Class D power amplifiers

Are class D amps finally ready for prime time for audioholics, even audiophiles, if not why not?

  • Yes

    Votes: 14 56.0%
  • Yes, but probably not audiophiles

    Votes: 1 4.0%
  • May be, it depends..

    Votes: 5 20.0%
  • Don't know

    Votes: 3 12.0%
  • No, they are not ready for prime time because..

    Votes: 1 4.0%
  • Yes, but only those with good specs confirmed by bench tests

    Votes: 1 4.0%

  • Total voters
    25
ryanosaur

ryanosaur

Audioholic Warlord
There seems to be some multi-channel issues but otherwise the results are pretty nice. Video coming tomorrow from what I understand.

Thanks for posting that. :) Where did you find it? I went looking for it since I've been following that inane A6A Thread, and it is nowhere to be found.
 
P

PENG

Audioholic Slumlord
There seems to be some multi-channel issues but otherwise the results are pretty nice. Video coming tomorrow from what I understand.

Thanks, don't know how I missed that.:D The FL/FR channels look good on SINAD but still can't compare with your DACs, but again, really good for an AVR.
 
T

tparm

Audioholic
Thanks for posting that. :) Where did you find it? I went looking for it since I've been following that inane A6A Thread, and it is nowhere to be found.
I’m in my car, I hope I didn’t spill the bean Patreon beans…. I think it’s on the normal page, hope anyway haha.
 
T

tparm

Audioholic
Thanks, don't know how I missed that.:D The FL/FR channels look good on SINAD but still can't compare with your DACs, but again, really good for an AVR.
I’m not even sure how I found it, haha. I have some questions that I’m sure will be answered; there a preamp or selectable output mode like 8015/8500? Can PEQ be combined with YPAO? Can PEQ be used in the analog domain? Why do the multichannel HDMI results suck? But, nice feature set and pretty good on the bench.
 
P

PENG

Audioholic Slumlord
Thanks, don't know how I missed that.:D The FL/FR channels look good on SINAD but still can't compare with your DACs, but again, really good for an AVR.
As far as I can remember, the 8500 and the 110 are the only two D+M models that have selectable channels to preamp mode. I don't think Yamaha has that at all, but will take another look.
 
P

PENG

Audioholic Slumlord
To make it easier to search for information on Class D amplifier designs, I added a few links in the first post.
 
T

tparm

Audioholic
@PENG still up for class D questions? Which input buffer did you choose with your VTV purifi based amp? Where does one find a discount code for. VTV? And how did you make your decision? And do you know what NAD is using in their C298?
 
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P

PENG

Audioholic Slumlord
@PENG still up for class D questions? Which input buffer did you choose with your VTV purifi based amp? Where does one find a discount code for. VTV? And how did you make your decision? And do you know what NAD is using in their C298?
I went with VTV's Eigentakt Eval1:

1ET400A - PURIFI (purifi-audio.com)

I was going to DIY it but couldn't wait for the long delivery as I have already promised someone my only remaining large class AB amp (Halo A21). The DIY would cost significantly more and that's the other consideration.

My decision is based on:

a) The Eigentakt Eval1 it was originally made as a demo evaluation kit for OEMs and it includes Purifi's only input buffer that can be bypassed.

b) It is the only Purifi amp that measured almost as good as the Benchmark AHB2.

SoundStage! Hi-Fi | SoundStageHiFi.com - Purifi Audio's Pint-Sized Powerhouses

On the practical side, I suspect 99% of their owners cannot hear the difference between this amp and Buckeye's $650 NC502MP but many will be able to hear the difference if they know which one is playing. For me, you probably know that on all else being equal basis, I do prefer amps that have better sound quality related specifications and measurements (not just SINAD) regardless of what the subjective reviewers opinions.

NAD uses their own SMPS and input buffer. The only Purifi amp that has the Purifi input buffer is the Eval1.
 
T

tparm

Audioholic
I went with VTV's Eigentakt Eval
Found it, thank you. I sold CD player that had about 3 hours on it and now thinking I may sell my Emotiva A7. I'll probably but a VTV 4 or 6 channel nCore amp for my effects channels (I can't decide if I am going to keep my front wides or not) and once that is done then I'll consider a 2 or 3 channel Purifi for my main channels.

Why not, I can experiment and basically break even on cost.... I like the idea of the C298, I am just not sure i can justify the cost over a VTV unit.

As always, thanks Peng.
 
P

PENG

Audioholic Slumlord
Found it, thank you. I sold CD player that had about 3 hours on it and now thinking I may sell my Emotiva A7. I'll probably but a VTV 4 or 6 channel nCore amp for my effects channels (I can't decide if I am going to keep my front wides or not) and once that is done then I'll consider a 2 or 3 channel Purifi for my main channels.

Why not, I can experiment and basically break even on cost.... I like the idea of the C298, I am just not sure i can justify the cost over a VTV unit.

As always, thanks Peng.
Keep in mind there are some made in the UK that you may prefer. NAD's advantage is they obviously have some competent engineers in their design team but they likely got most if not everything made in China. They is not always bad if they used the best parts for the price, but in Amir's teardown, the M28 did use some cheap capacitors. Purifi would likely use Rubycon's, at least that's what they used in the beginning iir.

Nord is one example of the made in UK one:
Nord Acoustics | About

For price, unless you wait for Buckeye, don't know why but you can email him, VTV's would be the best and amazingly they offer 30 days free trial and 2 years warranty.
 
T

tparm

Audioholic
Keep in mind there are some made in the UK that you may prefer. NAD's advantage is they obviously have some competent engineers in their design team but they likely got most if not everything made in China. They is not always bad if they used the best parts for the price, but in Amir's teardown, the M28 did use some cheap capacitors. Purifi would likely use Rubycon's, at least that's what they used in the beginning iir.

Nord is one example of the made in UK one:
Nord Acoustics | About

For price, unless you wait for Buckeye, don't know why but you can email him, VTV's would be the best and amazingly they offer 30 days free trial and 2 years warranty.
Thanks Peng, I recall looking at Nord and March a while back I recall them being pricy. I also recall the tear down of the M28.....

The Eval1 based VTV seems to be it for 2CH (minus the speaker connection options, maybe a little too eccentric for their own good), but then my channel count gets weird as their only 7Ch option is high-power nCore modules which are pricy and not necessary to drive my effects channels. And if I keep my wide channels (just sound weird for Spatial music but does add some effect to movies) then I'd need to do some weird combo to come up with 9 additional channels. I'll keep playing around, kinda fun.
 
Eppie

Eppie

Audioholic Field Marshall
I went with VTV's Eigentakt Eval1:

1ET400A - PURIFI (purifi-audio.com)

I was going to DIY it but couldn't wait for the long delivery as I have already promised someone my only remaining large class AB amp (Halo A21). The DIY would cost significantly more and that's the other consideration.

My decision is based on:

a) The Eigentakt Eval1 it was originally made as a demo evaluation kit for OEMs and it includes Purifi's only input buffer that can be bypassed.

b) It is the only Purifi amp that measured almost as good as the Benchmark AHB2.

SoundStage! Hi-Fi | SoundStageHiFi.com - Purifi Audio's Pint-Sized Powerhouses

On the practical side, I suspect 99% of their owners cannot hear the difference between this amp and Buckeye's $650 NC502MP but many will be able to hear the difference if they know which one is playing. For me, you probably know that on all else being equal basis, I do prefer amps that have better sound quality related specifications and measurements (not just SINAD) regardless of what the subjective reviewers opinions.

NAD uses their own SMPS and input buffer. The only Purifi amp that has the Purifi input buffer is the Eval1.
Did you research the Sparkos Labs input buffer options? Do you think they offer any significant advantage over the Purifi buffer?
 
P

PENG

Audioholic Slumlord
Did you research the Sparkos Labs input buffer options? Do you think they offer any significant advantage over the Purifi buffer?
Yes, I did do my research and found that they too emphasized transparency. Anyway, better to let them do their own talking so let me just quote:

Sparkos Labs, Inc. Discrete op amps for amplifying audio signals

Distortion Measurements:
We designed these devices to be as sonically transparent as possible. This means that the op amp amplifies the incoming signal, and produces an exact, larger copy at the output without coloring the sound or creating any distortion products (THD).
In other words, we sought to make these devices behave like the proverbial "piece of wire with gain".
The following plots were independently generated by ATM Audio of Spain. The way to interpret these plots is to know that the large spike in the middle is the input signal. Any other spikes to the right of it are things that the op amp "added to the sound" (The coloration or distortion products) . Those smaller spikes to right represent things that came out of the op amp, but didn't go into it.
Our intent was to produce an op amp that did no such thing. And we came pretty darn close. It should be noted, that not all manufacturers adhere to this design philosophy, and that some will purposefully add coloration and distortion to their devices to alter how they sound. And, hey, that's cool too. We aren't here to begrudge anyone's design philosophy. We are rather just trying to illustrate ours with some objective measurements.
Yet, some manufacturers and dealers will tell you this and that OPA has this and that sound signature blablabla..., so go figure.. In my opinion, there is no evidence to support Sparkos has any significant advantage over the Purifi's own buffer. The only problem is, you can't get the Purifi input buffer without getting their Eval units.
 
P

PENG

Audioholic Slumlord
Amps using the new Purifi module could be interesting.....I guess we'll see some offerings soon....
I would likely wait a year or so, until they come out with at least one updated version before I would grab one. It is not really necessary but I have enough amps now so I can afford to play extra safe.:)
 
lovinthehd

lovinthehd

Audioholic Jedi
I would likely wait a year or so, until they come out with at least one updated version before I would grab one. It is not really necessary but I have enough amps now so I can afford to play extra safe.:)
I'm just a spectator at this point, but would find the newer module more interesting if I were in the market....
 
T

tparm

Audioholic
Discussing either a 3 channel Eval build with stock binding post or simply an eval1 with regular binding posts with VTV now. Otherwise its this (lots of boxes). BTW, how does the 19" case fit in a regular 17" AV rack (already a dated pic from three weeks ago).
 

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