OK, drag me screaming and kicking

[tvrgeek]

to class D. Been doing a lot of research. Soooo much BS out there on magical input stages. ( a 30 year old Signetics OP-amp is better than most esoteric input stages) Seems the Hypex are the preferred. Finding smaller companies that are being well received. VTV and March as examples. Some, like PS seem to sell the same stuff for twice the price. I may, again may, try one out as most do have trial and return offers. No chance in hearing a good one around here as in NC, they seem to think a Denon AVR is high end. I have condescended to look as the availability of decent AB amps is shrinking fast. Either too expensive to start with, e.g. Benchmark, or all the hype for so-so like Cambridge. Rotel, NAD, and Parasound still make them but prices are getting up there. Seems all their efforts are also shifted to class D. Curious, many of the new amps are balanced input only. That does not seem logical for sub $1K consumer products. Logic might say someone like Parasound is not going to make a turkey, but I have a Z3 amp, and it is. Mostly I think the box is just not big enough for sufficient power supply caps. Wish I could find a schematic. Bought it as a bench amp and found it to be lacking.

I did spring for a new DAC, SMSL SanSkrit 10, and a USB isolator. I will be curious to see if I can hear any difference to my 15 year old Muse. ( .008% second order,20 to 20. All other distortion below my test threshold of 110 dB. ) I hope the isolator will remove that last bit of LF and 60 Hz noise I assume coming from the PC/music server.

[fpitas]

My benchmark for saying the Hypex UCD amps have very little distortion, especially crossover distortion, is listening to them directly connected to a friend's horns. So obviously that testimonial does you no good

Seriously, go read some of Bruno Putzeys' articles. He knows his class D. He might make you a believer in balanced signal transmission, too.

[tvrgeek]

Working on it. Going through the Hypex and Rane white papers. Delta is making it very wet today, so more time wasted on the computer.

I agree balanced IO can be good, but only if your IO design is good and many are not. For PA use, easy: Jensen. Actually mandatory in my book. But for hi-fi, it gets quite hard. THAT is helpful, but it is really easy to eliminate noise but cause huge distortion. Getting perfect balance is not easy. A lot of semi-pro or pretenders are not as good as single ended. DBX, Behringer to name two. Of course, cost is a problem. it should not be as the pro stuff has no cost issue, but the hi-fi side seems to want to add zeros for no valid reason other than they can. Made plenty of cables with an RC on the shield. The years I spent in Failure Analysis taught me a lot of other tricks.

I gather the UCD is one generation down to the N-Core. I'll review my data on balanced line drivers. It woudl probably be better to add a driver to my preamp than to hack the cable. Might signal a time to upgrade from my O-Audio sub plate. It was best of class, but a pretty low class.

[fpitas]

Working on it. Going through the Hypex and Rane white papers. Delta is making it very wet today, so more time wasted on the computer.

I agree balanced IO can be good, but only if your IO design is good and many are not. For PA use, easy: Jensen. Actually mandatory in my book. But for hi-fi, it gets quite hard. THAT is helpful, but it is really easy to eliminate noise but cause huge distortion. Getting perfect balance is not easy. A lot of semi-pro or pretenders are not as good as single ended. DBX, Behringer to name two. Of course, cost is a problem. it should not be as the pro stuff has no cost issue, but the hi-fi side seems to want to add zeros for no valid reason other than they can. Made plenty of cables with an RC on the shield. The years I spent in Failure Analysis taught me a lot of other tricks.

I gather the UCD is one generation down to the N-Core. I'll review my data on balanced line drivers. It woudl probably be better to add a driver to my preamp than to hack the cable. Might signal a time to upgrade from my O-Audio sub plate. It was best of class, but a pretty low class.

Yes, the NCORE line is pretty much state of the art for distortion. But I've listened to the UCD180s for many hours, and there's not a thing wrong with them. Hypex sells switchers they recommend to power them, and we used those. Tossed them in a box and added a decent line filter. Being obsessive, I put some big ferrite doughnuts around the wires from the supply to the amp. Of course you can build a linear supply too, but I couldn't see any advantage.

[tvrgeek]

Linear supply: Advantage if DIY as most fools can build one. A few of us pretty well.
Switcher: Buy the darn thing!

[fpitas]

Linear supply: Advantage if DIY as most fools can build one. A few of us pretty well.
Switcher: Buy the darn thing!

Sure, and you may have the stuff laying around for a linear supply. But we didn't, and my pal wanted a small enclosure.

[a4eaudio]

...Of course, cost is a problem. it should not be as the pro stuff has no cost issue, but the hi-fi side seems to want to add zeros for no valid reason other than they can.

As you correctly stated in the thread on divers made in China...its simple economics.

The N-Core has been considered as one of (if not THE) best implementation of Class D, but also one of the most expensive. (It is nice at least when the price does reflect the quality.) Bruno Putzey left Hypex and is now with Purifi and they have a line of amplifiers newer than N-Core. I haven't read about them, but I think the assumption is that they are cutting edge.

[fpitas]

Purifi offers a 6.5" woofer too, it looks pretty nice.

[donradick]

Dang it, now I have to subscribe to this thread also! Too much good info.

[tvrgeek]

This page shows me a lot of what is wrong with specs. I keep seeing " gillion Watts @ 1%" Well, what is it just shy of that? .00-something!. https://purifi-audio.com/eigentakt/

Does anyone sell a completed amplifier available in the US based on their module?

[Whitneyville1]

You can still buy Class A stuff and use it for a heater in the Winter. There are a couple of companies that still make very fine 4 tube ( 3-500Z Eimac-Eitel) direct coupled Class A mono-block amps that deliver 2000 watts RMS @2-12 ohms pushed by 60 amps of 240 volt AC EACH you can warm soup or donuts on and sound as good as your electric bill. It just isn't the ONLY way to get there today, or even the best way. Just like a 'fridge-sized four or five way speaker isn't the best way to cover 18Hz-35 Khz today. An excellent sub and a top-notch MT may be able to do a better job than a monster speaker if filling the Texas Dome at 160 dB isn't your goal. I still do silver photography as well as digital. Different end products, different goals. Like writing here vs: writing you a letter I mail you.

[fpitas]

You can still buy Class A stuff and use it for a heater in the Winter. There are a couple of companies that still make very fine 4 tube ( 3-500Z Eimac-Eitel) direct coupled Class A mono-block amps that deliver 2000 watts RMS @2-12 ohms pushed by 60 amps of 240 volt AC EACH you can warm soup or donuts on and sound as good as your electric bill. It just isn't the ONLY way to get there today, or even the best way. Just like a 'fridge-sized four or five way speaker isn't the best way to cover 18Hz-35 Khz today. An excellent sub and a top-notch MT may be able to do a better job than a monster speaker if filling the Texas Dome at 160 dB isn't your goal. I still do silver photography as well as digital. Different end products, different goals. Like writing here vs: writing you a letter I mail you.

I use one of those new-fangled transistor class A amps. Only 25W, though. Still a space heater.

[Wolf]

I was pretty sure VTV has one for sale with the Purifi module. Price is a bit rough though.....
Wolf

[tvrgeek]

I guess a class A amp on a horn as it needs all the help it can get. Sorry, too easy! We can build very good AB amps now, so class A best use is as the first two staged of a real amp.

I tried the tube game. Sure first gen SS were pretty bad, but we learned quick. Cary was not bad, VTL tired to be cleaner, but I believe the artist and engineer should decide how much distortion to add. I want an amp that amplifies.

Not heard one of course, but I have a hard time with the Purifi and other "magic" front ends. Going to be hard to convince me it is better than a decent OP-amp or THAT receiver. Advertising BS to make one milled aluminum box different from another to justify the price. Hearing is believing and that is hard with no retailers. Someone out there is slapping them in a cheap sheet metal box I am sure. Just not found it yet. All that billet does not sound any better and when in my cabinet I can't see it anyway.

Another good 6 1/2 is always welcome.

Off to search some more.

[tvrgeek]

Lots more reading.
In linear amps, going bigger than needed gave us more outputs, so less current per pair and better linearity. Noting new.
Now in class D, looking at the charts, they go to hell as they approach rated power, so we don't want an amp too small, but if we go with one way larger, do we run into loss of resolution as we are not using the full dynamic range and every step is larger?

In linear, for the same reasons we prefer an 8 Ohm load over a 4 as we can amplify voltage with less distortion than current. But in class D, is that still true? What is the effect on the linearity of the integrator?

Props to Alan March. I got a nice feedback from him. He says his ncor "approach the best of AB" Sounds reasonably honest and with the exception of OFC copper wire, not much other BS on their advertisement. Can't say that for some of his competitors. Of course "approach " is only close enough for horseshoes and hand grenades. If not equal or better, I should sit pat until I get older and hearing is worse, or they get better.