I thought it was time we had a pro- Class D thread. There's plenty of threads about comparisons, or detractors of Class D.
That's fine, you don't have to like Class D amps, and if you don't please go participate on one of those threads.
For those of us who are very happy and excited about having musical, capable amps that we can afford to keep on 24/7 and don't require large spaces to put them in, this thread is for you.
stfoth it’s been awhile since I knowingly gave any class D amp a good listen, maybe a decade. so, some folks absolutely love these things. others can hear the flaws. my impression from a decade or so ago was that I hated them (at least the few I heard), but really couldn’t put a finger on why--lots or power, ridiculous detail, etc. just something missing, and, inexplicably, my ears felt funny afterwards--almost like a ringing that shouldn’t have been triggered by the volume or duration. difficult to explain.
+1 stfoth, others hear it too, and if they can’t good for them. This is why there are for and against post, from both sides of the camp, so potential purchasers can make up their own minds, and be happy with it or disappointed. These forums are not a marketing exercises to create a push to sell more Class-D. As the opening post says " Please share your experiences with class D amps!"
Stop listening with your eyes (reading specs) and start listening with your ears. That is the only proof needed. And stop with the ten-year old stories. Get in the now.
And stop with the ten-year old stories. Get in the now.
The only current crop of D’s I’ve heard that have semi impressed, were the new Belcanto Ref 600M Monoblocks, yes they use the the newest "best" N-force NC500 modules that aren’t available to anyone but to Belcanto and other manufacturers.
But Belcanto modifies them from what I’ve we were told by the importer/demonstrator, that was to either cascade/parallel or series a couple of the low order switching noise output filters to give a sharper filtering effect of the switching noise.
But any speaker manufacturer worth his salt will tell you that doubling up on low order high power filters at or around the same area has it own set of problems with ringing ect.
I just got some digital amplifier company inline maraschino class d amps to replace my Odyssey kismet class ab monos and I'm amazed how good they sound. I used to have an emerald physics ep100.2se class d stereo amp and the inline maraschino blow that away and is on the same level as the kismets
"The only current crop of D’s I’ve heard that have semi impressed, were the new Belcanto Ref 600M Monoblocks, yes they use the the newest "best" N-force NC500 modules that aren’t available to anyone but to Belcanto and other manufacturers"
You should get your facts right. It's not N-Force, it's NCore NC-500 Hypex Module. And there is no modification to NC-500 module itself. Inside REF600 there are three circuit boards: a Hypex NC500 amplifier, a Hypex SMPS1200 power supply, and Bel Canto's input conditioning board with their Impedance Optimized Input Stage, for balanced, high common-mode rejection and to provide a low output impedance to the input of the amplifier board. The active element on the board is an LME49720 Dual High-Performance Audio op-amp in what appears to be a low-pass filter configuration.
"The only current crop of D's you heard is REF600" - Are you always been this short sighted that after listening to one class D amp, you see fit to under appreciate or rather condemn the recent innovations and forward progress in Class D camp.
I wonder how many Class A/B amps you auditioned before settling with the one you currently own? And is that the 'best" Class A/B amp made in the world?
If you seek the "best" in Class D currently available, I double dare you to audition Jeff Rowland's 925/725, Mola Mola's Kaluga and Merrill Audio's Veritas before you return to another Class D thread.
As one of the reviewer pointed out, "the REF600M didn't sound identical to some other amps was neither surprising nor a criticism of any of them. Of three recent amps of my experience, the REF600M was the warmest, the NAD Masters Series M22 the most detailed, and the Theta Dreadnaught D somewhere in between. Why should various amps based on circuit boards of the same technology (NCore) and made by the same company (Hypex) sound different? I don't know, but the amplifier boards aside, I could see physical differences inside these three amps. The big Theta uses a big linear power supply or two, while the more compact Bel Canto and NAD use a Hypex SMPS. Theta and NAD use the input circuit on the NCore amp board, while Bel Canto supplements it with a proprietary circuit"
Nord is making nc500 based amps with a user selectable and user changeable input buffer to "tune" the sound to one's personal preference. It has been getting great reviews and is offered at extremely low prices given the performance. It can be made to sound any way the user prefers....
You are right @stfoth, some 10 years ago, most class D amplifiers that I listen to sounded either hi-fiish -- like a Technics stereo of the early 1980s, or darkling, or hazy, or even outright screetchy... Yet, even some 10 years ago, some class D amps were already making real music... I fell totally in love and adopted one of the few class D amps which made real music without compromises: The Rowland M312 stereo.
Today the class D field is very different. While you might still find the occasional screetch owl out there, most class D amps seem to be making real music, and more than a few are exceptional music makers. In general, you cannot go wrong with amps based on NCore NC1200 or Pascal M-Pro2 modules.
George, Bel Canto M600 is a relatively entry level monoblock amp. Using the scaled down NC500 NCore module, They were conceived to fulfill price point of a price sensitive segment of the market. At $5K/pair, They are not an attempt to scale the summit of absolute performance levels of amps based on the full NC1200 modules or Pascal M-Pro2 and X-Pro2 modules.
Hi Lalitk, the Rowland M725 monos are based on a class A/B topology. You might have meant the M825 stereo instead, which like M925, sports NC1200 modules.
But any speaker manufacturer worth his salt will tell you that doubling
up on low order high power filters at or around the same area has it own
set of problems with ringing ect.
While this is true, this does not translate to the filters used in a class D amp, which is operating well outside of the audio band. The filter on a class D amp is blocking the switching noise of the amp and nothing more; it does not pay to have that filter go any lower than need be on order to be effective.
If the amplifier is switching fast enough, the internal inductance of the speaker itself is often enough to block the switching noise.
If this "effect" has been remedied, or if I was just imagining it all, maybe a summer amp?
Design plays a huge role! Some amps are not very involving and some are.
Some class D amps employ Delta-Sigma processing, some are simple Delta, some are self-oscillating (the latter require loop feedback to operate correctly, the former two can operate with zero feedback with careful design).
Scan frequencies can cover a wide range. Some have dynamically variable scan frequencies. Some amps employ op-amp input circuitry for the audio, others are discreet and its even possible to have passive input circuits.
So with all these variants you just have to try one out and see if it works for you.
Just FYI, Mytek has just posted info on their Class D amp to their web site.
The Mytek Amp fits perfectly under a Brooklyn DAC for a little under $2k. Order with the Brooklyn DAC and you get a $500 package discount ($3500 or so) which is a really good deal.
I’m bringing this over from another thread, but Primare seems to be using their own digital amp modules, and Hi Fi News test reports praises their performance, unaffected by load, and flat to 60 kHz is quite a feat!
I also noticed how well Hi Fi is keeping track of Class D. Their comments about the relative differences between Class D modules shows they are taking the genre quite seriously, unlike say Stereophile, which has never bothered.
Delta Sigma is not digital. It is a process used for digital encoding and there is a nuance there; its safer to say that data in a memory system is 'digital' (1s and 0s). It is also a good process for encoding for class D operation and is attractive because it allows for direct playback of a class D amp from a digital source, although unless there is some upsampling the clock speeds of most digital sources are far too slow for good class D operation.
All, not most, class D amps are an analog process. The funny thing is, if you want, you can use digital chips (for the most part, inverters) in the class D process. But it is very much an analog process.
If you use a delta-sigma encoding process, you are converting analog to digital, no? This AD conversion makes the amps "digital" a step most Class D amps do not need.
Otherwise, please show an example of a Class D amp which uses Delta-Sigma conversion which is not "digital"
If you use a delta-sigma encoding process, you are converting analog to digital, no?
No- not exactly. You are converting from analog to a pulse train. Very convenient for going digital from there, which is why its used in the digital encoding process. But despite that its still an analog process.
I get that this is hard to understand but when you see how much its affected by layout, the need to squelch oscillations and the like, that's when its obvious that despite the way its used, its actually an analog process. Digital stuff does not oscillate. Analog stuff can.
A lot of people think delta-sigma (also known as Pulse Density Modulation or PDM) is digital though (specifically 1-bit). I invite them to build the circuit; in solving the problems of making it work despite it being the circuit in a known-good diagram, that's when you really get that most circuitry that handles digital signals is actually analog. Put another way, the resulting signals are *treated* as if they are digital. I think some would say I am cutting the hair pretty fine, but that really is the truth of it.
BTW, we've moved beyond proof of concept and our scan speeds are up to 0.5MHz now (target is 3MHz, but we won't be able to do that with our through-hole prototypes due to afore-mentioned layout issues that are prone to oscillation at the higher rates). Its sounding pretty good too.
So apparently a short version was considered abusive. I thought I was being concise. This is me being perfectly reasonable.
The best educators lead by example. Those who show a willingness to listen, learn and adapt instill the same in others. I look forward to seeing more of that in this thread.
I have endorsed Class D myself, and had some input on this thread, although I very much like music with my Class D Audio amps, I had an ongoing problem, dealing with noise generated by my two CDA 254 amps. I even posted a thread on this issue. but got no response, so I thought I'd try again here.
I have a three channel amp that I use for surround and center, with one module run in stereo, and one module bridged to mono for the center. The power supply is used by both modules. This amp is subject to a fair amount of noise.
I also have, in a separate chassis, two CDA 254 amps bridged to mono, and while this amp sounds great musically, it has even more noise being produced than the three channel amp. Again, both modules share a common power supply. My first Class D Audio amp was a stereo CDA 254, having the power supply to itself. It was very quiet running in stereo mode. I didn't start having noise issues until there were two modules sharing the same chassis/power supply.
I have the half-baked notion that the noise is related to having more than one module sharing a common chassis/power supply.
I have tried to get an answer from Tom at CDA, but he won't reply. I'm hoping one of you kind gentleman,will offer your thoughts on my problem. I'm thinking on buying another chassis, transformer, and power supply, and see if using two mono-blocks (in bridged mode) will solve my problem. I'll be very interested to see what any of your replies might have to say.
I don't know enough about your amps to help you I am afraid. The DIYAudio web site is a great resource for kits and components.
The site is down for upgrading, but should be back up by Monday, July 10, 2017. I would ask there.
While some digital amps have noise issues when you put modules too close together, I would not think this was an issue. I would suggest try unplugging all but 1 module, and see if that does anything to the sound quality. If so I wonder if your issue is proximity.
The noise is a bit difficult to describe. It's similar to a 60 cycle hum, with a sort of "buzz" in addition to the hum. Strangely, when my home theater setup is on (Comcast DVR, Primare SP 31 HT processor, Sony HDL display), when making changes on the Comcast remote, the noise abates momentarily during the sequence of time the button is being pushed. I know this sounds far-fetched, but it happens.
Erik, Ralph, I appreciate your responses, thank you.
...when my home theater setup is on (Comcast DVR, Primare SP 31 HT processor, Sony HDL display), when making changes on the Comcast remote, the noise abates momentarily during the sequence of time the button is being pushed.
Hi Dan,
That’s certainly an interesting finding. Perhaps the DVR is the root cause of the noise, possibly even when it is turned off and most (but presumably not all) of its circuitry is unpowered. If you already haven’t, you might try disconnecting it and pulling the plug on it. Also, does the remote communicate with it optically, or via RF? If the latter, you might try removing its batteries.
To shed a bit more light on the subject, and I don't know in what way it may effect your idea of the issue, but when the Class amp is out of service, and my SET 300 B amp is in use, there is no issue with noise. Even when my HT system is in use with the SET amp (I use a separate tube preamp that the front two channels are connected to, including having the processor stereo cables run to the two channel preamplifier).
So, my thinking is the noise emanates from the Class D amp, not from the cable box or processor.
Thanks for the additional info, Dan. But if I understand correctly it still leaves open the possibility that the DVR or its remote may be the source of the noise, as it would seem conceivable that the class D amps may simply be more sensitive to pickup of electrical noise that is present in their environment than the SET amp. Perhaps as a result of wider bandwidth, or differences in gain (which is typically higher for class D amps than for SET amps), or any of the many other differences that may exist between the two designs.
Obviously what I was speculating is a somewhat wild guess, but it was prompted by your mention of the effects of the DVR’s remote.
@islandmandan , I'm with Al on this one. The amp should be fine with no input connected, go ahead and disconnect the input and see if you still have that noise. If so => amplifier, if not => input
Thank you Al, Ralph, for your always valuable input. I will re-insert the Class D amp into the system (I was taking time off from the noise, and very much enjoying the SET 300B in the system), and try what you have suggested. I'm wondering why, though, a single module, in stereo mode, is quiet, but a dual module/single power supply with both modules set to bridged mode is so darned noisy?
I disconnected the inputs on my stereo dual module Class D amp last night, and the right channel was silent. Inexplicably, the left channel was still noisy. Today, I rounded up some spare I/C's that were long enough to reach between the preamp/processor and the amp, disconnected the leads from the pre-pro to the separate tube preamp, and connected the amp directly to the pre-pro. The two channel and three channel Class D Audio amps are now quiet as a tomb.
From here on out, all my HT and multi-channel listening will be through the Class D amps, and two channel listening will be through the SET 300B and Transcedent Sound Grounded Grid preamp.
So your idea of the problem being input-related was spot-on. I also found I had my surround speakers connected to the rear surrounds on the pre-pro, which may have been causing some of the problems as well.
So, everything is working much better now, though I will be limited in my use of the Class D amp. I will have to re-think my connections to see how I can better utilize the Class D stereo amp, but at least for now, mission accomplished in attaining blessedly silent noise-free listening.
For that, I can't thank you men enough. Having your input on this forum is a true blessing!
Very nice to see almarg and atmasphere team-up, step up and use their knowledge/experience to solve islandmandan's noise problem. Nice job guys!
What I've consistently noticed from listening to good class D amps in my system, from my initial Class D Audio SDS-440-CS stereo amp to my Emerald Physics 100.2 to my most recently purchased D-Sonic M-600 mono-block amps, is their exceptional quietness; music seems to emerge with more impact due to the dead quiet background. I believe this silent quality is also a primary contributor to the other obvious characteristic of good class D amps: a very detailed presentation..
I'm almost certain these class D attributes will now be very evident to islandman now that his amps are operating in their typically silent manner.
My goal was a little desktop integrated or pre/amp combo.
After hemming and hawing and fretting I purchased an NAD D 3020. My local dealer had one $100 off.
I ruled out all of the Parasound Z series just because they are too big. at 9" wide they wouldn't fit on top of a speaker, like I need.
Plenty of digital and a couple of analog inputs make the input selection pretty good. There is also a bass boost which is perfect for my little desktop speakers.
So far so good. The one negative is really the volume display is hokey as hell, and it takes a lot of turns to adjust it.
The display has a series of numbers: -20, 40, -60, -80 and -100. As you turn the volume down the numbers dim, or go off. The physically larger sibling the 7050 has a graphical display with direct volume readings in dB. It was only a little more expensive, but seemed to lack analog inputs and was twice the physical size.
They call this a hybrid digital, but I could not find much information on what makes it a hybrid.
My only source right now is the PC, via analog, but I'm always careful to get motherboards with S/PDIF outputs so I'll try that eventually.
NAD calls the D 3020 a "hybrid digital amplifier," by which they mean that not all of its circuitry is in the digital domain. The D 3020 combines a Cirrus Logic DAC (eight channels mixed down to two) with a class-D output stage designed by Hypex, of the Netherlands. According to NAD, the output stages aren’t fazed by low-impedance speakers.
Hard to interpret exactly which part is which though, especially since Bruno Putzeys bristles if you call his amps "digital." Still, I will guess this is at least not a Hybrid a'la nuForce or Yamaha EEEngine, but something else.
This is a good performer, a huge step up fro my $20 Lepai 10W/ch digital amplifier. It is extremely quiet and smooth, without grain or harshness but also without warmth.
The bass boost is a huge help as my desktop speakers are pretty lean sounding. My previous experience with NAD DACs was pretty negative, but this is pretty easy to listen to. Tons of air and detail.
But zero warmth. In this sense it kind of goes towards the Emotiva/Asian processor sound qualities. Kind-of, but not nearly as bad as the worst of them. There's just no sweetness or warmth at all in the sound quality. "Stark" may be a good way to describe it, but without the thin/limited range effects I get from the worst of the Asian designs.
Reminds me a lot of the 1990's digital sound, if you took that and cleaned it up a lot.
So, killer, top of the pack? No. Quite enjoyable, space saving and feature packed is how I would put it.
As I mentioned before I have a Primare I32 and a Topping TP30 mk2 that I connect to the tape out to drive a Stax headphone system. I have a pair of old BA T-830s connected to the Stax adaptor for the hell of it. Sometimes, when I want the best sound from the Stax, I connect them directly to the Primare, which I did tonight. After a while I reconnected my 'big' speakers, Canton Ergos, to the Primare and popped I Robot SACD into the BDP-95. It sounded really good. I got to a loud passage and turned the volume down with the remote. Still too loud, so I turned it down some more. And more, and.. I finally put my glasses on and saw that the Primare was down to 0 volume and I'd left the TP30 on. I had been listening to the BA T-830s being driven by a 10 Watt (generous) class T amp the size of a sandwich in a 38'x28' room with the volume less than half way up and it was still too loud!
mains167 posts04-15-2017 4:52amNord One SE uses the same components as the Nord One UP, Hypex NCore NC500, twin SMPS1200A700 PSU’s in our beautiful sleek Japanese Mono Block or Stereo Chassis. SE comes with Nord Class A Discrete Input Buffer board with choice of discrete Op Amps, Sparkos SS3602 or Sonic Imagery 994 +£30 and Sparkos discrete Voltage Regulators. Choice of Dual Mono Stereo or Mono Block chassis these are what i use in the UK driving my soundlabs they sound amazing prices start around 600gbp up to 1700gbp for the top reference monos which are what i use i have heard nothing like them , very detailed , dynamic , powerful but so musical and natural sounding , i have tried half a dozen class D before these , no amp i have heard betters the nord they ship all over the world
Picked up a Calyx class d integrated over the weekend. Have to say I'm pretty impressed. Like it way better than the Rogue Sphinx I had for a short while. Lots of power, very smooth, good body to strings and voices, quiet as a mouse.
One really interesting thing about the Technics however is the heavy DSP processing they rely on to flatten the electrical amplitude and phase response. I'm tempted to do this with a miniDSP to see if I hear any benefits.
I have been using a miniDSP nanoDIGI (stereo digital in, quad stereo digital out) to equalize and bi-amp / tri-amp. Its very flexible. Using it I was finally able to tame the wild bass modes in my listening room. Get one, you won't regret it :-)
Yeah, I use it on my subwoofer along with bass traps and other room panels. It is essential for the last two octaves.
That’s not what’s being done here. DSP is used entirely for electrical phase and amplitude. The actual speaker/room response is not considered. Quite a heavy handed approach to making an amp perform like an ideal voltage source.
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