Stereophile did a review of the HCA-2. It got quite good critics from the sonic point of view (which is always subjective of course). But the measurements were not that impressive at all.
http://www.stereophile.com/amplificationreviews/729/
I also doubt that it has a double feedback loop when looking at its specs. Furthermore, most topologies taking feedback from the output filter show less load dependancy than this one (wasn't one of their claims that it is less load dependant than all the other class-d amps ?).
It shows exactly the same load dependancy (in terms of frequency response) like a circuit that I call "the simple tweak". I use this expression for the most simple kind of feedback-takeoff from the output filter, that can be implemented with carrier-based class-d amps.
I have seen pictures of its inside and it is hard to tell much more than that it actually has a nice build-quality.
Another new class-d amp has been presented by Onkyo. It seems that it takes feedback before the output filter. It also got quite good reviews even though its mesurements werent overwhelming.
I wonder how anyone can still build class-d amps without overall feedback. It isn't that complicated after all. You don't even have to rely on existing patents. Simply use known feedback control techniques.
As I already said, class-d amps have the potential to sound good even when they don't look that exceptional on paper.
regards
Charles
http://www.stereophile.com/amplificationreviews/729/
I also doubt that it has a double feedback loop when looking at its specs. Furthermore, most topologies taking feedback from the output filter show less load dependancy than this one (wasn't one of their claims that it is less load dependant than all the other class-d amps ?).
It shows exactly the same load dependancy (in terms of frequency response) like a circuit that I call "the simple tweak". I use this expression for the most simple kind of feedback-takeoff from the output filter, that can be implemented with carrier-based class-d amps.
I have seen pictures of its inside and it is hard to tell much more than that it actually has a nice build-quality.
Another new class-d amp has been presented by Onkyo. It seems that it takes feedback before the output filter. It also got quite good reviews even though its mesurements werent overwhelming.
I wonder how anyone can still build class-d amps without overall feedback. It isn't that complicated after all. You don't even have to rely on existing patents. Simply use known feedback control techniques.
As I already said, class-d amps have the potential to sound good even when they don't look that exceptional on paper.
regards
Charles
When I read the magazine reviews etc. I remember why I despise the Hi-FI industry so much.
Sure the front panel of the HCA-2 is very nice - it is after all an $1695 unit – but have a quick read of the operators manual: -
“A very low fuzz/crackling noise audible within 1-2 feet from the speakers is the HCA-2 own “self” noise and is normal”
Answers whey there’s no S/N specifications – 0.2% THD, self noise, Gentlemen are we really trying here?
Apparently, the designer developed the Harris Class D Eval. boards – I guess it explains all.
John
Hey – I’m in a real foul mood today – wonder why?
Sure the front panel of the HCA-2 is very nice - it is after all an $1695 unit – but have a quick read of the operators manual: -
“A very low fuzz/crackling noise audible within 1-2 feet from the speakers is the HCA-2 own “self” noise and is normal”
Answers whey there’s no S/N specifications – 0.2% THD, self noise, Gentlemen are we really trying here?
Apparently, the designer developed the Harris Class D Eval. boards – I guess it explains all.
John
Hey – I’m in a real foul mood today – wonder why?
Hi,
Actually while I did email them for a laugh, it seems they already have a spy in our midst, paulmc CEO of bsaudio, has posted about their hummbuster before, perhaps he'd be so kind as to jump in, it would be interesting.
Hopefully he's been reading this already and taking notes for what not to do in the future (we like alot more cold hard facts and alot less bs and hype). Maybe you'd be interested in retro fitting it with a UCD module from Hypex 🙂 C'mon Paul I know you're out there
Regards,
Chris
Actually while I did email them for a laugh, it seems they already have a spy in our midst, paulmc CEO of bsaudio, has posted about their hummbuster before, perhaps he'd be so kind as to jump in, it would be interesting.
Hopefully he's been reading this already and taking notes for what not to do in the future (we like alot more cold hard facts and alot less bs and hype). Maybe you'd be interested in retro fitting it with a UCD module from Hypex 🙂 C'mon Paul I know you're out there
Regards,
Chris
The HCA could very well be an old-fashioned implementation of a carrier based class-d amp. The only thing special about it is probably a "hand-sewn" summing integrator.
Although the specs are not that good it would only be fair to judge it after having heard it.
Regards
Charles
Although the specs are not that good it would only be fair to judge it after having heard it.
Regards
Charles
marketing talk doesn't make a product bad, it creates an aura around it. And that aura you have to like. Or not.
Take Linn. On their site they talk about their products in an ikea-kind-of style. simple, not too much information a customer wouldn't understand anyways. No nonsense (except for the K in all their products, of course 😉)
Now take psaudio. A completely different approach. Beta tester reviews, (semi) technical articles about different technologies, features, benefits, you name it.
Although i personally like the linn-approach better, there are probably more people that like the psaudio approach. Who am i to judge their marketing techniques? Add to that the fact that S/N ratios, damping factors, power ratings, thd+n graphs and whatnot don't say anything about how the amp really sounds!
So, lets quit bugging psaudio (or open another thread for that) and get back to the ucd180.
How big are your transformers, va-rating, voltage etc. How does this influence sound?
What's the psrr of the ucd module? couldn't find that anywhere...
Do I need a state-of-the-art extremely low output impedance psu with a LOT of capacitance etc?
Has anyone tried building a nicely regulated supply for these babies? Or maybe even a (ie OPA549) 'buffered' supply?
Has anyone tried replacing the opamps used?
I have about zip experience with class d amps...
Take Linn. On their site they talk about their products in an ikea-kind-of style. simple, not too much information a customer wouldn't understand anyways. No nonsense (except for the K in all their products, of course 😉)
Now take psaudio. A completely different approach. Beta tester reviews, (semi) technical articles about different technologies, features, benefits, you name it.
Although i personally like the linn-approach better, there are probably more people that like the psaudio approach. Who am i to judge their marketing techniques? Add to that the fact that S/N ratios, damping factors, power ratings, thd+n graphs and whatnot don't say anything about how the amp really sounds!
So, lets quit bugging psaudio (or open another thread for that) and get back to the ucd180.
How big are your transformers, va-rating, voltage etc. How does this influence sound?
What's the psrr of the ucd module? couldn't find that anywhere...
Do I need a state-of-the-art extremely low output impedance psu with a LOT of capacitance etc?
Has anyone tried building a nicely regulated supply for these babies? Or maybe even a (ie OPA549) 'buffered' supply?
Has anyone tried replacing the opamps used?
I have about zip experience with class d amps...
UsrV,
Very nice picture, that's what I love to see!!!!!
Indeed I would check the temperature, because in 4 ohm load and at higher soundlevels the T alone as heatsink will not be sufficient.
What is your powersupply voltage?
Did you already listen to the amps?
To the rest of the guys,
Perhaps we can start a new thread about 'what is currently available in the market on Class-D amplifiers?'
Best regards,
Jan-Peter
www.hypex.nl
Very nice picture, that's what I love to see!!!!!
Indeed I would check the temperature, because in 4 ohm load and at higher soundlevels the T alone as heatsink will not be sufficient.
What is your powersupply voltage?
Did you already listen to the amps?
To the rest of the guys,
Perhaps we can start a new thread about 'what is currently available in the market on Class-D amplifiers?'
Best regards,
Jan-Peter
www.hypex.nl
Jan-Peter said:UsrV,
Very nice picture, that's what I love to see!!!!!
Indeed I would check the temperature, because in 4 ohm load and at higher soundlevels the T alone as heatsink will not be sufficient.
What is your powersupply voltage?
Did you already listen to the amps?
To the rest of the guys,
Perhaps we can start a new thread about 'what is currently available in the market on Class-D amplifiers?'
Best regards,
Jan-Peter
www.hypex.nl
Thanks JP,
See my response to Bruno a bit further down after the picture. Should be fine.
As for supply voltage the limit was 50 V for the module so naturally I chose 49.99.
I'm sad to say that I will be going out of town for a weeks and will not have the time to finish it before then so listening to it will have to wait for 10 days...
UrsV,
Yes indeed I just read you construction, looks indeed ok!
Have a nice trip!
Regards,
Jan-Peter
www.hypex.nl
Yes indeed I just read you construction, looks indeed ok!
Have a nice trip!
Regards,
Jan-Peter
www.hypex.nl
slightly off topic..sorry
Let's look inside caraudio class D amps, and PSaudio creation will not seems so poor anymore. They have, at the moment, typical specs: THD 1-2% (note that's for subwoofer app.!!!), damping factor 100. Noone of these called "simply"("stupid" is more exactly) class D, but only "adapted class D", "advanced" etc! To achieve THD 1%@100W someone use 1Mhz carrier even:
<The Xtant1.1i adds local and global multiple nested feedback loops with premium MOSFETs and
OPAmps for switching stability and audio signal accuracy within the full range spectrum. This
results in an extremely high switching speed—over 1MHz
This enhances the musical reproduction by ensuring the higher frequencies (cymbals and
the like) compliment the entire frequency range to bring new realism to the Class D amplifier
sound experience.
The Audiophile Full Spectrum Class D Technology with Xtant’s attention to detail results in a
Class D amplifier that sounds better than many audiophile Class A/B amplifiers. It exhibits an
extremely low noise floor (-100db) eliminating the “hiss” common to many Class D amplifiers.
.>
Caraudio class D amps with typical class B efficiency are exist too. However manufacturers do not employ the designer, but probably instead of him employ the worker for erasing/renaming standard chips (ie CD4060->F16, comparator->B52 etc. kind of phobia?). In the caraudiophiles forums there is stable opinion regarding class D is a dirty/uncontrolled bass, for the full range class D isn't considered even. I try to protect class D reputation by explanation that amplifier's class isn't matter, but designer's class is matter ;-) So "new kid of the block" need reabilitation already.
PS: BTW, J.P. could blow up this wild market segment by the UcD based subamp for starting.
Let's look inside caraudio class D amps, and PSaudio creation will not seems so poor anymore. They have, at the moment, typical specs: THD 1-2% (note that's for subwoofer app.!!!), damping factor 100. Noone of these called "simply"("stupid" is more exactly) class D, but only "adapted class D", "advanced" etc! To achieve THD 1%@100W someone use 1Mhz carrier even:
<The Xtant1.1i adds local and global multiple nested feedback loops with premium MOSFETs and
OPAmps for switching stability and audio signal accuracy within the full range spectrum. This
results in an extremely high switching speed—over 1MHz
This enhances the musical reproduction by ensuring the higher frequencies (cymbals and
the like) compliment the entire frequency range to bring new realism to the Class D amplifier
sound experience.
The Audiophile Full Spectrum Class D Technology with Xtant’s attention to detail results in a
Class D amplifier that sounds better than many audiophile Class A/B amplifiers. It exhibits an
extremely low noise floor (-100db) eliminating the “hiss” common to many Class D amplifiers.
.>
Caraudio class D amps with typical class B efficiency are exist too. However manufacturers do not employ the designer, but probably instead of him employ the worker for erasing/renaming standard chips (ie CD4060->F16, comparator->B52 etc. kind of phobia?). In the caraudiophiles forums there is stable opinion regarding class D is a dirty/uncontrolled bass, for the full range class D isn't considered even. I try to protect class D reputation by explanation that amplifier's class isn't matter, but designer's class is matter ;-) So "new kid of the block" need reabilitation already.
PS: BTW, J.P. could blow up this wild market segment by the UcD based subamp for starting.
IVX,
Thanks for the tip, but in the past I have decided to STAY FAR AWAY from caraudio business.......
Prices are very low, and I don't see ANY reason for high power (>100w) in a car. There is normaly so much noise in a car that MP3 is (for me!) sufficient.
Let this world be for the competitors..........
Regards,
Jan-Peter
www.hypex.nl
Thanks for the tip, but in the past I have decided to STAY FAR AWAY from caraudio business.......
Prices are very low, and I don't see ANY reason for high power (>100w) in a car. There is normaly so much noise in a car that MP3 is (for me!) sufficient.
Let this world be for the competitors..........
Regards,
Jan-Peter
www.hypex.nl
Xtant isn't exactly a low end brand either. Car audio generally has very low margins, there's a few premium brands that are able to make a decent profit per unit, but they're a very small market segment.
Car audio is a segment where you need alot of power though. For one, just to get above the noise floor requires alot more power. As well, car audio subs tend to be designed with large motors, big VCs, and stiff suspensions, with makes them great for providing loads of output in very small boxes. Getting 120+dB from a one cube box is great, but it takes alot of juice.
Car audio is a segment where you need alot of power though. For one, just to get above the noise floor requires alot more power. As well, car audio subs tend to be designed with large motors, big VCs, and stiff suspensions, with makes them great for providing loads of output in very small boxes. Getting 120+dB from a one cube box is great, but it takes alot of juice.
Hi,
Juice is what class D is for. I tend to agree with Jan-Peter here though, car audio is all about power, so much power you can't even sit in it. Hi-Fi has no place in SPL competitions which is really all they seem to care about, UCD would be wasted in it.
Jan-Peter I found your new PDF file for the UCD180, perhaps you'd consider adding more information in it. For instance, most of the questions which always get repeated, what kind of supply, what size transformer, how much capacitance and what kind of caps... Raw DC or regulated.. that kind of stuff. Might save you having to answer it over and over again.
Regards,
Chris
Juice is what class D is for. I tend to agree with Jan-Peter here though, car audio is all about power, so much power you can't even sit in it. Hi-Fi has no place in SPL competitions which is really all they seem to care about, UCD would be wasted in it.
Jan-Peter I found your new PDF file for the UCD180, perhaps you'd consider adding more information in it. For instance, most of the questions which always get repeated, what kind of supply, what size transformer, how much capacitance and what kind of caps... Raw DC or regulated.. that kind of stuff. Might save you having to answer it over and over again.
Regards,
Chris
I'm curious how the Ucd180 react to different supply voltage levels with regard to sonic quality at moderate listening levels.
If I am using, say 10W of average power into an 8ohm speaker, will the sound quality be affected if I'm using 25V instead of 50V? Is there any reason to prefer a higher voltage even if a lower will suffice for the requested power level.
I have an unfounded belief that a class D amplifier could use a higher voltage to decrease switching time and therfore have better control. Is this totally bogus? Or is it something of the opposite, the shorter switching time increases overshot and general noise levels?
--- Mikael R
If I am using, say 10W of average power into an 8ohm speaker, will the sound quality be affected if I'm using 25V instead of 50V? Is there any reason to prefer a higher voltage even if a lower will suffice for the requested power level.
I have an unfounded belief that a class D amplifier could use a higher voltage to decrease switching time and therfore have better control. Is this totally bogus? Or is it something of the opposite, the shorter switching time increases overshot and general noise levels?
--- Mikael R
Re: slightly off topic..sorry
I don't exactly get what you're trying to say but i know hypex has a few class d sub (plate) amps, although not advertised on their site.
EDIT:
oeps, they do. the ds 1.2. overlooked that one.
IVX said:
I don't exactly get what you're trying to say but i know hypex has a few class d sub (plate) amps, although not advertised on their site.
EDIT:
oeps, they do. the ds 1.2. overlooked that one.
Yay!🙂matjans said:
The modules have about 65dB PSRR (frequency independent). I tend not to use overrated supplies because I found the sonic benefit to be rather small. The quality of the power supply caps does more than the quantity.matjans said:
My own reference amp has a 160VA transformer and 2x4700uF - for a stereo amp (2x90W).
(The new "esoteric" design, 1.2kW/2ohms, on the other hand, uses 2x20000uF all black gate caps and a 1kVA transformer. Yeah it sounds a bit better 🙂.
rosbacke said:
Yes/no. In general MOSFET switching times increase with increasing voltage (more gate charge to throw about). It means that the relative portion taken up by dead time gets longer at lower voltages. If an amp was designed to operate at 50V, reducing supplies to 25V, THD is likely to go up. The UcD180 module is best used as designed.
The UCD400 circuit has drivers that prevent this mechanism (the reason for this design change was different though). It will produce the pretty much the same THD at any power supply voltage. Of course, who would buy a UCD400 module to run it at 25V...
Now, if you only need 10W at any time, you're better off building a power stage with lower voltage FETs (same Ron), because it'll easily provide faster switching times than a similar power stage made with higher voltage FETs.
toroid supplier
for those in australia, i found a local transformer manufacturer that will custom wind toroids to your spec.
they are making me up a 300VA 33+33V, which i will use to drive a pair of UcD180's (which i hope will arrive any day soon now!)
they are called TorTech, www.tortech.com.au.
the transformer i ordered cost $99 australian ($70US) - which is not too far above what an off the shelf 300VA toroid would cost here.
cheers,
ben
for those in australia, i found a local transformer manufacturer that will custom wind toroids to your spec.
they are making me up a 300VA 33+33V, which i will use to drive a pair of UcD180's (which i hope will arrive any day soon now!)
they are called TorTech, www.tortech.com.au.
the transformer i ordered cost $99 australian ($70US) - which is not too far above what an off the shelf 300VA toroid would cost here.
cheers,
ben