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旧 Aug 12th, 2011, 16:00     #1
silent_fish
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默认 Active Preamp, Passive Preamp

Active Preamp, passive preamp, resistor preamp, transformer preamp, no preamp?

http://www.high-endaudio.com/RC-Linestages.html

代码:
REFERENCE COMPONENTS


LINE STAGES 

UPDATED JULY 2011

INTRODUCTION 

CLASS A

CLASS B 

CLASS C

THE BOLERO TEST

OTHER INTERESTING LINE STAGES

READERS LETTERS

INTERNAL LINKS 

INTRODUCTION


FUNDAMENTAL PERSPECTIVE

Any system that sounds better with the addition of an "Active" line stage is an unequivocal indication that:

That system, as presently configured, requires an Active Line Stage.
The vast majority of audio systems require an active line stage. Further, the elimination of the active line stage is a long-term goal that requires each and every component to be optimized and matched with regards to both sensitivity and impedance (and cables for low capacitance). So, to be ruthlessly frank...

This means that most systems, at most times, will require an active line stage.
Finally, never forget that all active line stages are actually "passive" line stages along with (active) amplification. In short- you can't avoid using a passive line stage in any circumstances (unless you want no volume controls). The only issue/choice/decision, in this instance, is whether you want an active stage in addition to the passive.


THE ORIGINAL PURPOSE (AND NEED) OF PREAMPLIFICATION

Always keep in mind that preamplifiers came into existence to equalize and amplify the very low-level phono signals from a turntable. Most tuners and tape decks had their own volume controls, and didn't need a preamplifier when used on their own. Also, many power amplifiers had their own volume control. After CD players became popular, and turntables became relatively rare, preamplifiers became (theoretically) "obsolete" and/or "redundant".


THE "EVOLUTION" OF THE MARKET

However, rather than lose the sale of a (now) obsolete component, the manufacturers began marketing a "new" component, the "line-stage" (which is just a preamplifier without a phono stage).

They could have placed the line-stage directly within the CD players themselves, which would have been more convenient, economical and even have saved the cost of an extra pair of cables (a sonic benefit too). They predictably didn't. Why? Profits.

Where were the "underground audio magazines" (who were supposed to be looking out for the interests of their readers) while this "transition" was all happening? They were giving "rave reviews" to these (now) expensive and unnecessary components. 

Top

CLASS A


COINCIDENT STATEMENT LINE STAGE

The Coincident Statement Line Stage (CSLS) is the finest component of its type that I have ever heard. Much more than that, it is the most "perfect" electronic audio amplifying device, of any type, that I have ever heard. Further, based on my experiences, which are shared below, I believe that the CSLS can never, and will never, be significantly improved on in the future, no matter what the price or the technology used. I realize that these are unusually strong words, but I believe I can, and will, back them up.

First of all, any veteran reader of this website is aware that I don't "like", and, much more importantly, need a line stage. This is why I was very reluctant to audition and review the CSLS, or any other line stage in existence for that matter. Other audio websites (Stereo Mojo and Enjoy the Music) gave the CSLS "raves" and "awards", but that meant nothing to me, due to my somewhat unique circumstance. However, I ended up with the CSLS (and the matching phono stage), and I finally found the time to start experimenting with it last fall.

I initially thought it would be simple and fast, like my prior evaluations of other line stages, both active and passive, but this was not the case. This time it was different, and it has taken me a considerable amount of time to figure things out, mainly in an effort to logically connect and match my (and others) personal observations and experiences with the different technologies which created them.

In fact, the entire line stage situation is surprisingly complicated. Let me explain... 


Part One- Some Personal Line Stage History & Perspective

I have been experimenting with line stages, and/or their absence, for three decades now. It began in early 1981, when, it is important to remember, line stages, per se, didn't even exist as individual components. They were just one part of a full-function preamplifier, which always included a phono stage as well.

A few months before I opened my audio store, I found myself with the (Mitch) Cotter Phono Stage and the matching Cotter MC Transformer, along with the Audio Research D-150 power amplifier (then stock), along with the original Quad ESL-57 speakers (modified), the Linn Sondek LP-12 turntable and a Denon 103S cartridge (tonearm now forgotten). Despite my best efforts (and even my own brother working for Cotter), I was not able to get the matching Cotter line stage (which was, and is, extremely rare). So, I used the line stages of some high quality full-function preamplifiers (which had their own phono stages), such as the Citation 11, Dynaco PAT-5, Dayton-Wright SPS and ARC SP-3.

Then, one day, realizing that the D-150 had its own volume control, I decided to bypass the line stage I was using at the time, and instead connected the Cotter Phono Stage directly into the ARC amplifier. It was a bit of a pain, since the single stereo volume pot was at the back of the amplifier. Still, I felt the results were well worth it. It turned out that the sound was obviously improved; it was purer, cleaner, faster, more direct and immediate etc. However, due to the relative insensitivity of the Quads, the volume was just too low for too many records, making it impractical, but the seed had been planted. So I committed myself to eventually making a direct connection work, and without any sonic compromises.

After that, there were numerous similar experiments in the 1980's*, in both my store and personal system, but I feel they are redundant, and would like to now focus on my personal situation with the Jadis JP-80 preamplifier, which I purchased in 1989, and I still own today. The JP-80 has been at the center of every experience I've had, with both phono stages and line stages, since then.

*PS Audio designed a preamplifier (PS IV), which I demonstrated and sold in my store, that allowed the user to bypass the line stage with the push of a button.


Part Two- The Jadis JP-80 ERA (1989 to Today)

I first used the Jadis primarily with high-output MC cartridges (it has no MC stage, as does their current "MC" version), until I purchased the Expressive Technology SU-1 MC transformer. Literally overnight, I went from too little gain to having excessive gain, even with low-output MC cartridges. The problem was that the volume pot, using individual resistors, didn't allow fine adjustments below 10 o'clock, and I was usually at 9 o'clock or below, so the music was almost always too loud or too soft. This was obviously highly frustrating.

Thinking things over, I decided to attempt turning my gain problem into a plus by removing the line stage, but this strategy created another problem. How was I going to find out if I could successfully bypass the line stage, without the major hassle of actually bypassing it internally first, and without any guarantee that it would work?

Of course, I could simply use the tape output instead, which bypassed the line stage, but that created yet another problem; the tape outputs also bypassed the volume controls. This meant there would be full volume at all times, which placed both my then amplifiers (Jadis JA-80) and then speakers (Wilson WATTS modified) in serious jeopardy. (The JA-80 did not have its own volume control, as did the Audio Research D-150 in my earlier experiment.)

This dilemma was the inspiration for the creation of The Bolero Test, which solved the problem, and has also helped many other audiophiles since then. In short, the test was highly successful, so I bypassed the JP-80's line stage in 1992. (Over the years since then, I also eventually removed the tape monitor, the mute circuit, the cathode follower section and, finally, the two mono volume controls, which turned the selector switch, in effect, into the "mute switch".)

The (modified) JP-80 preamplifier had now been converted, basically, into a "phono stage". Subsequent experiments, with various dedicated line stages, confirmed that none of them were able to make an improvement in the sonics when inserted into my system. These results were verified by numerous listeners, and not just myself, because I recognized my "animus" towards line stages, which had began a decade earlier (1981). I wanted no prejudices to cloud my observations.

This has been my system's status quo from 1992 until now (though I've made many further improvements to the JP-80 over the years, in both the circuit and the power supply). Then the CSLS arrived...


The CSLS - A Simple Description
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旧 Aug 12th, 2011, 17:34   只看该作者   #2
hugoo
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默认

看的我头晕。
这家伙的网站看着怎么这么业余?

这个Coincident的东西都死贵死鬼的,再好,也买不起

-------------------------------
You Cannot Be Serious!
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