Class D power amplifiers

[AcuDefTechGuy]

Ammmm, my ATI class D amps are heavy. Not Mac heavy, but heavy nonetheless.


Sent from my iPhone using Tapatalk

Your ATI amps are more like class A/B/D.

Heavier than Class D, but lighter than class A/B.

 

[PENG]

@PENG I always enjoy your post and have learned form you so don’t take this argumentative, but inquisitive. A general statement first, I don’t understand everyone’s concern over heavy amps. Yes AB amps can be heavy, my A52+ is no lightweight, but once it was in my rack, it isn’t a burden. I am not a reviewer, and if I was I wouldn’t rack mount my gear, so I don’t move my stuff around on a regular basis.

Now, I have owned 4 AVRs/Processors in less than two years, and especially the A110 had some weight to it, but once again it’s not like it was a burden.

I assume the lack of noise and distortion (measurements) are the appeal of class D amps? Does size realty matter (see what I did there…..)?

And I always enjoyed your post, though half the time I would get the impression that you are likely in the "subjective camp" and I am more in the other, but that's more the reasons I enjoyed reading your posts too. Its also what makes such forums fun places to spend time on. There would be no fun if everyone says the same thing.

I know weight and size don't matter to a lot of people but it certainly can be an important factor to those who have their own reasons. In my case, it wasn't a factor when I had only a couple of amps and was younger and stronger. As a small person, I had no trouble picking up my 85 to 90 lb GSD and GRD (an oversized one) 20 years ago. It was not easy to carry a 79 lb A21 in the box because of the shape (more difficult than a heavier dog) but it was still manageable. As you said, once in place you would leave it there for a long time anyway. Over the years, I have accumulated 6 (more at one point) amps that I can count quickly. That's just power amps and they were all in use at one time or another. So real estate became a factor too, aside from the WAF thing. That's just me. There are guys like ADTG who just complained about having to move those heavy boxes, much more often than us because he has become a part-time dealer, so the more he sells the more he has to move those 50+ lb boxes. For someone like him, imagine if all AVRs and amps switched to SMPS and class D amp modules..

Then there are people who have smaller rooms, or older, even single female hobbyists, all of them would likely welcome the much smaller and lighter class D amps and would consider it a major factor.

I would not switch from class A, AB to class D just because of the weight and that's why I had kept the Bryston and Halo amps for so many years. Now my heaviest power amps are the Marantz amps, the 2 channel one weighs just under 50 lbs. I felt ready to switch only after spending time reading up on SMPS/Class D amp and then realized the much smaller size and lighter weight will not result in lesser "sound quality". And of course my wife was happy to see those big boxes go through the door, in fact offered to help moving them out.

A bonus for the real estate gain for me is, now I can put my DACs and preamp much closer and the shorter interconnects much less clutter.

 

[Kvn_Walker]

I hope Parasound comes out with a Hypex version of their New Classic design. The NC line has every feature I want in a power amp except balanced inputs:

A/B speaker selection
Rear panel Gain controls
Audio Sensing trigger/standby

Blows my mind how many amps don't have those features, even at much higher price points.

 

[PENG]

So why class D?

To me, and a suspect a lot of people, the main reason is efficiency. Apparently the first commercially available class D amp kit was in 1964, so it has been almost 60 years in the making.

Given the excellent specs and bench measurements of the Purifi amps, thanks to Bruno Putzeys who's design have been adopted by mainstay amp manufacturers including ATI, Lyngdorf Marantz, NAD and the higher end ones such as Bel Canto.

Bruno Putzeys: Head of the Class (D, That is) | Sound & Vision (soundandvision.com)

If you search the topic, you will see that there had been many disadvantages of class D amps in the early days, but 60 years is a long time for engineers to improve on the technology to the point that it is now ready for prime time, or the likes of ATI and NAD would have started to join.

So again, short story: Efficiency, that implies environmentally friendly too I suppose..

Long story, a 9 minute read:

Class D Audio Amplifiers: What, Why, and How | Analog Devices

There is a part of me that thinks it old be cool to buy an HTP-1, new Monolith Class Ds and two 13” THX subs; super low noise and distortion, but would it really sound better than what I have? I don’t know…..

You probably know what I am going to say so I won't disappoint you:

No, it would not really sound better than what you have because what I believe what you have are transparent enough to have no audible sonic signature, except when DSP functions are used, for reasons you cited yourself.

For you, I don't see any reasons to switch to class D amps unless you can put the extra real estate (by switching) to good use and/or you think energy reduction/environmental considerations are a factor.

 

[Alex2507]

even single female hobbyists,

You can't talk about Doug like that.
She is married.

 

[Mikado463]

I hope Parasound comes out with a Hypex version of their New Classic design. The NC line has every feature I want in a power amp except balanced inputs:

A/B speaker selection
Rear panel Gain controls
Audio Sensing trigger/standby

Blows my mind how many amps don't have those features, even at much higher price points.

View attachment 52467

back of that amp cracks me up.......'Designed in SF, Ca, USA' and made where ?? !! I know, if it were made here it would have cost twice as much !

 

[Billy106]

I wish...I had research this route prior to purchasing my new AVR. I needed something small and form fitting to use with my space...with the aforementioned design in this thread I could've bought a 7ch downsized amp "D" and done separates....given my restrictions...now I'm in a quandary because I'd like to add some added amplification to my 3 fronts and use the AVR to power my surrounds + Atmos but my receiver has outs only for the LR fronts....granted my room is not huge but I'm always cognizant of its limits and employ max volume limitations and it would be nice not having that in the back of my mind...lol.

 

[Mikado463]

And I always enjoyed your post, though half the time I would get the impression that you are likely in the "subjective camp" and I am more in the other, but that's more the reasons I enjoyed reading your posts too. Its also what makes such forums fun places to spend time on. There would be no fun if everyone says the same thing.

I know weight and size don't matter to a lot of people but it certainly can be an important factor to those who have their own reasons. In my case, it wasn't a factor when I had only a couple of amps and was younger and stronger. As a small person, I had no trouble picking up my 85 to 90 lb GSD and GRD (an oversized one) 20 years ago. It was not easy to carry a 79 lb A21 in the box because of the shape (more difficult than a heavier dog) but it was still manageable. As you said, once in place you would leave it there for a long time anyway. Over the years, I have accumulated 6 (more at one point) amps that I can count quickly. That's just power amps and they were all in use at one time or another. So real estate became a factor too, aside from the WAF thing. That's just me. There are guys like ADTG who just complained about having to move those heavy boxes, much more often than us because he has become a part-time dealer, so the more he sells the more he has to move those 50+ lb boxes. For someone like him, imagine if all AVRs and amps switched to SMPS and class D amp modules..

Then there are people who have smaller rooms, or older, even single female hobbyists, all of them would likely welcome the much smaller and lighter class D amps and would consider it a major factor.

I would not switch from class A, AB to class D just because of the weight and that's why I had kept the Bryston and Halo amps for so many years. Now my heaviest power amps are the Marantz amps, the 2 channel one weighs just under 50 lbs. I felt ready to switch only after spending time reading up on SMPS/Class D amp and then realized the much smaller size and lighter weight will not result in lesser "sound quality". And of course my wife was happy to see those big boxes go through the door, in fact offered to help moving them out.

A bonus for the real estate gain for me is, now I can put my DACs and preamp much closer and the shorter interconnects much less clutter.

Good post Peng and I agree. Until the day comes that we downsize or whatever I have no plans to replace my PASS X260.8's

Years ago when I was running with a pair of M/L Spire's a friend of mine who owns an Audio mfg company here in Pa gave me one of his 'Hybrid' Class D amps (http://www.rogueaudio.com/Products_Medusa.htm) to give a try. I thought they performed admirably. They had no trouble driving the stats.

 

[PENG]

I wish...I had research this route prior to purchasing my new AVR. I needed something small and form fitting to use with my space...with the aforementioned design in this thread I could've bought a 7ch downsized amp "D" and done separates....given my restrictions...now I'm in a quandary because I'd like to add some added amplification to my 3 fronts and use the AVR to power my surrounds + Atmos but my receiver has outs only for the LR fronts....granted my room is not huge but I'm always cognizant of its limits and employ max volume limitations and it would be nice not having that in the back of my mind...lol.

With the current shortage, you may as well just be happy with what you have now and make a move when the supply chain issues get sorted. Except you may want to grab one of those Buckeye amp as I think price can only go higher as demand goes up.

 

[lovinthehd]

back of that amp cracks me up.......'Designed in SF, Ca, USA' and made where ?? !! I know, if it were made here it would have cost twice as much !

Well, from a legal marking standpoint for importation, it doesn't qualify since there's no equivalent marking for the foreign origin. Wonder if these are from their own photo files for advertising? Is an actual amp marked the same? They used to be down the peninsula like in Palo Alto, didn't know they moved up to the city....don't know the extent of the assembly/manufacturing there is/was either way, tho makes me curious and doubtful it takes place in the city itself. Think I'd read they were US made.....bt just looked at a Halo photo showing "Made in Taiwan" not near the San Francisco stuff, and even a smaller font....that at one time would yield a Customs marking violation notice.....at least I don't think they've changed the marking rules.....

 

[ryanosaur]

Ammmm, my ATI class D amps are heavy.

Not Mac heavy, but heavy nonetheless.


Sent from my iPhone using Tapatalk

Your ATI amps are more like class A/B/D.

Heavier than Class D, but lighter than class A/B.

The Hypex ATI amps use a linear power supply rather than a Switch Mode Power Supply.
The weight is mostly in that distinction right there, as the SMPS would be a fraction of the weight, especially if ATI is using a toroidal transformer.

 

[tparm]

The Hypex ATI amps use a linear power supply rather than a Switch Mode Power Supply.
The weight is mostly in that distinction right there, as the SMPS would be a fraction of the weight, especially if ATI is using a toroidal transformer.

I think the new Monolith Class D amps look interesting (I bring this up due to their collaboration with ATI). Sounds like they are using nCore modules like ATI but a SMPS instead of linear. I wonder if this is something we will see in a new or revised ATI line or a proprietary PS for/from Monolith?

 

[tparm]

A bonus for the real estate gain for me is, now I can put my DACs and preamp much closer and the shorter interconnects much less clutter.

Thanks @PENG Interesting that for some reason you mentioning your DAC reminded me of something off topic; after I switched to the AVM 70 I took my Gustard X16 out of my system as the 70 in 2.2CH, digitized and with ARC engaged sounds great. I do wonder though if the analog input on the 70, even with "convert" (re: digitized) set to "no" is a true analog path? The sound quality and sound stage were not drastically different when comparing like they were with the X4700, A110 and to a lesser degree the RMC-1L.

Anyway, derailing things here, but a curious muse and if you care to comment I'd invite your thoughts.

 

[snakeeyes]

I haven’t researched this recently.

Which of the class D amps are the best out there right now in 2021?

 

[PENG]

Thanks @PENG Interesting that for some reason you mentioning your DAC reminded me of something off topic; after I switched to the AVM 70 I took my Gustard X16 out of my system as the 70 in 2.2CH, digitized and with ARC engaged sounds great. I do wonder though if the analog input on the 70, even with "convert" (re: digitized) set to "no" is a true analog path? The sound quality and sound stage were not drastically different when comparing like they were with the X4700, A110 and to a lesser degree the RMC-1L.

Anyway, derailing things here, but a curious muse and if you care to comment I'd invite your thoughts.

I have to do some digging into the AVM 70, because for some reason I seem to remember Anthem would route even analog input signals to the ADC>>>DSP>>>DAC path whereas D,M and Y would bypass them in direct mode.

Purely based on specs and measurements the Gustard X16 is of course far superior as you are talking about at least 20 dB difference in THD+N based on bench test results. I doubt even real certified golden ears can hear the difference between -90 dB and -120 dB THD all else being equal, under normal conditions even in an extremely quiet room with 15 dB noise floor.

Just for fun though, now that I have very quiet Hypex and Purifi amp, I was able to use one of the amps to compare the hiss/hum between my AVR-X4400H and AV8801. Amazingly, the AVR-X4400H that has at least two octopus sucking on it, including fibre TV, Fire stick, Apple TV, 3 power amps, 3 Ethernet hubs, PS4, 3 BDP, 1 HDDVDP, 2 Active subs and 11 speakers, was audibly quieter than the AV8801 that only has the aux XLR input connected. So much for those copper shielding, copper mounting plate and balanced I/Os. With the Denon, I could turn the volume to maximum, that is +18 and could only hear something with my ear touching the speakers, and I am very sensitive to hum and hiss.

 

[PENG]

back of that amp cracks me up.......'Designed in SF, Ca, USA' and made where ?? !! I know, if it were made here it would have cost twice as much !

The Halo series are still made in Taiwan, not sure about the Classics but I would bet Taiwan as well.

 

[ryanosaur]

I haven’t researched this recently.

Which of the class D amps are the best out there right now in 2021?

Hypex NCore and Purifi are the best modules I’m aware of. I’ve heard people talk about Pascal also, but I don’t know much about them.

 

[tparm]

I have to do some digging into the AVM 70, because for some reason I seem to remember Anthem would route even analog input signals to the ADC>>>DSP>>>DAC path whereas D,M and Y would bypass them in direct mode.

Purely based on specs and measurements the Gustard X16 is of course far superior as you are talking about at least 20 dB difference in THD+N based on bench test results. I doubt even real certified golden ears can hear the difference between -90 dB and -120 dB THD all else being equal, under normal conditions even in an extremely quiet room with 15 dB noise floor.

Just for fun though, now that I have very quiet Hypex and Purifi amp, I was able to use one of the amps to compare the hiss/hum between my AVR-X4400H and AV8801. Amazingly, the AVR-X4400H that has at least two octopus sucking on it, including fibre TV, Fire stick, Apple TV, 3 power amps, 3 Ethernet hubs, PS4, 3 BDP, 1 HDDVDP, 2 Active subs and 11 speakers, was audibly quieter than the AV8801 that only has the aux XLR input connected. So much for those copper shielding, copper mounting plate and balanced I/Os. With the Denon, I could turn the volume to maximum, that is +18 and could only hear something with my ear touching the speakers, and I am very sensitive to hum and hiss.

I think you could be right about the signal path in the Anthem. And that’s pretty wild about the 4400 vs 8801 haha.

 

[Pogre]

Oh boy. You're putting ideas in my head!

I mean, I should be able to get enough for my Monolith to pay for a class D replacement and then some...

Why?

Why not?

 

[M Code]

back of that amp cracks me up.......'Designed in SF, Ca, USA' and made where ?? !! I know, if it were made here it would have cost twice as much !

ParaSound amplifiers are assembled in Taipei, Taiwan the factory is very experienced and builds for many other audio brands including Harman/Kardon, SpeakerCraft, Outlaw Audio.....

Just my $0.02...