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Martin Schöön Martin Schöön is offline
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Default 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
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Arny Krueger Arny Krueger is offline
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"Martin "Schöön"" wrote in
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Anyone here with firsthand experience of amplifiers
based on Tripath's ICs?


Yes. IME, worse then mediocre.


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Eeyore Eeyore is offline
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Default 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

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Trevor Wilson[_2_] Trevor Wilson[_2_] is offline
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Default 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


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Default 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




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Kevin McMurtrie Kevin McMurtrie is offline
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Default Tripath?

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.

--
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Arny Krueger Arny Krueger is offline
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Default 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.


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Eeyore Eeyore is offline
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Default 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


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Default 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.


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Chris Morriss Chris Morriss is offline
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Default 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


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Chris Morriss Chris Morriss is offline
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Default 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
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Kevin McMurtrie Kevin McMurtrie is offline
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Default 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.

--
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Arny Krueger Arny Krueger is offline
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Default 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.


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Default 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

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Schöön Martin Schöön Martin is offline
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Default 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


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Chris Morriss Chris Morriss is offline
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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
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Martin Schöön Martin Schöön is offline
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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
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Chris Morriss Chris Morriss is offline
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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
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Martin Schöön Martin Schöön is offline
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Default 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
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Arny Krueger Arny Krueger is offline
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Default 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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