[Construct]

Products like that Crown amplifier are really only designed to deliver a lot of power cheaply, and do so without blowing up or shutting down. Sound quality is pretty far down on the list of features.

How do I know this? Well, I haven't heard that particular Crown amplifier in the link, but everything in that pro audio price range that I've encountered sounds like shit to me. The guys in my band seem to enjoy it but they only respond to loud and louder. (I wear ear plugs now.)

That kind of gear is fine for its intended purpose, and you can make it sound OK for short periods of time (if your bandmates cooperate), but I would never use it for home music playback.

Construct,

Remember that other thread where you said "Folks really need to start with speakers, not gear. Too much self doubt and impulse choices influenced by others." This sort of find the best sounding megawatt-amplifier predicament is the reason why I don't think a person should pick speakers first and worry about gear later. I'm only bringing it up as a point of general discussion, becasue many of these threads relate to each other.    Just my friendly opinion.

No see, you may have read into that the wrong direction.  I was postulating which direction to go were I to get a set of VMPS RM2/ FST speakers.  In my previous VMPS experience, those speakers really need a no-kidding 200wpc/8 ohms or better much like my ATC's did.  The crown was just one of many potential economic solutions.  I think it was at at Sebastian Bach concert there were crown amps employed.  The sound was hard, and incredibly "hot"  in the upper midrange.  It wasn't the house sound system because other bands have never sounded that way.  Banks of crown amps...  And yes---I keep to my guns about speakers first.

 

[JimJ]

Products like that Crown amplifier are really only designed to deliver a lot of power cheaply, and do so without blowing up or shutting down. Sound quality is pretty far down on the list of features.

How do I know this? Well, I haven't heard that particular Crown amplifier in the link, but everything in that pro audio price range that I've encountered sounds like shit to me. The guys in my band seem to enjoy it but they only respond to loud and louder. (I wear ear plugs now.)

That kind of gear is fine for its intended purpose, and you can make it sound OK for short periods of time (if your bandmates cooperate), but I would never use it for home music playback.

Construct,

Remember that other thread where you said "Folks really need to start with speakers, not gear. Too much self doubt and impulse choices influenced by others." This sort of find the best sounding megawatt-amplifier predicament is the reason why I don't think a person should pick speakers first and worry about gear later. I'm only bringing it up as a point of general discussion, becasue many of these threads relate to each other.    Just my friendly opinion.

Cheaply?

Price some of Crown's stuff lately?

[roymail]

The best Crown system I ever heard was in a large church.  After talking to the sound guy, he opened the sound room which had a floor to ceiling rack of professional Crown amps.  He explained that each JBL Pro driver was separately driven by a dedicated Crown amplifier.  The installation and sound was amazing.  The occasion was a wedding with live singers and music.  Best I ever heard for pro gear.  However, VERY EXPENSIVE.  And, definitely not inexpensive Class D stuff. 

[Quiet Earth]

Yeah, not a slam on Crown or the pro audio market either, just sayin' that the $300 pro audio amp selection is best left to the PA market that it is intended. Same goes with cheap powered monitors, man I really hate ours. But that's OK, they fill a price point and get the job done. No problem.

I used to drool over the Crown brochures when I was a kid . . .    . . . some of that gear is still cool. 

Construct,
Stick to your guns bro........ just sayin',,, ya' know?

Keeping in line with the subject title, I would like to see more development in the ultra low power solid state market. Amps in the 1 to 10 watt range. It might be fun to build a solid state kit that could compete with flea powered single ended triodes during the hot summer months.

[roymail]

I apologize for getting off topic.  I think we've talked enough about inexpensive Class D pro amps.

For the same money, you can put together an amazing home audio Class D Audio amp that is of *MUCH* higher quality.  I posted the link in post #2.  If you missed it, here you go.
http://www.audiocircle.com/index.php?topic=76400.0

Here's the link to the Class D Audio home page.
http://classdaudio.com/index.php/

Reading through this thread would be time well spent for anyone interested in a home audio Class D amp. 

[Norman Tracy]

As a manufacturer of a line of class-D amps currently using ICEpower technology I have followed this discussion with interest. On the sound quality side I have kept quiet as the fact I chose to invest the 5-figure amount to bring the product line to market is I believe ample evidence I judged the basic technology is quite good and our implementation delivers outstanding sound quality. If we want to discuss sound quality further I will be pleased to address that in another post on this thread.

What I do find interesting and wish to comment on is Construct’s question “Class d:  less parts, same cost as class A/B.  Why?” Then John ‘TheChairGuy’ adds “I've thought the same for some time. If it isn't a unanimous decision in Class D's favor on sound quality alone over A/B...at least it could claim some kind of 'value' status relative to A/B.  But, I haven't seen that in the actual marketplace.”

Starting with the most obvious I grant “it isn't a unanimous decision in Class D's favor on sound quality alone over A/B”. I would hope readers of this forum are aware in hi-fi circles “a unanimous decision” is NEVER reached. Critics of audiophiles and the pursuit of hi-fi point to this as evidence we are all a bunch of self-delusional borderline Obsessive Compulsive Disorder fools.  As an engineer who makes a good chunk of my living outside the audio arena I see the diversity of technologies employed as typical. When it comes to technology there are always different tools and devices to achieve a given result. The choice of tools and techniques will influence the nuances of the result achieved. How important those nuances are is entirely dependent on the context of where and how the technology is being deployed. Back in the world of high end hi-fi I personally view class-D as a third major option the other two being tubes and solid-state linear class-A/B amps.

Now onto the question of 'value' class-D relative to class-A/B.  For real world examples I list below our ACG basic stereo amp then some (much) less expensive examples from Dayton Audio then examples from the lines Audio Advisor sells. In the following list ‘wpc’ is short for ‘watts per channel’ and I list both 8 and 4 ohm ratings when specified, prices are from the seller’s web sites. Also note the “class-T” referred to in the Dayton examples is the Tripath version of class-D.

Audio Crafters Guild example

ACG 1000 Stereo Amp - 500 wpc @ 8 ohms 1000 wpc @ 4 ohms $1995

Parts Express/ Dayton Audio examples

Dayton DTA-2 Class T Digital Audio Amplifier Module 15 wpc (no power supply) $14.46
Dayton DTA-1 Class T Digital Amplifier 15 wpc $30.00
Dayton DTA-100 Class-T Digital Amplifier 50 wpc $89.50

Audio Advisor examples

Cambridge - 840W - 200 wpc @ 8 ohms; 300 wpc @ 4 ohms $2,395.00
Musical Fidelity - M6PRX  - 260 wpc @ 8 ohms $3,499.00
Bryston - 14B-SST2 - 600 wpc @ 8 ohms 900 wpc @ 4 ohms $8,695.00

Let’s consider the above list and the product’s ‘value’ in price order. As a firm believer that you have to listen for yourself the value considerations will concentrate on the physical aspects like power in measured watts, the power supply backing up the watts, and case work.

Dayton DTA-2 is cheapest and I include it because its price is dangerously close to single digit dollars! How’s that for class-D delivering on the promise of lower cost through smart silicon? It is a DIY module and the builder has to supply his or her own case and power supply. Still if you want to DIY a set of desktop powered speakers that will blow away anything from Best Buy this is the deal. To the ardent DIYer this is good value.

Dayton DTA-1 for an extra $15.54 you get a plastic case and a little inline power supply. This is Dayton’s version of the Sonic Impact amp that got so many playing around with Tripath chips a few years ago, even leading to a couple of hi-fi startups being founded. Use this with a speaker based on the Fostex FE103 and don’t ask it to play too loud or too deep into too big a room and you will agree for three tens it’s a great value. Just do not use heavy speaker cables or they will pull the thin polystyrene case right off your shelf. If your source is not an iPod you will need an adapter for the 1/8” input jack.

Dayton DTA-100 is a 50 watt amp in a nice small aluminum case you can buy and maybe get a little change from $100 after you pay shipping. I have not heard or held it but the pictures show a nice little brick of an amp with RCA ins and Banana jack outs in a good looking extruded aluminum box. Assuming it sounds good I believe this is a good example of the value = (cheaper than equivalent class-A/B amp for similar performance) Construct and John were calling for above. At $0.90/watt the DTA-100’s dollar/watt ratio is outstanding.

ACG 1000 Stereo Amp and Cambridge - 840W will be next up in the price order and are the closest match for a class-D vs. class-A/B value comparison. At 22x and almost 27x times as expensive compared to the DTA-100 we are well past the starter/second/desktop system categories now comparing full sized powerful basic stereo amps for use in advanced hi-fi rigs. The case work is of similar size and quality, of course I like the styling of ours better but that is objective. I aim to bring value by using all aluminum construction and engrave and filled lettering on both front and rear panels. The ACG amp is built in USA using internationally sourced components, the Cambridge is from PRC. For $400 less the ACG 1000 Stereo Amp delivers 300 wpc more at 8 ohms and 700 wpc more at 4 ohms compared to the Cambridge - 840W. The class-D amp also brings completely dual mono power supplies to the party. Does this count towards “some kind of 'value' status relative to A/B”? At $5.99/watt the 840W’s dollar/watt ratio is closer to the norm.

ACG 1000 Stereo Amp and Musical Fidelity - M6PRX are an interesting comparison. With the class-D ACG amp the dollar/stereo watts ratio is $2/watt while buyers of the class-A/B MF amp pay $6.73/watt. And this ratio exists when again the ACG amp is built in the USA and MF in PRC. Some will count the MF amp as better styled; now that they have pulled back from their more baroque designs I agree this generation of Musical Fidelity looks quite good. My tastes were formed by the classics from Marantz and Mark Levinson when those companies were run by their namesakes so I prefer simple black or silver anodized boxes. Beyond the audio arena I am drawn to the Bauhaus School as exemplified by the great mid-century Braun styling. Again the choice of a more sculpted busy look vs. simpler form follows function is a personal one. On the question of relative values the styling plays a role because as it is made more complex the retail price must go up or be paid out of cost savings taken from internal content and/or functionality.

ACG 1000 Stereo Amp and Bryston - 14B-SST2 will be the final comparison I make in this class-D vs. class-A/B value discussion. I chose the Bryston as an AAA-list hi-fi company who manufacture in North America and the 14B model because like the ACG amp it features extremely high power. In fact we now have a case where the class-A/B out-powers the class-D with 100 more watts at 8 ohms but 100 less watts at 4 ohms. The fact the class-A/B amp’s output does not quite follow Ohm’s law and double into 4 ohms shows how it is using an unregulated power supply vs. the switch mode regulated supplies in the ACG amp. The class-D ACG amp dollar/stereo watts ratio is $2/watt, the class-A/B Bryston amp is $7.24/watt. A big chunk of the added cost on the Bryston is the pounds and pounds of aluminum in its heat sinks and chassis; this will translate into greater long term power output capability another reason I grant it is more powerful. Now obviously at these power levels for home hi-fi use I argue the point is to have sufficient voltage and current headroom that the amp never clips. The ICEpower module can output its 1kW continuously for 15 seconds before the thermal protection circuit activates which in my experience has been sufficient. On the casework and styling one look at the massive heatsinks and thick CNC machined faceplate on the 14B and it is obvious where a good chunk of the $8k is going. Personally I like its styling combining old school rack mount amp form factor with subtle modern detailing. Thus on the value side the class-A/B Bryston while expensive ranks very high on both capability and pride of ownership. The class-D ACG example shows how in the sparse ranks of kilo-Watt hi-fi amplifiers by leveraging both the technology of silicon replaces iron and the economies of scale by sharing a major subassembly across the hi-fi and pro-sound markets the capability offered for the cost can be very high.

This post has almost turned into an article. Three years into selling the ACG 1000 series of amplifiers I have obviously thought a lot about these issues and trust this has not been too much of a data dump on this thread. Modern product design is a complex matrix with both quantifiable design specifications and more ethereal even emotional aspects like the industrial design all factoring into ‘value’. My intent above was not to show how one of our models could outpoint and slay selected straw men. I personally believe those who turn hi-fi into a sport and are constantly looking to crown “the best” are immature. Any of the amplifiers discussed can be used to make a good to amazing hi-fi rig. What I hope I have accomplished is to illuminate a few of the trade-offs in design emphasizing those around that early decision of class of operation. I also sought to answer Construct’s and John’s assertion that class-D has failed to deliver value by giving specific examples where the technology has delivered on its promise.

Happy Listening

Norman Tracy
Audio Crafters Guild

[Construct]

Mr Tracy,           
    This was the kind of reply I was hoping for, not a snarky "Depends on what YOU call fidelity"  as that is contentious, not an answer.  Your post was a thorough examination---not just hearsay or speculation. 
     
        $1995 for 500 watts of class D power that is capable of high fidelity and not the sound associated with a hard and opaque PA system is indeed plenty of competitive value.  It is not priced like spectron and the other $3k, $4k+  class D amps out there.  I should have stated that I use companies as a yardstick like Outlaw, AVA, Emotiva and a few others offer well-reviewed class a/b products for direct pricing that would run double, triple and quadruple the price in a boutique. Boutique names (as you know)are often priced arbitrarily, especially since a lot of it is made in China anyway. I have outlaw products and they live up to the press. 
               
While I tend to agree (because it's subjective), I would caution you or any audio manufacturer against using phrases like " I personally believe those who turn hi-fi into a sport and are constantly looking to crown “the best” are immature. "  as it will alienate some of those that may be looking at your product now. I have been down that path before in my youth, and I have separated myself from any such attitude.  To paraphrase Hemingway: I have met too many that are of broad bank accounts and narrow minds.  Virtually every brand at one point proclaims they are the best (in so many words) or superior to x,y,z.   I personally am looking for brands (along the lines of the brands I have mentioned)  that don't charge more than the cost of a new 600 cc motorcycle  to own. I have stated that I avoid any company that is steeped in pretentious snobbery/vanity/chest puffing ego pricing.     And finally in our defense about value... we cannot possible have awareness of all quality class d products out there or the pricing.  We can go by a wide swath of kits, pa and boutique brands as our reference.  Now we have something else to consider.  At this point, for speakers like ATC, VMPS and others that need power, I'd rather have $1995 worth of 500 watts than $3,000  worth of 100 watts when much of the price is pretense and outsourcing. Again, thanks for the post---but remember that potential clients range from the sensible and practical to the obsessed and pretentious.  It's only a hobby and people who don't indulge in it consider all of it immature. "You paid $10,00 for a stereo for just SOUND???  I could buy a nice bass boat or a used pickup for that, something useful. " (I have heard that many times) That, and taking a swipe at customers/board members is a foul ball.             

[lowtech]

I've heard a Class D Audiosource amp (Tripath-based) that I was less than impressed with...however, a few Class H Arc Audio Minis in a friend's Audi were amazing

I owned two of those AudioSource amps (they used the Tripath chipset) and thought they sounded pretty damn decent - especially for their diminutive price.

[Spectron]

Hello,

Interesting discussion and I want to contribute to it by sharing views of Spectron Audio on some aspects of power amplifier (class D or not) design goals

I must agree FUNDAMENTALLY with Mr. Tracy that "When it comes to technology there are always different tools and devices to achieve a given result ". Good example is already in this thread. AmpDesigner33 wrote "...feedback.... affects the sonic quality of the amp in a negative way ". Spectron chief designer, John Ulrick is control engineer by education and our entire amplifier design is based on his (proprietary) feedback design (plus some other stuff). You take out the feedback from Spectron and we are "gone".

Mr. Tracy continued "...The choice of tools and techniques will influence the nuances of the result achieved. How important those nuances are is entirely dependent on the context of where and how the technology is being deployed." I absolutely agree with him!!!

I love tubes, I believe, even as I write, that tube amplification, done right, exhibits most fidelity to acoustic music. Unfortunately as speakers demand in power raise, output transformer induced artifacts became intolerable for my ears. Besides OTL amplifiers, only class D has potential to drive difficult loads CORRECTLY, and here I am, in class D thread. [ Obviously, I exclude ultra heavy class A amplifiers from this discussion - I can't move these begemoths, can't stand their heat without "heavenly sound" of OTL amp - so, sorry, here I am out ]

So in the world of high-fidelity (as oppose to that of pro-audio where Spectron is largely involved) from mine and John prospective class D amplifier must have two simple goals:

1) To satisfy any speaker's electrical demand
2) To provide highest fidelity to the acoustic music.

Regarding the control, both the feedback and power capability define the amplifier in question. For example, Spectron is fully stable with loads up to 0.1 Ohm. Regarding the power ...I am scared to open Pandora box here. Let me briefly and very gently touch it. I mean no offense to anyone.

POWER:

Here is one of the definition of power capability: " ...The ICEpower module can output its 1kW continuously for 15 seconds before the thermal protection circuit activates "

I am sure unwillingly - but its irrelevant info and moreover misleading too. The laws in United States requires to disclose continuous power in 2-channel amplifier as the power at which amplifier run both channels at minimum 5 minutes, as well as its bandwidth and level of distortion during the test ( There are still arguments about power definition of multichannel amplifier). Somewhere else in this thread its stated that since ICEpower double its power with halving impedance then the power supplies are fully regulated. Well...how any power supply can be fully regulated without, at very least, power factor correction, PFC? And to the best of my knowledge in hi-fi Universe only Jeff Rowland claims to have PCF in its power supplies. Spectron has it but ONLY in its pro audio amplifiers where we use only switching power supplies.

My personal views on what is really constitute power capabilities of the power amplifier are published in EnjoyTheMusic ( http://www.enjoythemusic.com/magazine/manufacture/0708/index.html ) If you will see it then its most certainly NOT continuous power. For me its just useless spec. I, personally, eager to have ultra low distortion "explosive" headroom and both are not the same.

Also, I like a few SET amplifiers and thus I cannot discuss seriously notion of "price per watt" as anything remotely relevant to the music appreciation and  reproduction :

FIDELITY TO ACOUSTIC MUSIC

My one and only criteria to this aspect of amplifier (or crossover or whatever) design is as following. I am former concert pianist and when I design audio equipment I want to hear Steinway exactly as I remember it. That's all. The rest of it just boring details. Plus reliability, service etc

I do admit that my and John Ulrick approach to the design (and thus pricing) will not serve everyone. For example, people who shop audio equipment indexed to specific motor vehicle or other (better, I presume) audio equipment may or may not be happy. People with very specific tastes e.g. romantic euphonic sound also belong to the same category.

We must recognize that new power amplifier is not THE liver transplant and people can live without it. Its pure luxury and everybody has a full right to design amplifier from the scratch as we do ( - as a matter of fact John Ulrick is inventor of first hi-fi class D amplifier which he demonstrated at CES 1974 in Chicago. At that time he was a President of Infinity Loudspeakers - some may remember these speakers) or buy finished modules/power supplies from Philips or B&O. The end user has an equal right to buy luxury he wants - something which remind him Rock or Jazz concerts attended in youth or sound of favorite motorcycle. Its nobody's business but his.

At the end I urge the audiophile not to base decision to buy or not to buy certain amplifier based on its class but only on its sound, service reputation and price (as we all pay mortgage, regretably).

Simon Thacher
Design teams
Spectron Audio
& Joule-Electra

[Construct]

Spectron amps have never disappointed me.  They do represent the level of refinement that I wish I could afford.  But then again, that brings me back around to cost.  Like passlabs, krell and mark levinson, Spectron builds amps that really aren't affordable by the average music lover.  Except for the Musician III Stereo Signature Mk2 ($3995)  everything else is $5K  plus.  Amazingly capable, but like all other "Ultimate"  devices well above the cost of a class AB like the Bryston 4bsst2 AVA, and Mccormack DNA. 

[srb]

Like passlabs, krell and mark levinson, Spectron builds amps that really aren't affordable by the average music lover.  Except for the Musician III Stereo Signature Mk2 ($3995)  everything else is $5K  plus.  Amazingly capable, but like all other "Ultimate"  devices well above the cost of a class AB like the Bryston 4bsst2 AVA, and Mccormack DNA. 

The Spectron Musician III Mk2 (600W/ch - $3995) would be the most likely comparable model to the Bryston 4BSST2 (300W/ch - $4550) or the McCormack DNA-250 (250W/ch - $3995), so I don't see it "well above the cost" of those, and depending on personal sound preference, could be a better value based on the higher wattage.
 
The AVA Fet Valve Ultra+ 550 (280W/ch - $2395), sold Internet Direct, does sell for a lot less than the Bryston, McCormack or Spectron, which are sold by dealers.
 
Steve
 
 

[Construct]

The Spectron Musician III Mk2 (600W/ch - $3995) would be the most likely comparable model to the Bryston 4BSST2 (300W/ch - $4550) or the McCormack DNA-250 (250W/ch - $3995), so I don't see it "well above the cost" of those, and depending on personal sound preference, could be a better value based on the higher wattage.
 
The AVA Fet Valve Ultra+ 550 (280W/ch - $2395), sold Internet Direct, does sell for a lot less than the Bryston, McCormack or Spectron, which are sold by dealers.
 
Steve

You kind of repeated my point.  I said "with the exception of..."  and gave the solitary model that is commensurate with others.  I have owned a few AVA in the past and they are even better now (with lower ohm stability and higher output)  than when I owned mine years ago.  AVA represents the most I will ever spend again on amplification.

[CodyRed]

Cary Audiio once had a Class D amp, the Cary A306 that was introduced in 2005:

http://www.aaa-audio.com/images/6moons-news/6moons-news.htm

It never took off in the market place. I own this amp which I purchased used. I'm still trying to figure out what I have in this Class D amplifier (is it great or is it average? I still don't know yet) as I continue to try different gear with it. I currently have the Cary SLP 05 preamplifier, Krell SACD Standard mk lll, and Ohm Walsh 5-S3 speakers (all gear running balanced).  I haven't made up my mind about it yet. Appearance wise its beautiful. Still working on system builidng around the A306. Anyone familar with it?

[face]

A friend of mine had that amp, he said it wasn't one of the better examples of Class D.  He's much more fond of Wyred's amps.

[cliffylfd]

Hi, not sure if this is the right thread for this question , I see a few of the members on here that have own some versions of "Classdaudio" amps,whether self builds, or like myself  built by Tom of Classdaudio.
I have  the SDS 250c for a number of years now, my model has the gain controls on back panel. I was wondering what have past owners of Classdaudio amps moved onto and what overall improvements in sound quality it brought to their listening?. Also, did any past owners make any mods to their amps,( that would also work with the  sds 250c) that  made improvements to the sound of their amp?
CJ

[goryu]

Their class d GaN amps use outdated class d amp designs which have no post filter feedback resulting in a frequency response that is dependent on the speaker load, which of course varies with frequency. These amps work well with some speakers and not so well with others. Look at what people said 25 years ago when Tripath came out with load dependent class d amps. Class d amps have come a long way in 25 years and these new GaN devices has benefits but to exploit those benefits for amplifiers, they need to be run at a high oscillating frequency- which the classdaudio designs do not do. It's just a marketing gimmick the way they have implemented them.

[cliffylfd]

Cheers goryu, I was looking for ex "classdaudio"  owners  who found  a  better performing Class D amp from a different  company  or maybe even give up on Class D altogether, what are they using now.
CJ

[goryu]

I have owned or heard many class d amps over the last 25 years. Right now, the hypex and purifi amps are state of the art and competitive with just about anything out there regardless of price or class.

[cliffylfd]

Thanks goryu again, wasn't aware of purifi , I had heard of hypex. The Purifi seems to the most liked on searches I did...food for thought.

[Stercom]

Check this little GaN amp out. Very high value with excellent sound quality.  I owned one for about a year based on a recommendation from here on AudioCircle.
https://premium-audio.com/mini-gan-5-balanced-2-channel-power-amplifier-3.html