My experience with D-Amps
tuckers -- Tue, 10/31/2006 - 23:06
I have owned a coupel of Digital Amps, and have had a few more on loan. I have owned the Spectron Musician II and the Bel Canto Evo Monoblocks. I have had at my home several of the newer Tripath amps including the Red Wine ones. I have had the Roland Ice Power amps at my home, and a few of the other ones too. I have had the Channel Islands amp at my home too, as well as the Nu Forces.
They do not all sound the same. Some sound much better than others. I like the sound of the Spectron best in terms of balance and musicality.
The NuForce was initially impressive, but the effect wore off very quickly. I think the NuForce's have a lot of potential, but I wish they had a different designer!
I have liked the sound of the Red Dragon ICE amps at shows, and would like to spend some time with them.
Overall, I still prefer the sound of a good tube system, or some of the best Solid State systems over any of the digital amps I have listened too.
One of my top priorities in audio is an organic/wholistic sound. This is the area that digital amps fall flat on their faces IMHO. While they may sound dynamic, forceful, sweet, pure, clean with deep bass etc., they don't have the same naturalness, or display the rich tonality of natural instruments that even modest tube systems do. Every digital amp I have heard that sounds sweet, begins over time to sound Splenda sweet, artifical. One of the things I listen for (since I studied it for 8 years) is piano. And it is very telling.
The most telling was my experience with the NuForce's. I really liked them for about three days. They had a very clear presentation, a liquid sound, very controlled in all aspects, especially the bass. Then I began to hear a sameness or boring quality to the sound. I was listening to a small jazz combo, and I was thinking that the piano was a synthetic piano. Hmm, I know this player and he only uses Baldwin pianos. I put on a classical piano piece and that piano sounded synthetic too. I put on a few more and found the same effect. Switching back to my tube amp, it was an ah-ha moment. Gone were the synthesisers, and the real pianos were back. Doing some comparative listening between amps and I found that synthetic quality on many instruments, room acoustics etc. All voices had a very slight sound like they had gone through a digital effects processor. The amps sounded great on standard electronic pop fare, but put on some naturally produced music, and they fell on their face.
I do think that one day digital amps will come of age. But they need to be in the hands of designers who can hear and improve the designs to sound more like real music, and less like our hi-fi expectations. Which is what the best designers in Audio do now with older technologies.
But lest I sound too doom and gloom, let's remember what the early solid state designs sounded like! Phase Linear! Crown! They were horridly unnatural and unkind to the music. And they have come so far. Digital amps will also improve to a greater degree I think. Hopefully that day will come someday before my beloved NOS tube stocks give out!
Your experience with the Nuforce units is very similar to mine, and your experiences in general are pretty in-step with our Class D survey in Issue 166. And you are so right about early solid-state. Out of curiosity, what speakers are you listening to?
Hi Wayne,
My experience listening to Class D has been primarily with my current Horning Akibiades (high efficiency, full range, extremely revealing) http://www.horninghybrid.com, and also Vandersteen 5s, and earlier with Revel Ultima Salons.
My system is listed on the Asylum http://cgi.audioasylum.com/systems/2908.html
John Hughes
Hi John,
Thanks for the reply. I'm not familiar with the Horning speakers (and thanks for the link) but do know the Revel's and Vandersteens. This continues to raise questions of how Class D designs interface with speakers and cables.
Wayne
I owned an ARC 300.2 amp for just over a year. During that time I had the chance to do much critical listening and to make comparisons with a Krell FPB300 and an ARC VT100 MKII tube amp.
Associated Equipment: ARC REF CD7, ARC REF3, ProAc D38, Kimber Select cables, Exactpower EP15A, SP15, Shunyata Python helix cords, Kimber Palladian PK10 power cord for amplifer, dedicated 20 amp lines, zoethecus racks.
The ARC 300.2 replaced a Krell FPB300 in my system. My music room sits on the second floor of my home. I live in Texas. Picture a night listening to music in the middle of August with the Krell cranking. Not pretty. Head to head the 300.2 seemed to have more stage depth, equal midrange and detail on the top end. The 300.2 is a very dynamic sounding amplifier. It projects the attack of instruments and dynamic range of music as well or better than anything I've tried. Nothing in my experience matches a Krell amp for bass extension, depth, and definition. The 300.2 held it's own in this area so I bought it. NO HEAT. NONE. Out of the box or when the 300.2 was turned off for any period of time, the amp sounded cold, hard, constrained especially on the top octaves. After a few days the character of the amp changed dramatically; everything got more relaxed and natural, better stage depth, width, better midrange warmth, and better air in the top octaves When I bought the amp, my dealer gave me a Kimber Palladian PK10 power cord to evaluate. He told me to NOT put it in until I had the amp for about a month. When I finally installed it on the 300.2 the results were very noticeable: much more air and better detail around high frequencies, slightly better bass depth and definition, "blacker" background. The "secret sauce" to extracting the best performance from the ARC 300.2 in my experience is:
1. Leave it on all the time. According to the Exactpower EP15A the 300.2 draws only 50 watts. The VT100 MKII draws 525 watts and the Krell FPB300 could not be plugged into the EP15A because it drew more than 1500 watts and shut down the EP15A.
2. Try this amp with the Kimber Palladian PK10. It makes a noticeable improvement to this amp.
3. Try all silver speaker cables. I borrowed a friend's AQ Killimanjaro all silver speaker cables. I heard better treble detail and air.
I bought an ARC VT100 MKII on A'gon. It came with a new set of tubes. After installing the tubes and setting all operating parameters on the input tubes, drivers, regulators, and output tube bias, I did a comparison of the 300.2 to the VT100 MKII. I like the tube amp better. I hear more stage depth, better bass pitch definition, more overall warmth, better space around instruments in the top octave. The 300.2 is a bit more dynamic for sure. The VT100 MKII sounds more like music to me. Sold the 300.2. Heat was a problem again. I got a computer controlled air handler, some additional duct work, and a thermostat added to the air conditioning unit that feeds my music room and the second floor of my house. When the temperature in the music room starts to rise above the level of the rest of the upstairs, the air handler channels more cold air to the music room. Fixed the problem. Don't ask how much. But it is extremely cool! Sorry.
The Absolute Sound editors did a good job of explaining the sound of the 300.2 Some of them complained about the high frequencies in the Class D amps they reviewed. I believe they have a point. I also believe they could have gotten better results with some of the tips above but I have an easy test to prove their point regarding unnatural sounding high frequencies. On Ray Brown's "Soular Energy" CD, cut 1, "Exactly Like You", about 45 seconds into the cut pianist Gene Harris plays a single note on the upper register of the piano forcefully, for emphasis. The note jumps out of the speakers at you. On the 300.2 this note is dynamic but seems somehow truncated or muted; not natural sounding. On the ARC VT100 MKII this note has much better tone, sounds more natural and like a real piano. The note seems to decay forever in the soundstage. Just one example.
I liked the ARC 300.2 amp. It's dynamic, and a great sounding amp. I believe that the designers of Class D amps will continue to refine their designs and these amps will get better over time. Someone needs to figure out how a Class D amplifier's output filters interact with speaker loads across a broad frequency spectrum and we might see even better sounding Class D amps. For now, I like the natural sound of the ARC VT100 MKII so I'll stick with glowing glass.
I have never heard the ARC, but it's a Tripath-based design isn't it?
Yes. It uses Tripath chipset.
Note that there are at least 20 Tripath class D modules/chipsets. Characterizing an amp as "Tripath" alone doesn't tell you much, although the ARC sounds different enough from non-Tripath designs that you can't help but think Tripath/ARC are doing something different in this particular design.
I can really appreciate the comparison with the VT100. Do you remember what the VT100 cost when new?
According to the Audio Research database, the price for this amp was $4,995 upon introduction in 1998, and increased to $5,995 on 05 February 2001. See this page:
http://www.arcdb.ws/VT100/VT100.html
I've only heard the VT100 in dealer showrooms and at audio shows, and have not enjoyed the sound. The 6922 frame-grid triode is notoriously harsh for an audio vacuum tube, and this may be why ARC replaced it with the 6H30 in the MkIII version. If the MkII VT100 sounds better than the ARC switching amp, then the ARC switching amp is seriously flawed.
I have no experience with the VT100, but I think it is interesting that two things are often happening:
1. Class D amps are compared with more expensive amps to explain their limitations (in this case a 100 wpc amp that cost 50% more than the 300.2 five years ago)
2. Class D amps are, correctly I think, criticized for imperfect treble performance, but usually with little mention of the advantaged performance of class D
I can appreciate the comparision above with the VT 100 because it starts by mentioning the dynamic performance of the 300.2.
I can't speak to whether the treble from the ARC switching amp is better or worse than the VT100 because I have not heard that switching amp. I do know that my Gilmore Audio Raptors give me the best treble I've heard anywhere with my Magnepan MG-20s, and the performance only gets better as I find and remove sources of electrical noise in my house.
RF noise from switching power supplies would seem to be the gross problem with many of the other switching amp designs in the market. Many of them have the power supply on the same circuit board as the amplifier. I can't see how the designer could reduce the RF noise to the point of a good linear amp with such a choice.
Therefore, I believe the reported problem with treble in the present crop of switching designs is due to design oversights and is not inherent in the technology. It is easier to overcome this problem with intelligent design than it is to overcome the problems of microphonics in tubes or self-modulated bandwidths in transistors used in linear amps. Very clever designs can ameliorate these problems, but they cannot be eliminated. Switching amps will eventually out-perform all linear designs.
You may be right about Class D flaws being relatively simple engineering mistakes. That said, the 300.2 has a traditional, transformer-based power supply, but I'd still say its treble isn't perfect (when compared with designs at 3-20X the price). And I still think the 300.2 is a great amp from a musicality standpoint.
Well, I am wrapping up an extended audition of the Raptors. I had a pair for a bit over a week. I did about three nights of extended listening and had a couple of friends over to listen as well. So, of course take my comments from the perspective of one set of ears and one system that may or may not be an ideal match for these amps.
They are very good amps for the money and they are free of most of the problems associated with digital amps.
They do not have any kind of high-frequency hijinks. No treble distortions, whiteness, graininess, bumps in frequency etc. They do cover all the treble range, cymbals having a nice clarity. But they are slightly dark sounding (which is always a preferable leaning with solid state of any stripe IMHO). You do hear recording venure air and information, but there is also a sense that the last bit is missing from the picture.
The midrange is very neutral and well fleshed out. Images have weight and their own natural body. Many D-amps have been missing this. I can hear no coloration of the midrange at all. In fact this amp is more neutral than my reference overall.
The bass is tight, tuneful and prodigious. It's a bit too tight for my taste on my speakers (every amp/speaker combination will act differently in this regard). Which is directly connected with the excellent damping factor of the amps. I think the Nuforces had the best bass I have had from my system, and the Raptors don't quite hit that mark on my speakers.
One of the things you notice about the Raptors right away is the neutrality and the percieved transparency. I particularly liked them on big orchestral pieces, where it played crescendos slightly louder and with less strain than my reference (the Raptor has 6 times the power rating of my reference).
Soundstage and imaging is excellent, being wider than my reference, but not as deep.
One of the people over at my house was the local Shindo dealer, who is the ultimate tube/analog devotee. He has not heard a D-amp that had acceptable sound. Playing various vinyl selections from classic blues to rock we really enjoyed the Raptors. He commented that with a really good system, it's hard to focus on the audio. So he was impressed with the Raptors, and has finally heard a D-amp that sounds good.
You may have read my comments about digital amps in regards to how they don't sound as natural to my ears as a good tube amp. Most of the digital amps I have heard lend a kind of synthetic quality to acoustic instruments. The Raptors do not. But they do simplify the music a bit. My best example is violin. I try to play violin and have a few in my listening room. On the Raptors, in recording after recording, you could hear the strings of the violin, but some of the overtones of the body of the instrument were subdued or missing. I setup comparisons between the amps and my poor violin for two victims. Both came to the conclusion that the tube amps let through more overtones, tones, and expression than the Raptor. This was also evident in piano, voice etc. on acoustic recordings. I did not really notice this when listening exclusively to the Raptors, except on delicate classical pieces where these kind of overtones stand out.
The Raptors did an excellent job on macrodynamics. However, overall they sound a bit reserved. I don't know what to attribute this to, but the music just didn't get up and boogie quite as much as my reference. They always sounded like they were holding back just a little. It could the large damping factor.
Overall however, I thought the Raptors are really great performers for the money, and I am seriously thinking of getting a pair for a second system.
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