Today's silly question; why should amplifiers sound different?

I notice that over on TonyL's Pink Fish, there's a thread on the subject as to why Naim stuff is so dynamic. It is now quite large and I couldn't be bothered reading all through it, but it raised the question in my head; why should amplifiers sound different. Peter Walker of Quad once described an amplifier as "a piece of wire with gain", and in my early days of listening to hi-fi (starting in the early '70s), there was nothing about amplifiers sounding different - this seems to be a recent phenomenon.

So, can anyone out there please explain to a non-electronics person why amplifiers should sound different? I would have thought that there is a limited number of possible amplification circuits and that many amps must therefore use pretty much the same circuitry. Does it come down simply to different components (better quality components= better sound performance)? Or is there more to it than that?

(I really must find a Naim dealer and listen, just out of curiosity - I've never actually heard any Naim. There must be one in Zürich somewhere).

 

I'm not probably the best person to answer this question as my electronics knoledge is only slightly above average. However it depends on many things.

Some transistors have greater memory effects, i.e the music is stored for a fraction of a second, this can make the sound harsh.

The size and type of capacitors well effect the dymanics of the sound because of the it directly affects the amount of energy avaliable for peaks in the music.

Thw qaulity of components also can affect the sound quality as its in the signal path. The purer the materials and conductors used the better.

The amount of power the amp has (i.e how powerful the tranistors are) means it can control the music better. Also amps that can deal with heat better also sound better as they won't distort as much. If an amp has very poor heatsinks it will distort. This why a lot of cheap power amps used in pubs etc have fans on them.

I hope this helps but you probably already knew all this.

 

I think he was refering to the "perfect amplifier" with that statement, one that doesn't add any distortion to signal.

I can't attempt to answer you question as I'm not an electronics expert but I do know that certain manufacturers voice their products differently. Hence amplifier quality will ultimately come down to the listeners prefered taste.

 

Amplifiers are complicated things. The "wire with gain" model is one used a great deal in teaching people, but in my opinion it is VERY misleading.

If you consider a single emitter follower transistor circuit, your signal comes into the base of the transistor (ignore bias for the moment, we'll assume it's sorted), and the transistor has a gain of 100 or so. That means we get our signal plus 100 times our signal going out of the emitter into the load.

Where has this 100 times the signal come from? The power supply. Thus, in my opinion, the power supply counts for a hell of a lot more in the amplifier than the "wire with gain" model suggests (because in that model, we draw a nice +Vdd rail, and a -Vss rail, and they give us a beautiful, clean and lovely +/- 50V or whatever, but in real life that DOES NOT HAPPEN).

So, sticking with powersupplies, if a (linear) supply is poorly regulated, we will get 100Hz ripple in a sawtooth (which has other harmonics). This will feed to our output.

And, if a power supply isn't stable enough, the voltage rails will fall when the amplifier is being driven hard, essentially reducing its power.

Coming to the signal parts of the amplifier, the input stages will have an effect. First of all, the input impedance may or may not cause the output stage of your source to behave in an unusual manner. Second, since the voltage gain from this point forward is quite high, the quality of resistors used is of prime importance so as to avoid thermal hiss (turn your amp to maximum volume and walk up to the speakers. You should be able to hear a hissing/white noise, especially so on a phono stage (due to yet higher voltage gain). This is thermal noise).

Of course, we know that there are various amplifier output stage designs. Class A, Class AB, Class B, Push-pull variations, Class D/T. Within the classes, yes, a lot of amplifiers DO sound similar as they will have similar distortion characteristics. However, power supply, quality of components, etc will vary and give rise to differences in sound there.

Then there's the issue of layout. It's all very well having a schematic of a circuit that works on paper. However, when you come to build that design on a PCB you can end up with ground loops causing humming, things interfering with one another and just generally not doing what they're supposed to.

Casework. Rigidity and weight can affect microphony (more of a problem with valves of course, but at a very low level it can affect solid stage amplification) and shielding.

So, there's a few reasons for you.

 

Aha, but what kind of wire? <ducks, covers>

Tony.

 

There are those on the objectivist extremes of our little hobby who contend that all reasonably well built amplifiers sound the same. I'm not one of those people btw

Michael.

 

It would be great if all hi fi components could have the same characteristics as a straight wire with gain. ie nothing added, nothing taken away.
You could create the perfect system with no synergy or compatibility issues.:MILD:
________
Glass bubblers

 

I have absolutely no idea whatsover.

I have tried loads of amps, some I like and some not so, they all do sound different, and you can have much fun, they are all real individuals with distinct personalitiesof their own.

The only thing I can explain it by is the sum of the whole put together, meaning you can't take a little bit and say it has really good sound quality.

I have heard poor sound with great ingredients, so I think by and large the 'character' of sound that emerges is largely a result of the design, the whole, and this cannot be predicted at all. You try telling a designer you want tight bass, transparent mid, and non tiring treble.
He couldn't design it in, he could put the things in that are reputed to do that, for eg a big power supply, and lots of powerful transistors, modern ones, but you couldn't give him a sound spec. and get exactly that out. In fact try doing that, commission a designer your PRECISE sound quality, he couldn't do it.

this leads me to think, good components making bad sound, that the components are not that critical, as the designs were very compenant, and vice versa, I have heard old designs with run of the mill components to sound fab.

Personally, I really like naim, I heard a demo of a denon dcd835 and pma 350se against a naim system. Naim power amps are all the same, the dearer ones have a bigger psu, that's all.

And the cdi is the most musical cd my ears have ever heard, inc. chords dac64 and a fully modded eikos.

needless to say, the naim blew the denon away totally.

I was truly shocked.

I was even more shocked to discover naims circuits. They are based upon old american rca applications notes, no magic at all, no posh components, old design, very simple circuit, nothing mysterious about them.

the only slilghtly unusual thing is the output stage topology, quasi complementary is the technical word, it was designed to save cash. Its measured performance is not marvellous.

The only conclusion I have come to is this.

There sound quality (character that comes out) cannot be built in as such, but the simpler the circuit, and sometimes even if it means a poorer measured performance, most times the sound is better than a complex japanese design designed for technical perfection.

Simple is best.

 

I confess to tending towards that view, Michael, but that's based on a very small amplifier sample. I've long since forgotten what the very first one sounded like (a Sansui AU-101), but the others (Quad 33/303, Quad 44/405-2, Linn Wakonda/LK85/LK100 and EAR 834 pre-amp (operating through the 405-2)) are still with me. To my ears, none of these sound much different from the others (until the Linns went active that is). I guess I simply know what I like for my (almost completely classical) listening and I buy that type of sound. Perhaps, I tell myself, I should listen to more amplifiers, but then I ask myself, why bother?

 

I'd turn it around: since all amplifiers are different, why should we expect them to sound the same?

A long, long time ago, I heard an early example of the Musical Fidelity B200. It sounded pretty good. The importer asked what I thought of it, and I said it was going to be a pretty good amp at the 2000 DM price point. I was then told it was going to cost less than 1000 DM.

Some time later, a dealer friend loaned me a later sample, and it sounded much worse. Two identical amps, on the face of it, but a substantially different sound.

IIRC the first sample I'd heard was made in England, with European components. The later production came from the Far East and used parts available from Far Eastern suppliers. The same design, the same values of the components, just different suppliers and possibly different manufacturing techniques. And very different results.

 

Re: Re: Today's silly question; why should amplifiers sound different?

But are they, Markus? They are different (I thought) only because everyone puts a different badge on them, but that's all. I thought they couldn't be that different under the skin, simply because the number of variables in the equation couldn't be that great. Obviously that't not the case. When I look at Isaac's splendid and occasionally comprehensible answer (I'm not an electronics person, remember), I rejoice that I'm not an audiophile!

 

I'm no electronics expert either, but confess I'm somewhat intrigued by the latest Sony ES series AV receivers, in that they are using digital amplifiers.

Now I realise, and speaking as an Naim owner, that Sony and so called high end products don't usually go in the same sentence, but I'm intrigued. as over in the US, I've read on a couple of HT forums of owners of VERY expensive AR valve amps trading them in on the top Sony DA9000ES digital receiver, as apparently it has a very smooth liquid so called valve sound that rivals the AR's, provides HT DD & DTS decoding etc, and costs a great deal less into the bargain.

I've read some of the details, and as a layman re amplifier design, it strikes me that the digital approach seems to address many conflicting issues with analogue amplifier design, re the tweaking and getting the balance of things right to get the best results out of a particular design.

No doubt digital will have it's problems, but simplicity seems to score very highly in it's favour as far as I can tell.

So is digital amplification the way forward in amplifier design perhaps?

Just some curious thoughts

Cheers

John....

 

tones, I believe you read German? In Switzerland, you should have access to the German magazine Stereoplay. That mag regularly publishes graphs of dynamic distortion characteristics of amps, i.e., how does an amp distort at varying power levels. You'll find substantial measured differences between amps.

Some amps have low distortion, other amps have high distortion. Some amps may have highish distortion, but the distortion change is linear, i.e., as the power output is increased, the various harmonics rise at the same pace. Other amps will have certain harmonics (3rd and higher being the most unpleasant, especially the uneven-numbered ones) that rise faster than others, i.e., they distort in a non-linear fashion, which is something that doesn't happen in nature and which is a pretty good indicator of unpleasant sound.

So, given that there are measurable differences between amps in areas which have been proven as audible, why should there not be differences? Not that I'm saying al differences are based on this mechanism alone, but since there is at least one mechanism which is "science"proofed", if you will, I can see no reason why there shouldn't be other mechanisms which have yet to receive scientifi attention, but which will influence the sound whether they have recognised by science or not.

I really do think that you should get out a little and listen to some different makes. Have you been at titian's? You could bring your amps to his place and compare his set-up with yours; I'm sure he'll be glad to have you over.

I'd be surprised if you didn't hear a difference. Whether that difference will be musically important to you is a whole 'nuther matter.

Oh, and there is a learning curve associated with hearing differences. If I may stray off-topic for a moment, I recently did a comparison between speaker cables (touchy subject, I know). On the first chanegover, I heard nothing. On the second, I did hear something. Now, some will say I was expecting a change and that was the reason I did hear one. But the change I heard was against my expectations: I fully expected the cable I tried to sound better than the one I had been using before, it was much more lavish and expensive. But in fact, what I heard was a slight degradation in sound. I had to overcome my expectation bias to hear what heard.

No reason to think you are unable to overcome your expectation bias and find differences between amps.

 

Re: Re: Re: Today's silly question; why should amplifiers sound different?

Woohoo! I'm getting better!

 

actually Isaac, I think one thing is you are erring on the 'technical' design side, and the most important thing to me is the sound, do I like it?, and you appear to be assuming excellence in design will translate to sound quality, in my experience this is not so, also, I have heard many amps in the same category, and they sound different, there is a shed load more to it that simple distortion characteristics,

oddly enough, the amps that do sound similar to me are push pull valve amps, pentode types, el84, 34, and poss 6550s. they have a similar signature, still differ, but there is a definite similarity.

I would say from what I have heard that tranny amps are more variable than valve ones?
Also, perhaps due to mains, as yet I haven't found valves to be extremely upset by poor mains, but haven't tested this much yet.


the bias, as you will know, is only to minimize crossover distortion, that is all, there are MANY more distortions present in amplfiers, speaker induced, how complex you 2nd stage is, (voltage stage) loading by the output stage, the input stage complexity, possibly the most elaborate part of the amplfier, the methods for stability compensation ( little capacitors designed to reduce the feedback at high frequencies to stop you amp frying your speakers). The amount of feedback, possibly very significant.
All these affect the distortion character, and I am not convinced, measurements being low, this is audible in itself, it may well change the overall character of the sound that results, but you can't really isolate an effect IMO.

As an aside, distortion is widely held among experts to be inaudible below around 0.2%, or the other way around you only notice its effect on sound above 0.2%.
2nd harmonic is meant to fatten out the sound a bit, make it smoother,
3 rd adds a bit of brightness

even is meant to be nicer
odd harsher.

when you get to higher harmonics these are unmusical and add greyness and harshness to the overall sound, if they are a significant %

 

Regarding John's question, is "digital" amplification the way forward, the answer, imo, is clearly yes.

Why did I put digital in inverted commas? Because it's a bit of a misnomer. Class D is so called no because D stands for digital, but because it came after class C, which came after B, etc. Class AB that most of us know is a cross between class A and class B.

The other reason it gets called digital is because the output switches between high and low (it has two possible states, like a digital system). The distinction is subtle, but class D (and T) are "switching" or "PWM" (pulse width modulation) amplifiers.

Why are they the future? Because the future of hifi in the mass market is more living-room friendly, and more channels. With LCDs and plasmas, the TV no longer takes up half of a british living room, so the hifi isn't allowed to either :SWMBO: The very high efficiency (~95%) of PWM amplification makes them good for this, because power supplies can be smaller, little to no heatsinking is required (unlike my Class AB amp with several square feet of heatsink per 100W channel) so the component can be made very small. In addition, cheaper, smaller switchmode power supplies can be used because if the psu switching frequency is tied into the amplifier's PWM frequency then the output filters of the amplifier will remove both. Thus a manufacturer can make a tiny little box (by class AB standards) that will give you 5x100W for real.

Many companies are going that way. Bel Canto in the high end famously gave up their life-long champion Single Ended Triode amplifiers in favour of the Tripath Class T (a variation on class D, mainly a marketing thing), and Sony have released some high-end S-Master class D amplification. Looking more widely, Harman Kardon are using the D2Audio PWM module, and there are various others on the market (sharp and yamaha have their own, Michaelab is working on his LCaudio based amp, etc).

The other side of it is that for the costs involved, class D and T can (but do not necessarily DO) sound extremely good. Better or worse than "traditional" amplification (worth noting that Class D came about in the 50s) is down to taste of course (much like solid state vs valves).

For the mainstream market (mini/micro systems, hometheatre, etc) within the next 3 years class D amplification will be the majority of products sold. In hifi as we know it, of course there will be manufacturers who will stick by class A, AB and so on, just as there are manufacturers who stick to valves. However, I think we will see more and more class D amplifiers here as well.

The other side of "Digital" with regard to class D amplification is that they can be and often are microprocessor controlled with DSP (D2Audio, Sony S-master and Tripath Class T all are). This means that any analogue input is converted to digital, processed, output to the output drivers, where the "conversion" to analogue is essentially a by-product of the amplification process. Of course, this means that many of these amplifiers can take a digital input. Sony, unsurprisingly, have tied their S-master amps to the bit rate of SACD (2.8 something MHz).

The comments previously about simplicity being a good thing for sound... well, it doesn't get much more simple than that. The bits on the disc are essentially driving the output drivers of the amp. All you need is an SACD pickup, feed into the output drivers, filter the HF off and there's your sound.

Of course, the worry must be that several manufacturers will use the same modules (eg D2, Tripath) and they will sound the same. There is some tweaking that can be done (eg the Bel Canto implementation of the Tripath was rather different to the Veritas), but that varies with chipset (the D2 is almost untweakable in hardware terms. Can do lots with software on it though). Of course, power supply design and quality will remain a significant issue. What will probably result is that different amplifiers using the same chipset will have a similar sound, much as two push-pull valve amps using the same valves will also have a similar sound. The other details will still have an effect.

 

Of course excellence in design doesn't necessarily make something good. There are large areas of design I didn't touch on, and my first post was by no means an exhaustive list. They were just a few examples of things that can and will affect the sound of an amplifier.

Let's put it this way. A ford focus and an aston martin DB7. Both do the same job. The focus is easier to get in an out of, more reliable, safer, more efficient, and for the most part it is technically "better". I still want the DB7.

 

a round of applause, Issac, for these well structured and informative posts. :beer:

an excellent analogy.

 

Re: Re: Re: Re: Today's silly question; why should amplifiers sound different?

No offence meant, ol' bean, but a lot of it was 'way over my head! (Polymer chemist remember). But thank you for trying, I do appreciate it.

 

(a) Yes, I do, but I rarely read any hi-fi magazines these days, because they all seem to trot out the same old rot. And in any case the Geman magazines seem to love testing equipment that costs the GNP of Belgium. I'm not in that market (actually, I'm not in any market).

(b) No, I don't. I asked the question out of curiosity, because I'm happy with what I've got and there's really no point. I'll audition my next amp when one of mine rolls over and dies.

As a matter of fact I'll be down at Titian's place in early May. However, there's no point in comparing amps, because his system is one in which the CD player alone costs about three or four times all the hi-fi I own (both systems) - even the ICs (something called Fadel Coherence) cost more than my entire hi-fi! I go there to listen to music, and Titian is above all else a music lover who has sought to reproduce a concert hall in his home and is fortunate enough to have the means to do it. With a system like that, why waste time comparing amplifiers when there's music to be heard?