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#1
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Power Amplifers - The high end and new technologies?
Greetings,
At one time, I was immersed in high-end audio, but over the last 10 years, my time has been consumed by other interests. Yesterday, my beloved Sumo Andromeda III power amplifer blew the left channel rail fuses on power-up. I replaced the fuses, which again blew immediately when the amplifier was powered on. I contacted James Bongiorno, who was kind enough to repond quickly with the bad news. The MOSFET design of this amplifier evidently isn't run-of-the-mill, so finding someone competent to fix it would be tough. More difficult would be finding parts, so I've resigned myself to the fact that my Andromeda III may have to be laid to rest.... Being away from this hobby for such a long time has left me in the dark when it comes to new technologies in amplification. The Andromeda III was a refreshing product in the world of high-end; high-end performance and power, without the astronomical prices that seem to plague the hobby nowday's. I'm not one of the fortunate few than can afford a Pass, Levinson or Rowland product. In need of a replacement, I started browsing the net to see what was available. I see the Aragon's, Krell's, Classe's, etc. still aboud, but I was intrigued by a product from Dutch company Acoustic Reality. Their eAR amplifier evidently uses digital technology based on something called ICEpower. I have no clue what this is, so I was wondering if anyone was familiar with this technology. Does it have sufficient current to drive complex loads? I recall a friend mating a Carver magnetic field amplifer with Martin Logan Sequel II's, and the load killed the Carver amp, despite it's claimed power of 500/wpc. I wonder about something that can be so small, yet deliver 1000/wpc. Also, what about so-called "commercial" amplifiers, from companies such as Crown? I had Crown equipment years ago, and at the time, it was considered "high-end." How does commercial equipment differ from the likes of a Krell? Is it simply 5" faceplates made of titanium and CAD designed heat sinks? Cutting to the chase, I need a new amplifier to mate with my Sonic Frontiers SFL-1 pre-amp, powering Von Schweikert VR-4's in a very large room. The Sumo's 240/wpc fit the bill, so something in this power range is needed. Any input/advice/direction would be greatly appreciated!!!! I guess I'm officially back in the hobby!! Thanks! |
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#2
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Seadweller wrote:
Greetings, snip Cutting to the chase, I need a new amplifier to mate with my Sonic Frontiers SFL-1 pre-amp, powering Von Schweikert VR-4's in a very large room. The Sumo's 240/wpc fit the bill, so something in this power range is needed. Any input/advice/direction would be greatly appreciated!!!! I guess I'm officially back in the hobby!! I have used the Counterpoint SA220 with these speakers, but like your amp, parts are hard to come by and if it blows, well, good luck. It can be updated by the original designer, but I am not willing to pay the cost. So, I looked for a solid state amp to fit the bill of driving these speakers. I found a used Parasound HCA2200 MkII. Wonderful! |
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#3
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"Seadweller" wrote in message
... Greetings, At one time, I was immersed in high-end audio, but over the last 10 years, my time has been consumed by other interests. Yesterday, my beloved Sumo Andromeda III power amplifer blew the left channel rail fuses on power-up. I replaced the fuses, which again blew immediately when the amplifier was powered on. I contacted James Bongiorno, who was kind enough to repond quickly with the bad news. The MOSFET design of this amplifier evidently isn't run-of-the-mill, so finding someone competent to fix it would be tough. More difficult would be finding parts, so I've resigned myself to the fact that my Andromeda III may have to be laid to rest.... Being away from this hobby for such a long time has left me in the dark when it comes to new technologies in amplification. The Andromeda III was a refreshing product in the world of high-end; high-end performance and power, without the astronomical prices that seem to plague the hobby nowday's. I'm not one of the fortunate few than can afford a Pass, Levinson or Rowland product. In need of a replacement, I started browsing the net to see what was available. I see the Aragon's, Krell's, Classe's, etc. still aboud, but I was intrigued by a product from Dutch company Acoustic Reality. Their eAR amplifier evidently uses digital technology based on something called ICEpower. I have no clue what this is, so I was wondering if anyone was familiar with this technology. Does it have sufficient current to drive complex loads? I recall a friend mating a Carver magnetic field amplifer with Martin Logan Sequel II's, and the load killed the Carver amp, despite it's claimed power of 500/wpc. I wonder about something that can be so small, yet deliver 1000/wpc. Also, what about so-called "commercial" amplifiers, from companies such as Crown? I had Crown equipment years ago, and at the time, it was considered "high-end." How does commercial equipment differ from the likes of a Krell? Is it simply 5" faceplates made of titanium and CAD designed heat sinks? Cutting to the chase, I need a new amplifier to mate with my Sonic Frontiers SFL-1 pre-amp, powering Von Schweikert VR-4's in a very large room. The Sumo's 240/wpc fit the bill, so something in this power range is needed. Any input/advice/direction would be greatly appreciated!!!! I guess I'm officially back in the hobby!! The best price/performance ratio I know of in a good sounding high powered amp is the Outlaw Audio M200 monoblock, sold on the web. They are 200w (8 ohm) and 300w (4 ohm) power amps with excellent, delicate sound when called for and balls-to-the-wall power when called for. They are slim, rack mount size and weigh 18 lbs each. They cost $299 ordered directly from Outlaw, with a 30 day money-back guarantee. They also come up occasionally on Audiogon used and sell quickly. www.outlawaudio.com |
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#4
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"Cutting to the chase, I need a new amplifier to mate with my Sonic
Frontiers SFL-1 pre-amp, powering Von Schweikert VR-4's in a very large room. The Sumo's 240/wpc fit the bill, so something in this power range is needed." Crown and other pro amp makers fit the bill nicely, you will be surprised at how much prices have fallen on audio amps that delever full value for price. Several of the pro amp companies have digital amps and some come with dsp frontends that allow considerable control over making it work best in your listening space. They are small because the huge brute force power supplies used to drive complex loads can now be realized with new technology. |
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#5
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On 17 May 2005 02:34:54 GMT, TonyP
wrote: Seadweller wrote: Cutting to the chase, I need a new amplifier to mate with my Sonic Frontiers SFL-1 pre-amp, powering Von Schweikert VR-4's in a very large room. The Sumo's 240/wpc fit the bill, so something in this power range is needed. Any input/advice/direction would be greatly appreciated!!!! I guess I'm officially back in the hobby!! I have used the Counterpoint SA220 with these speakers, but like your amp, parts are hard to come by and if it blows, well, good luck. It can be updated by the original designer, but I am not willing to pay the cost. So, I looked for a solid state amp to fit the bill of driving these speakers. I found a used Parasound HCA2200 MkII. Wonderful! I support the above recommendation, and would add the Bryston 4B SST. Lots of good, clean power, and a 20-year warranty. More than adequate for the excellent VR-4. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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#6
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TonyP wrote:
Seadweller wrote: Greetings, snip Cutting to the chase, I need a new amplifier to mate with my Sonic Frontiers SFL-1 pre-amp, powering Von Schweikert VR-4's in a very large room. The Sumo's 240/wpc fit the bill, so something in this power range is needed. Any input/advice/direction would be greatly appreciated!!!! I guess I'm officially back in the hobby!! I have used the Counterpoint SA220 with these speakers, but like your amp, parts are hard to come by and if it blows, well, good luck. It can be updated by the original designer, but I am not willing to pay the cost. So, I looked for a solid state amp to fit the bill of driving these speakers. I found a used Parasound HCA2200 MkII. Wonderful! Odyssey is a company worth looking into. Their Extreme monos would fit the bill for under $2000 used and Audiogon has a couple of pairs for sale right now. -JC -JC |
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#7
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Seadweller wrote:
Also, what about so-called "commercial" amplifiers, from companies such as Crown? I had Crown equipment years ago, and at the time, it was considered "high-end." How does commercial equipment differ from the likes of a Krell? Is it simply 5" faceplates made of titanium and CAD designed heat sinks? I've not listened carefully to Krell, so I can't speak to how good they are or are not. But as you've asked about commercial amps, I've been running some of the newer Hafler pro-grade amps and I've been very pleased with them. They are MOSFET amps and have that characteristic MOSFET sound, which I personally like. Pro-grade amps are engineered to withstand abuse, both from bad signals, difficult loads and poor physical handling, in addition to poor environmental conditions. They also are typically made to rack mount. So whatever load you throw at 'em, they should be able to handle it. One major flaw with pro-grade amps is that the great majority of them are fan cooled, which means noisy. VERY noisy. The Hafler amps are mostly air cooled and have pretty sizeable heat sinks as a result. I'm very happy with mine and one nice thing about them is that they cost significantly less than your typical high-end, Krell or Rowland Research amp. Try to find a dealer that will let you try out a Hafler amp before buying it. Or alternately, find one that will let you purchase it with a right to return it within 14 days or such. Hafler is a solid product. Russ |
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#8
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Russ Button wrote:
Seadweller wrote: But as you've asked about commercial amps, I've been running some of the newer Hafler pro-grade amps and I've been very pleased with them. They are MOSFET amps and have that characteristic MOSFET sound, which I personally like. Now I have read your idea about the Mosfet amp or sound a couple of times. What is the paticular "sound" of a Mosfet amp? How is it different from a BJT amp? Could you cite some references (other than anecdotical tales)? Is it possible to measure this characteristic and which kind of measurement is it? -- ciao Ban Bordighera, Italy |
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#9
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Ban wrote:
Russ Button wrote: Seadweller wrote: But as you've asked about commercial amps, I've been running some of the newer Hafler pro-grade amps and I've been very pleased with them. They are MOSFET amps and have that characteristic MOSFET sound, which I personally like. Now I have read your idea about the Mosfet amp or sound a couple of times. What is the paticular "sound" of a Mosfet amp? How is it different from a BJT amp? Could you cite some references (other than anecdotical tales)? Is it possible to measure this characteristic and which kind of measurement is it? I have no idea if you can measure it. It's my understanding that MOSFET transistors, like tubes, distort on even order harmonics, rather than odd order harmonics like your typical solid state amp. That being the case, they tend to have a rather tube-like sonic quality. I owned a B&K ST-140 amp for about 16 years, which was a relatively early MOSFET amp. The Hafler MOSFET amps I'm running sound very similar. But like everything else you read here, you have to go listen for yourself and make up your own mind. Anecdotal tales are really a reflection of personal experiences, not a scientific sampling. As I said, I like what I personnally perceive to be a sound characteristic of MOSFET amps. You have to go listen for yourself. Russ |
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#10
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Russ Button wrote:
I have no idea if you can measure it. It's my understanding that MOSFET transistors, like tubes, distort on even order harmonics, rather than odd order harmonics like your typical solid state amp. Sure you can measure such differences. It's a myth that MOSFETS are more tube like than BJT's. When optimally biased, BJT's produce about he same spectra of byproducts as MOSFETS, and actually produce less in quantity. (better linearity) BJT's also have significantly lower output impedance - an important advantage in amplifier output stages. Also, in general, MOSFET P channel devices are a much worse match to the N channel devices than with bipolar devices, which decreases linearity in complementary circuits. The main advantage of MOSFETS is better high frequency bandwidth, (somewhat mitigated by their high input capacitance) and the potential for somewhat greater reliability, due to the negative temperature coefficient, which makes thermal runaway less likely. But BJT's implemented with proper design techniques don't really have that problem in practice. IOW, cheap and dirty MOSFET output stages are usually more reliable than that counterpart in BJT's. |
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#11
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Ban wrote:
Russ Button wrote: Seadweller wrote: But as you've asked about commercial amps, I've been running some of the newer Hafler pro-grade amps and I've been very pleased with them. They are MOSFET amps and have that characteristic MOSFET sound, which I personally like. Now I have read your idea about the Mosfet amp or sound a couple of times. What is the paticular "sound" of a Mosfet amp? How is it different from a BJT amp? Could you cite some references (other than anecdotical tales)? Is it possible to measure this characteristic and which kind of measurement is it? Two factors here in the main: Mosfets tend to clip "soft" compared to bipolars which clip "hard". You do run into clipping more often than you may think with the average =90dB/1w/1m speaker and even a 200 watt amp. Secondly, the Hafler amps use a composite current/voltage feedback method and iirc, current amplification inside the amp circuit, so the circuit itself is slightly different than the typical amp - I think they call it "transimpedance" or used to do so. Mosfets do tend to have a different spectrum of harmonics compared to bipolars, although in any push-pull design "second harmonics" are going to be surpressed anyhow. All amplifying devices have a different spectra of harmonics both in terms of amplitude and order... which is part of the reason that some people really like the way triodes sound. :- ) In addition a typical Mosfet amp is biased somewhat into class A, moreso than the typical bipolar amp - although there are exceptions. Early on there was what was called "mosfet haze" which was due to poor circuit design, not some aspect of the Mosfet itself. Merely having Mosfets in a circuit does not assure you of good quality sound or anything else. _-_-bear |
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#12
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Very informative! A lot of stuff here I didn't know.
Thank you! Russ BEAR wrote: Two factors here in the main: Mosfets tend to clip "soft" compared to bipolars which clip "hard". You do run into clipping more often than you may think with the average =90dB/1w/1m speaker and even a 200 watt amp. Secondly, the Hafler amps use a composite current/voltage feedback method and iirc, current amplification inside the amp circuit, so the circuit itself is slightly different than the typical amp - I think they call it "transimpedance" or used to do so. Mosfets do tend to have a different spectrum of harmonics compared to bipolars, although in any push-pull design "second harmonics" are going to be surpressed anyhow. All amplifying devices have a different spectra of harmonics both in terms of amplitude and order... which is part of the reason that some people really like the way triodes sound. :- ) In addition a typical Mosfet amp is biased somewhat into class A, moreso than the typical bipolar amp - although there are exceptions. Early on there was what was called "mosfet haze" which was due to poor circuit design, not some aspect of the Mosfet itself. Merely having Mosfets in a circuit does not assure you of good quality sound or anything else. _-_-bear |
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