Class D amps for home audio applications?

[Quattro Pete]

I remember some years back, the general attitude was that Class D amps were nowhere near as refined as Class A/B amps. Has this changed in recent years? Are Class D amps worth considering? From a price per Watt perspective, they are certainly very attractive, but I'm wondering from a sound quality/neutrality perspective...

Anybody has some recent experience with Class D?

Thanks!

 

[Quest]

IMHO Class D amps have come a long way (tripath in mind), while to some it may not sounds as refined(suave) as certain solid state amps (or better yet: not as lucid as some tube amps, particularly tube-based SE amps), it's still better (IMHO) sounding than most low to mid-fi grade solid-state class-B amps.

Again, this is just my subjective observations. I can live with class-D amp for non-critical listening @ home.

Q.

 

[dparm]

Check the distortion figures. Class D have come a long way and in some designs are matching A/B in that category (though it gets expensive). An OTS Class D is going to lose to A/B in terms of distortion though. Typically a D is targeted for apps that need to be very efficient and compact.

So to answer your question, I have seen Class D amps that match A/B but they cost a fortune since the engineering is intense and the components have to be top-notch. SVS uses Class D and I'd put their products in an upper-tier for sure (at least until you get up into the insane custom stuff).

Mid-range home audio is going with BASH a lot these days. BASH borrows some things from AB and D. My sub relies on BASH and I honestly think it's sufficient even for my trained ears.

 

[Quattro Pete]

Originally Posted By: dparm
Check the distortion figures.

I am talking about rather low end stuff, like this:
http://www.crownaudio.com/pdf/amps/XLS_Datasheet_CRO137.pdf

The way they give their THD ratings is somewhat flaky/iffy to me, but I would probably never crank it up to anywhere near its full power, so maybe this is irrelevant.

The high end stuff as you say would cost as much as A/B amps, in which case I'd just get an A/B amp.


By the way, this would be used to power home speakers, not subs.

 

[dparm]

Any reason you have your eye set on that? Those are typically reserved for PA systems and AV setups in "meeting rooms". They're quite powerful for their size but aren't build for great sound quality.

Unless they're really cheap or you need something extremely loud, I wouldn't bother.

A receiver/amp with BASH would probably satisfy your needs.

 

[JHZR2]

Wasnt the panasonic class D receiver line getting great marks a few years back? Havent tracked it much since then, though do have one in service in the VI that is still running great.

Cant say Ive ever critically listened, but IIRC lots of folks did and found it to be an excellent approach.

Granted this is a receiver and not just an amp, but that's what I recall...

 

[Quattro Pete]

Originally Posted By: dparm
Any reason you have your eye set on that? Those are typically reserved for PA systems and AV setups in "meeting rooms". They're quite powerful for their size but aren't build for great sound quality.

A guy on another forum was recommending it, claiming it's as clean as any amp out there, but with more headroom. Something tells me it's just pure talk on his part though. What I did like about this Crown is that it allows you to apply a high pass filter, thus saving your smaller speakers from receiving low end bass which they can't reproduce anyway. My main stereo receiver does not have any bass management features.

My other consideration was AudioSource AMP310 (which I think uses a more traditional amp, not Class D) with half the power at about the same price as the Crown (about $400 or so). No high pass filter though. My gut feeling is that this AudioSource would deliver better quality, but again, I'm really not up to speed on modern Class D amps.

 

[Quattro Pete]

Originally Posted By: JHZR2
Wasnt the panasonic class D receiver line getting great marks a few years back?

Good point. I actually have one of these in my living room and it's been working very well.

 

[Malo83]

Have an older Elite reciever that I need to upgrade, Class "D" seems like the way to go

http://www.pioneerelectronics.com/PUSA/Home/AV-Receivers/Elite+Receivers/SC-57

 

[sleddriver]

THD is spec'd at 0.5% @ 1KHz; IMD is 0.3%. Not near as clean as the more $$$ HW. However, the THD & IMD of your LS are probably much higher than this, so you may not even notice. It all depends on what you're used to AND how old you are AND lots of other things.

 

[Volvohead]

Originally Posted By: Quattro Pete
Originally Posted By: dparm
Check the distortion figures.

I am talking about rather low end stuff, like this:
http://www.crownaudio.com/pdf/amps/XLS_Datasheet_CRO137.pdf

The way they give their THD ratings is somewhat flaky/iffy to me, but I would probably never crank it up to anywhere near its full power, so maybe this is irrelevant.

The high end stuff as you say would cost as much as A/B amps, in which case I'd just get an A/B amp.


By the way, this would be used to power home speakers, not subs.


I'm a bit old-fashioned, but there is no way an 11 pound power amp stage is going to produce the wattage they're claiming into any meaningful load. I've got an amp that can deliver that sort of wattage (and into nearly 1 ohm), and it weighs over 80 lbs.

I'd bank on a 25wpc model that weighed 25-30 pounds at a more modest price point over these amps.

It's all about the power supply. More real power requires more weight in the trannies and filters. That costs real money.

I don't understand the rage with these new lightweight "megawatt" amps. I thought the Japanese wattage wars ended in 1980. What kind of speakers are you driving and how loud into what space?

It's amazing just how lovely a 6BQ5 output can sound . . .

 

[edhackett]

This is what I don't like about class D amplifiers. There is always some of the switching frequency imposed on the signal. It's virtually impossible to get rid of it all. This is a $1600 a pair amp.

Yea I'm a curmudgeon, but my EL34's make me smile.

Ed

 

[Quattro Pete]

Originally Posted By: Volvohead
I'm a bit old-fashioned, but there is no way an 11 pound power amp stage is going to produce the wattage they're claiming into any meaningful load. I've got an amp that can deliver that sort of wattage (and into nearly 1 ohm), and it weighs over 80 lbs.

I'd bank on a 25wpc model that weighed 25-30 pounds at a more modest price point over these amps.

My hearing isn't what it once used to be, so take it for what it's worth, but to me, at higher volume levels (open 1300sq ft basement with 9ft ceilings) this D amp sounds cleaner than my 25 lb H/K stereo receiver supposedly rated at 150 WPC @ 4 Ohm.

 

[Quest]

@ VolvoHead:

Times have changed to the point where now switchers roam every stretch of the world in terms of compactness, weight vs performance.

Class-D amp is based on switchers, thus the small footprint (or very high power to weight ratio) because of very high efficiency.

That being said however, my perception of class D amps are, IMHO, similar to that of Pete's meaning it sounds clean. Imaging is ok and there's a hint of perceivable (YMMV) hardness/cold in the sound, typically associated to the high order harmonics coming from switchers (design/implementation).

While I'm still firmly believe in vacuum tube and/or MOS-FET designs in terms of sonic attributes, I do not put down class-D amps at this moment. It's just that Class D amps doesn't satisfy my audio needs at this moment in terms of critical listening.


Q.

 

[Volvohead]

Originally Posted By: Quest

. . . That being said however, my perception of class D amps are, IMHO, similar to that of Pete's meaning it sounds clean. Imaging is ok and there's a hint of perceivable (YMMV) hardness/cold in the sound, typically associated to the high order harmonics coming from switchers (design/implementation).
Q.


I guess I won't be having any of those in our house, although I suspect our Squeezebox Radio (that plays background chatter on the deck during BBQs) might have one. If it doesn't run though a bottle (preferably pre-1965), I really don't like listening to it as much. Yeah, I'm a mid-Century dinosaur, but the music sounds great.

One old litmus test for gauging an amplifier's power ability was reading the mains fuse rating on the back case. A manufacturer can claim all they want in the ad copy, but you can't B-S the UL on the mains fusing. Factor in the efficiency percentile heat loss from that, and that's all she'll output. And that still doesn't guarantee the current will be there at the lower impedances.

These new megawatt amps remind me of the old Soundcraftmen pieces that used to advertise in SR way back when (when Julian Hirsch thought everything measured and sounded the same . . . 1975, 1980?). Eighteen hundred gazillion watts into -3 ohms and it didn't even get warm.

 

[Volvohead]

You gotta love audio makers and what they sometimes say. I took a slightly closer look at this "2500 watt" beast Crown amp to be "treated with respect". All that power coming through an IEC mains jack breakered at 200 watts:

http://www.crownaudio.com/pdf/amps/142169-1_XLS3_MultilingualManual_032410.pdf

Guess this PA amp doesn't need a dedicated circuit after all.

 

[Quattro Pete]

I am tempted to order an AudioSource AMP310 to compare its performance to this Crown XLS1500 that I'm playing with right now. One thing that I really like about this XLS amp though is the high pass filter so that I don't overstress the bass drivers in my smaller speakers.

 

[Quattro Pete]

Originally Posted By: Volvohead
You gotta love audio makers and what they sometimes say. I took a slightly closer look at this "2500 watt" beast Crown amp to be "treated with respect". All that power coming through an IEC mains jack breakered at 200 watts:

http://www.crownaudio.com/pdf/amps/142169-1_XLS3_MultilingualManual_032410.pdf

Guess this PA amp doesn't need a dedicated circuit after all.

The XLS1500 that I'm looking at also says "200 Watts" written on the back next to the power cord plug. If I'm understanding this article correctly, FTC only requires amps to operate continuously at 1/8 of their rated output power. So is that why Crown can claim the amp delivers 1550 Watts (200x 8)?

http://www.eetimes.com/design/audio-desi...ts?pageNumber=2

On the other hand, the 200 Watts listed on the back may just be a typical power draw and not a max power draw. It'd be nice if Crown offered info regarding what amperage rating that internal circuit breaker has... If it's rated at 12 Amps, I suppose theoretically it could draw around 1500 Watts of power. And what's the typical efficiency of Class D? Over 90%?

 

[Quattro Pete]

FYI, Crown confirmed that it's a 12A circuit breaker.

 

[Quattro Pete]

I picked up a more traditional AudioSource AMP310 for comparison's sake. It's rated at 150W per channel @ 8 Ohm,
From a sound quality perspective, I can't tell any difference between it and the XLS. Then again, we're talking about unfinished basement where it's impossible to hear a whole lot of detail. From power perspective, the XLS felt like it definitely had more, and that's with my HK driving it which does not put out enough voltage to fully drive pro-audio gear like this XLS which expects somewhat higher voltage input.

The main problem with the XLS is that it just looks somewhat cheap and cheesy in a home audio setup. It also has an unusual shape making it difficult to stack since it was designed to be rack mounted. But if you can get past the looks, it is one heck of an amp for the price, IMO. Low pass/high pass filter is a nifty little bonus.