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Class D amps done well
Old 29th November 2007
  #1
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🎧 15 years
Class D amps done well

I'm not a fan of most of the Class D amps that I've heard previously but this one has it going on: Red Dragon Audio

He seems to be using the 1000W top-o-line model as a basis and changing a few components, using a wood chassis for "sonic reasons", and a host of other changes he obviously can't share. Sounds truly good to me at all volume levels, deep tight bass, mids and top all there without harshness. If you're looking for a Class D amp, I don't see how you could do much better, only sideways. And as far as high end amps go, the Levithans seem a bargain to me.
Old 29th November 2007
  #2
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pinwale's Avatar
 
🎧 10 years
I really like the ideas of this technology! I have heard some of the IcePower-based Bel Canto 1000s (nice), and have heard favourable reports about Hypex' offerings. What modules are the Dragons based on? Is the wood chassis supposed to have some kind of audible effect, or are you saying you just like the woodwork?

Also, as you posted this in the mastering forum and not the living-room forum, I wonder how is it that you've auditioned any of these amps when your monitors have their own amplifiers? Have you binned your Barefoots?

Cheers!
Old 29th November 2007 | Show parent
  #3
Mastering
 
🎧 15 years
I have no idea which brand or type of Class D module that Lipinski uses, but they have found some way to put sonic magic in there, so it isn't just the choice of module. To my ears, the new Lipinski amps are as powerful (or more), clean, solid, pure and have as much depth as my Pass X 250 Class A.

Class D, in my opinion, has finally gotten there, not all implementations are the same, so go with the company you trust to do the grounding, power supply and ancillary equpment right. It's not trivial to get the power supply right, especially if you do a switching supply.

I wouldn't even enquire which module the company uses. In the end, the key is in the listening. I've grown less and less enamoured of Class AB amps in the past few years and thought I would have to remain with expensive, power-hugging, non-ecological amps for my listening pleasure, but the Lipinskis have turned this around.

Reportedly also the new Bel Canto's are the bees knees.

BK
Old 29th November 2007 | Show parent
  #4
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I'm with that Bob, they need modifications to be used in anything other than subwoofers IMO. Stock class D sounds makes audio flat and homogeneous. These are basedon the B&Os 1000ASP. The Barefoots have allowed me to compete at the highest level so no, they're not at risk. And yes I've auditioned these amps for 3 weeks or I would not be posting ... in a mix room.
Old 29th November 2007 | Show parent
  #5
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pinwale's Avatar
 
🎧 10 years
Quote:
Originally Posted by lucey ➑️
I'm with that Bob, they need modifications to be used in anything other than subwoofers. Stock class D sounds makes audio flat and homogeneous. These are B&Os 1000ASP.
Ah, so those are built around the IcePower modules. That is a nice amp!

Quote:
Originally Posted by lucey ➑️
The Barefoots have allowed me to compete at the highest level so no, they're not at risk.
Wow, competing at the highest level? Good for you! Good. For. You. Self-aggrandize much?

Quote:
Originally Posted by lucey ➑️
And yes I've auditioned these amps for 3 weeks or I would not be posting.
On what speakers? I heard the Bel Cantos (which afaik, use the same amp blocks) on PMCs and thought it really controlled them well.
Old 29th November 2007 | Show parent
  #6
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🎧 10 years
The best Class-D amps I've heard are from Halcro. I lived with the DM-58 monoblocs for a while and really like them. With the Wilson's, they didn't have that "magic" that the Pass Labs amps do. I haven't heard them on many other speakers systems. I think I've heard them on B&W and Avalon though. To get Class-D "right", they have to be ubber expensive. I'd encourage anyone who wants to hear what Class-D can really sound like, go take a listen to the Halcro amps.

Regards,
Bruce
Old 29th November 2007 | Show parent
  #7
Barefoot Sound
 
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🎧 15 years
It's true. Class D has come amazingly far in recent years. However, I have yet to find a class D amp that I'm happy with in the highest frequencies. The tweeter we use in the MM27 is one of the most transparent and low distortion dynamic drivers in the world. It reveals a sort of angular strident character with even the very best class D amps. That's why I've' taken a hybrid approach, using class A/B with a regulated supply on the top channel. Taken "off the shelf", all of the top-of-the-line class D amps I'm aware of show a sharp upturn in distortion and a sharp downturn in output impedance in the region of 1kHz to 2kHz. And by about 6kHz to 7kHz they become unacceptable for my application. I'm open to the possibility, but I'm skeptical that peripheral modification could drastically change this situation. And I find it very difficult to believe that anyone outside of the major players has the wherewithal to design their own class D core. This literally means designing and fabricating your own ICs.

Anyhow, I've always loved the sound of good linear amps with regulated supplies. They have a clarity and solidity that is just wonderful. The problem is, if you want a powerful amp of this type, it winds up being very large and expensive. When this latest generation of class D emerged I was really happy to hear that they gave the same sense of clarity and solidity; only much more powerful, efficient and far smaller. This was surprising. But then a really top-flight amp designer clued me in on why this is. A typical unregulated linear power supply relies on the 60Hz power input to refresh the supply caps. Apart from using monstrous banks of capacitors, this never really provides stable supply rails. A switching supply, on the other hand, chops up the power input into 400kHz+ chunks. Then using modern class D topographies, those power chunks essentially get fed straight through to the amplification stage. The fast refresh rate is akin to having a regulated supply.

But like I said, I still don't think class D is quite there with respect to the highest frequencies. That's why I'm really happy with this hybrid approach. It maintains the same solid, transparent charter over the entire spectrum without the minor failings of class D in the top end. One more generation, and I can clearly imagine going fully class D.

Thomas
Old 29th November 2007 | Show parent
  #8
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Quote:
Originally Posted by pinwale ➑️
I heard the Bel Cantos (which afaik, use the same amp blocks) on PMCs and thought it really controlled them well.
on wich pmc have you heard them ?
i think to replace my 4bsst for a custom biamping or triamping solution based on the hypex modules for my IB2s
but will test a large band first, i'll let you know
Old 29th November 2007 | Show parent
  #9
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Quote:
Originally Posted by DSD_Mastering ➑️
The best Class-D amps I've heard are from Halcro. I lived with the DM-58 monoblocs for a while and really like them. With the Wilson's, they didn't have that "magic" that the Pass Labs amps do. I haven't heard them on many other speakers systems. I think I've heard them on B&W and Avalon though. To get Class-D "right", they have to be ubber expensive. I'd encourage anyone who wants to hear what Class-D can really sound like, go take a listen to the Halcro amps.
I've been listening on Acoustic Zen Adagio Jrs., and their recommendation was the Halcro MC20 for a more dry presentation, or the Red Dragons for more juicy low mids and top. The Wilsons need a little traditional A/AB color IMO to really shine, so Pass makes more intuitive sense.
Old 29th November 2007 | Show parent
  #10
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🎧 10 years
Quote:
Originally Posted by livingstone ➑️
on wich pmc have you heard them ?
i think to replace my 4bsst for a custom biamping or triamping solution based on the hypex modules for my IB2s
but will test a large band first, i'll let you know
IB1s

Hypex holds a lot of interest for me too. Hope your test goes well.
Old 29th November 2007 | Show parent
  #11
Craneslut
 
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🎧 15 years
Bruno Putzeys's Hypex amps look to be the new hot setup in switching amplifiers.
Old 29th November 2007 | Show parent
  #12
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Quote:
Originally Posted by Brad Blackwood ➑️
Bruno Putzeys's Hypex amps look to be the new hot setup in switching amplifiers.
I'll have comments on that in a few days....


GR
Old 29th November 2007 | Show parent
  #13
Lives for gear
 
🎧 15 years
IMO Bel Canto nailed it with their first Tripath-based eVo series. They are balanced, fast, clear, and robust, just superb all around. Certainly Class D amps are an excellent choice for any audio setup. The only way I have run for a while now, for all my studio/HT/SR systems.

Steve
Old 30th November 2007 | Show parent
  #14
Mastering
 
🎧 15 years
Quote:
Originally Posted by barefoot ➑️
It's true. Class D has come amazingly far in recent years.


However, I have yet to find a class D amp that I'm happy with in the highest frequencies.
You might change your mind after you hear the implementation in the Lipinski Amp. It's sweet, open, clear, warm, extended in the high end. And I have done EXTRA careful comparison with the Pass. As a matter of fact, Andrew Lipinski set out to equal or beat the Pass as his benchmark for the design of the amp.

I believe that a well-designed Class D module, with the right power supply, internal grounding and front end, will sonically equal or outperform Class A. Since I'm a BIG fan of the Pass, I reached this conclusion reluctantly and only after extensive listening. Lipinski charges a lot for their unit, but I suspect 99% of that is to make up for the R&D since from the point of view of parts count and pound for pound, a Class D amp is far less complex. And the Pass uses, like 20 output devices per channel, I think!
Old 30th November 2007 | Show parent
  #15
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Quote:
Originally Posted by bob katz ➑️
I
Since I'm a BIG fan of the Pass, I reached this conclusion reluctantly and only after extensive listening.
Hey Bob... did you compare to the Pass XA series (not the switching X series)? Though I've never heard the Lipinski's in a controlled environment, I'm sure you'd be hard pressed to think any Class-D could ever equal a well designed pure Class A!

Regards,
Bruce
Old 30th November 2007 | Show parent
  #16
Gear Head
 
🎧 15 years
Lipinski Amps - Class D

I Agree , I own the Lipinski amps , they power my Lipinski 707's.
They are the best solid state amps I've heard. I've compared them
to amps with that combination at many different price ranges.
Old 30th November 2007 | Show parent
  #17
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🎧 15 years
Quote:
Originally Posted by DSD_Mastering ➑️
Hey Bob... did you compare to the Pass XA series (not the switching X series)? Though I've never heard the Lipinski's in a controlled environment, I'm sure you'd be hard pressed to think any Class-D could ever equal a well designed pure Class A!

Regards,
Bruce
They come pretty close! there are some class a designs that outclass the hypex modules. like this one:

ExtremA, a reference class-A DIY amplifier - Measurements

But the difference is not so big and I think they give Bryston and Pass a run for their money on transparancy. That said no special magic either just wire with gain.
Old 30th November 2007 | Show parent
  #18
Mastering
 
🎧 15 years
Quote:
Originally Posted by DSD_Mastering ➑️
Hey Bob... did you compare to the Pass XA series (not the switching X series)? Though I've never heard the Lipinski's in a controlled environment, I'm sure you'd be hard pressed to think any Class-D could ever equal a well designed pure Class A!

Regards,
Bruce
*

Of course i'd be hard pressed to believe it. I was skeptical until I did! Lipinski said that he did his shootout against the more advanced (later) Pass model than the one I have.

BK
Old 30th November 2007 | Show parent
  #19
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🎧 10 years
IIRC BK used Krells to keep his NYC apartment warm... years ago.

If Bob says digital can sound good it does. IMO a good amp doesn't have any sound... many other parts of the signal chain are equally or more challenging to design. GIGO? Speaks?

JR
Old 30th November 2007 | Show parent
  #20
Mastering
 
🎧 15 years
Quote:
Originally Posted by JohnRoberts ➑️
IIRC BK used Krells to keep his NYC apartment warm... years ago.

If Bob says digital can sound good it does. IMO a good amp doesn't have any sound... many other parts of the signal chain are equally or more challenging to design. GIGO? Speaks?

JR
Hi, John! Great to see you here in the forum. Interestingly, I started with the Krell KSA-100 (class A), sold that and flirted with a great sounding class AB Hafler for a number of years, then, when I got the Lipinskis, I had to go back to Class A because the Lipinskis are so revealing they revealed the Class AB grain. I tried some Brystons and rejected them and eventually ponied up for the Pass. Now I'm "flirting" with Class D! Especially as I move to surround, the thought of 3 Pass X250s in this room from (currently) a single 20 Amp socket is suicide.

BK
Old 30th November 2007 | Show parent
  #21
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Quote:
Originally Posted by bob katz ➑️
Now I'm "flirting" with Class D! Especially as I move to surround, the thought of 3 Pass X250s in this room from (currently) a single 20 Amp socket is suicide.

BK
Not your first flirtation with class D.

Do you still remember the early Bel Canto well enough to comment on how it compares to the Lipinski?


GR
Old 30th November 2007 | Show parent
  #22
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🎧 10 years
Hi Bob long time no chat.

Yes class D is interesting.. pretty much a different animal with different strengths and weaknesses. Much of the technology is just regurgitated switching PS technology, but it's been around for decades now so a few are getting it refined enough to be a serious contender.

I don't like to pimp anybody since I haven't personally compared what's out there today but Bruno Putzey seems to be one of the guys who gets it and has the chops to do it well. I've heard some modified Tripath variants that didn't suck but the basic chip set IMO wasn't ready for prime time.

Be well..

JR

EDIT: BTW for high power SR QSC has a new amp getting good reviews and Crown has a pretty high power series but they seem to have gone a little wimpy on their output filter (load interaction at very HF).

When making thousands of watts class D really shines.

Last edited by JohnRoberts; 30th November 2007 at 05:47 PM.. Reason: addition of content
Old 30th November 2007 | Show parent
  #23
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I'm a little weary of the whole "Bruno's new thing" adoration, especially since no one's heard it, and since his first efforts needed so much help to be world class. Rings of the trust/hype that comes with any brand name. If he were the man to beat for tone his last designs would not have been bettered by so many on the sonic front. Perhaps he's a technical pioneer but not a tonemeister? His new thing with the tweakers on it for a time may be amazing, but there was nothing great about his first efforts if we look at it only from the tone category. His ideas were the genius, the sonic implementation fell to others IMO.
Old 30th November 2007 | Show parent
  #24
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🎧 10 years
What I get weary of is when folks don't believe that my new TV in its wooden case has a better picture than TV's plastic cases.

I like reading posts here because it's a forum which (usually) represents critical thinking in audio.
Is believing that wrapping an amplifier in wood to improve sound actually "critical thinking"..........probably not.

If anything, it would cause me to not take the designer seriously as somebody pursuing the finest audio amplification, but rather an audio designer trying to appeal to the folks who read Stereophile and The Absolute Sound.

(I read both magazines now and then, but with a large grain of salt).
Old 30th November 2007 | Show parent
  #25
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Quote:
Originally Posted by silverking ➑️
What I get weary of is when folks don't believe that my new TV in its wooden case has a better picture than TV's plastic cases.

I like reading posts here because it's a forum which (usually) represents critical thinking in audio.
Is believing that wrapping an amplifier in wood to improve sound actually "critical thinking"..........probably not.
I've not heard the metal box vs the wood, and neither have you, so what do we know for sure? I know that Red Dragon sold an early version in metal to a classical violinist. And that person was willing to pay more for the same thing in a wood box (for sonic reasons). These amps appear to be fragile to interference and it seems to matter. These are things the tweakers find out by listening after the theory guys move on to the next brain game. The kind of wood, that's part of hi fi hype, the fashion show element, and that's admitted ... but for reasons beyond me wood matters.

I got into this amp from the recommendation of the speaker designer, who was killing people at the hifi shows with this particular combo. I asked him about making me a cheap one in a plain box with no dragon logo. But the box needs to be wood.
Old 30th November 2007 | Show parent
  #26
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🎧 10 years
Sorry, I'll leave you guys to debate wood vs. metal or whatever...

Since class D has new ways to screw up too, details matter. I only mention Bruno as being one who IMO seems to understand the technology, I make no claims about any of his specific designs while I would be inclined to check out his work if I was in the market (I'm not). FWIW, I have seen a number of less than satisfactory efforts in the decades that class D has been around.

I don't believe amplifiers should have tone or impart any coloration on signals. The primary benefit of class D is efficiency. There are far easier ways to get extended frequency response and linearity.

I will now slowly back out of this area... and return to the objective world.

JR
Old 30th November 2007 | Show parent
  #27
Mastering
 
🎧 15 years
Quote:
Originally Posted by Greg Reierson ➑️
Not your first flirtation with class D.

Do you still remember the early Bel Canto well enough to comment on how it compares to the Lipinski?


GR

YOU'RE RIGHT, I flirted with Class D briefly at the time I decided on the Pass. But it's not entirely fair to Bel Canto to say that I rejected that amp. I also looked at cost effectiveness and the stereo Bel Canto that I rejected didn't have enough low end "poost" to compete with the Pass. But I imagine that if I had plunked down the money for the dual chassis dual/mono Ice models I might have found they have far more power supply current to deal with the extreme demands of loudspeakers like the Lipinskis.

One key to the Lipinski amps is EACH amp contains TWO 350 watt or so modules and so you are truly bi-amping EACH section of each loudspeaker. There is truly power to spare.

BK
Old 30th November 2007 | Show parent
  #28
Barefoot Sound
 
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🎧 15 years
Quote:
Originally Posted by bob katz ➑️
I believe that a well-designed Class D module, with the right power supply, internal grounding and front end, will sonically equal or outperform Class A. Since I'm a BIG fan of the Pass, I reached this conclusion reluctantly and only after extensive listening.
I am open to the possibility. But like I said, I'm also skeptical that peripheral implementations can make a dramatic difference in MY application when they don't address core amplification issues like switching frequency, shoot-through, etc. And we are talking about slightly different applications. I believe you're driving a passive crossover, while I'm directly coupling the tweeter to the amp. Plus, my tweeter has lots of copper in the magnetic gap and other things that pull third order distortion and IM distortion way down. I'm not trying to get into a pissing contest, but they are different situations.

Also, I'm not necessarily a fan of class A, if you're referring to no-feedback topologies. To me, many no-feedback amps just sound nice often because they mask otherwise objectionable distortion with generous amounts of 2nd order harmonic distortion. I'm not familiar with the newer Pass amps, so I don't know if this is the case with your amp. But sweet and tubey is not what I'm looking for. I want very low distortion overall. Of course, this needs to be done intelligently. You have to design the amp so you also pull down the odd-order harmonics and intermodulation, keeping their ratios low compared to the even harmonics. Otherwise, you end up with that cold transistor sound that everyone hates. Although, none of the class D's I've heard have that tubey 2nd harmonic thing going on. So maybe that's not the sound your referencing anyway and I'm just spiraling off topic.

Quote:
Originally Posted by bob katz ➑️
Class D amp is far less complex. And the Pass uses, like 20 output devices per channel, I think!
The complexities of class D go way beyond device count. The devices themselves are enormously complex. A modern high speed, high power switching mosfet might look simple enough. But it sits on the pinnacle of a virtual Mount Everest of semiconductor processing technology. These are not the sort of things that small companies develop and implement on their own. And it's these devices that fundamentally limit core class D performance. For example, even brilliant modification isn't going to get us a high power amp switching at 20Mhz (a sort of "next generation" speed). Present devices wont allow it. To do this we need to wait for companies like International Rectifier or Toshiba to make such devices available. And they're certainly going to want to sell a lot of them. So it's a fairly level playing field with regard to most core class D technologies.

Thomas
Old 30th November 2007 | Show parent
  #29
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🎧 10 years
I'm looking to try the Musical Fidelity 550k Supercharger. I know it got a great review in Stereophile, not that they are the authority. They did get the Pass/WATT/Puppy combo spot on.
For anyone who has an underpowered amp or wants more "grunt", this seems a viable option.

Regards,
Bruce
Old 30th November 2007 | Show parent
  #30
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silverking's Avatar
 
🎧 10 years
Quote:
Originally Posted by lucey ➑️
These amps appear to be fragile to interference
What type of interference exactly does wood protect electrical components from that a traditional metal enclosure doesn't?

Just wondering.
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