Well I do not really understand you saying so??
It is obvious that you did not grasp the concept of ballanced/unballanced audio, and in addition did mix it up with single ended topology.
The latter I do understand, since nerds more or less accepted single ended as a term covering unballanced interfaces as i.e. RCA cables.
To make it even clearer to know the difference between ballanced and unballanced audio, you should look after CMRR data.
CMRR = Common Mode Rejection Ratio, which is only valid for ballanced audio.
Ballanced audio has the benefit of being close to completely insensitive to induced noise or hum, since induced hum or noise are induced on both the inverting and the non inverting parts of the signal. Thus you have noise cancellation, if the inverting and non inverting amplifiers are completely mirrored. If they are not, you have common mode signals present, and can calculate the common mode rejection ratio.
Try to do that to an unballanced push pull design, that would be real fun
Ballanced audio is called for in studios and for other pro tasks, where long cable runs are necessary. For home audio unballanced is both sufficient, and in my opinion also the best way of interfacing signals. At some point in the late 80´s or the early 90´s ballanced audio found its way into home audio, mostly with a degrading effect.
This because of common mode signals deriving from differences between the inverting and non inverting amplifiers, and also because the convertion from unballanced to ballanced is an extra amplification/convertion stage needed in the signal path, unless the whole amp is ballanced from one end to the other.
The latter is rarely seen, and when it actually is so, you´ll know it because of the cost. In fact a ballanced power amp is the same as a bridged power amp, which again means that you need two amps pr. channel.
Kurt von Kubik,
This implies all kinds of devices on this planet (probably in the whole Universe, maybe even in the Multiverse, but not quite sure).
The signal is not single-ended, the stage is, where the output signal is referred to ground, meaning that the full signal is carried by one device, so it must be biased in class A. (Devices in balanced circuits can also be biased in class A). Now, we were talking about distortion characteristics, the essentially different harmonic spectrum created by single-ended and balanced circuits. Here, it would be necessary to start by describing the nature of harmonics. Distortions occurring when the signal is amplified by more than one device can indeed be severe, in any case, the signal is never purely processed.
This implies all kinds of devices on this planet (probably in the whole Universe, maybe even in the Multiverse, but not quite sure).
The fact is sound is so subjective.
It also seems to be a fact that you all are still "searching" for some elusive quality in your designs etc, that technical perfection seems to be eluding you from.
I am also thinking that musical instruments have their own characteristics, probably "unwanted" resonances etc if seen through the eyes of a purely technical designer, and that if they were computer designed then these could be elliminated. It is these very charactersistics that make them what they are however, it is just that we do not fully understand what makes one sound so pleasing and another less so.
It also seems to be a fact that you all are still "searching" for some elusive quality in your designs etc, that technical perfection seems to be eluding you from.
I am also thinking that musical instruments have their own characteristics, probably "unwanted" resonances etc if seen through the eyes of a purely technical designer, and that if they were computer designed then these could be elliminated. It is these very charactersistics that make them what they are however, it is just that we do not fully understand what makes one sound so pleasing and another less so.
I´m not sure you are right about this.
My family are all playing the piano, so we´ve got a nice piano in the house.
Also we´ve got guitars as well.
Some years ago I went to the music store, looking for a new guitar, which I´ve tried to do earlier. The surprise for me was, that the sonic difference between instruments has become a lot smaller. Earlier the cheap guitars sounded thin, blodless, inhuman and reminded me of pulling a cats tail.
That is no longer the case, even for low price instruments. Of course the better instruments hav richer sound and more volume, but I was actually very surpised about the rich and romantic sound of a 200$ guitar.
The shopkeeper told me, that this has happened because the chineese/Vietnameese or what so ever, also now uses CNC tools.
This lifted the quality of especially the cheap ones.
A few weeks ago, the pianotuner came by my house and tuned our nice old Danish piano - Hornung & Møller, which is a nice respektable handcrafted instrument with beautifull looks. I asked him about the piano, and he liked it, because it is completely untangled and easy to tune. Then I asked him if it still represented any value, the answer was NO!
A brand new Yamaha piano will cost around 10K$ at the same size. But I´ve always found the normal size Yamaha´s a bit thin, their grand concert pianos though are magnificent. But then I went to the shop, just to experience if he was right about the sound of the new Yamaha´s, afterall he is the one selling them. But he was, the Yamaha is a perfectly engineered instrument, with a very fast keyboard and a full and rich sound.
They also had Steinways in the shop as well as Fazioli, and the choise between these are becoming more and more a matter of size and taste.
They are all together engineered to perfection, but any pianist will have preference for i.e. thye feel of the keyboard, the resistance which influences the intonation and volume of your play.
But what I wnated to say was, that those small peculiarities caused by handcrafting are almost gone these days.
Instead you have a standard quality on which you can count always. And that is just about what pianists like the most. It must feel as if it was his own piano he is playing, just in another place.
Hifi gear of course, is just to pass all this through without any changes, or at leasy with as few as possible.
This can actually be done to quite realistic standards, you can eventually test this with some of Tacets records TACET - Die Website . They made 3 different records where instruments are played, so you can compare them.
One record with 5 different pianos, one with guitars and one with violins incl. all the most precious ones.
And they even made 2 records where different types of miking is done, called "Das Microfon" Vol I and VOL II
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Hi Kurt Von Kubik,
You have written all that, and I am just trying to sum up what I "feel" about how the sound is reproduced
My reference, post number 50, just a humble "Chappel" piano about 25 years old now.
http://www.diyaudio.com/forums/soli...es-class-distortion-increase-frequency-3.html
When we are talking HiFi and passing the sound with the least added distortion, the old "piece of wire with gain" approach if you like, it becomes clear that many designs come very close to that, yet still the listeners/designers are dissatisfied. Typical of this equipment is the situation where only a few records/CD's sound "good"...
Then there is the system that just really sings, the music is suddenly all important, you find you are not listening to hifi anymore, the performance shines through and on most recorded material, not just a handful of chosen pieces. Suddenly there is a real soundstage in front of you, not just a two dimensional cut out, there is depth, height, you can accurately place the musicians... it's something that once experienced makes you realise the shortcomings of other or previous equipment (maybe better technically, but what good that if you don't like listening to it)
I have found what works for me... and any further design I attempted would have to build on those strengths, and whether or not it took the design further from technical perfection would be largely irrelevant. The system has to have that "compulsive listening" factor about it, that makes you want to explore the music.
You have written all that, and I am just trying to sum up what I "feel" about how the sound is reproduced
My reference, post number 50, just a humble "Chappel" piano about 25 years old now.
http://www.diyaudio.com/forums/soli...es-class-distortion-increase-frequency-3.html
When we are talking HiFi and passing the sound with the least added distortion, the old "piece of wire with gain" approach if you like, it becomes clear that many designs come very close to that, yet still the listeners/designers are dissatisfied. Typical of this equipment is the situation where only a few records/CD's sound "good"...
Then there is the system that just really sings, the music is suddenly all important, you find you are not listening to hifi anymore, the performance shines through and on most recorded material, not just a handful of chosen pieces. Suddenly there is a real soundstage in front of you, not just a two dimensional cut out, there is depth, height, you can accurately place the musicians... it's something that once experienced makes you realise the shortcomings of other or previous equipment (maybe better technically, but what good that if you don't like listening to it)
I have found what works for me... and any further design I attempted would have to build on those strengths, and whether or not it took the design further from technical perfection would be largely irrelevant. The system has to have that "compulsive listening" factor about it, that makes you want to explore the music.
Hi Lumba
As relevant as anything when compared to the original question... does anyone have a circuit for............
As relevant as anything when compared to the original question... does anyone have a circuit for............
The question 'Why does Class A distortion increase with frequency?' is not very happily expressed, the distortion rise with frequency depends on design, not on Class A.
If I look only the entirely uncommon THD spectrum you posted from "Stereoplay", I would say, you are right. But it could also be that there are measurement errors. If you read the whole article, this measurement is contradictory with the results to the results by listening sessions, also performed by stereoplay.
Therefore I have try to translate this "Stereoplay" article in the english language. It was not always possible through a for me temporarily "idiosyncratic" German language (I often found in such magazines). I have this aeras marked with "????".
Here the result:
===================================================
Test Power Amplifier Densen B350 German magazine "Stereoplay" June 2004 page 48 German/English from http://densen.dk/B-350/Stereoplay 6-04.pdf
Nordlichter / Northern Lights
Schon mal eine prima Idee, dass Densen die Kühlrippen mit einer Alu-Schale abdeckt. Für ihre Monoblöcke ließen sich die dänischen Ingenieure aber noch viel mehr Schlaues einfallen.
Ever seen a great idea that Densen covers the heatsinks with an aluminum shell. For their power amp mono blocks the Danish engineers realizes a wide range of smart circuit ideas and specialties.
Wenn Messtechniker alter Schule einen Verstärker bejubeln, löst das bei einem Highender eher Skepsis aus.
Wenig Klirr, kaum Rauschen, hoher Dämpfungsfaktor, all dies lässt sich mit einem einzigen Schaltungstrick erreichen, der Gegenkopplung heißt. Und der, weil er zu einer unnatürlichen Oberwellenverteilung führt (siehe
5/03), das Ohr zu allermeist erst recht irritiert. Ein verantwortungsbewusster Verstärkerbauer genehmigt sich das vermeintliche Allheilmittel nur in möglichst geringen Dosen.
If measurement engineers of old school celebrate an amplifier, then music lovers rather skeptical.
Low THD, low noise, high damping factor, all this can be achieved with only one circuit trick - so called "negative feedback" (NFB). And - because NFB causes an unnatural harmonic distribution (see results
5 / 03), the audible impression would be even more irritated. A responsible amplifier developer uses the supposed panacea "NFB" only in small doses.
Weltweit nur ganz wenige, und da zuvorderst der tüchtige Densen-Chef Thomas Sillesen und seine Männer, verzichten sogar ganz darauf. Wobei die Tapferkeit - ihr Monoblock- Pärchen B 350 kostet immerhin 6800 Euro einen sehr beträchtlichen Aufwand erfordert.
Only very few engineers worldwide completely avoid the NFB, especially the famous leader of Densen, Thomas Sillesen and his crew. This decision, however, requires very considerable efforts. Therefore their monoblock pair of B 350 will cost 6800 euro.
Hinterher korrigieren gilt nicht (????), deswegen braucht es
Because the lack of NFB the following is required:
"Ad I" (??) blitzsaubere und super stabile Versorgungsspannungen. Konkret: pro Block einen fetten 750-Watt-Netztransformator und dazu ingesamt 83000 Mikrofarad Elko-Speicherkapazität. Wobei sich die zehn dicken, von Wima-Folien-Hochfrequenz-Helfern begleiteten Einzelkondensatoren nicht irgendwo in einer Ecke, sondern in zwei Dreiecksformationen präsentieren, die mit einer Breitseite jeweils direkt neben dem zu versorgenden Endtransistor (extradicke von Sanken) stehen.
First extremly clean and super stable supply voltages. I. e. Each block used a large 750-watt power transformer and at whole a capacitance value of 83.000 uF as storage capacity. Additional there are bypassed high frequency capacitors from Wima. All this capacitors are very close by the extra-thick output power devices from Sanken
"Ad 2" (??) mussten die Ingenieure eine Schaltung ausbaldovern (??), bei der jeder Halbleiter haarscharf genau eine elektrische Umgebung sieht, in der er den zu verstärkenden Signalen den linearsten Abschnitt seiner Arbeitskennlinie offeriert. Und wo ein Kollege einem anderen, komplemenär angeordneten mit der Kompensation kleiner Fehler aushelfen kann. (very hard resp. unpossible to translate !!!)
All dies kann mit Standard-Widerständen mit den üblichen Normreihen-Werten nicht gelingen. Deswegen mussten so eng tolerierte (0,1Prozent) wie teure Spezialanfertigungen des renommierten Herstellers Vishay ran. Indem die Dänen das Präzisions-Potpourri (???) schließlich im Auflötverfahren auf eine doppelt kaschierte Profi-Teflonplatine setzten, beugten sie zudem elektrischen Abweichungen vor, wie sie aufquellendes Pertinax hervorufen kann.(also very hard resp. unpossible to translate !!!)
Secondly - the engineers had to design a circuit, in which each semiconductor operates in their ideal aera of transfer curve, and in which a NPN transistor his antagonist, the PNP help out with small error compensation
All this can't perform with standard resistor devices, that have usual tolerances. So there are tolerances about 0.1 % inside from the manufacturer Vishay and in a custom-made version, i. e. special made for Densen.
Additional there are a multi layer teflon pcb (printed circuit board) to avoid destroy through the solder process so as unwanted parasitic effects through dielectric properties. (my own interpretation, but I think, this is that which was meant)
Ein kleiner Schalter auf der Rückseite der B 350 gestattet es dem stolzen Besitzer, die letzte Anpassung selbst vorzunehmen. Je nach Kette dürfte mal die kleinere oder die höhere Empfindlichkeits-Stellung bessere Ergebnisse bringen, wobei sich zwecks Direktanschluss eines CD-Players so oder so „high" empfiehlt.
A small switch on the back of the B 350 allows the proud owners to make the last adjustment itself. Depending on the preamplifier in one case the smaller and in other case the higher sensitivity one get the better results. If I connect a CD player without pre amplifier to the B 350, the lower sensitivity is recommend.
Im Kontext mit Referenz-Vorstufen durften die Densens in „normal" musizieren. Im besten Sinne als "normal und natürlich" stellte sich dann auch die Klanghaltung der Dänen heraus. Keine Raumzaubereien, keine obskuren atmosphärischen Düfte... Stattdessen fetzte ein Jazzpianist mit kernigen Akkorden und
glasklaren Läufen umso entschlossener los, während Drummer-Hiebe rhythmisch ins Schwarze trafen. Gegenüber der super geradlinigen Spielweise erschienen die eigentlich schon präzisen AVM-Monoblöcke "M 5" (3/99 55 Punkte) wankelmütiger, weshalb das Densen-Paar mit einem Zähler mehr klar in die Absolute Spitzenklasse kam.
Together with different pre amplifiers, that all have reference status, the B350 operates in the position "normal." The sound impression was absolutely "normal and natural," No stereo magic, no obscure atmospheric sounds ... A jazz pianist plays with robust chords and crystal-clear streams, while drummer-strokes rhythmically hit the bull's eye. Compared to the super straightforward, tight and clear sounding AVM mono block devices, model No "M5" (test in Stereoplay March 1999 score: 55 points) the Densen pair was much less fickle and therefore clearly grouped in the absolute top class (with even a counter more above AVM's 55 points of "M5").
Symmetrie statt Gegenkopplung: Der Endtransistor auf der rechten Seite verarbeitet
Plus-, der Kollege links Minus-Signalauslenkungen.
Symmetric instead of feedback: The transistors on the right side handles
Plus, the colleague left the minus voltage swing.
=====================================================
Unfortunately, many things I don't understand. For example, I do not understand by the last paragraph what one has to do with the other
Independend of this - conclusion after read this test for the reader:
excellent sound quality in any case.
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Hi Kurt Von Kubik,
You have written all that, and I am just trying to sum up what I "feel" about how the sound is reproduced
My reference, post number 50, just a humble "Chappel" piano about 25 years old now.
http://www.diyaudio.com/forums/soli...es-class-distortion-increase-frequency-3.html
When we are talking HiFi and passing the sound with the least added distortion, the old "piece of wire with gain" approach if you like, it becomes clear that many designs come very close to that, yet still the listeners/designers are dissatisfied. Typical of this equipment is the situation where only a few records/CD's sound "good"...
Then there is the system that just really sings, the music is suddenly all important, you find you are not listening to hifi anymore, the performance shines through and on most recorded material, not just a handful of chosen pieces. Suddenly there is a real soundstage in front of you, not just a two dimensional cut out, there is depth, height, you can accurately place the musicians... it's something that once experienced makes you realise the shortcomings of other or previous equipment (maybe better technically, but what good that if you don't like listening to it)
I have found what works for me... and any further design I attempted would have to build on those strengths, and whether or not it took the design further from technical perfection would be largely irrelevant. The system has to have that "compulsive listening" factor about it, that makes you want to explore the music.
I completely disagree about this handfull of recordings sounding good, when no distortion is added, actually it is the opposite.
I don´t know where these stories about low distortion causing teethcracking and sterile sound comes from, but it might be from designers unable to design properly.
Any amp, having its THD lowered - anything else equal - will perform both more natural and smooth. I´ve tried this so many times, that I´m quite certain of that.
Often the term "analytical" is rated as a negative term, describing cold, bright and overprecise sound, in which I do not at all agree.
To me analytical will eventually reveal the point of acoustical => electrical transitioin, which happens to be the microphone placements.
If the miking is done well, you will have an impressive experience of the music, if not, it will be different at least, and so it must be.
Adding distortion will ruin both recordings, not just the good one.
Excactly
Class A does not have any generic property for rising distortion with rising frequency.
Actually one should consider, that all amps are class A amps, except power stages.
And that is alone the final current gain output stage of a poweramplifier. Everything else, incl. analog stages in CD players, preamplifiers, input stages in poweramplifiers, linestages in taperecorders, tuners etc. etc. are all operating as class A amplifiers. the reason for that is: Very low distortion.
No problem, since you're just adding another drop in the cumulative steaming biomass of the high end audio world.
And then what
That is the question.
On one hand we see THD values that have nothing to do with high fidelity and on the other hand, the notion of a nearly perfect sonic reproduction without finding any weaknesses.
What to believe the music lover, who is usually in most cases no technican or engineer, if not even the experts are able to properly assess a device?
I can add only two thoughts,
1. This just shows again how subjective this whole argument is.
2. And finally, my amp appears to meet "all" your subjective criteria so on the one hand could I say it's must be approaching technical perfection, or on the other that "we just don't fully know" why vanishingly small distortions colour the sound as much as they seem
Happy listening...