AVR or Amps with Class D amplifiers: what are my options? - AVS Forum
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Old 06-14-2010, 06:35 PM - Thread Starter
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I currently have a Yamaha RXV-3200, and am looking for an upgrade. My second setup contains the Panasonic xr55, after many recomendations on a low cost solution for my second room.
The reason I am looking into Class D amps, is that a love the sound from my panasonic setup. I know this has been debated, but to me the sound is much more clean and dynamic.

The question is, what modern Class D solutions are available? Pioneer? I am also open to a pre/pro solution, but what are the options beyond Sonic?
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Old 06-14-2010, 07:00 PM
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Only current receivers with class D amplification I know of is are the Pioneer SC series models.

"But this one goes up to 11"
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Old 06-14-2010, 07:09 PM
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Doesn't Rotel use class D amps in their receivers?
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Old 06-14-2010, 07:10 PM
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What´s up with Class D amps? any advantages? sorry for the noob question.
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Old 06-14-2010, 07:19 PM
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From what I gather, Class D is just more efficient, allowing more powerful amps in a smaller space?

I like turtles.
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Old 06-14-2010, 07:51 PM
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Originally Posted by ronesp View Post

Doesn't Rotel use class D amps in their receivers?

Without running to their website and looking up model numbers, I seem to remember their 7.1 channel 100wpc model is class D, while the 5.1 channel 75wpc model is A/B.
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Old 06-14-2010, 07:58 PM - Thread Starter
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Looks like both are class D, x5 channels. Huge differences in wattage 250 per vs. 100 (and a mamouth price difference BTW).
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Old 06-14-2010, 08:01 PM
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Originally Posted by Fedex1980 View Post

What´s up with Class D amps? any advantages? sorry for the noob question.

Your classic receiver amplifier design is class B (or class AB which is practically the same thing.)

Due to the physics of how the circuit works, class B is roughly 50% efficient. 50% of the energy used in the amp does not go to the speakers. Actually, that's not nearly as inefficient as speakers themselves, which are the real weak link.

Class D amplifiers are more efficient than class B. That means a smaller power supply for the same amount of power, less heatsinking because less energy gets wasted as heat, and I guess a cheaper power bill (don't think it's going to save someone 100's a year, but it should be cheaper to run, and maybe more importantly, less work for your AC to cool.)

They are also more expensive to make, I guess due to the fact they need to run at high frequencies. They have also been criticized by some for various reasons - I am not sure whether those critisisms are real, or whether they are being driven by a dislike of the new kid on the block (actually the idea of class D has been around a long time, but the technology did not exist to make good amps with it until recently.)

"But this one goes up to 11"
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Old 06-14-2010, 08:05 PM - Thread Starter
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Aren't they also "Pure digital"?
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Old 06-14-2010, 08:07 PM
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Originally Posted by ratboy View Post

Looks like both are class D, x5 channels. Huge differences in wattage 250 per vs. 100 (and a mamouth price difference BTW).

You're right. I thought you were asking about AVRs since you mentioned your Panny AVR.

Sorry.

Their AVRs are as I posted though.
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Old 06-14-2010, 08:08 PM
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Originally Posted by ratboy View Post

Aren't they also "Pure digital"?

A power amp can't be "pure digital," unless it has a digital input.

"But this one goes up to 11"
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Old 06-14-2010, 08:20 PM - Thread Starter
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So I guess I should revise my request for those that have a digital input that transfers directly to the chipset, correct? Do the Pioneers do this? Are there seperates with a reasonable cost that do this as well?
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Old 06-14-2010, 08:27 PM
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Originally Posted by ratboy View Post

So what makes my Panny, and the others list as "Digital" AVRs?

The way a so-called true digital amp works, is that it has digital inputs.

What they do is to convert the digital PCM to PWM (which drives the class D output stage,) directly.

Most class D amps have analog inputs (and I believe you will find the Pioneer receiver's have amps with an analog input stage.) The analog is converted to PWM. ICE amps also have analog inputs.

I believe there's an advantage to having an analog input stage, in that it's easier to implement a feedback loop between the input and ouput to linearize the amplifier (make it's frequency response more linear.)

I am not sure how they pull off feedback in class D amps with digital inputs.

"But this one goes up to 11"
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Old 06-14-2010, 08:43 PM - Thread Starter
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Originally Posted by MichaelJHuman View Post

The way a so-called true digital amp works, is that it has digital inputs.

What they do is to convert the digital PCM to PWM (which drives the class D output stage,) directly.

Most class D amps have analog inputs (and I believe you will find the Pioneer receiver's have amps with an analog input stage.) The analog is converted to PWM. ICE amps also have analog inputs.

I believe there's an advantage to having an analog input stage, in that it's easier to implement a feedback loop between the input and ouput to linearize the amplifier (make it's frequency response more linear.)

I am not sure how they pull off feedback in class D amps with digital inputs.

This is definitely dissapointing. Although I am no audiophile, I am certainly a fan of the Panny "digital" amp, as compared to the class a/b based amps I have owned in the past. I was really hoping to go higher end with this type technology, but it sounds like there is really no answer at this time. I was a big skeptic when I saw all the hype about the Panny (and never would have dreamed of owning a pannasonic audio piece), but I can't deny it's performance.
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Old 06-14-2010, 08:48 PM
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Never heard the panny. ICE amp modules have been used in some very expensive amps though. They have gotten some positive reviews.

Admittedly the power supply on the Pioneer, is not up there with the power supply used in external amps using the ICE modules. But until it runs out of power, one might speculate the Pioneer SC models should do very well.

Then there's always the argument that amplifiers sound very much the same, as demonstrated in a number of unsighted listening tests

"But this one goes up to 11"
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Old 06-14-2010, 08:53 PM
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Quote:
Originally Posted by Fedex1980 View Post

What´s up with Class D amps? any advantages? sorry for the noob question.

My Klipsch XF-48 power speakers are bi-amped (High Frequency: Class A/B, Low Frequency: Class D). No matter how hard they are driven, or for how long, it's essentially impossible to detect any rise above room temperature in the speaker's amp covering...

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Old 06-15-2010, 07:03 AM - Thread Starter
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For me it's not about the efficiency or heat, it's about the audio quality. Despite the better build of the ICE amps, they evidently have an analog element. The direct digital sound of the Panny design is what I prefer.
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Old 06-15-2010, 08:13 AM
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Originally Posted by ratboy View Post

For me it's not about the efficiency or heat, it's about the audio quality. Despite the better build of the ICE amps, they evidently have an analog element. The direct digital sound of the Panny design is what I prefer.

All Class D is analog. Period. The only difference you can have is when the signal gets converted from digital to analog.

I like Hypex UCD.

"Vintage" is good for wine, not for A/V equipment.

-Dan D.
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Old 06-15-2010, 09:22 AM
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Quote:
Originally Posted by ratboy View Post

For me it's not about the efficiency or heat, it's about the audio quality. Despite the better build of the ICE amps, they evidently have an analog element. The direct digital sound of the Panny design is what I prefer.

Have you compared them side by side in a controlled environment?

"But this one goes up to 11"
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Old 06-15-2010, 09:26 AM
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Originally Posted by DonoMan View Post

All Class D is analog. Period. The only difference you can have is when the signal gets converted from digital to analog.

I like Hypex UCD.


All speakers are analog. I'm not sure what advantage there would be to putting a DAC in a power amplifier. I kinda like mine to do only one thing, and do it well.
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Old 06-15-2010, 09:31 AM
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Quote:
Originally Posted by ratboy View Post

For me it's not about the efficiency or heat, it's about the audio quality. Despite the better build of the ICE amps, they evidently have an analog element. The direct digital sound of the Panny design is what I prefer.

They do make class D amps with digital inputs, but how is that going to work? Unless you have digital outputs for all channels.

e.g.

http://nadelectronics.com/products/m...ital-Amplifier

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Old 06-15-2010, 09:40 AM - Thread Starter
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Isn't that like saying speakers are analog, so my input sources might as well be analog as well?
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Old 06-15-2010, 09:45 AM
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Originally Posted by ratboy View Post

Isn't that like saying speakers are analog, so my input sources might as well be analog as well?

No.

-Digital storage is better as it resists degrading.
-Digital transport between components is generally a good idea because it resists any noise that the relatively long interconnect adds. Also, it means fewer wires to run, generally. In the case of optical digital, it can even isolate from potential ground loops.
-It is most efficient to have one good DAC in a central location.

But inside the receiver, the amplifiers are so close and in a shielded location (the receiver's chassis) that those advantages are negated. Some Class D implementations do not use a "traditional" DAC to convert to analog audio, but the low distortion figures from measurements of these "traditional" configurations show that there is nothing to improve on. The only thing to work on is efficiency.

I'm not going to argue against the "digital for longer" audio paths, but they're not going to make better sound.

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Old 06-15-2010, 10:00 AM
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Originally Posted by DonoMan View Post

No.

-Digital storage is better as it resists degrading.
-Digital transport between components is generally a good idea because it resists any noise that the relatively long interconnect adds. Also, it means fewer wires to run, generally. In the case of optical digital, it can even isolate from potential ground loops.
-It is most efficient to have one good DAC in a central location.

But inside the receiver, the amplifiers are so close and in a shielded location (the receiver's chassis) that those advantages are negated. Some Class D implementations do not use a "traditional" DAC to convert to analog audio, but the low distortion figures from measurements of these "traditional" configurations show that there is nothing to improve on. The only thing to work on is efficiency.

I'm not going to argue against the "digital for longer" audio paths, but they're not going to make better sound.

Excellent summation!!!!!!!!!!!!!!

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Old 06-15-2010, 01:10 PM
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Also, all that cool "processing" stuff, like manipulating soundfields and room correction doodads like Audyssey would not be possible in the analog domain
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Old 06-15-2010, 01:57 PM
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Also, all that cool "processing" stuff, like manipulating soundfields and room correction doodads like Audyssey would not be possible in the analog domain

Yes, this is another plus for digital inputs to the receiver. In most modern receivers, processing is indeed digital, so an analog source (which likely used a DAC to end up as said analog source) would have to go through an ADC at the receiver, be processed, and then go back through the receiver's DAC.

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Old 06-15-2010, 02:49 PM
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Originally Posted by DonoMan View Post

In most modern receivers, processing is indeed digital, so an analog source (which likely used a DAC to end up as said analog source) would have to go through an ADC at the receiver, be processed, and then go back through the receiver's DAC.

I know this may be a controversial statement for some, but this scenario is really no big deal. This back and forth conversion could likely happen many multiple times without any audible degradation with modern processor designs. It's just not....elegant.
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Old 06-15-2010, 02:51 PM
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I agree that it is minor and should be inaudible, but it is undesirable either way.

"Vintage" is good for wine, not for A/V equipment.

-Dan D.
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Old 06-15-2010, 04:00 PM
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Don't get me wrong, I have no qualms with the purists out there. In fact, it's my natural tendency to be OCD about these things. I just try to constantly remind myself to concentrate on actual science and not feed my illness.

In fact I just put a Sunfire 7X400W amp in my system even though my OCD was telling me to buy an amp that weighs at least 130 lbs. with a THD of 0.0000001% at rated output. It was tough to place the order for the Sunfire that had all that terrible noise I would never hear, but I'm glad I did.
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Old 06-16-2010, 06:46 AM
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Quote:
Originally Posted by MichaelJHuman View Post

Never heard the panny. ICE amp modules have been used in some very expensive amps though. They have gotten some positive reviews.

Admittedly the power supply on the Pioneer, is not up there with the power supply used in external amps using the ICE modules. But until it runs out of power, one might speculate the Pioneer SC models should do very well.

Then there's always the argument that amplifiers sound very much the same, as demonstrated in a number of unsighted listening tests

I have heard the my friends Pioneer SC-25 which sounded very nice with his B&W speakers. They have 5" woofers so I really cannot judge its ability to deliver bass. According to Pioneer, they made some changes to the design to meet their specs which do support 140 watts per channel RMS. Other ICE amps do not quote that standard. B&O also discusses dynamic power in their specs so I am suspect about the standard ICE modules ability to so deliver continuous power.

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