Our listening mechanism is naturally far more sensitive than we experience now. Normally everything we hear is interpreted by what we know and therefore we are not really listening. If the ear and brain, as you say, take more time to "analyse" the music, than certainly we are hearing, but definately not listening.
Even if all amplifiers measure differntly. the disortion there is nothing comparetd to what colouration, distortion, nonliniarty erergystorage and you name it adde by the loudspeaker transducer and yet through all that we register subtle changes to the amplification sometimes to a degree where the harsh sound of SS makes an otervise nice system unbearable.
One must not forget very very different distortion spectral content of speaker transducer and amplifier. And, modern transducers (drivers) have quite low distortion, less than 0.3% (Accuton, Eton), which is mostly 2nd and 3rd harmonic. Some beloved non-feedback amps produce higher distortion of higher order and especially odd harmonics, though it sounds unbeliavable.
You might be right that the drive units you mention have low distortion,. But I can ashure you that those distortion figures are purely steady state an also in a very limited bandwith. In practiocal use and under transient conditions the distortion is much much higher. Only ribbon transducers with almost 0 mass can perfor like you say. Dynamic drivers suffer from mass they can accelerate and the cant stop. But if you play a sime thats not a problem. But a musical tone with complex content the distortion. But let this not become a dicoussion about speakers. I just mentioned them because they are a vital tool in judging the stuff we build and the are shurely not without flaws. They most often set the limit to performance, so things can come out different but its hard to judge upor down.
PMA said:
Pavel,
WRT your circuit,
It is closed loop, so probably better in it's own thread,
(feel free to start one), but I think it is very good.
The bootstrapped IP collectors is nice approach, I use this
myself often.
Questions:
- What rails are you running
- Would a CCS be better than 30k R's on Q1/2
- How does it measure?
- Is the 10k OP R to limit OLG
Cheers,
Terry
Terry,
I do not feel like starting a new thread. I will briefly reply here.
I have not build that CFB preamp shown, only simulated. It is based on experience with realized power amp:
http://www.pha.inecnet.cz/macura/next.htm
The power amp differs in the end stage, which is a CFP follower. It is a class A non-feedback design and measurements can be seen on the linked page.
Regarding the CFP preamp, I do not plan to build it recently, as I am engaged in active filter speaker project.
1) the rails were expected +/-30V and quiescent current of 50mA.
2) the CCS would probably be better than 30k resistors.
3) according to simulation it would measure very well, but not excellent.
4) the 10k resistor was used to simulate the load.
Regards,
Pavel
I do not feel like starting a new thread. I will briefly reply here.
I have not build that CFB preamp shown, only simulated. It is based on experience with realized power amp:
http://www.pha.inecnet.cz/macura/next.htm
The power amp differs in the end stage, which is a CFP follower. It is a class A non-feedback design and measurements can be seen on the linked page.
Regarding the CFP preamp, I do not plan to build it recently, as I am engaged in active filter speaker project.
1) the rails were expected +/-30V and quiescent current of 50mA.
2) the CCS would probably be better than 30k resistors.
3) according to simulation it would measure very well, but not excellent.
4) the 10k resistor was used to simulate the load.
Regards,
Pavel
I have listened to several Ayre power amplifiers, that's why I dare to criticise the non-feedback approach. I have found very similar sonic behavior of my non-feedback designs. The sonic preferences are very individual, and in case of impossibility of direct comparison (like in this long-distance discussion) I prefer measured performance to verbal approval.
I don't mind differences in opinion, but Charles, Nelson and I, for example, make a living at making 'good' sounding products. We don't necessarily even completely agree with each other, but we let the 'marketplace' decide what is a successful design. This usually means that we try our best to make the design satisfactory to our design opinions at the moment, but we seem to be more open minded than many of you.
For example, once I was asked by an associate (who wanted to give me some needed work) to make a 'super' power supply for a preamp originally designed by Nelson Pass. The existing power supply was adequate by any nominal engineering standard, but my friend wanted me to build something more substantial. I did it, because I needed the project at the time to pay my bills. Well, it was done and given to the client.
Later, at the CES, I came into the VMPS listening room and Gordon Holt was there. Brian Cheney (my associate) asked me if I would like to hear the 'differences' in sound between the nominal supply, and the 'super' supply with this preamp. I expected to hear little or nothing. BUT, there was a significant difference, and Gordon Holt heard it easily as well, to the point that he bought the 'super' supply from Brian, and I was commissioned to make another one.
In 'Stereophile' a few months later. The preamp got an 'A' rating, but ONLY with my 'super' power supply. What a complication! I was not set up to make power supplies, but I started to get orders, anyway. I also got complaints from Nelson, or one of his associates that it should not matter what supply was used. However, the proof was in the listening, and I was then reminded that my Vendetta power supplies were relatively wimpy, so I upgraded the Vendetta power supply to the A series, with some sonic success as well. Later, Nelson or one his associates made an updated supply for the preamp and I was 'off the hook' so to speak, and I did not have to make any more power supplies for another designer's preamp.
I learned something from this, and I hope that Nelson did as well. You must TRY things sometime, NOT just 'reason' or rationalize what is audible or not audible.
For example, once I was asked by an associate (who wanted to give me some needed work) to make a 'super' power supply for a preamp originally designed by Nelson Pass. The existing power supply was adequate by any nominal engineering standard, but my friend wanted me to build something more substantial. I did it, because I needed the project at the time to pay my bills. Well, it was done and given to the client.
Later, at the CES, I came into the VMPS listening room and Gordon Holt was there. Brian Cheney (my associate) asked me if I would like to hear the 'differences' in sound between the nominal supply, and the 'super' supply with this preamp. I expected to hear little or nothing. BUT, there was a significant difference, and Gordon Holt heard it easily as well, to the point that he bought the 'super' supply from Brian, and I was commissioned to make another one.
In 'Stereophile' a few months later. The preamp got an 'A' rating, but ONLY with my 'super' power supply. What a complication! I was not set up to make power supplies, but I started to get orders, anyway. I also got complaints from Nelson, or one of his associates that it should not matter what supply was used. However, the proof was in the listening, and I was then reminded that my Vendetta power supplies were relatively wimpy, so I upgraded the Vendetta power supply to the A series, with some sonic success as well. Later, Nelson or one his associates made an updated supply for the preamp and I was 'off the hook' so to speak, and I did not have to make any more power supplies for another designer's preamp.
I learned something from this, and I hope that Nelson did as well. You must TRY things sometime, NOT just 'reason' or rationalize what is audible or not audible.
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