Class D versus the rest

Folsom · « **Reply #400 on:** 19 Oct 2014, 01:11 am »

Some speculate it has an incredible amount of feedback. The feedback parts may have a lot to do with detail bloat. (If there are any)

Jon L · « **Reply #401 on:** 19 Oct 2014, 01:43 am »

Quote from: DaveC113 on 19 Oct 2014, 12:18 am

it works fine with my tube preamp

So did NCores with my tube preamp. A nice tube preamp with good detail resolution Yet with just a touch of tonal richness goes a long way with these class D amps IME.

Steve · « **Reply #402 on:** 19 Oct 2014, 02:23 am »

Hi Dave,

Quote

It's input impedance is 10k RCA and 20k XLR, I'm using RCA. So far I've just turned the gain to about 9 o'clock and it works fine with my tube preamp, it has cathode follower outputs so a couple hundred ohms output impedance... not sure I'd want to try using the gain controls as a volume adjustment.

I was wondering what type of output from the cathode followers? Is it transformer coupled, capacitively coupled, or DC coupled output?
If capacitively coupled, by chance do you know the capacitor size in uf?

Thanks for your time, and good luck Dave.

Steve

wushuliu · « **Reply #403 on:** 19 Oct 2014, 05:32 am »

Quote from: DaveC113 on 19 Oct 2014, 12:18 am

One thing that's interesting is that it accentuates details, it seems to make them louder and more noticeable. Stuff that was more in the background is brought forward.

Or is that just a sign of a lower noise floor?

Freo-1 · « **Reply #404 on:** 19 Oct 2014, 12:11 pm »

Quote from: wushuliu on 19 Oct 2014, 05:32 am

Or is that just a sign of a lower noise floor?

Nope. This generally called compression, and it's a limitation of the Class D design filtering. The trick in reproducing audio correctly is to be able to reproduce the low level detail accurately, with the proper dynamic contrast. In my listening tests, this is an area that the Electrocompaniet Class A excelled at compared to the Class D Yamaha.

cab · « **Reply #405 on:** 19 Oct 2014, 12:29 pm »

Quote from: Freo-1 on 19 Oct 2014, 12:11 pm

it's a limitation of the Class D design filtering.

Please explain.

DaveC113 · « **Reply #406 on:** 19 Oct 2014, 01:37 pm »

On some things the volume-leveling, or compression is pretty obvious. It gives the impression that the amp has more detail but it's possible this will cause fatigue.

Steve, the preamp is an Aikido design, so it's a White cathode follower with cap output, I use .47 uF Jupiter copper foil.

wushuliu · « **Reply #407 on:** 19 Oct 2014, 02:20 pm »

Quote from: Freo-1 on 19 Oct 2014, 12:11 pm

Nope. This generally called compression, and it's a limitation of the Class D design filtering. The trick in reproducing audio correctly is to be able to reproduce the low level detail accurately, with the proper dynamic contrast. In my listening tests, this is an area that the Electrocompaniet Class A excelled at compared to the Class D Yamaha.

So it turns the music into an mp3. That does't sound fun.

Folsom · « **Reply #408 on:** 19 Oct 2014, 02:37 pm »

Quote from: wushuliu on 19 Oct 2014, 02:20 pm

So it turns the music into an mp3. That does't sound fun.

Not exactly.

Fatigue from class D is due to noise. Some low dynamic class D don't seem to exhibit it, but have higher distortion. Unfortunately it's harder to deal with on a SMPS that isn't as nice as a Hypex.

OzarkTom · « **Reply #409 on:** 19 Oct 2014, 03:53 pm »

Quote from: Salis Audio on 19 Oct 2014, 02:37 pm

Not exactly.

Fatigue from class D is due to noise. Some low dynamic class D don't seem to exhibit it, but have higher distortion. Unfortunately it's harder to deal with on a SMPS that isn't as nice as a Hypex.

Unfortunately, I had way to much fatigue from the NC400's and NC1200's on my system, but lets just blame that on my AC in my home town so we don't start another uproar here. No way anyone here could have listened to those amps here on a Friday or Saturday night. I also had fatique with the Eximus S1 and the Stello AI700 integrated although at a much lesser degree.

My Crown will be here on Monday, so we will see on how it stands up to my bad AC. I will also compare it to the TBI with the Astron power supply. The Astron stepped the TBI up another notch or two on SQ than the tour amp sounded, while totally eliminating the Friday and Saturday night fatigue that I had with it powered by AC.

Freo-1 · « **Reply #410 on:** 19 Oct 2014, 04:43 pm »

Quote from: OzarkTom on 19 Oct 2014, 03:53 pm

Unfortunately, I had way to much fatigue from the NC400's and NC1200's on my system, but lets just blame that on my AC in my home town so we don't start another uproar here. No way anyone here could have listened to those amps here on a Friday or Saturday night. I also had fatique with the Eximus S1 and the Stello AI700 integrated although at a much lesser degree.

My Crown will be here on Monday, so we will see on how it stands up to my bad AC. I will also compare it to the TBI with the Astron power supply. The Astron stepped the TBI up another notch or two on SQ than the tour amp sounded, while totally eliminating the Friday and Saturday night fatigue that I had with it powered by AC.

Tom, I don't the the AC alone is the source of listener fatigue. Check out this link:

https://www.nuforce.com/index.php?option=com_k2&view=item&id=620:q-what-are-the-problems-with-class-d-digital-switching-amplifiers&Itemid=405

OzarkTom · « **Reply #411 on:** 19 Oct 2014, 05:47 pm »

Quote from: Freo-1 on 19 Oct 2014, 04:43 pm

Tom, I don't the the AC alone is the source of listener fatigue. Check out this link:

https://www.nuforce.com/index.php?option=com_k2&view=item&id=620:q-what-are-the-problems-with-class-d-digital-switching-amplifiers&Itemid=405

I have always felt that these Class D amps needed a good linear power supply to have better SQ and less fatique. Ir sure made a difference on the TBI.

That is a great link, Freo-1. I wish I had that before I bought this Crown.

cab · « **Reply #412 on:** 19 Oct 2014, 06:43 pm »

Quote from: Freo-1 on 19 Oct 2014, 04:43 pm

https://www.nuforce.com/index.php?option=com_k2&view=item&id=620:q-what-are-the-problems-with-class-d-digital-switching-amplifiers&Itemid=405

Quote

Nevertheless, it is nearly impossible to engineer a conventional Class-D amplifier that handles the full requirement, 20-20,000Hz, for full-bandwidth music reproduction...The fundamental flaws of conventional Class-D amplifiers remain unresolved...

Hypex ncore proves this completely false....

Folsom · « **Reply #413 on:** 19 Oct 2014, 06:50 pm »

They still work just fine. Despite the "flaws" people are nutto over. Are they different? Uh, yay...

guest61169 · « **Reply #414 on:** 19 Oct 2014, 06:59 pm »

Quote from: OzarkTom on 19 Oct 2014, 05:47 pm

That is a great link, Freo-1. I wish I had that before I bought this Crown.

Don't worry. Some of the worst sounding amplifiers I've ever owned have been Class AB.

rodge827 · « **Reply #415 on:** 19 Oct 2014, 07:23 pm »

Here is a review of another Crown amp that uses Drivecore tecnology:

http://www.arccinema.com/crown-ct8150-comtech-drivecore-amplifier/

There are 4 different versions of the CT amp (CT475,CT875,CT4150,CT8150) ranging from $1100.00 - $2500.00.

The reviewer, Andrew Robinson preferred the sound of the 8150 over the XL2000. He is more about home theater use, but...

Freo-1 · « **Reply #416 on:** 19 Oct 2014, 08:19 pm »

Although the Yamaha and Ncore amps sound good overall, the Nuforce link is basically accurate. As Nelson Pass once said about Class D amps:

"Class D amplifiers are switches with tons of feedback. It's amazing that they work as well as they do."

cab · « **Reply #417 on:** 19 Oct 2014, 08:40 pm »

What is amazing is that some just can't get over the fact that a great many people find nothing wrong with the better class d amps and actually prefer them. This whole class d debate is so old and tired that what is really amazing is that people still continue to perpetuate it...

Personally, I couldn't care less what a class a amp designer has to say about class d, or those with OCD who change amps every other month. I know how the ncore sound in my system, and I know that I am not alone in my assessment of their sound. It's nice to find something really good and just enjoy the music.

All this "class d is flawed", "class d is this", "class d is that"...so much meaningless drivel....the proof is in the pudding: Hypex is doing just fine.

Not everyone's system will thrive with a transparent, neutral amp that lets all the upstream deficiencies through. Nor is everyone after a wire with gain. I wouldn't suppose class d is for everyone, just like tubes aren't for everyone. But those who wish to find flaws and fault the technology should make better use of their time and just move along. Class d is here to stay...

wushuliu · « **Reply #418 on:** 19 Oct 2014, 08:43 pm »

Freo-1 · « **Reply #419 on:** 19 Oct 2014, 10:48 pm »

People seem to take this issue personally, as if one is not allowed to question. Some people love their Class D amps, while others do not share their enthusiasm. So what. There are technical arguments to be made on all sides of the issue. The whole purpose of websites like this is to debate the merits and shortfalls of audio reproduction in general.

There are technical issues with ALL amp classes, period. There is no such thing as "A straight wire with gain". All equipment imparts its own sonic signature, based on its technical design aspects. The terms neutral and transparent are relative. Measurements into a resistor do not tell one how an amp will sound with a complex speaker load. One person's neutral is another's forward/aggressive sound.

If you like your Class D, you can keep your Class D...

Class D versus the rest

guest61169