Class D amps

kfr01 · « **Reply #20 on:** 6 Mar 2006, 04:59 pm »

OT, but just out of curiousity, which Krell integrated was it?

miklorsmith · « **Reply #21 on:** 6 Mar 2006, 05:02 pm »

KAV 300i trying . . . not . . . to . . . hijack

kfr01 · « **Reply #22 on:** 6 Mar 2006, 05:32 pm »

Quote from: Dan Banquer

There is a new article up at audioholics on Class D amps by Bruno Putzeys.
http://www.audioholics.com/techtips/audioprinciples/amplifiers/SwitchingAmplifierBasics.php

Another article on this very same subject that I have been working on, will follow shortly.
d.b.

Yeah, sorry. In an effort to bring this back -on- topic, I had the opportunity to demo the Exodus UCD400 amp a month or so ago.

It sounded impressively similar to the other $1,000 to $2,000 solid state amplifiers I was able to listen to around the same time period. No double blind testing was done, or even quick a/b testing, but I was favorably impressed by Exodus's UCD implementation.

I doubt that "digital" amplifier technologies will seriously compete for a large share of "hi-fi" 2-channel systems anytime soon, but I think this has more to do with negative stigma than actual audible differences. I have no doubt, however, that a "hi-fi" 2-channel system could contain a "digital" amplifier. Indeed, the Exodus UCD amplifier sounded very hi-fi to my ears.

I believe that for home theater and car audio, "digital" audio technologies should garner mass acceptance. The high efficiency / low heat designs just make sense in those environments.

Having said all this, I ended up buying a Parasound HCA-3500 class a/ab amplifier rather than the UCD. It just felt more musical with my system...

skrivis · « **Reply #23 on:** 6 Mar 2006, 05:50 pm »

Quote from: kfr01

Yeah, sorry. In an effort to bring this back -on- topic, I had the opportunity to demo the Exodus UCD400 amp a month or so ago.

It sounded impressively similar to the other $1,000 to $2,000 solid state amplifiers I was able to listen to around the same time period. No double blind testing was done, or even quick a/b testing, but I was favorably impressed by Exodus's UCD implementation.

I doubt that "digital" amplifier technologies will seriously compete for a large share of "hi-fi" 2-channel syst ...

You do have to question why you'd want to go with a Class D design. It's usually because they will be smaller and less expensive for a given amount of power. They may also use energy more efficiently.

For a large PA system, Class D makes a lot of sense, and that's where the first products were aimed at.

Smaller size is also good for a receiver that has 7 channels of power amp built in.

For other uses, why accept the drawbacks of Class D when the benefits may not be meaningful?

Charles Calkins · « **Reply #24 on:** 6 Mar 2006, 06:04 pm »

I have a pair of CIAudio class D-200 amps. They are the best amps I've ever owned. They are also the best bang for the buck. I know there are better amps out there but my search for better has ended. Seems guys look down on class D amps. Maybe some are better than others. Please don't knock the CIAudio's D-200 amps. Want to hear them? Stop by my house someday. Then you will see what I mean.

Cheers
Charlie

miklorsmith · « **Reply #25 on:** 6 Mar 2006, 06:23 pm »

My little Clari-T acquits itself very nicely on my 10x the price speakers. When I had a tubed preamp in the rig, it was alluring AND honest.

Even with a SS pre, it's a very nice amp. But, I crave tubes somewhere and must pursue tube amps. I will keep the Clari-T, as there will always be a home for it with me.

skrivis · « **Reply #26 on:** 6 Mar 2006, 06:30 pm »

Quote from: Charles Calkins

I have a pair of CIAudio class D-200 amps. They are the best amps I've ever owned. They are also the best bang for the buck. I know there are better amps out there but my search for better has ended. Seems guys look down on class D amps. Maybe some are better than others. Please don't knock the CIAudio's D-200 amps. Want to hear them? Stop by my house someday. Then you will see what I mean.

Cheers
Charlie

According to the web site, they're $2300/pr. I can think of an awful lot of other amps that would seem to offer more for less money.

Somebody saved a lot of money by not having to supply heatsinks and big power supply components. It doesn't seem to be the customer who saves the money though...

_scotty_ · « **Reply #27 on:** 6 Mar 2006, 06:45 pm »

skrivis,the D200 has a conventional supply and the OEM cost on the UCD modules cannot be ignored, each monoblock weighs 15lbs. Some money may have been saved but not much. See link: http://www.ciaudio.com/D200.html
Scotty

Kevin Haskins · « **Reply #28 on:** 6 Mar 2006, 07:09 pm »

Quote from: skrivis

According to the web site, they're $2300/pr. I can think of an awful lot of other amps that would seem to offer more for less money.

Somebody saved a lot of money by not having to supply heatsinks and big power supply components. It doesn't seem to be the customer who saves the money though...

For small botique audio companies (of which I'm a member) the cost of a couple heatsinks is not a meaningful part of the cost equation. Class D amps are not really any cheaper to sell than a Class A/B amplifier from my standpoint.

There are two cost attributable to a product. Fixed cost that you spend on development and parts cost that are a function of every production unit you build. For small companies that only sell a couple hundred units the up-front fixed cost of developing a product are the largest part of the equation. The actual parts cost of a couple heatsinks is almost insignificant in the overall cost.

For a Phillips, Sony or other large consumer electronics company the situation is almost reversed. The parts cost is very significant in the final product cost.

skrivis · « **Reply #29 on:** 6 Mar 2006, 07:31 pm »

Quote from: Kevin Haskins

For small botique audio companies (of which I'm a member) the cost of a couple heatsinks is not a meaningful part of the cost equation. Class D amps are not really any cheaper to sell than a Class A/B amplifier from my standpoint.

There are two cost attributable to a product. Fixed cost that you spend on development and parts cost that are a function of every production unit you build. For small companies that only sell a couple hundred units the up-front fixed cost of developing a product are t ...

I've seen a lot of places claim they're expensive because they use such expensive parts.

Given that Class D won't save any money at these low production levels, I still have to question why anyone would want one.

My comments on the CIA D-200 amps were really based on my observation that something like Frank Van Alstine's Ultra 550 amp costs less and comes with a lot more.

I'm not going for lots of channels in one box, nor am I building a touring PA rig, so a non-Class D amp seems like a better bet.

Kevin Haskins · « **Reply #30 on:** 6 Mar 2006, 07:44 pm »

Quote from: skrivis

I've seen a lot of places claim they're expensive because they use such expensive parts.

That can be part of it... you won't see the big names using tweako parts. I doubt they would use a Cardas post or botique capacitors.

Quote

Given that Class D won't save any money at these low production levels, I still have to question why anyone would want one.

I think for the same reason they would like any amp, how it works for their application. If people didn't think the newer Class D amps sounded better they wouldn't be using them.

skrivis · « **Reply #31 on:** 6 Mar 2006, 08:15 pm »

Quote from: Kevin Haskins

Quote from: skrivis
I've seen a lot of places claim they're expensive because they use such expensive parts.

That can be part of it... you won't see the big names using tweako parts. I doubt they would use a Cardas post or botique capacitors.

Quote

Given that Class D won't save any money at these low production levels, I still have to question why anyone would want one.

I think for the same reason they would like any amp, how it works for their application. If people didn't think the newer Class D amps sounded better they wouldn't be using them.

Ah, but why do they think they sound better?

They're currently cool, just like anemic little tube amps are, so I have to wonder if that's why people think they sound good or not.

I've heard some Tripath and ICEpower amps and didn't think they were very good at all. Kind of the fingernails on the blackboard type of thing.

Perhaps the UCD modules fix all that?

That still leaves me wondering because the amps I heard didn't seem to do anything spectacularly better than a more conventional amp.

ctviggen · « **Reply #32 on:** 6 Mar 2006, 09:20 pm »

I'm seriously considering class D (Hypex UcD) because I need 8 (or 10, if I use a center channel) of amplification for my front right/left speakers, if I build the Linkwitz Orions. With the Orions, which have active filters and you put the amps between the active filters and the drivers, I'm thinking that there will be little difference between amps. Therefore, why not use something light, low power (in terms of power when "off"), easy to build, etc.? A four channel amp with Hypex modules would be relatively cheap and easy to build. My gut says that in the application I'm going to use them in, UcD modules will be as good as solid state. But that's only my gut, and I have no true data (for at least a little while).

kfr01 · « **Reply #33 on:** 6 Mar 2006, 09:28 pm »

Quote from: ctviggen

My gut says that in the application I'm going to use them in, UcD modules will be as good as solid state. But that's only my gut, and I have no true data (for at least a little while).

ctviggen: Neither me, my wife, nor my friends could honestly say the UCD clearly sounded worse than any solid state a/ab amplifier we've heard. We heard more sonic similarities than differences and the chassis barely warmed after hours of play. In my opinion, UCD is perfect for multichannel needs.

_scotty_ · « **Reply #34 on:** 6 Mar 2006, 10:15 pm »

Here is a link to a review of Hypex modules with measurements and typical performance characteristics. http://www.hardwareanalysis.com/content/article/1822/ Amplifiers built with these modules should measure similarly.
Scotty

Occam · « **Reply #35 on:** 6 Mar 2006, 11:11 pm »

Its rather depressing to see the turn that this thread has taken. Bruno's article -
http://www.audioholics.com/techtips/audioprinciples/amplifiers/SwitchingAmplifierBasics.php
Please - actually read and digest BOTH pages.
Its not about the merits of switching type amplifiers vs A/AB amps, it about the tremedous variability among switching amps themselves.
On the second page there are oscilloscpe waveform pictures of what I claim is the NuForce Ref9. It shows a tremendous amount of 'shoot-through'. This is the obvious reason for the substantial interference the NuForce products continue to visit upon FM reception. The article clearly explains why. The article clearly does not blame the balanced H-bridge topology for this hash, it clearly lays the blame on poor implementation. The B&O ICE H-Bridge does not spew crap accross the FM band. [and as far as I know, the latest revision of NuForce continues to constain (an understatement) your FM listening pleasure.]

The last oscilloscope picture is of the UCD400's output waveform. It does not show the same massive amounts of 'shoot-through'. The Hypex amps do not crap up one's FM reception.

For obvious reason's, Bruno wasn't going to specifically identify the amps examined; I will... and have.

So now on this thread, we've got folks questioning and defending the Hypex modules. In heaven's name why? Did any of you actually read the article? You have been clearly told why the NuForce amps CONTINUE to pollute the FM band, and absolutely no one picks up on it.....

And on the NuForce Circle we've an ongoing bitch slap broughhaha....
http://www.audiocircle.com/index.php?topic=26272
They don't like what has been said. The article writer isn't around to defend his article, and certainly the conditions of the testing was not adequately described. So why don't the NuForce partisans post their own measurements and graphs. Why doesn't NuForce? Why don't they post their own screenshots of the output waveform to disclose the extent of shoot-through?

The Shadow knows.....

Kevin Haskins · « **Reply #36 on:** 7 Mar 2006, 12:10 am »

Quote from: skrivis

Ah, but why do they think they sound better?

For the same reasons anyone thinks a product sounds better than another. Sometimes it does, sometimes the listener thinks it should and sometimes it doesn't.

Quote

They're currently cool, just like anemic little tube amps are, so I have to wonder if that's why people think they sound good or not.

I've heard some Tripath and ICEpower amps and didn't think they were very good at all. Kind of the fingernails on the blackboard type of thing.

Perhaps the UCD modules fix all that?

I really like some of those anemic little tube amps!

The amplifiers are just a tool. Like any tool they can be misused and sometimes another tool is better for the job. I've yet to hear the Hypex amps sound anything remotely harsh. They are not as romantic as a singled ended 300B but hey... they don't have that type of distortion spectrum.

I've no idea what your reference is but I have a couple free demo amps floating around. Rather than tell you what I hear you can have the chance to listen to them and come to your own conclusions. How it sounds in your system and room is more important than how it sounds to some reviewer anyway.

Quote

That still leaves me wondering because the amps I heard didn't seem to do anything spectacularly better than a more conventional amp.

You know I would just ignore the technology and listen to them based upon the same merit you would any amplifier. Ignore the fact that it is a Class D amplifier and just judge it like you would a typical Class A/B ampifier.

MarkM · « **Reply #37 on:** 7 Mar 2006, 02:30 am »

Quote from: skrivis

Beyond that I think I'll keep my opinions to myself.

Given that Class D won't save any money at these low production levels, I still have to question why anyone would want one.

My comments on the CIA D-200 amps were really based on my observation that something like Frank Van Alstine's Ultra 550 amp costs less and comes with a lot more.

Take AVA's OmegaStar line, not the very best products they offer, but solid values. Consumers choose OmegaStar products based on hmmm, budget, tastes, preferences, etc. That is what you own, correct?

If you haven't heard the Hypex designs, perhaps you don't have a decent reference as to where it has advanced. AVA makes some great gear, but Frank is always developing new product that offers better sonics than previous models.

"Class D" is still delevoping and who knows where it will end up. The Hypex design must be good, because a fair amount of audio veterens are buying. The Hypex modules are appealing to the DIY community, which if I used your logic, are 1/2 the price of the Ultra 550.

I will be demoing Kevins amp in a couple of weeks. It will be matched with an AVA T8.

I'll let you know how the combo sounds skrivis.

art · « **Reply #38 on:** 7 Mar 2006, 03:53 am »

I have trying to stay out of this one, but my mail box keeps filling up.

UcD- and ICEpower based-amps have similar amounts of EMI. The performance ICEpower-based ones are sensitive to load impedance, the UcD-based ones are not.

For better or worse, NuForce has a reputation of generating excessive amounts of EMI. Having said that, a buddy of mine has one and he loves it. He knows nothing of EMI compliance, and could care less that guys like me seem to be appalled by the levels that it is rumored to have.

(And no......he has never compared it to any of ours. I said that he is a friend, not a robot.)

Bottom line is:

If what you have sounds good to you, that is probably all that matters. Technical parameters aside, everything sounds different to everyone on different systems.

But we already knew that, right?

Pat

randytsuch · « **Reply #39 on:** 7 Mar 2006, 07:57 am »

Quote from: Occam

Its rather depressing to see the turn that this thread has taken. Bruno's article -
http://www.audioholics.com/techtips/audioprinciples/amplifiers/SwitchingAmplifierBasics.php
Please - actually read and digest BOTH pages.
Its not about the merits of switching type amplifiers vs A/AB amps, it about the tremedous variability among switching amps themselves.
On the second page there are oscilloscpe waveform pictures of what I claim is the NuForce Ref9. It shows a tremendous amount of 'shoot-through'. This ...

Hi Occam
I am pretty surprised nobody is responding to this, thought someone would when you named the companies the pictures came from.

I may get in trouble for this, but I wonder how many people understand those two pages. Those two pages were very techinical. but they were also very educational
.
But the bottom line point I think you are getting at is that it is silly to group all class D amps together, just like it would be silly to group tube or even chip amps together. It comes down to implementation and details. Looks like somebody is paying more attention to the details.

Too bad nobody has hooked up a spectrum analyzer to these guys, to get a good picture of what frequency and how much noise they put out, but the scope pics clearly show more noise from Brand X.

Randy