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Good Class D amps ??


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Mola Mola's Kaluga monoblock amplifier ($16,500 USD per pair),which  had their measurements shown on P.1 of the other thread, are from Bruno Putzeys company Mola Mola, and  are using the latest generation nCore amplification technology..

 Many other amplifiers use these higher powered NC1200 versions.The Bel Canto  REF600M monoblocks have similar shaped output measurements, but not as good as the enhanced higher output power Mola Mola.

The Kaluga circuit is designed around modules that are apparently enhanced versions of the NC1200 created for OEMs., also shown on the same page has similar looking measurements, although the tweaked flagship model from Mola Mola has achieved lower distortion figures .

 

More info about the Bel Canto REF600M (Price: $4990/pair)

Quote
 
Bel Canto  REF600M monoblocks :
Inside 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.
Read more at https://www.stereophile.com/content/bel-canto-eone-ref600m-power-amplifier#QlxKMqg0heVxdC91.99

 

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

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9 minutes ago, Ralf11 said:

Technics has a Class D using GaN devices

 

and the nad M series?  are they Class D?

 I don't know about the rest of the Technics Master range, but The Masters Series M22 is based on a version of Hypex Electronics' model NC400 NCore amplifier module that has been customized for NAD.
Read more at https://www.stereophile.com/content/nad-masters-series-m22-power-amplifier#Hjkw5oqW1daEkfmi.99

 

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38 minutes ago, esldude said:

Below are the graphs at moderate power from Stereophile testing of three well known brands of very powerful amps of class D, A and AB operation.  Which is which? The drive level is at 8 ohms, 4 ohms and 2 ohms with lower impedance giving higher distortion in each case.  We are looking at roughly 20 watts into the 8 ohm load and all amps are capable of well over 250 watts.  This graph is THD+N vs frequency. 

 

 Perhaps a case of selective choosing,(?)  as NONE of those amplifiers' specifications  are particularly impressive.

 There are many lower powered designs available as DIY kits at a fraction of the price that will easily outperform these amplifiers at 20W, and almost certainly at a much lower cost ! e.g. the Silicon Chip Ultra-LD Mk.3 200W Amplifier, which has since been superseded by the Mk.4 version

e.g. http://www.altronics.com.au/p/k5165-ultra-low-distortion-mk.3-135w-stereo-amplifier-kit/

 

SC ULD 3 p.1- Specifications.jpg

SC ULD 3 p.4a.jpg

 

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16 minutes ago, esldude said:

 

Yes, definitely selective choice to get across the point class of operation isn't by itself a key parameter.   BTW your graphs in this post don't show THD vs Frequency.  All the amps in my earlier post show very low distortion at rated power at 1 khz. Actually a somewhat deceptive practice among class D amps as they do better than than at higher frequencies usually. 

 

I could have picked this Benchmark which I think JA said might be just measuring his AP rather than the amp.  This one near 30 watts rather than 20 watts btw.  

 

This Benchmark and the mystery amp I posted above are among the best such I have seen with this measurement.  

 

The other thing worth noting looking at Soundstage.net measures is nearly all amps actually have lower distortion at higher power until just before max power.  So the idea your smaller 20 or 30 watt amps would show better than the 20 watt results for 300+ plus watt amps isn't surprising.  Shows the importance of sizing amps and speakers for minimum distortion.  When is the last time someone discussed that.   

 

These 300 watt amps operating at 20 watts in the Stereophile graph of THD+N vs Frequency more than likely show lower distortion at higher power.   Such nuances are why amps might sound different with different speaker loads while all having similar measured performance.  A topic not discussed or investigated nearly enough. 

 

1115BAHB2fig07.jpg

 

 

 

 Attached is the SC ULD -Mk.3 which has since been superseded and improved on by the Mk.4 version which I don't have a copy of.

Note that the graph here shows THD + N at 100W into 8 ohms.

 The performance is substantially better at lower powers.

 

SC ULD 3 p.3a.jpg

 

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3 minutes ago, esldude said:

So that is very good, but not quite equal to the Benchmark measurements posted above or the other amp tested by Soundstage.net which btw is the large Bryston mono amp.  The only one to pass  the transparency listening test both sighted and blind by the Swedish AES. 

 But the complete kit, including metalwork for this one is only $749 !!

http://www.altronics.com.au/p/k5165-ultra-low-distortion-mk.3-135w-stereo-amplifier-kit/

 

This old 2011 design can also be further improved by Input and Output device selection !

 An experienced DIY person could markedly improve the measured performance of this amplifier.

 

 

 

 

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2 minutes ago, esldude said:

Yes, looks like a darn good amp and a super value for what performance you get.  But that wasn't really the topic here.  

No.

  You are still trying to show just how good Class D amplifiers can  be in comparison with a decent modern Linear design ! :P

 The SC ULD 3 can also be further audibly improved with a simple front end balancing technique, but you refuse to accept  that any further audible improvement can possibly be heard at such already low distortion values !.

 

http://www.diyaudio.com/forums/solid-state/133018-current-mirror-discussion-15.html

 

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16 minutes ago, esldude said:

At normal listening levels the differences in distortion you think are audible would be like adding or subtracting an amount of sound that is 30 db below the audibility of human hearing, and with noise in the listening room obscuring it even then. 

 However , the fact is that these findings were verified by several DIY Audio members, both in the original and a later SC ULD mod thread , from which  you have already previously seen the measured levels at around -130dB.

 Both Nelson Pass and Douglas Self who were participants in the original thread had no problems with the findings either.

Perhaps they know a wee bit more than you do ? :D

Douglas Self was already recommending matching of LTP transistors to 1% in his books.

The spike around 7KHZ is an artefact of the PC used.

 

5v7Nv5.jpg

 

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1 hour ago, esldude said:

A level of astounding BS.  All designs have areas that have to be handled.  AB is doing the handover without distortion.  A is having low distortion with enough power and current.  All devices and classes of operation have issues.  There is currently no electronic device (tube, bipolar transistor, FET etc) that has a straight transfer curve.  

 According to prominent Audio designer and Author Douglas Self :

Quote

Class-AB
This is not really a separate class of its own, but a combination of A and B. If an amplifier is biased
into Class-B, and then the bias further increased, it will enter AB. For outputs below a certain level
both output devices conduct, and operation is Class-A. At higher levels, one device will be turned
completely off as the other provides more current, and the distortion jumps upward at this point as
AB action begins. Each device will conduct between 50% and 100% of the time, depending on the
degree of excess bias and the output level.
Class -AB is less linear than either A or B , (my emphasis) and in my view its only legitimate use is as a fallback
mode to allow Class-A amplifiers to continue working reasonably when faced with a low-load

 

 

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1 hour ago, crenca said:

What is a good class D design in your opinion (you know, the topic)?

 I presume that you have seen the comparison graphs between the latest design Class D amplifiers and a good Class A or Class B design ?

 I have yet to see ANY graphs of Class D amplifiers where there isn't a tenfold increase in distortion between 5KHZ and 20KHZ in some cases, and as low as 2KHZ at some modest power levels, to 20KHZ.
Even the flagship Mola Mola Kaluga from Bruno, which starts off at around .0013% to almost 5KHZ at 10W power output, has almost a 100 fold increase in distortion from around 5KHZ to 20KHZ !

It's not too shabby though at around .004% at the low power level of 1W into 8 ohms though.
 Recent design Class A and Class B designs can however have distortion figures as low as (or better) than .0006% to 20KHZ.

 

It all comes down to whether or not you believe that very low distortion matter or not with Solid State amplifiers.
I would put it to you that the improvement that many members in other areas of the forum are hearing with modifications to various types of equipment, involves improvements in distortion figures of at least as low as the distortion in the Mola Mola Kaluga at an output power of 1W, perhaps even less.

The human ear appears to be far more sensitive to low level distortion, in the absence of higher level masking music material than most give it credit for.

 

"  The area that Class A needs help is just another area (e.g. heat/power/efficiency, etc."

 

Why should this be of concern for people who use say, 20W to 50W maximum Class A amplifiers, when Class D amplifiers used by many members at ear splitting levels into inefficient speakers STILL consume far more electricity overall ?

 Have you gone " Green"  and become a " Tree Hugger " too ? :D

 

 

 

 

 

20W Class A at 10W vs. Bel Canto Class D..jpg

 

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10 hours ago, barrows said:

Because the idle dissipation is the problem.  Take my former Pass Labs amplifier, it required at least an hour of warm up to reach thermal equilibrium and its best operating condition.  It seemed to sound even better though when left on overnight.  In any case, I could not predict with an hours advance notice when I was going to be listening, so if I wanted the amp to sound its best it had to be left on 24/7.  Although it was not a high power model, it still idled at ~250 watts.  So that is a significant energy waste.

 I imagine that someone like Nelson Pass has since found a way to overcome this problem ?

A well designed SS amplifier should sound very close to it's best within minutes of switch on.

 The main problem is with the front end devices fully stabilising.  The output stage transistor Bias can also take a little while to reach it's designed value. This can also be overcome by proper temperature compensation measures.

They tried to do this in some power transistors using an integral separate diode.(ThermalTrak)

With my DIY Class A Preamps and Power Amplifiers I use a method of temperature compensation in the Input Differential Pair , using a Silicon Diode with a similar temperature coefficient.

This was discussed in a DIY Audio thread from 2008.

 

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7 hours ago, barrows said:

 I also find Herbies Tenderfoot soft/tall footers are a better match with this amp than the Stillpoint Minis I used to use.

 

Of course, you are undoubtedly referring to performance issues, not their looks.

 Not that some members will accept that things like this DO matter!

 A C.S.I.R.O (Au.) friend of mine is a big Herbies footers fan too.

 P.S.

 As expected, some very nice workmanship on your part.

 

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37 minutes ago, barrows said:

but ultimately the Ncore had a lower noise floor,

There is no valid reason why the Pass should not have had a lower noise floor unless it was a much earlier design, or it's main filter electros had partially dried out due to heat related issues.

The nCore obviously would need a huge amount of work done to eliminate the extremely high RF/EMI generated by the switching action at a very high power level, partly due to FCC requirements, whereas the Pass would not need this.

 Could it be that the nCore has a noise gating action in the absence of a valid signal ?

If so, I suppose something like this could also be done with a Linear amplifier to further improve S/N to ridiculously low levels for specification boasting purposes ?

 

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16 minutes ago, monteverdi said:

Did you ever had a newer Hypex (or Anaview) derived amp next to a Passlabs?

 Just remember that many of you would be pitting the very latest technology against a much earlier design  Pass amplifier.

Linear Amplifier design has also further improved in recent years as evidenced by the extremely high S/N of the Benchmark design.

 

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13 minutes ago, barrows said:

Hahaha, you are making me laugh:

 

1.  Look at the specs, the amp was the X150.5, and no it was not old or anything.  I was the first owner and purchased it new.  

     The Ncore amps are exceptionally low noise.  Anyway can see this in the specs.

 

2.  I did the listening tests of this right here in my own living room, it was easy enough to hear the differences.  And this was 

     was not short term listening alone, I tested over a year long period.

 

Please stop posting this nonsense when you clearly have no direct experience of it, and cannot even be bothered to look at the noise floors, or S/N ratios...  This info is not hard to find, and no i am not going to be bothered anymore to go and look it up for you.  Look at the noise floors with signal, in order to rule out your absurd theories...

Again, I will repeat that there is no valid reason why a well designed recent Linear Amplifier can't at least equal the S/N of your beloved switching amplifiers. This is evidenced by the most recent Benchmark design which claims the highest S/N of any amplifier.

You are pitting the latest and greatest (?) Class D amplifier against the attached !

Give me a break. There are far better Pass designs at higher starting prices.

 

" classaaudio.com.au/index.php?id_product=200&controller=product

The smallest stereo in the X.5 series, offers a nice basic stereo power amplifier......

 

X150.5 / Specifications     Gain (db) 26

     Power Output /ch (8 ohm) 150

Power Output /ch (4 ohm) 300
 
Input Impedance,(Kohms) 30 / 20
 
Leaves Class A @ pk Watts 10
 
Power Consumption (W) 200
 

 

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7 minutes ago, monteverdi said:

Also energy efficiency should as important as sound quality in evaluating amps.

 

Try telling that to the numerous Vacuum Tube Amplifier lovers in the forum ! ;)

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

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14 minutes ago, barrows said:

I am still a great admirer of the Pass Labs amps, and if I ever got some much more efficient speakers, I could imagine the current Pass Labs XA 30.8 in my system as well, given that the capitol was available.

 

Unfortunately, you chose to offer a comparison of the very latest nCore technology against what is a basic Nelson Pass affordable design with a very limited power in the Class A region of 10W.

I haven't heard this particular Pass amplifier , but I have heard the large Pass Class A 100W (150W ?) monoblocks through a >Au $100K system, which even presented a very real simulation of height in  a 16/44.1 downmixed recording of a Storm from a Chesky Hybrid SACD. It's rendition of the storm made me involuntarily jump.

Given further improvements in the flatness of the distortion spectrum to 20KHZ in future Class D designs, they will undoubtedly command a much larger share of the market. I just don't believe they are quite there yet.

 

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13 minutes ago, barrows said:

Stop making excuses.

 I'm not the one making excuses.The facts remain about the huge increase in distortion figures to 20KHZ with the nCore amplifiers that you refuse to accept can affect transparency.

 I tried to be conciliatory and meet you half way in my recent post, but then you just had to come back with this comment, didn't you ?

 

 I am  out of this fanboi thread. I will leave you to GUTB.

 

 

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Just now, esldude said:

While something stays below .01 % THD at high frequencies is better performance I don't think it is audibly different than one which rises to .1% or manages .001%.  

Dennis

 Just briefly, before I leave this Fanboi thread.

If I posted figures like those shown on page 1 of the other thread,for distortion vs. Frequency with my 15W Class A amplifier,

or any other Linear amplifier for that matter, you would just about wet yourself laughing , and tear it to shreds in your reply post !

 Because you own a Class D amplifier you make excuses for the same deficiencies, claiming they can't compromise transparency.

I have yet to previously see you let go of measured deficiencies so obvious with any other type of equipment.

 You would rip the design to shreds and claim that it couldn't possibly work as well as many claimed, possibly quoting Archimago and posters in other forums as well. O.o;):P

 

Alex

 

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Just now, esldude said:

Find an instance of me doing such a thing.  I don't think I would on something that hit a tenth or two at 10 khz and above.  I might if it occurred at lower frequencies because they might under some circumstances be audible.  And I have said, it would be better performance if that didn't happen.  Yet I don't think it a real big audible thing.  

 

Closest I can recall is how some tube amps of moderate power quote a bandwidth at 1 watt and 1 % distortion with less bandwidth and more distortion at higher powers.  And yet I also have said I enjoy the sound of those despite those numbers. 

 

You conveniently ignore your attacks on the USB Regen which had pissy little artifacts at levels you consider are well below audibility .

 Anyway, carry on with your preaching to the converted.:P

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

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Just now, barrows said:

Your bias is so strong you cannot see the forest for the trees.

 

I only mentioned the 100W Class A because you mentioned the one you owned that went to 10W in Class A

 Attached is very similar to what I personally use.

 That's what a genuinely transparent amplifier should measure something like .

BYE !

20W Class A Distortion.jpg

 

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1 hour ago, firedog said:

Most manufacturers don't have  the knowledge or experience  to produce such a PS, so they don't. Too much trouble and expense for them. If you don't have experience designing them, why go to the trouble and R&D expense of producing a suitable one when alternative technologies exist that are known to you and suitable? And cheaper for you. 

While I agree with the first part. I think the expense is more likely to come down to economies of scale.

 I don't believe that if enough of these types of SMPS were produced that the cost would be a problem.

 Have you any idea how much a large toroidal transformer capable of powering a high power amplifier costs (500VA or more) ?

Add to that the sheer weight of the beast, and the larger enclosure needed for the amplifier as a result.

 Good metalwork is not inexpensive either, and would need to be substantial to support such a heavy transformer.

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

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41 minutes ago, esldude said:
  4 hours ago, Nordkapp said:

Would you mind briefly outlining your education and background in science or engineering, @GUTB  ??

 

 

Not happening.

Talk about snobbish. :o


What do your Academic qualifications have to do with the enjoyment of music, and your ability to discriminate between good quality sound and crap ?
 If this was the case, many modern record producers with their OTT amounts of compression must have run away from school straight after Primary School !

 

loudnesstrend.gif

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

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3 minutes ago, esldude said:

Is your system also neurotypical?

 

Your usual Objectivity out of the window, and running with the Hounds Dennis ?:o

I also note that recently you are also using a great deal more sarcasm lightly camouflaged as Humour.

You can do much better than that !

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

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29 minutes ago, Ralf11 said:

it was hilarious

 

even if GUTBs fanboi didn't like it

 I am NOT a GUTB Fanboi.

 There is no excuse for some of the comments made about members that you may not agree with.

 I have already posted distortion graphs that clearly show that  some Class D amplifiers can NOT possibly be completely transparent, no matter how many people may like and prefer them.

This includes Dennis himself, who owns and uses a Class D amplifier, yet his usual listening with his test equipment has on this occasion been thrown out of the window. :P
 

They are clearly technically far from perfect at this stage of their development.

The same Fanboi silliness goes for Vacuum Tube vs. Solid State,Vinyl vs. Digital, Mac vs. P.C. etc. etc.. 

 

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

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1 hour ago, Ralf11 said:

Sandaleck, that isn't what Gutb said - you have a tendency to try and change the subject when you are caught out

 

 I didn't quote anything that GUTB said ! 

Do you have a reading comprehension problem ??? 

Perhaps you should stick to your " Slut-Equipment shaming"  instead of people ?;)

 

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

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