recently retired and was curtailing my listening hours because of the valve amps. I decided to switch to ss if (and only if) I could find an equally good or better sounding a ss amp. I was looking at Class A, AB and D and home auditioned a dozen amps and was expecting one of the Class A ones to win my affection. However not so, although the Accuphase A-36 is a great amp, but a little too civilised and slightly lacking in impact. The dozen included the NAD M32 and I decided upon this great amp in the end, despite it being one of the least costly.

This was upgraded to M33 when it became available and the Unos upgraded to Duos (pre-Omega) and currently Duo XDs. I'd now like to try the M33 against the Atma-Sphere Class D monos and the ADG Audion monos to see if either offered better sound than the NAD.

Did you home demo these 3 amps with your Duos, or was the decision after research, reviews and showroom demos? I did my tests at home after buying used amps, one new one and the rest were dealer demo units. But all were tested against the 845 mono SETs and other ss amps I had at home at the time.

Are you UK based? I guess not as the other amps you mention are unlikely to be available here - not yet anyway! If you are, I'd like to invite you to visit, bringing your miniscule but lovely Audions and we could do a NAD vs AGD workout with Duo XDs!

Thanks. Peter

PS- Do you leave the Audions on 24/7 or switch them off? I'm sorry they don't have a trigger option so they could be powered up from the preamp.
Hi Peter,

I had a trial of the NAD M23 and found that to be very convincing. I would have trialled the Atmasphere Class D but there is no dealer in the UK. Ralph does offer a trial/teturn but I didn’t want the hassle of Customs duty etc if I did return the amps.

I bought the AGD Audions from Valhifi. Greg does offer home trials but his amps were out for review. So, after a fair amount of research, I decided to take a flyer and buy them.

Within the first song I knew I’d made the right decision! You might also want to take a look at the AGD Tempo di Gan stereo amp which does have trigger function.

I currently have a PS Audio BHK preamp which has two triode valves on the input so I don’t want to keep them powered on. I therefore also power down the Audions in case of any switch on thumps etc.
 

uzzy

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it's all about the timbre and tonality of acoustic instruments. Not interested in "emotion" because any emotion is in the music itself. Not interested in soundstage because I listen from various different points in the room. Not interested in "bass slam" because I'm a double bass player and a double bass absolutely does not "slam" - that's an electronic artefact. All music has dynamics but I don't want exaggerated dynamics, just what's there already.
Ok .. to get the emotion that is in the music you need an amp that can produce the dynamic range without distortion or clipping.

I can understand your comment on sound stage because I chose Gale 401s many years ago over other speakers that imaged better but were nowhere close on "realistic sound and tonal qualities"

As for Bass slam .. it is a term used by many and in itself means all things to all men. For me it is bass realism .. even with a double bass you feel the note and with a lot of systems you hear the bass but you do not feel it. So for me bass slam is a realism that you feel like a Fender Precision in Rock hitting your chest or the dynamics of the plucked string on a double bass where the nuances are many.

I do not know about exagerated dymanics as I do not see how that can be achieved but what i do seek is realistic dynamics that we hear at live concerts. Having said that a classical concert can achieve 110db and more but that does not really work in a living room
 

Jazid

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Ive had a couple of pricey class d amps with SMPS, and couple of cheap class d amps with LPS. I am of the opinion that the power supply topology seemed to have more to do with the sound than the amplifier topology, linear PSUs sounding more "natural" in my limited experience. Just for the record I am not saying this as a devoted LPSU fanboy, just an observation.
 

MartinC

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That's an interesting observation @Jazid that for some reason I hadn't considered before. For what it's worth my vintage (by Class D standards!) Bel Canto power amp has a pretty hefty transformer as part of it's obviously linear PSU.

BC Transformer.jpg
 
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Strider

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The Extron power amps I'm using have so much more heft and bass resolution I can now hear fret scrapes and finger tapping. They go outrageously loud but donrt err toward stridency or a ball of upper mid distortion, they don't quite have the sophistication of the Rega Elict R and not the absolute resolution of the Primare I30 but they're closer to the Primare than the Rega.
I like the Rega Elicit R but its a bit too polite for me, simple recordings and wonderful soundstage but doesn't have the bass or top end I been after since the Primare went to the gods but these are keepers - I can't wait until the Tisbury Passive II arrives..

apparently the have some high end Infineon chips?
 
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hiesteem

peacebro
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Amplification is such an important part of the overall presentation within the chain. There's so many different ways to go. However my reason for staying with my amp is it compliments and performs so well, now it's been rebuilt that is!
It can be an expensive and frustrating experience to get that right. However it's good to hear all the choices that are available and peoples personal experiences.
 

exdem

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I've just bought myself one of these.

1677172040412.png

Audiophonics MPA-S250NC Hypex ncore class D.

It's awesome. :)
Installed 2x AUDIOPHONICS MPA-M250NC Power Amplifier Class D Mono NCore NC250MP today.

How are you getting on with your Hypex? I think I just opened Pandora's Power Amp .. not sure, really not sure. I do not get how PWM sampling at 500kHz is not considered digitisation. The bass/mid - control - dynamics are incredible. Top end not convinced on first few hours listening - soundstage and imaging too. Reminds me of CDs after listening to vinyl. Sorry first thoughts - just being honest. I do like how D is super small, light and efficient, and is the future. I was comparing to the power amp section of an MF M3i using same pre-amp stage.
 
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JANDL100

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Installed 2x AUDIOPHONICS MPA-M250NC Power Amplifier Class D Mono NCore NC250MP today.

How are you getting on with your Hypex? I think I just opened Pandora's Power Amp .. not sure, really not sure. I do not get how PWM sampling at 500kHz is not considered digitisation. The bass/mid - control - dynamics are incredible. Top end not convinced on first few hours listening - soundstage and imaging too. Reminds me of CDs after listening to vinyl. Sorry first thoughts - just being honest. I do like how D is super small, light and efficient, and is the future. I was comparing to the power amp section of an MF M3i using same pre-amp stage.
Well, I tend not to keep hifi things long.
I sold my Audiophonics amp on after having similar reservations as you.

But for me there is something uniquely appealing about class D. I'm currently playing around with Cyrus ONE and TEAC AX 501 integrated class D amps. I think they improve on the Audiophonics in terms of in the room vividness, 3D imaging, midrange tonality richness and a smoother (but not smoothed over) top end.
I'm not feeling the box swap itch about them yet.
 
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Psilonaught

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Hi Peter,

I had a trial of the NAD M23 and found that to be very convincing. I would have trialled the Atmasphere Class D but there is no dealer in the UK. Ralph does offer a trial/teturn but I didn’t want the hassle of Customs duty etc if I did return the amps.

I bought the AGD Audions from Valhifi. Greg does offer home trials but his amps were out for review. So, after a fair amount of research, I decided to take a flyer and buy them.

Within the first song I knew I’d made the right decision! You might also want to take a look at the AGD Tempo di Gan stereo amp which does have trigger function.

I currently have a PS Audio BHK preamp which has two triode valves on the input so I don’t want to keep them powered on. I therefore also power down the Audions in case of any switch on thumps etc.
Which Atma-sphere amps do/did you have and do you find the AGD Audions superior or merely "close" to the OTLs?

Why has he put the boards in an octal pentode tube, seems very gimmicky to me. Or can you use them in other pentode amplifiers?

I own MA-1 monos and would never consider leaving them on for more than a few hours. I mate them to a KR Audio P135 with EML 45 mesh globes.

Regarding Ralph's class D amps, I've read a number of US forum posts about excited OTL owners trying to like them over their OTL amps and failing. They always eventually found something was missing. Probably why I see quite a few on hifishark...
 
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Owl

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I’ve recently purchased an MBL c51 integrated. It’s a class d design. It’s sounds warmer and more tonally saturated than many other amps I demoed which were class A or AB. It’s certainly not thin, artificial or paint stripping in any way
 
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Psilonaught

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Class D can be easily influenced by a buffer like a DAC so it isn't surprising that class D can sound wildly different.

Keep trying to convince yourselves that class D is as realistic as the sound of a directly heated triode. Good luck with that. 😂
 
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hearhere

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Regarding Ralph's class D amps, I've read a number of US forum posts about excited OTL owners trying to like them over their OTL amps and failing. They always eventually found something was missing. Probably why I see quite a few on hifishark...
Could you point me to some of these US forum threads please? I have found the contrary - that most A-S Class D owners are thrilled to bits with them. So much so in fact, that I searched around and eventually found a pair (the only pair outside the US) on HiFi Shark. I bought them unheard and they are very good sounding amps.

Wheather they are actually better than the Purifi Eigentakt based NAD M33 is another matter. I can switch between the two amps and I'm hard pressed to find any difference in sound at all. They are both pretty great amps and I'd never go back to valves.

If anyone would like to hear these two amps and offer their expert opinion, I'd cordially invite you to do so. Peter
 
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Psilonaught

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Could you point me to some of these US forum threads please? I have found the contrary - that most A-S Class D owners are thrilled to bits with them. So much so in fact, that I searched around and eventually found a pair (the only pair outside the US) on HiFi Shark. I bought them unheard and they are very good sounding amps.

Wheather they are actually better than the Purifi Eigentakt based NAD M33 is another matter. I can switch between the two amps and I'm hard pressed to find any difference in sound at all. They are both pretty great amps and I'd never go back to valves.

If anyone would like to hear these two amps and offer their expert opinion, I'd cordially invite you to do so. Peter
https://forum.audiogon.com/discussions/atma-sphere-class-d-amazing?page=6

Interesting thread where the OP starts out stating the Atma-sphere Class D amps are amazing and then saying on page 6 that effectively they can't beat the mid-range of his MA-1 amps.

Separately on the same page a 300B user says the same thing,

The bass on them might be superior to my MA-1 but I use 600w class A/B on my magnepan's bass panels so I don't have to worry about that.

Nope, I'm sorry, this is exactly like the experience I had with a very high end solid state dac. Initially I preferred it over my triode (45) dac, but after about two weeks I realised that the DHT magic was missing, and I ended up selling that dac.

Power triodes all the way.
 
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