Click title to read one, or click date to read all below it.
12-08-04
Hi, guys: i think my airy2 is finally getting broken in. ... Suttlaw
12-08-04
Gregadd, excellent and well-argued post, at least when i re ... Dougdeacon
12-08-04
Suttlaw: you might want to consider the aerial sw-12. Gregadd
12-08-04
Dear gregadd: you, like me, have to learn a lot on all those ... Rauliruegas
12-08-04
Dear steve: about the phono cable i recomended: analysis plu ... Rauliruegas
12-08-04
Raul,so what ss amp/preamp/phono do you have? Audio999
12-08-04
Raul,upon reading the same stereophile article from the 1994 ... Twl
12-08-04
Raul, if i could listen to 20-30 hours of live music per mo ... Gregadd
12-08-04
Raul, i wasn't going to say this, but i do have to respond t ... Gregadd
12-09-04
Hi twl:*****" so yes, i understand your concerns about ... Rauliruegas
12-09-04
Dear gregadd: that's exactly the point and where the differe ... Rauliruegas
12-09-04
Raul,once again what ss amp/preamp/phono do you have? Audio999
12-09-04: Teres
Uggh, this is suppose to be an analog thread, but I just can't resist countering Rauls outrageous tube amplifier comments. I have designed, built and modified a number of amplifiers, both tube and solid state. So my comments are based on actual listening experience.
Tubes and transistors are both devices that produce gain using similar concepts but with quite different characteristics. Tubes have good linearity (low distortion) but low gain. Transistors on the other hand have very poor linearity (high distortion) and very high gain.
To get around the distortion problems most tube amplifiers and all transistor amplifiers use feedback to eliminate distortion. Here I use the term distortion in a very broad sense, anything that deviates from the original signal including frequency response, noise along, harmonic and IM distortion. More feedback means lower distortion, including the "equalizer" effect that Raul mentioned. Since transistors have very high gain and it is easy to produce lots of feedback and therefore very low distortion, ruler flat frquency response, high damping factor, vanishingly small harmonic distortion, blah, blah. Tube amps on the other hand have much more limited gain and can only produce limited feedback. The result is considerably worse distortion measurments, in spite of the fact that they are lower distortion devices to start with.
But there is a significant hitch to this story. It turns out that feedback has a clearly audible negative effect on sound. To date I don't know of anyone that is able to measure this affect. It does not show up in any of the standard distortion measures. This is part of why there is so much controversy about this topic. I have a lot of first hand listening experience regarding feedback and I assert that this is both real and significant.
So like so many things audio it all boils down to compromise. Feedback brings both good and bad to the table and the optimum balance is both system and taste dependent.
In a given context and a set of personal preferences there will be an optimal balance between feedback and distortion. That optimum balance will not be the same in a different system or with different tastes. So it's never as simple as choice between feedback or no feedback or for that matter tubes or transistors.
The goal for good amplifier design is the lowest possible distortion with the smallest amount of feedback. That means that the amplifier needs to have the lowest possible open loop distortion. Open loop distortion is the level of distortion before feedback is applied. A well designed amplifier implemented with high quality components will require less feedback to arrive at a distortion goal and will therefore sound better.
So if you look at amplifiers from the perspective of levels of feedback the high feedback end of the spectrum is the exclusive domain of trasistor amplifiers. On the opposite end of the spectrum is single ended triode amplifiers with no feedback at all. Each have their strengths and weaknesses.
Personally I find that nirvana is a zero feedback amplifier. But the no feedback path is not for the faint at heart. Everything has to be perfect or you will hear it. Component quality become hugely important. Speaker choices are very limited and there are major speaker/amp synergy issues. Feedback extracts a price but it does make things a lot easier.
Chris
Teres (System | Answers | This Thread)
12-09-04
Audio999- raul is not going to tell you. ever. he's not g ... Jimbo3
12-09-04
Chris & tom, thanks for the informative (raul, you understa ... Jphii
12-09-04
Jim,i think you are right. he didn't anwswer my question abo ... Audio999
12-09-04
Wow! just tuned into this thread. no offence here honestly. ... Ecclectique
12-10-04
Audio999- fact is that raul needs to take considerable time ... Jimbo3
12-10-04
Well, how about that? Twl
12-10-04
Dear twl and teres: with respect to the answer given by mr. ... Rauliruegas
12-10-04
"the ideal amplifier's mission is to work as a perfect ... Gregadd
12-11-04
Anybody notice how raul's english improved about an order of ... Armstrod
12-11-04
Raul, i do agree that there are some favorable characteristi ... Twl
12-11-04
Dear twl:*****" the distortion from this(my personal) a ... Rauliruegas
12-11-04
Raul? Vvrinc
12-11-04
Raul, yes, i know that tubes are voltage devices. bipolar t ... Teres
12-11-04
indeed. one wonders who actually wrote it. is some ss amp bu ... Dougdeacon
12-11-04
Raul- would love to test it for three months. everyone els ... Jimbo3
12-11-04
Raul, anyone who thinks that the location and order of harmo ... Twl
12-12-04
Dear teres:****" ultimately, there will never be such t ... Rauliruegas
12-12-04
Dear twl:****" raul, anyone who thinks that the locati ... Rauliruegas
12-12-04
Here is a very recent article "cut and pasted" fro ... Twl
12-12-04
And my last post was premised on the damping data alone, and ... Twl
12-12-04
Raul- if you really wanted someone like me to learn, how 'b ... Jimbo3
12-12-04
Dear twl: just checked out your system. was curious about ... Suttlaw
12-12-04
Suttlaw, that rottweiler "tweak" can go anywhere h ... Twl
12-12-04
Perhaps we can talk some time about the real weakness of tub ... Gregadd
12-12-04
Gregadd, those frqequency extreme and transient softness iss ... Twl
12-12-04
Also if the transformer is eliminated entirely as with tube ... Rushton
12-13-04
Hmmm... audioholics seems to have somewhat contradicted the ... Sean
12-13-04
Here's a link to the entire article. http://www.audioholics ... Twl
12-13-04
To me, the key here is not whether there may be some slight ... Twl
12-15-04
Tom mentions i agree. esepcially considering how the relevan ... Gregm
12-15-04
I still haven't had a chance to read the articles, but i jus ... Sean
12-15-04
If you want to know what kind of frequency reponse your syst ... Gregadd
12-15-04
Hi: this statement comes from audioholics ( the twl link ):* ... Rauliruegas
12-15-04
Clear audio, vpi, linn, maybe basis, maybe walker. not neces ... Elinor
12-15-04
i hope this puts an end to this discussion. "...gregad ... Gregadd
12-15-04
Dear gregadd: ***" i hope this puts an end to this disc ... Rauliruegas
12-16-04
Good grief, raul, get over yourself. Jimbo3
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