Understanding Amplifier power/ratings

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bluestar

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Hey Guys, this is very general and broad topic I know but maybe some members who understand this can shed some light.

I have a mckintosh 5300 100W amp, it works very well with medium - high efficiency (Easy to drive) speakers and most bookshelves but I recently took it to a dealers and tried with multiple low - medium 3 ways speakers like the atc SCM 40 passives and some other 'power hungry speakers' and as expected it failed to perform as well as much higher end 125W A/B amps and 250 W class D high end amps.

Theoretically - even if I only need 20W to reach the same DB level then why is class A/B 80 watts sometimes not enough but a Tube 30W is ?

I understand that 'current' and 'capacitance' measurements are also very important with wattage as well as 'Peak & Continuous wattage', so why are these not standard measurements with all amplifiers and dealers keep talking about 'quality of the current' and 'transformer' size but aren't all these measurable in terms of amperes or micro-farhads etc. What are the other measurements that one can email the company for to get a better idea of how much they are capable of besides wattage per channel and distortion etc ?

I started looking at class D amps using pre-optimized chips like Hypex and Purifi that measure well and this company Nord that uses it and has a 1200W per channel amp for about 2 L, the measurements for its 500W amp are here https://www.audiosciencereview.com/...-and-measurements-of-nord-one-nc500-amp.7704/ - it was recommended and had clean power till 200W per channel at 8 Ohms and costs 1L ! Why aren't more people using products like these ? Why aren't more companies selling products with these chips that have proven power (continuous and peak) and low distortion across frequencies ? Or is it just about companies tweaking their product till they get 'the sound' or is it that if they use these chips they can't charge very high prices ?

I know a lot of questions and all over the place but thoughts ?
 

Enkay78

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It’s nice you started this.
Even I was heavily interested in these amps, off course Class Ds

1. Sabaj a20a (balanced)


2. SMSL ao200

The price to performance is fantastic. I even am contemplating using the lesser price Sabaj a10a , buy 2-3 of them to power my surrounds and use 2 Sabaj a20a for my LCR.

SMSL and Sabaj both are powered with same Infineon chips. And look at their measurements, crosstalks etc.

a subjective view on Sabaj a20a :

As you know me @bluestar , I still remain a big proponent for measurements. I have bough Sabaj D5, Topping D90se and Topping A90 based on measurements and I am not disappointed at all.
 

Enkay78

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Why aren't more people using products like these ? Why aren't more companies selling products with these chips that have proven power (continuous and peak) and low distortion across frequencies ? Or is it just about companies tweaking their product till they get 'the sound' or is it that if they use these chips they can't charge very high prices ?
Cambridge is now selling Ncore

 

chander

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Why aren't more people using products like these ? Why aren't more companies selling products with these chips that have proven power (continuous and peak) and low distortion across frequencies ? Or is it just about companies tweaking their product till they get 'the sound' or is it that if they use these chips they can't charge very high prices ?
There are a few superlatives associated with Class D amps which are not very flattering and in general they aren't considered "audiophile". I am not saying they are so - but what I have generally read and discussed amongst friends.

Now there are many companies making these, some big names and some very expensive equipment too. There are takers and with the lines slowly getting blurred between the D and other classes, they could be big in the future - they haven't yet been accepted universally by the more discerning/critical/audiophile crowd. Again from what I have read and discussed with friends.

I also feel that most of us grew listening to a certain kind of sound and that is what brings the familiar happiness. It is like sparrows, when you hear them you know it is a bright day outside. A subconscious trigger, hence the sound of tubes is so highly regarded, LPs with all their pain points brings that nostalgia, the little pops and cracks brings happiness. It is how we are wired I guess - feels like home. So a change so massive that changes it all (if Class D associated sound signature is true at all), there will be resistance and general apprehension. Look at how much Class A vs Class A/B still triggers people - now going down 2 more alphabets and skipping "C" completely is obviously going to cause mayhem :p. But this is just my introspection. I may be completely wrong here.

I personally have experienced/heard a few. My recent experience and hence understanding is that they sound perfectly normal. Look at how many Crown fans we have here and more and more HT enthusiasts on various forums are going that way. The difference between them and any other class A/B amp is similar to various amps within the Class A/B topology. People say they are dry, analytical, soul-less, I personally didn't think so. I mean - similar adjectives are used for different class A/B amps too in comparison. I can from experience say that a Class D & a Class A/B have as many differences as there are between the Roksan K3 & and an Audiolab 6000a (I have owned both). I am not sure if Class D - a well tuned one are starkly different to what different class A/Bs tuned by different engineers are. But I do not have golden ears and a comment like this in most hifi forums will bring the wrath of heavens down upon me :p.

Regardless - I am hopeful for the future of Class D, let's see where it goes.
 
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Enkay78

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Maybe I am not an audiophile enough, I never couldn’t discern the difference between class A and D….or the tube sounds. (The fact that I am in a clinical profession could also do with it). But yes I do can discern distortions. I have don some hearing test online, and found I am not too bad ;).
I am not el cheapo….or anathemic to aesthetics , but I balk at all these expensive amps which are supposed to sound great….and when measurements are brought about….or even when the intervals are shown, the ‘magic’ somehow vanishes, replaced by a question of ‘Am I paying for an objective value of subjective one?’. I mean I am into this hobby for the music.
The fact that I don’t have much opportunity to audition varieties of amps could also be a reason. But somehow I am not disappointed by good measuring DACs or AMPs.
Personally I feel Class D is the future. And class A/B will be an outdated tech ……for nostalgic purpose (I am not making a battle cry…..but just an observation how things are going). Wireless Class D active speakers/system are coming in a big way , more affordable and going to replace the sounbars etc. ( Sony Hta 9 https://www.sony.co.uk/electronics/sound-bars/ht-a9 is an indicator of future to come. These will become more popular driving demands. )

Teac, NAD, Marantz, CA are going class D way…..and they won’t be alone. Boutique amps may either die out or remain as they are “boutique”. But guess when generation millennial gets older which tech will remain?

Personally I look forward to more performance/price driven by the newer chips…..with excellent THD and SNR. (Sabaj a20 balanced amp is an interesting product…..and an indication of what future is amps will become. DACs have already reach the threshold for audio quality)
 

Decadent_Spectre

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Music and video are subjective experiences and can not be quantified. To believe in objectivity is something people do when they need to believe there is something that is the "best" which objective measurements provide a standard so they can be sure they have the "best" and also to make themselves feel like they got their money's worth as people often correlate equipment cost with performance and there is a large section of AV enthusiasts who can not afford the extremely expensive gear that is often praised, so by buying cheaper well measuring gear they not only feel like they got the best but also they got their money's worth. On the flip side they feel like the expensive audiophile equipment is making a fool out of people by selling under performing (objectively) equipment for hefty amounts.

IMO A/V is subjective and people should buy whatever they like but it is notable here that objectivists are the ones who shout the loudest and are the ones who get the most angry on forums.

To come to amps, IMO it is subjective and one should listen and decide.
 

bluestar

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It’s nice you started this.
Even I was heavily interested in these amps, off course Class Ds

1. Sabaj a20a (balanced)


2. SMSL ao200

The price to performance is fantastic. I even am contemplating using the lesser price Sabaj a10a , buy 2-3 of them to power my surrounds and use 2 Sabaj a20a for my LCR.

SMSL and Sabaj both are powered with same Infineon chips. And look at their measurements, crosstalks etc.

a subjective view on Sabaj a20a :

As you know me @bluestar , I still remain a big proponent for measurements. I have bough Sabaj D5, Topping D90se and Topping A90 based on measurements and I am not disappointed at all.
Thanks Enkay, Will go over these, I guess if these measure well then the right next thing to do is to try them and see if they subjectively sound good and are a 'good match' with the speakers you have. Very interested in low cost good measuring devices... but overall I was trying to understand 'current' and why class D and Class A Wattage don't mean the same thing at all and what are the other contributing factors in a amplifier that lead the capability of driving 'hard to drive' speakers even though the wattage is the same. if someone can explain this would be great thanks.
 

chander

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Do you mind explaining your question a little more? I was reading on these lines fairly recently so if your question is slightly streamlined, I might be able to share some resources if they align.
 

bluestar

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Do you mind explaining your question a little more? I was reading on these lines fairly recently so if your question is slightly streamlined, I might be able to share some resources if they align.
My core questions is about what are the other objective measures of an amp like current and capacitance and give you a real idea of what they can drive since wattage is not always a good indicator for this, for example - class d 100 watts many times cant drive well what a 20 watt tube can drive . and i am not referring to the tone or anything but just feels like the speaker is not getting enough power. Other 100 watt higher end class d amps can however drive the same speakers, so what do the higher end class d amps have that the lower end one doesnt?
 

chander

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for example - class d 100 watts many times cant drive well what a 20 watt tube can drive
Is that really true? Have you experienced this? It is a genuine question - I am not being sarcastic :).

I am asking as whatever Class D amps I have heard they get very very loud. At present I am considering changing my Amp to a Class D Model 30 as I loved the sound it produced with Quad Z2 bookshelves.

**I will also share some of these resources I mentioned here - when I get the time to look for them!
 
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chander

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here you go - as promised @bluestar - there are a few more - if I find them I will post them.
 

Bloom@83

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Is that really true? Have you experienced this? It is a genuine question - I am not being sarcastic :).

I am asking as whatever Class D amps I have heard they get very very loud. At present I am considering changing my Amp to a Class D Model 30 as I loved the sound it produced with Quad Z2 bookshelves.

**I will also share some of these resources I mentioned here - when I get the time to look for them!
@chander if possible also hear your same speakers with a pure class A power amp(something like a Nelson Pass F5 ).They are big , weighty beasts , emit lot of heat but the sound is something….
 

chander

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@chander if possible also hear your same speakers with a pure class A power amp(something like a Nelson Pass F5 ).They are big , weighty beasts , emit lot of heat but the sound is something….
I would love too. But I do not have anything "pure" nor do I know anyone who has it! This is one thing I would love to hear and I doubt I have ever heard.
 

keith_correa

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for example - class d 100 watts many times cant drive well what a 20 watt tube can drive .
Can you please cite some examples of your experiences where you found this to be the case?

and i am not referring to the tone or anything but just feels like the speaker is not getting enough power.
I'm having trouble understanding this. What exactly do you mean? Why do you get this "feel"? What exactly is the feeling? Lack of output from the speaker? Lack of bass?

There is the "damping factor" to consider. There are many who believe that this determines the ability of an amp to "drive" a speaker well.
 

chander

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I did another A/B today morning :p. A class D basic XLS 1002 vs a Marantz PM6006, went to meet a friend, he uses PM for stereo and the class D PA for his HT. He was leaving Goa for a few months so I made it a point I do this today.

Now he is driving a very humble Diamond 11.1 with PM rated at 45W & Crowns at 200W+ this is an unfair comparison but we are discussing the fact that 20 W of pure A should choke the daylights out of 100W of D, by that logic I am guessing 45W of Class AB (with first couple of watts of Class A bias), should definitely choke the hell out of Class D 215W odd available on the Xls.

Disclaimer - this experiment was done by 2 audiofools, so it is far from scientific and could account for a big ol' turd for all I know, we do not know how to gain match, we have no idea what wattage was being used when we drove the speakers to a certain DB level.

Experiment methodology -
1 - The 11.1s are rated at 87DB @2.83V @ 1M - so we translated that to 87Db per W (if it is absolutely wrong - just laugh and ignore).
2 - 2 apps were downloaded for DB measuring (for accuracy - very scientific) - simple thing no extended graphs - as we realised we both know nothing what those graphs mean. I downloaded Decibel X for iOS and my friend downloaded some free app on android.
3- Now we played some music ensuring that the sound rarely peaked beyond 87DB from the speakers and we were within 2M of the speakers (toed them in a way that the sound stage was pointed at us) and then played - I for the first time realised how loud 87DB is BTW - it s ridiculous. Now I do not feel too bad about my Quads being 84Db sensitive. (I do not have golden ears but I have pretty sensitive ears and good enough hearing).
4 - Now with this experiment - I believe we were trying to do and achieved was - we are pretty much using the first couple of W - which should be pure class A in case of the PM and comparing it to the first few watts of the XLS. So this should account for pure class A vs class D. Am I correct?
5 - Anyways being complete idiots we concluded that is what it means and compared the sound in terms of whether the speakers feel restrained or not.

Now - not comparing the sound quality as both amps had very different sound signature - with both having very enjoyable sound really, we tried to "hear" if it feels like something is choking or we need to crank up the volume and make it louder than 87Db for crown to shine.

NOPE! Both are uncomfortably loud at 87DB, both have very decent details - neither are extremely amazing :p, both have their own strengths, XLS sound louder at 87DB - not sure why, maybe because it is a bit top heavy/treble heavy but also has more bass at 87DB. Another thing we both observed was that marantz would sound better as we keep gaining more - so for example when we went from 80Db -87Db it sounded progressively cleaner - thought at 87DB it was just too loud, XLS sounded the same from 80Db-87Db just kept getting louder and was very loud at 87Db - so much so we had to take a 15 minute smoke break - after listening to Crown at 87Db for less than a minute.

There was something about the crown though it was not as detailed as the 6006 and a bit treble heavy - BUT, much better at low volume and much cleaner at low volume - very quiet background (till the fan comes on) and sounds wider.

****Like I said this experiment was done by 2 idiots, who know nothing, so this is not the final word into the Class D vs Class A, but for now I feel satisfied enough that Class D are pretty decent and for the price quite a steal - I am convinced enough to suggest friends to look at Class D too if they got something that needs a lot of power. Need to hear a pure Class A to feel the real difference.
 
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bluestar

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Is that really true? Have you experienced this? It is a genuine question - I am not being sarcastic :).

I am asking as whatever Class D amps I have heard they get very very loud. At present I am considering changing my Amp to a Class D Model 30 as I loved the sound it produced with Quad Z2 bookshelves.

**I will also share some of these resources I mentioned here - when I get the time to look for them!
Hey,

So i do feel we are going to in circles after this reply but here goes

Yes, I have experienced this first hand. Its not that the class d can't 'drive' the speaker, it can but its very thin and it really feels like the speaker needs a lot more power. I tried the same with a low wattage tube and the speakers didnt seem to need anything more... maybe you guys are right and it has nothing to do with technical specs but just preference and sound quality that is preferred.

Heres another thing i have noticed - Theoretically if you need 5 watts to get a speaker with a specific efficiency to play at Y DB which is your preferred listening level - that wattage to BD relationship seems to be much more accurate with tubes and class A ; with mid end class D amps like the NAD 388 which i have, i have to go way above that level to get to the preferred listening level. Granted i'm not sitting there with a DB meter and also I am not checking the wattage output of the amp and am judging it off the % volume which may not be purely linear but gives you a fair idea.

Please note, i don't dislike class d sound at all, its just something that i've noticed playing around with the amps that I own and various experiments done at dealers. Experiments at home have been between NAD 388, Wellsington R8 from china hi-fi between the class d and tube. At dealers i have tried out much higher end class d amps of 225W per channel where the difference was a lot less.
 

chander

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So i do feel we are going to in circles after this reply but here goes
Sorry if I have made it into a stupid noob circus :p, the curiosity got me and hence I started digging in and posting here. I am like the vampire who is always sucking off the good experienced knowledge here and in return dump a verbal diarrhoea :p.
 

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With a tube pre, (even a cheap one) the crowns sound much better. Not lean, not treble heavy just right for my tastes. My playing levels rarely go above 75 DB at my seating position which is around 6 feet from the speakers.

Edit: I have to now take my crown xls 2502 and my tube pre to my dealer friend to test it out with the Quad Z2s.
 
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bluestar

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Sorry if I have made it into a stupid noob circus :p, the curiosity got me and hence I started digging in and posting here. I am like the vampire who is always sucking off the good experienced knowledge here and in return dump a verbal diarrhoea :p.
haha I love ab testing of any kind but this was a very complicated Ab test and actually instead of just changing one variable i.e. A & B you had 4 variables - 2 amps and 2 speakers which complicates matters.

Can you simplify your conclusions? i can't seem to parse out the conclusions from the writing. The only issue i can see here is you were using fairly high powered class d amp with 200W per channel +, i think the point of the discussion was to say that mid end class d of 100W or below struggles with 'tough to drive' speakers that seem to need a lot of current (Especially low efficiency 3 ways ) whereas tubes the 5 watts is all you need.

its another thought, if an audiophile only technically needs 5 watts to get to desired db then why do people even bother with getting 200 - 500W per channel class d amps, whats the point ? when is the last time you saw a 15W class d amp but people buy 15w tubes all the time.
 
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