High end Class D amps?

By the way, if you are using a toroidal transformer and you use metal plates or bolts to secure it to the chassis....you are closing down the sound. You want your toroidal transformer off the chassis on a piece of wood an mounted using tie wraps and glue or a wooden plate on top and teflon screws......way better sound.

Just a FWIW: the problem you are addressing here is the mounting. Most toroid transformer manufacturers supply mounting hardware, and if you use it the transformer will run hotter than it should. This is because the mounting bolt is steel, its magnetic and while a toroid is supposed to contain its magnetic field very effectively, in practice it does not, so that bolt becomes a magnetic short. If you install one just for fun, you'll see that the bolt is running hotter than the transformer. The solution is really very simple: just use a stainless non-magnetic bolt and no worries. And does this sound better? Yes it does- we discovered this phenomena about 25 years ago and its a nice tweak to any amplifier- the sound will 'open up' a little and of course the transformer will run cooler and make slightly more voltage- both audible and measurable!

Yes, but none yet "so far" that have taken the full major advantage of the 1.5mhz switching speed on offer when GaN Technology is used

Actually GaNFETs and MOSFETs are both capable of switch far faster than the switching speeds seen in all class D amps including Technics. The problem isn't how fast the devices are! Its how much noise is created (or not) by the switching at power; how much RFI is created, how much of this noise is then affecting other parts of the amplifier circuit, and then there is the issue of the 'body diode', which is where GaNFETs actually have the advantage over MOSFETs. This gets a bit technical, but has a lot to do with the coil in the output filter, which stores energy and then has to release it. Essentially its what is called a 'flyback' voltage (named after flyback transformers in old analog TVs), working in a manner similar to that of a spark coil in a car. In a nutshell, the output device can behave oddly- you tell it to turn off and it won't, partially due to capacitance effects on the gate of the device and partially due to the body diode of the device, which is a primitive diode formed in the passive layers of the device when its made (and I am vastly over-simplifying in this regard!!).  The filter coil flyback voltage can be effectively used to kick the GaNFET into its off state. That's a more important reason to use them than their speed, since MOSFETs have made so many gains in the last few years.


An important reason to keep the switching speed a bit lower is dead time. Dead time is invariant with frequency- no matter how fast you switch or how slow, the minimum amount of dead time you will need stays the same. So as you switch faster and faster, the output device is waiting for a greater and greater percentage of its ON time. This causes distortion to go up. Its true that Technics has a faster switching time, but it does not seem to be doing them any good IMO as they are paying the price in several different ways- increased cost without increased performance due to the associated issues with speed.

I have owned several amps over the years. Mostly mid fi until the last ten years I owned the Krell Chorus, Theta Dreadnaught D nc1200 based and the ATI Nc500 based amps. I kept seeing Cherry Amps mentioned in these class D amp threads. So I figured I would give it a try. Well to say I fell in love would be an understatement. I have 11 channels of Cherry Amps. But I can honestly say they don’t all sound the same. They all sound good but the best I have heard are the mono maraschino’s with the biggest 60 volt power supply with tripple capacitance. These little amps have bested some high end amps. The amps were Musical Fidelity M8 700m’s. The Cherry Maraschinos just sounded so much smoother and real. I know I won’t choose anything else ever. It is the perfect amp for me.

Dont forget the Dark Horse AGD PRODUCTION ... Class D certainly is in a higher level of performance than ever before. Many of the old issues with class D are gone. Something to realize is class D is the leading amplifier technology when compared to A and AB for HiFi.

Heres what makes AGD my top choice by a good amount when it comes to Class D. First off my personal opinion is Alberto Guerra is a better designer than Bruno Putzey. why ? well for one his products sound better to me. Next Alberto designs all the way down to the GaN device itself. Yes, that means not only does AGD not use someone elses class D module, it means AGD has thier own GaN device that is not available to anyone else. Why on earth ?  because the GaN devices on the market that are most plentiful and best from a supply standpoint and least expensive to spec into your amp design are made to be used in battery rechargers. If you are lucky you get the milspec devices used for LIDAR in the military. The AGD output device is the first and only GanFet to be designed ground up for HiFi. So when we start with that , we start at the Pinnacle of GanFet and Class D design. Forget all the others this one is different and its clear to hear. These amps are made in USA. The "Baby" of the family is a monoblock called "Audion" can be held in an outstretched hand is made from Gorgeous custom milled aluminum  with a mirror polish offered as an option. It has both RCA and XLR Inputs and WBT NextGen binding posts . Its output is 80W at 8 Ohms, but do not be deceived, it can deliver 32A of current . Thats right one reviewer powered Apogee Scintilla with this mighty mite. Why have you not heard of it ? Because it is a brand of attraction not a brand of promotion. The best brands in the world for anything are not on the fast track to push product. They steep in the market and people find out about them if they are the right buyer. Prime example Viola Labs. Most have never heard of it nor understand that it stems from the brand of HiFi considered by many to represent the most extreme example of sonic quality ever made in our industry, which was Cello, which came from the man Mark Levinson. Well AGD sounds better than Cello, Ive compared to Duet. My first buyers have been my S.E.T guys... the most hardcore of audiophiles. I have a return policy mind you and NOT ONE pair has come back. One of my guys in California has Berning 300B monos that are built to the hilt, Silver Would transformers and original Western Electric 300B tubes.. The tubes cost more then the pair of monos does. And AGD Took the cake. So I know that hearing is subjective , but if one of these amps is to be considered most innovative and most unique its the AGD for sure,  hands down,  no questions asked . Anyone want to challenge ? I am available to back my mouth up with proof in the form of shootout and recording . Do yourself a favor check out the AGD Audion , its only $7500 per pair and is 100% proprietary, sounds line no other, comes in a flght case with die cut internal foam and 2 5 foot audiophile power cables, no molded crap cord. The amp is guaranteed to overjoy you or your money back , no restock fees.  

Most toroid transformer manufacturers supply mounting hardware, and if you use it the transformer will run hotter than it should. This is because the mounting bolt is steel

A least that’s one you got right and we can agree on, this has been known btw forever since toroidal’s were first released, and especially when the bolt is in contact with the chassis earth, sorry but you did not discover it. (so no self back pats) My Hungarian EE boss (rip Steve De’Ratz) back it the 80’s told me about this, as his family tree had something to do with the first ones. And it also applies to any air core chokes, in speakers, amps, anything.

i have Nuprime MCH-K38 and MCX-4 which use the same proprietary power boards, class A and D hybrid, the former can be bridged and in that mode has more control, detail and punch. Next week I will be comparing these family offerings to the Starke Sound AD.320, which can also be bridged and is starting to get great reviews but is new. The construction quality is excellent and it too uses proprietary power boards, again not ICEPower or Hypex Ncore, and is a class AB and D hybrid. All amps should be considered for muti channel high end class d systems.