Time to buy a class D amp?

niodari OP

BUT the best will be if you use 2 x stereo S500's and vertically bi-amp them. (Not bridge them)
http://www.classicspeakerpages.net/IP.Board/uploads/monthly_2016_03/7_Vertical_Bi-Amp.jpg.ba97802ae9...

Cheers George

BTW the M500 monoblocks if real monoblocks, will sound better than a pair of "bridged stereo S500’s" even though the S500’s will have more watts.

Cheers George

I’ve found a nice deal online for two Red Dragon S500 Monoblocks for $2K and I am just about ready to jump the trigger.

 
When you say you’ve found a nice deal on 2 S500 monoblocks for $2k, I hope that’s new, as when in stock they are only $799 each new!
https://www.reddragonaudio.com/collections/amplifiers/products/m500-mkii?variant=248192058

Cheers George

That went nowhere for me.🤷‍♂️
Would have been nice to know what each amp sounded like driving both speakers, oh well, thanks I guess.🤷‍♂️

Cheers George

Servo controlled woofer is much different from a low output impedance amplifier

I didn’t say it was the same, I said it controls even better the cone movement than the amps damping factor alone can.
I’ve asked you three times now, go away please, and stop stalking my posts.

IMO it is possible to overdamp loudspeakers and thus truncate the bass notes

This statement gives a wrong impression for amplifiers output impedance. That should really be.
There are a small minority of speakers that are "overdamped" by bad design or being purposely overdamped designed, and it's the speaker manufacturer problem to get the "Q" correct. Not because the amp is over-damped or underdamped.
And amps are also supposed to measure as flat as possible regardless of load impedance they see. 

From the Speaker design bible
.707 is said to be the correct "Q" with respect to damping. A higher Q indicates a woofer that is underdamped (loose) while a number lower than .707 indicates an overly damped woofer.

There is no such thing as too low for an amps output impedance. They even build speakers with "driver servo control circuits" to control the bass driver excursions even more and faster than the amps can do.

A classic example of trying to corner the amp/speaker market was the Linn/Naim scam of the 80's when a "purposely overdamped speaker" was mated with a "purposely under damped amp", when together they were a match and sounded good.
When either were substituted for something else and there was either, no bass because of being too tight, or too much soft woolly bass.
When a Krell was substituted for the amp, there was very little bass, (what!!! a Krell with no bass!!) that raised the eyebrows.
Needless to say this idea was Linn/Naim was exposed eventually and they did stopped doing it probably through fear of being called cheats, great marketing idea though if you have no conscience.

Cheers George     

 I currently have two listening spaces, one with an AB amp, the other with D monoblocs. The D monoblocs sound great.

Ok I'll bite, which do you prefer the "sound of" forget everything else?

Cheers George

Very high levels of feedback, in an intelligently designed class D amp, are actually utilized to optimize the sound quality throughout the entire audible frequency spectrum.

This can also be said about linear amps, but they sound crap when done. The goal is to have the best engineered design with the lowest distortions without negative feedback, and then if it can be done just a little local feedback around the input/driver stage to clean things up, but no global feedback compassing the output stage as well.

It was Matti Otala back in 1970-80’s that was the guy behind it all in solid state amps, and is still used today by the very best, but hard to design for. Look for today's amps that say in their description/specs "no global negative feedback"


Cheers George

The proof will be in the pudding, as there are Class-D’s coming out with little or no feedback, Merrill Elements being just one with it’s said to be a very good sound.
From EE Online

"If none of these issues are addressed, it is difficult to achieve PSRR better than 10 dB, or total harmonic distortion (THD) better than 0.1 percent. The standard solution for compensate for the poor performance of a Class-D system is to add negative feedback, but a large amount of negative feedback increases Transient Intermodulation Distortion (TIMD)."

Question is does Putzey’s designs with large amounts of feedback, ever state TIMD "Transient Intermodulation Distortion" I think not only ever seen THD specified
https://pdfs.semanticscholar.org/b3c0/a892a982ebde91f83f228905dac30186f827.pdf

Cheers George

comfortably driving 1000W into 4Ω and up to 2000W into 2Ω

That’s way too vague. Just like Merrill quotes.
Ask him this, it should be done by independent bench testing, but he should tell the truth.

In stereo what is the RMS wattage "both channels driven just before clipping"into 4ohms @ 1khz

In stereo what is the RMS wattage "both channels driven just before clipping"into 2ohms @1khz

See if you get a straight answer, not even Merrill would give an answer to this and I asked 2 or 3 times on the Element 118’s (true monoblocks not bridged stereos) their was a dead silence with this like he never seen the posts, even though he happily answered many others I asked, and his amps are in a higher league than these I believe.

Cheers George

GaN based Class-D in that they are going for bench specs as opposed to sonic excellence.

I worry when a manufacturer says this, (trust me it sound better)

We are able to achieve better bench specs than any other Class-D we’ve seen

Then further down he says this????? (hang on he just said spec don’t matter)


The proof’s in the pudding when we see independent measured specs on.
what switching frequency used
output filter corner frequency
switching frequency residue on output
dead time performace
phase shift figures from 2khz to 20khz
rms output wattage just before clipping into 8ohm, 4ohm and 2ohm.
All of which are known Achilles Heel’s of class-d

Cheers George

Could we combine pretty face with nice legs without chain smoker in class D?

Not yet affordable, one day maybe, or now if you can afford the Technics SE-R1, it addressed all of the ugly's of Class-D dead time (big girl) and switching frequency (chain smoker).

Cheers George

Let me note that MEGAschino is not a typical representative of class D: it is quite heavy (about 20 kilos)

Because it has a linear power supply using a massive toroidal transformer, which to me is a good thing, never been keen on noisy switch-modes no matter how well built.

Patented and proprietary circuitry designed in-house. Could be good, no off the shelf stuff like many others use.
Still nothing on how it handles 2ohm loading and if it’s got good current drive down that low (increasing it’s wattage a lot from 4ohms)

https://www.cherryamp.com/dac-home

Cheers George

I went from a Parasound A21 to Class D, no difference in sound.

Something seriously wrong there.

What is it with Class-D owners, my last loved amp lasted more than 8 years, sources usually 4-5 years.
But Class-D owners seem to be in a hurry to get somewhere by changing their Class-D's like like they are a pair of socks or jocks.

Cheers George

If it has a switching carrier frequency of about 1.5 MHz, perhaps georgehifi may even be interested.

No it's only got 500khz similar to everyone else with the same associated phase shift problems, but they advertised it as "very fast 500,000hz switching" just to intimate it's even quicker, "but 500,000hz is 500khz", that was fixed in their ad once pointed out to them.
So you draw your own conclusion to what kind of manufacturer they are for tying one on.

niodari 
I am not sure about Red Dragon as they (S500) seem to be not so tolerate with low impedance speakers

Not just Red Dragon, look at any Stereophile lab test on class-D for 2ohm loading and they either. 
1:switch off and go into protection. 
2:or they don't even bother to test them because they go unstable. 
3: or their performance is very average and actually go down (have less) in total watts with 2ohms compared to 4ohms. When they should if strong with good current ability go higher by at least 1.5 x's compared to 4ohms wattage.

Cheers George

How can you say "It’s not hifi yet"

Because they still have two important problems to improve on, phase shift and dead time. Which the above GaN equipped SE-R1 addresses, but it's not for the common man to afford.

Cheers George

It’s not hifi yet but getting closer.

👍,
Getting closer with development using GaN Tech, but the top one so far SE-R1 or similar is not affordable yet.

Cheers George

development deserves a 100% support from all of us

👍

yep!

FWIW I’ve run a bunch of Class D amps over the last several years all the time and no tweeter meltdowns.

I didn't say it happens with all, just one version of those Class-D's  that I've seen.
And when as Texas Instruments say, when the output filter is set too high to get more bandwidth from the amp.
Like some one said here they have one that goes to 1mhz in bandwidth!! this one will certainly over time cook or quickly the tweeters voice coils.

I even leave them on most of the time as recommended.

I don't think this is a good practice, as you don't know or hear how much switching noise is being let through to the tweeters, if a bit, it can slowly temper and blue the voice coils, as what happened to my friends Wilson tweeters, they still worked, he was just complaining that his highs had deteriorated, and yes those well known expensive Class-D's were left on 24/7 for over 1 year on his speakers. 

Cheers George

Again back in product protection mode.

Read again from Texas Instruments, far more authoritative than you Ralph, and this is still with the output filter in place, but with it set too high, without it and you have a tweeter meltdown.

From Texas Instruments:
On output filters of Class-D amps that are set too high corner frequency.
"A concern with the switching waveform being dissipated in the speaker is that it may cause damage to the speaker"

This is what happened to my mates Wilson 8’s above, as Wilson does not use a Zoble Filters on it’s tweeter and I on any of their speakers tweeters.

Cheers George

Actually thanks to twoleftears ’s dog, this would be a great way for Class-D owners if they have a young’ish dog to tell if their output filter is set too high or too low, as they will be one the other, or combo of both, eek!

Just watch to see if they react when in the same room when you turn on and wait for the delay to switch on your class-D amp/s.
I would say if you get no reaction you’ll have the "set too low filter" and you have a Class-D that is not hard or bright at all, but I bet it’s number 2: of the above.
If they run out of the room or react you know it’s the high filter number 1: above.

From Texas Instruments on output filters of Class-D amps that are set too high corner frequency.
"A concern with the switching waveform being dissipated in the speaker is that it may cause damage to the speaker"
This is what happened to my mates Wilson 8’s above, as Wilson does not use a Zoble Filters on this tweeter and I think all their speakers.

Cheers George

Anyone stating class D is "noisy as hell" very obviously doesn’t know what the heck they’re talking about.

Why did twoleftears dog run out of the room when it was turned on??

Go near one with a portable am radio tuned off station around 600khz (or whatever your switching frequency is) and see what you get out of the radio.

If you look at their output on a oscilloscope they are more than just noisy as heck! And that (undetectable to human) noise goes through to the tweeter if it’s not Zobel’ed as many hi-end ones aren’t

Take the output filter off the output and they are an abomination of noise that the military could almost use as a mind altering stun weapon.

Not noisy at all. sure Cheers George

Since I perceive none of these effects in my system using numerous class D amps, by your own definition your claimed class D deficiencies don’t exist in my system.

Good on you, your one of the few that do, for every one that does, there's two that don't

However, I'm still willing to keep an open mind and will listen to any class D amp you deem to be perfected in the future just in case your claims are actually valid and I can perceive the audible results.

Good way to hedge your bets. That way you won't end up with egg on your face when you do. 

Clearthink’s attitude towards, indifference to, or hate of, all things class D seems obvious. :-P

 It's pretty hard not to, when you know somethings not quite right in the upper-mids and highs, and then see this kind of phase shift going on in that same area https://ibb.co/48SSmLL . It’s enough to make clearthink think?

Cheers George

Whenever I turn on my Class D amp, my dog goes running out of the
room...

That's the residual switching noise coming out of your tweeters freaking your dog out, because the output filter can,t get rid of it totally without effecting the audio band even more than it does with phase shift.
If the switching frequency were higher then the filter can be higher, and filter out all of the switching noise without any phase shift down into the audio band.

Technics does this with GaN Technology in their $$$$$$K SE-R1 Class-D power amp with a switching frequency at 1.5mhz instead of what everyone else uses at 600khz

Cheers George

I’ve found a nice deal online for two Red Dragon S500 Monoblocks for $2K and I am just about ready to jump the trigger.

They use the same  Class-D modules, slightly moded by Pascal that you’ll find in the $10K Rowland Research Continuum 2.

https://forum.audiogon.com/posts/1820971?highlight=Rowland%2B%2BContinuum%2BRed%2BDragon

Me, I’d advise you to go a nice linear A/B amp

Cheers George

You say you hear somethings not quite right in the upper-mids and highs, and phase shift going on in those areas. Could you, respectfully, enlighten me as to what you are hearing?

Not just me, unless you’ve been hiding under a rock, it a common complaint.

What I hear from that technology, is dependent on where the "output filter is set" to filter out the switching noise.

1:Too high and it lets through too much switching noise but with reduced phase shift into the audio band, this to me sound hard and bright on music.

2:To low and it roll off the highs and causes too much phase shift into the audio band, but it filters out more of the switching frequency, this to me sound soft and opaque in the highs, and not involving in the mids, but at least it’s not hard.

Nuforce with their many different 9 models tried different versions V1 V2 V3 in them, of the above output filter that were retrofit-able for customer that had issues with the sound.
One of those version filters that was set way too high actually caused bluing of the Wilson Watt Puppy tweeter voice coil with HF switching noise (that only twoleftears dog can hear), didn’t stop them working just blue’d the voice coil with "undetectable to us" switching noise that was let through to them slowing cooking them over time. Naturally the diaphragms had to be replaced, he got rid of those amps.

I know from your past posts you are not a fan of class D.

BTW, Incorrect I’m not a fan of it’s two Achilles Heels, dead time and switching frequency. And I have said many times I’ll be the first to get one when they don’t have these problems and are a module I can buy an throw in a box like they do now with the old technology, but say they "modify it" so they can charge $$$$$ for, if you look at a $10k Contiuum Class-D, it has a $100  class-D module in it (modified of course), the same module is used in the $500 Red Dragon S500 class-D, this is not uncommon.

Cheers George