Class D amps seem poised to take over. Then what?


I am certainly biased by my lifetime final amp being a Class D. But I know that after 30+ years of development, Class D seems to be on a high plain. I know there are now many, many companies focusing on Class D and, maybe, a good handful already as good as it gets. My Class D amp is as smooth and beautifully musical as a great tube amp and as punchy and detailed as a great SS amp. I am satisfied and done with my search. A class D amp has effectively taken me off the amp merry-go-round. It’s about time after 50 years. And, for me, this Class D is a milestone. Will all other classes of amps fade away?
mglik

Showing 36 responses by georgehifi


Wow, not only an "fuser" but a racist as well, that explains all, and has something against our Aussie Dingo's too😵

Cheers George
“Youth ages, immaturity is outgrown, ignorance can be educated, and drunkenness sobered, but stupid lasts forever.” -Aristophances
You must be describing yourself there, because all your shilling here, is "making out" that the Class-D you’ve got coming will be able to drive these hard to drive speakers to sound their best, a little secrete for you, it won’t! -Georgehifi




🤦‍♂️
Just look at their independently measured 2ohm wattage figures (if you can find them) then compare to their 4ohm wattage figure, and see if the 2ohm even tries to come close to doubling the 4 ohm wattage figure, and post it up **** **** and if you don’t you full ** ****
AGD is that every record in my collection is now highly listenable Regardless of recording quality

That’s great, I’m not saying/never it’s not with the right speaker loading.

I’m correcting someone who has attempted to misinform the members here, about what speakers they can’t drive to their best, either through total lack of EPDR load understanding or outright just wishful thinking because they own one, and think they are the answer to everything🙏

Cheers George


your posts are quite comical and i detect the lack of knowledge. Once again you know zero of what you say.
Everything has been proved, it is you that is the unknowledgeable one with no idea, and no will to learn, and with a fixation with what the AGD amp is cable doing and not doing.


And please no more paste and copy or boring links.
Only because you know nothing of EPDR speaker loading, and are not even willing to try to understand what it is🤦‍♂️, I’ve tried, but you have https://ibb.co/6yVxb0Q 😉

I come on here to provide to others my experience.
But which tell them false stories of what the AGD is capable of doing into low EPDR bass loads of around 1 to 1.5ohms. That is why I post measurement proof to correct your falsehoods.
I sold my Wavac 300b tube amp and Pass XA25 because they were collecting dust as my class d was superior to both to MY ears.

You used an SE 300b or a XA25 to drive a pair of Wilson WP 5.1’s!!!!
No wonder you think the Class-D AGD is the be all and end all to those 2 amps, which btw had no hope of driving the 5.1’s correctly, look at the combined impedance and -phase angle, the EPDR is around 1 to 1.5ohm in the bass very hard to drive. And like I say now also even for the AGD, but it’s better than what you had.
https://www.stereophile.com/images/archivesart/watpup5fig03.jpg
A demanding load, its impedance (fig.2) reaching a current-hungry 2.4 ohms in the upper bass, although this will be moderated by the relatively innocuous phase angle in the same region. The rise in impedance above 100Hz is due to the low-pass crossover; the low port tuning is revealed by the magnitude saddle between 20Hz and 40Hz.
If you wish to learn a little about EPDR load of speakers on amps go here.
 https://forum.audiogon.com/discussions/epdr-more-important-than-impedance-alone
I’m a ham radio operator and it generated RFI which was picked up by my transceiver. Went back to class A/B and now no noise.

You can check this yourself, get a portable "am radio" tune it around between 500-700khz "unmuted" turn up the volume, and go near your Class-D amps speaker terminals with it and even switchmode wall warts, and listen to it scream.
This is "what it looks like" on Stereophiles oscilloscope square wave shot (top pic) https://ibb.co/xgHv8dZ

But now Stereophile don’t show that pic anymore and filter it out with their AP test gear filters so you don’t see it, which should not be allowed, in my books as it's not representative of what comes out the amps speaker output.
They say it’s because the noise overloads the AP gear, but that’s bs because they didn’t use it years ago, with the same gear, and if it does then they should fix it not hide it.

Cheers George
Well..george has an MO of trying to cherry pick items to bolster his view.

You really need to get educated on this.
Look at the paragraph direct above your last post, even he back down on the flagship Wilsons I mentioned that a Class-D can't drive to their best. And he cherry picked the ones that can, (Sophia, Sasha ect)  because they have far easier loading that the Class-D won't be too taxed with🤦‍♂️
Even the big high bias amps built with BJT's can't do it.

Oh dear🤦‍♂️, to say that an amp doubles, is just a "saying", maybe it should read "close to doubling", but hey, I didn't make up the saying.

No! amp can  perfectly double it wattage from 8  to 4 to 2 ohms, that would be a furphy, and would be like saying perpetual motion is a reality.
These companies that claim double wattage when impedence is halved don’t give the actual 8ohm measurement

Usually if they don’t, they are hiding something. Stereophile does for Class-D if you read the Lab Tests on them and that’s usually is in the negative.
But even Stereophile doesn’t usually do 2ohm testing on Class-D’s as they are usually pitiful, when compared to the good linear solid BJT state amps for putting out big (doubling watts) current.

Cheers George
You keep mentioning Wilson’s as being hard to drive, where does this come from?

For someone who "says" they’ve owned Wilsons, you are not very au fait or even interested in how they measure or behave, in particular the loading they present for amps to see. And they have many models that are in that same low EPDR loading bracket.
From HiFi News Lab Report
Impedance phase is quite well controlled but still the EPDR falls to a low of 1.2ohm/67Hz, with further minima at 129Hz (1.8ohm) and 410Hz (1.9ohm). So the Alexia 2 presents a challenging load to the amplifier, albeit not so much as its predecessor Mk1 (min EPDR 0.9ohm!!!!).

Output Power: 2 x 70 W @ 8 Ohm, 2 x 130 W @ 4 Ohm


It wasn’t mentioned
Let see what happens into 2ohm un-bridged. (bet they can’t handle it) and those Wilson’s mentioned hit 0.9ohm!!!.

Cheers George
georgehifi
Next you’ll say an OTL of Ralphs can drive those Wilsons to their best properly, because they too will stay stable into them and not oscillate.🤷‍♂️
atmasphere
The sales manager of Wilson had our amps for many years. FWIW our OTLs are inherently stable and will not oscillate with any load or input signal condition.

Dream on sunshine, were talking about driving the Wilsons mentioned here.
Trust you to try to skew it around to make out that your OTL amps could even come close to driving these, the hardest of Wilsons to drive
(Always looking for the self promoting angle)
Everyone has an opinion - which is good - not everyone agrees with another persons opinion


Difference is, these are measured facts, and not my opinion.
And if one dismisses them then this is what they believe, 
https://i.dailymail.co.uk/i/pix/scaled/2013/12/18/article-0-1A2B262D00000578-818_636x382.jpg
as every decent piece of audio gear is designed by the laws of electronic design 


They can come close if good, like the BJT ones I mentioned.,
Where many Class-D go backwards! instead of trying to double, if independently measured into 2ohm from the 4ohm wattage, that shows just how current limited they are.


It amazes me how someone can say a Class-D like the AGD has no limitations into one of the hardest know speakers to drive, and for it to sound it's best.
@georgehifi - wouldn’t it depend on the original rating at 8ohms, the power supply rating that feeds the class D modules?

No, although it to needs to be beefy, look at any Class-D that has been independently wattage tested into 8ohm 4ohm 2ohm regardless of powersupplies (most won’t get test into 2ohms), they are fets, and fets can’t do doubling of 8 to 4 to 2ohms (current) like complimentary bi-polars (bjt) can do like in the the Gryphon Antillion, bigger Krell, D’Agostino Boulder, etc etc etc

Also look at my post in the  "Pass X260.8 vs Bryston 7B3" thread

Cheers George
I hate it when people talk about subjects they know nothing about.
You need to hate yourself then, as you have no idea about the performance of Class-D even when using GaN Fets into 8 4 2 and 1ohm at it’s "current ability" (wattage doubling) at these loadings. And how those Wilsons demand it to get the best out of them.
Next you’ll say an OTL of Ralphs can drive those Wilsons to their best properly, because they too will stay stable into them and not oscillate.🤷‍♂️

Don’t have to, the AGD is just GaN based Class-D slid into a "bogus" empty tube envelope, which uses (horror) the base pins for all it’s contacts 🤦‍♂️

And there no way the AGD can do what say the Gryphon Antilion can do into the Alexia, Alex, or XLF’s bass, if you do own any of these, they go down to 0.9ohm EPDR (Equivalent peak dissipation resistance). It’s a measurable fact.

Don’t get me wrong, I never said it won’t sound any good, just not the very best for those speakers. And if I had the money for them I’d have the money for the best amp also.

Cheers George


Guarantee put a Gryphon Antilion stereo or monoblocks on them and you'll change your mind in an instant.
And if you don't there's something seriously wrong.

Cheers George

FACT!!!!
No way can ANY Class-D compete with doubling of wattage into impedances 8 > 4 > 2 and 1ohm (current ability) like BJT amps Gryphon Antillion, bigger Krell, D’Agostino Boulder, etc etc etc can

Class-D "may" not blow up, because of severe current limiting at 2 and 1ohm but they can’t drive into those low impedances like those BJT above amps can.
Anyone who says they can is just shilling for sales.

A friend Edgar Kramer, editor/owner of Soundsatge Australia has the Wilson Alexia MkII, and no Class-D he’s tried and reviewed and I’ve heard at his house has sounded any where near as good on them, as his Gryphon Antilion does, especially in the bass where those Alexia’s are 0.9ohm loading.
I will also say the Technics SE-R1 which I rave about is also in that same situation, as GaN Fet like Mosfets output stages can’t do current like BJT’s can into low impedances, 1 or 2ohms

Cheers George


jbhiller
I’ve tried a couple class D units. They were good but not great to me. I’m game to try some more.


If you can get hold of a Technics SE-R1 flagship or at least it’s cheaper integrated the SU-R1000
The SE-R1 addresses the "Achilles Heel" of Class-D, (ultra sonic switching noise down into the audio band) Technics takes it up 3 x higher and so filters it up 3x higher also, which results in 3 x less switching noise in the audio band.
It’s been said the SU-R1000 integrated does it also, but not confirmed by Techinics.

These are the only Class-D’s so far to take full advantage of the GaN Technology’s far higher ability to be able switch 3 x higher.
Other manufactures using GaN are only half exploiting it, and still using the old 3 x lower switching frequency, like all other Class-D’s do since the 90’s, so really not much advantage using GaN if not used like Technics have.

This top pic is what the switching noise looks like on the output of a Class-D going to the speakers a 10khz square. https://ibb.co/qBnNwVJ
Now Stereophile use an "AP (Audio Precisions) temporary test bench filter" on the output to give the illusion of a cleaner bottom pic, and they never give the top pic anymore, this is done in my view as to to not freak potential; buyers out.

Cheers George
...yes, but is Class D stable into 2 ohms?
Sadly not, like good Class-A/B's can be using BJT (bi-polar) output stages, especially in current delivery.

Cheers George

There you go again, do you not get it? 

YOU ATTACK PERSONALLY !!!

If you have none, try giving some electronic technical proof for your arguments quoted from someone else, instead of attacking personally.  
You’re the one who brought up the topic of fuses.


Yes "fuses and other snake oil" not people, big difference!!!!!! and you bit and attacked me and my dog personally, and yes I consider my Dingo a person.
You choose attack the members/people/dog, probably because you have no electronic knowledge you can call on.

earlflynn

May just buy a Technics G-700 to hear how it sounds in my system


Go the far better integrated the SU-R1000, it’s said it also uses the far higher switching speed of 1.5mhz like the flagship SE-R1, which cuts down greatly the switching noise intruding down into the audio band. (class-D’s achillies heel)
And Technics is the only one I know of that has exploited this GaN technology feature so far.
https://www.stereophile.com/content/technics-presents-discussion-their-reference-class-su-r1000-digi...

Cheers George
Admin had a knee jerk reaction to the unfounded claims

All noise, when a subject is attacked for being snake oil, voodoo or whatever, that is fair game and keeps the shillers down.
But you then retaliate by attacking the poster or in the last case their dog personally. And that’s where the difference is, and why you get deleted more than anyone on Audiogon.🤦‍♂️
@georgehifi who is a fuser? Not I.
No, nonoise the one your bagging on.

Cheers George
Lets end this. I do not like you would rather play with rattle snakes than listen to you.

He's a strong avid fuser, and that about sums it up in one word

"FUSER"

Cheers George

sandthemall
That’s sort of how digital works.

 Hate to tell you this, but Class-D is not digital.

Cheers George


Only two from Technics so far are in Class-D royalty.
They are the Technics SU-R1000 Integrated and the SE-R1 Power-Amp, both use the GaN technology, the SE-R1 uses it to the max, with a 1.5mhz switching speed, it’s yet to be proved/written if the SU-R1000 has gone the extra yards and used this 3 x higher switching speed.

Cheers George