Ralph get it right your the false one with strawman mentality, you can’t
have it both ways, the two 150w amps (Technics SE-R1 v Orchard Bosco)
are very different, and will not be the same, and I’m sure your answers
are "protection blurb" for what you have coming. Stick to tubes that's
where your cred is. If you look back at this you will see that I am not claiming that they are the same. I was simply saying that a module the size of a pack of cigarettes is that way on account of it has to be so to ameliorate noise issues. And again, your argument quoted above is yet another Strawman. A Strawman is an argument different from the one which which your opponent in debate has presented; by then knocking down a different argument you can still think of yourself as correct. It works only if others don't notice the slight of hand. You've been correct in your arguing but incorrect in addressing my points. |
You are saying this 0.9kg 150w Gan amp
https://orchardaudio.com/bosc
Will not be shamed by this Technics SE-R1 54kg 150w GaN amp Nope. Didn't say that. I merely pointed out that class D circuits have to be compact. The above is a Strawman logical fallacy; thus inherently false. |
I’m talking about dinky ones the size of cigarette packet, some that can do 120w Maybe something you don't understand is that the size of a class D circuit board says little about its power. They have to be small in order to keep radiated noise down. So traces are short (less inductance), there are usually at least 4 layers in the board and so on. So a board that is the size of a pack of cigarettes is that way even if it can make more power. Most circuit boards (modules) employ ICs to do most of the class D functions- comparator, drivers for the outputs, high side switches and so on. This helps them be more compact and so less noisy. Our prototype boards make 100 watts and despite being relatively discreet (no dedicated chips) its smaller than a pack of cigarettes too. That's just common sense on the engineering side. I'm sure the actual Technics amplifier circuit is quite compact as well- my guess is that because of its very high switching speed, its even more compact! |
I’m not talking about wattage Ralph, and you know that very well, give
up and try not to go into product protection mode, when ever GaN is
mentioned. This comment does not make sense when compared to The ones around now using GaN’s are either dinky little office type
class-D’s or expensive ones that haven’t utilized the technology as far
as Technics did. 'Dinky' in this part of the world means 'small'. And since you chose to make the usual ad hominem attack, can you get it that we've been working with GaNFETs in most of our prototypes except the very early ones? Why not, they're quite inexpensive! |
The ones around now using GaN’s are either dinky little office type
class-D’s or expensive ones that haven’t utilized the technology as far
as Technics did. This statement is false. The Technics amplifier is only 150 watts, which is similar power as many of its GanFET competition. |
It WILL NEVER be as good as tubes,class a or good a/b NEVER!!! As a tube amplifier manufacturer I have to disagree with this comment. We are a tube amplifier manufacturer that is also developing a class D amp. Our tube amps have gotten excellent reviews and numerous awards in the high end audio press; in particular they are known for their transparency and musical nature. So I'm not making this statement lightly. No-one knows the future but we do know that people make innovations. We made one and its why we have a patent application filed on our class D amp; I am of the opinion that class D has a lot to offer in the transistors vs tubes debate. IOW, I wouldn't say 'NEVER'... There is a thing called a 'technology/performance' or 'innovation' curve. Its generally the shape of an S. At the beginning, when the technology first appears, a lot of time and money goes into its development, with small increases in performance. As the tech gets sorted out, with small amounts of time and money much larger performance increases occur; then as the tech is mature (think transistors and tubes here) then larger amounts of time and money yield incremental improvements. Class D is in the middle of the curve, so its still possible that smaller companies like mine are able to make big improvements. There are a lot of players in class D so 'never' seems dubious to me. |
Not to steer this off topic, but no system can produce a convincing
life-like sound, partly because the recording equipment cannot capture
it. I've seen systems belie this statement. In particular, a direct microphone feed driving headphones can fool many audiophiles with great ease. I advise actually working with good mics and recording gear and see if you still say this. |
As it stands now the switching frequency noise output filter, has phase
shift effects that reach right down to 5khz, that doubled for the worse
at 10khz and doubled worse again 20khz. That's what many listeners find
objectionable, in the upper mids and highs. This statement is false. The filter is set to be operational at a fairly high frequency, and are usually 12 db per octave filters. 6 db/octave filters exhibit phase shift over the widest range, so if the pole frequency is at 90KHz you could see some artifact at 9KHz but not at 5KHz. But most filters I've seen are 12db/octave and so don't have phase shift artifact anywhere within the audio passband. What many listeners likely 'find objectionable' is not the filter- its likely something else. Several issues exist that can account for that- higher ordered harmonics caused by poor loop feedback implementation, breakdown of the encoding scheme at higher volume levels, distortion from the input circuit... but its not the filter. IME a good class D amp has artifacts, but not the kind typical to traditional solid state, so in many cases I find especially the later generations to be more musical than traditional solid state. |
The problem is not dead time, or notch distortion. The problem is
audibility and connecting that to any particular technical choice. Dead Time has nothing to do with notch distortion, but the chance exists that I mistook the gist of your comment. It’s not false as Ralph would have you believe.
It is "also" a
problem, but isn’t the "major problem", and the cause is of what many
dislike what they hear in the upper/mids and highs which is a product of
the switching noise and it’s associated filter.
It is believed that the dead time will also be vastly improved with a 3mHz switching speeds.
George, you've not thought this thru. You are correct that by increasing switching times you can decrease distortion. However, its not the filter that is an issue, in fact as the switching time goes up, there is a point where the inductance of the load is enough to eliminate the requirement for a filter! (Usually the filter fails to remove all the high frequency component. This component is known as the 'residual' and if the filter is designed properly, will be a sine wave of low amplitude. As such it will not interfere with other equipment and is far too high to be heard!) Now as you go higher with switching frequency, distortion goes down, but with any particular switching device- oh- I'm repeating myself; here's my comment that you apparently didn't read from above: The problem is that dead time causes distortion. So with any given
output device, there is always a certain minimum distortion and
associated maximum switching speed. Nelson's analogy is correct however, so imagine not having to wait for a transistor to shut off before the other one turns on! Now we can switch at much higher frequencies and with much less expensive parts. Alternatively, an amp with a lower switching frequency but no need for dead time can have distortion as low as an amp that needs the dead time and is switching considerably faster. |
By definition, zero deadtime means that the devices must be both on and off at the same time, a physical impossibility given any reasonable technology. :) that is why we have a patent filed. Difficult takes a while- impossible is just a bit longer. A Class D amp with Zero dead time is likely an amp with a short lifespan. So far they run stone cold even when on for days on end. |
“The TDAI-2170 is 100% digital, without sound-deteriorating
digital-to-analog conversions. The digital signal drives the speakers
directly, with no translation and no middleman.”
It takes a
digital signal and amplifies it without a conventional dac. The signal
remains completely digital right to very point where the signal is fed
to the outputs....only at this point does the signal convert to analog.
This unit is not a Class D amp.
@grannyring While this is the hype, the fact remains that all class D amplifiers employ an analog process. I think there is a lot of confusion about what is digital and what is switching, and also what must be analog. Here's a link that might help: https://www.hypex.nl/img/upload/doc/an_wp/WP_All_amps_are_analogue.pdf |
Cyrill Hammer (Souloution)
"if
you want to have your product performing at the cutting edge it is not
possible with today’s known switching technologies. In order to come
close to the performance of the best linear design we would need
high-current semiconductors that provide switching frequencies of
several MHz or even GHz."
This is the one, that I
believe hits the nail on the head, and why to some that hear it Class-D
sound in the upper ranges hasn’t come of age yet.
Only Technics
with their unobtainable $30k SE-R1 comes close with a 1.5mHz switching
frequency instead of what all the other are using today 400-600kHz. But
as Cyrill Hammer states it should be even higher.
The quote from Mr. Hammer is false. Here's why: As @merrilaudio states, the problem is dead time. Dead Time is the delay time that has to be inserted in the circuit so that both output devices are prevented from being partially on at the same time. If this isn't done, a phenomena called 'shoot through current' occurs. This causes the output devices to heat up and fail. The problem is that dead time causes distortion. So with any given output device, there is always a certain minimum distortion and associated maximum switching speed. Technics sort of got around the problem by brute force- going to an output device that was so much faster that they could reduce deadtime and also switch faster (BTW their 150 watt version of this is about $18,000....). However eliminating dead time is what works- you can actually have lower switching frequencies with lower distortion if you don't have to have deadtime circuits! As some of you may know, we've been working on a class D for a bit over a year and a half. Although we are known for tube gear, in particular OTLs and balanced tube preamps with direct coupled outputs, it turned out that we seemed to have something to bring to the class D table. May a year ago we had working concept, today we have prototypes that demonstrate how a class D sounds if deadtime is eliminated. Our amp is not based on anyone's modules and we have a patent filed with another on the way. So far the prototypes have switching speeds between 250KHz and 500KHz. The amp is very smooth and extended, lacking grain or harshness. It easily compares to many tube amplifiers in that regard. It is zero feedback and exhibits soft clipping. We don't think its ready for prime time yet; in that regard I've yet to hear a class D (including the Technics) that is, but we are very excited about our class D as it sounds better than any we've heard. I think merrilaudio knows what we are talking about; eliminating deadtime is the single most important hurdle to cross in class D amp design (especially if you can run MHz+ switching speeds), and I'm going to go on record that any amp that employs deadtime to work is an amp that will become obsolete. |
We should also throw in pure digital powered dacs Just to be clear: all forms of class D are analog devices. I know, switching this, digital input that and on and on but class D is still analog. Just so there's no confusion :) |
You don’t have to go that route, but it’s time we shrugged off the myths
and descriptions of Class D that come right out of the 1980’s. Make that 1990s.... |
