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#1
Posted to rec.audio.tech
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Tripath?
Anyone here with firsthand experience of amplifiers
based on Tripath's ICs? For example: http://www.41hz.com/ -- Martin Schöön "Problems worthy of attack show their worth by hitting back." Piet Hein |
#2
Posted to rec.audio.tech
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Tripath?
"Martin "Schöön"" wrote in
message Anyone here with firsthand experience of amplifiers based on Tripath's ICs? Yes. IME, worse then mediocre. |
#3
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Tripath?
Martin Schöön wrote: Anyone here with firsthand experience of amplifiers based on Tripath's ICs? Sort of ages back. I was considering using them for our products. Why do you ask ? Graham |
#4
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Tripath?
"Martin "Schöön"" wrote in message ... Anyone here with firsthand experience of amplifiers based on Tripath's ICs? **Yep. They're expensive, REALLY poor performing, unreliable POS. They were a con-job from day one. Trevor Wilson |
#5
Posted to rec.audio.tech
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Tripath?
Martin "Schöön" wrote:
Anyone here with firsthand experience of amplifiers based on Tripath's ICs? For example: http://www.41hz.com/ Yes - I purchased one from www.cadaudio.dk that didn't work, and have had years of coresspondence (pretty much one-sided, not many replies) and no resolution. But that's not Tripath's fault ! geoff |
#7
Posted to rec.audio.tech
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Tripath?
"Kevin McMurtrie" wrote in
message In article , (Martin Schöön) wrote: Anyone here with firsthand experience of amplifiers based on Tripath's ICs? For example: http://www.41hz.com/ I haven't used them personally but I read their sample schematics and docs. They're not audiophile but they're nothing to worry about for the MP3 generation. Their primary feature is enabling ultra-compact amplifiers with low complexity and cost. The irony is that the Tripath amp I have, which is based on their TA2020 chip and a few discrete transistors, is neither smaller nor cheaper, nor simpler than a comparable linear amp would be. The parts count and size is inflated by the low pass filter on the outputs. The heat sinks are tiny, but everything else is pretty much regular-sized. The output filter network is almost half the amp, and is loaded with inductors that were no doubt not free. |
#8
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Tripath?
Arny Krueger wrote: "Kevin McMurtrie" wrote (Martin Schöön) wrote: Anyone here with firsthand experience of amplifiers based on Tripath's ICs? For example: http://www.41hz.com/ I haven't used them personally but I read their sample schematics and docs. They're not audiophile but they're nothing to worry about for the MP3 generation. Their primary feature is enabling ultra-compact amplifiers with low complexity and cost. The irony is that the Tripath amp I have, which is based on their TA2020 chip and a few discrete transistors, is neither smaller nor cheaper, nor simpler than a comparable linear amp would be. The parts count and size is inflated by the low pass filter on the outputs. The heat sinks are tiny, but everything else is pretty much regular-sized. The output filter network is almost half the amp, and is loaded with inductors that were no doubt not free. Sure, but it'll use less power than a linear amp. That's a main reason why switching amps have become popular, although I note that the supposed popularity seems to have waned recently. I was SERIOUSLY considering Tripath for a new product back around 2000 but I wasn't impressed by the demonstration where I wanted to run it at its full power sine wave rating but the rep said the demo amp wasn't designed to cope with that ! What the hell were they thinking of ? Graham |
#9
Posted to rec.audio.tech
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Tripath?
"Eeyore" wrote in
message Arny Krueger wrote: "Kevin McMurtrie" wrote (Martin Schöön) wrote: Anyone here with firsthand experience of amplifiers based on Tripath's ICs? For example: http://www.41hz.com/ I haven't used them personally but I read their sample schematics and docs. They're not audiophile but they're nothing to worry about for the MP3 generation. Their primary feature is enabling ultra-compact amplifiers with low complexity and cost. The irony is that the Tripath amp I have, which is based on their TA2020 chip and a few discrete transistors, is neither smaller nor cheaper, nor simpler than a comparable linear amp would be. The parts count and size is inflated by the low pass filter on the outputs. The heat sinks are tiny, but everything else is pretty much regular-sized. The output filter network is almost half the amp, and is loaded with inductors that were no doubt not free. Sure, but it'll use less power than a linear amp. In most office and home applications that's not an issue. Even in mobile applications like a car, there's plenty of power available. That's a main reason why switching amps have become popular, although I note that the supposed popularity seems to have waned recently. I see using them in cell phones. I don't think they have gone anywhere with portable music players. I was SERIOUSLY considering Tripath for a new product back around 2000 but I wasn't impressed by the demonstration where I wanted to run it at its full power sine wave rating The Tripath module I have was rated well optimistically. but the rep said the demo amp wasn't designed to cope with that ! What the hell were they thinking of ? The problem I saw was that ignoring your first nasty bit of news, the amps had a lot of nonlinear distortion related to the switching, well below clipping. I mean like 2-3 dB below clipping. They also had a relatively high output impedance in the top half of the audio band. |
#10
Posted to rec.audio.tech
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Tripath?
In message , Kevin
McMurtrie writes In article , (Martin Schöön) wrote: Anyone here with firsthand experience of amplifiers based on Tripath's ICs? For example: http://www.41hz.com/ I haven't used them personally but I read their sample schematics and docs. They're not audiophile but they're nothing to worry about for the MP3 generation. Their primary feature is enabling ultra-compact amplifiers with low complexity and cost. The corporate web site appears to have been abandoned in late 2006. Most of the products that have documentation are marked as obsolete. The last PR entries are about lawsuit settlements. They weren't really anything new in the Class-D world. If you want to buy Class-D modules with real quality performance I suggest you have a look at the UCD range on the Hypex website. -- Chris Morriss |
#11
Posted to rec.audio.tech
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Tripath?
In message , Arny Krueger
writes Snipped... The problem I saw was that ignoring your first nasty bit of news, the amps had a lot of nonlinear distortion related to the switching, well below clipping. I mean like 2-3 dB below clipping. They also had a relatively high output impedance in the top half of the audio band. The Tripath design took its NFB from before the output filter, so the rising impedance of the output inductor became important. The UCD design is one of the few that take the NFB after the output filter and use the phase shift of the filter (together with other components) to set the self-oscillating frequency. For those who are interested, it's worth reading the paper that Bruno Putzeys (then of Philips) presented at an AES conference a few years ago. It details the background behind the UCD design. -- Chris Morriss |
#12
Posted to rec.audio.tech
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Tripath?
In article ,
"Arny Krueger" wrote: "Eeyore" wrote in message [ snip ] Sure, but it'll use less power than a linear amp. In most office and home applications that's not an issue. Even in mobile applications like a car, there's plenty of power available. There's never enough power and cooling available! Car audio is especially problematic because 12V wiring is expensive and there's no room for cooling. My Roku Radio uses a Class D amp so the entire enclosure can be a tuned woofer cabinet without overheating. Small electronics use Class D so that the audio amp fits on the main PCB without extra copper layers for cooling. Home theater also seems to have reached the point where the Class D electronics are cheaper than the bulk. Half of the new models I saw this Christmas were Class D. -- I don't read Google's spam. Reply with another service. |
#13
Posted to rec.audio.tech
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Tripath?
"Kevin McMurtrie" wrote in
message In article , "Arny Krueger" wrote: "Eeyore" wrote in message [ snip ] Sure, but it'll use less power than a linear amp. In most office and home applications that's not an issue. Even in mobile applications like a car, there's plenty of power available. There's never enough power and cooling available! It's a matter of perspective. For example, in a car you have to deal with heat from the exterior in the summer. Such tiny amounts of heat that the car radio makes is relatively small. Car audio is especially problematic because 12V wiring is expensive and there's no room for cooling. Car audio as done by large OEMs is no mystery to me, if you know where I live. I have a number of close friends in the business, and I've been in a number of engineering shops that specialize in car audio, both OEM and supplier. My Roku Radio uses a Class D amp so the entire enclosure can be a tuned woofer cabinet without overheating. Small electronics use Class D so that the audio amp fits on the main PCB without extra copper layers for cooling. Historically, class D has been a no-no for OEMs because of EMI concerns. That is changing about right now, as switchmode equipment with really low EMI is becoming available. Home theater also seems to have reached the point where the Class D electronics are cheaper than the bulk. I haven't been watching that market very hard lately, as I mostly work with SR and recording these days. Half of the new models I saw this Christmas were Class D. Consumer audio is heavily driven by costs. One benefit of switchmode equipment is that one model can work efficiently with all the different kinds of AC power that is used worldwide. |
#14
Posted to rec.audio.tech
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Tripath?
Arny Krueger wrote: The problem I saw was that ...... the amps had a lot of nonlinear distortion related to the switching, well below clipping. I mean like 2-3 dB below clipping. Yes. For a while they had an application note that explained that. It looked like 'fuzz' on the output waveform that's reminiscent of instability in linear designs. It wasn't a disaster from a spec viewepoint since it was all beyond the audio range but it didn't give one confidence. Graham |
#15
Posted to rec.audio.tech
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Tripath?
Chris Morriss writes:
In message , Arny Krueger writes Snipped... The problem I saw was that ignoring your first nasty bit of news, the amps had a lot of nonlinear distortion related to the switching, well below clipping. I mean like 2-3 dB below clipping. They also had a relatively high output impedance in the top half of the audio band. The Tripath design took its NFB from before the output filter, so the rising impedance of the output inductor became important. The UCD design is one of the few that take the NFB after the output filter and use the phase shift of the filter (together with other components) to set the self-oscillating frequency. For those who are interested, it's worth reading the paper that Bruno Putzeys (then of Philips) presented at an AES conference a few years ago. It details the background behind the UCD design. -- Chris Morriss Interesting. I get 37 hits on Bruno Putzeys on AES' web. Do you remember which year or at what location (since that is usually how one remembers at which symposium one did or heard what)? -- Martin Schöön "Problems worthy of attack prove their worth by hitting back" Piet Hein |
#16
Posted to rec.audio.tech
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Tripath?
In message , François Yves
Le Gal writes On 17 Jan 2008 09:02:01 +0100, (Schöön Martin) wrote: Interesting. I get 37 hits on Bruno Putzeys on AES' web. Do you remember which year or at what location (since that is usually how one remembers at which symposium one did or heard what)? Try http://www.ciaudio.com/ucd_aes.pdf That's the one, thanks Francois. I remember when I saw that paper for the first time. My first thought when I saw a self-oscillating class-D amplifier based on a phase-shift oscillator using the output filter has the dominant phase-shift element was: 'How simple, I really wish I had thought of that'! Sadly I hadn't :-( -- Chris Morriss |
#17
Posted to rec.audio.tech
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Tripath?
François Yves Le Gal writes:
On 17 Jan 2008 09:02:01 +0100, (Schöön Martin) wrote: Interesting. I get 37 hits on Bruno Putzeys on AES' web. Do you remember which year or at what location (since that is usually how one remembers at which symposium one did or heard what)? Try http://www.ciaudio.com/ucd_aes.pdf Thanks, I'll study it imminently. I have also found quite a bit of literature on International Rectifier's web. -- Martin Schöön "Problems worthy of attack show their worth by hitting back." Piet Hein |
#18
Posted to rec.audio.tech
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Tripath?
In message , Martin Schöön
writes François Yves Le Gal writes: On 17 Jan 2008 09:02:01 +0100, (Schöön Martin) wrote: Interesting. I get 37 hits on Bruno Putzeys on AES' web. Do you remember which year or at what location (since that is usually how one remembers at which symposium one did or heard what)? Try http://www.ciaudio.com/ucd_aes.pdf Thanks, I'll study it imminently. I have also found quite a bit of literature on International Rectifier's web. The IR AMP5 design is quite nice, but it is a sigma-delta self-oscillating design using the controlling feedback signal from before the output filter. This gives very low distortion, but the Zout of the reconstruction filter is in series with the loudspeaker and its crossover network. I've measured errors in the amplifier output response of over 4dB above 10kHz when feeding speakers whose crossover networks present a very reactive load. My professional interest is in the design of class-D amplifiers feeding step-up transformers for 100V line PA systems. The load-invariant property of the UCD technique copes admirably with the enormous variation of load impedance that these amplifiers see. (Dependant on the number of speakers connected to the amp output and their power tapping). -- Chris Morriss |
#19
Posted to rec.audio.tech
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Tripath?
(Martin Schöön) writes:
Try http://www.ciaudio.com/ucd_aes.pdf Thanks, I'll study it imminently. I have also found quite a bit of literature on International Rectifier's web. This Saturday was pretty gloomy weather-wise so I spent some time class-D-surfing. Here is something I found (you have to scroll down to the middle of the page): http://www.hificritic.co.uk/scene/news.aspx Comments? Thoughts? -- Martin Schöön "Problems worthy of attack show their worth by hitting back." Piet Hein |
#20
Posted to rec.audio.tech
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Tripath?
"Martin "Schöön"" wrote in
message (Martin Schöön) writes: Try http://www.ciaudio.com/ucd_aes.pdf Thanks, I'll study it imminently. I have also found quite a bit of literature on International Rectifier's web. This Saturday was pretty gloomy weather-wise so I spent some time class-D-surfing. Here is something I found (you have to scroll down to the middle of the page): http://www.hificritic.co.uk/scene/news.aspx Summarized as follows: " From a technical viewpoint it now seems permissible to: 1 Feed broad-band radio frequency noise into the power supply outlets 2 Feed broad-band radio frequency noise to the line and ground connections 3 Drive broad-band radio frequency noise into the speaker cables and loudspeaker. (up to 500MHz with up to 2V generally measured at around 50kHz) 4 Define the output impedance using a significant passive filter, with a result which varies with frequency and is dependant on speaker loading 5 Allow the amplifier to be marginally or completely unstable with either high or open circuit output loading 6 Employ soft compressor clipping circuits prior to full power clipping to prevent feedback saturation. 7 Employ high order negative feedback to improve in-band distortion figures and low frequency output impedance. 8 Specify numerically high damping factor at low frequencies and claim that this guarantees fine bass.(regardless of the interface to the loudspeaker or any other property of the circuit) 9 Use steep low pass filters to limit the upper high frequency range, partially negating the purpose of wider bandwidth, source material e.g. SACD, while the resulting filter phase shifts may be audible in the working band. 10 Have low bandwidth input circuits which are highly susceptible to stray high frequency input signals, including upper band noise shaper signals and DAC artefacts. The result is poorer treble sound quality and measurable distortion. 11 Have power output circuits with poor high frequency resolution resulting in high levels of intermodulation products at the high frequency end of the spectrum 12 Have 'sampler' noise-shaped noise floors. The latter vary dynamically with the level, frequency and complexity of the input signals. 13 Have comparatively small power supply reservoirs, in the light of their low frequency output current potential and available power. 14 Have thermal dissipation limitations due to the small power module size which means that dynamic variations are present in the performance with time and temperature. 15 To protect the fragile output stages all kinds of pre-clip and aggressive fold back protection regimes are included which are frequency dependant and are also programmed for duty cycle. Unexpected sound quality variations may result when operated at higher powers and with more difficult loads. 16 Operate at an equivalent sample rate which is insufficient for good resolution above 7kHz. DSD, 1 bit pulse-width modulation operates at 2.4MHz, nearly ten times the usual rate presently used in Class D amplifiers. 16 Deliver high, constant DC voltages (up to 70V) relative to local ground at the output terminals and hence also the loudspeaker connections and cable. (not of course between the +,- terminals as both of these are at the same dc potential) 17 Use a high feedback switch mode power supply which has to react dynamically to the power draw variations of the power amplifier with the music programme. Generally these are designed for supplying dc and are demonstrably imperfect faced with near audio bandwidth loading at a wide dynamic range. Essentially the supply constitutes a form of audio amplifier yet it was never intended to be optimised for such duty. " I would rate some of these concerns as being valid, and some as being questionable. |
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