Current amp vs Voltage amp


Two different topologies with different intent. There are arguments for and against both technologies. Not having a electronics background I'm tying to get a clearer understanding.

Speaker matching including impedance and power requirements: how does one match 1:1 :: amps:speakers? General rule of Higher sensitivity benign/high impedance to tubes, and, low medium/sensitivty variable impedance to SS (considering they can be of higher power rating)?

This is not to see which is best, but to better understand the process of matching components.
deadlyvj
I suppose everybody thinks their way is best, when in fact there always turns out to be many ways to skin the cat, including the means to superior sound quality, though personal preferences always determines what happens in the end.

Economics, convenience and ease of use are real factors for most along with superior sound. So that largely determines what is best.

Each paradigm has advantages and drawbacks. Which matters most will determine the winners.

Regarding sound quality alone, I would guess power paradigm has advantage of lower risk of bad sound up front for many, while results with voltage will be more variable case by case. However voltage scales to larger applications more cost effectively these days I would think.

Again, the game changer on the scene of late are high performance, high efficiency switching amps, that take a lot of cost and risk out of the equation for voltage amp applications. In lieu of these, I personally would be more inclined to go the current/tube amp path I think. I had strongly considered it during last major upgrade phase but decided to give Class D amps a try first, and am glad I did.
Historically speakers with lower impedances are more likely to be able to produce wave form fidelity than speakers with higher impedances.

[facepalm]I can't let that one pass[/facepalm]. Its well known for decades that the Quad ESLs have had very low distortion (re.: 'wave form fidelity'[sic]), some of the lowest out there. Yet the ESL57 and 63s both have a fairly high impedance.

In fact impedance has nothing whatsoever to do with waveform fidelity in a loudspeaker. That is entirely a matter of design.

There are many good reasons for speakers to have a low impedances and the market place has proven this for a long time now.

The 'good reasons' are sound *pressure*, not sound *quality*. I recommend you reread my previous comments. Its one thing if I say it- I own a small company that makes tube amps. But its another thing entirely when transistor amp manufacturers say that, and especially when that is re-enforced by the distortion measurements. We are talking about distortion that is audible too. Go ask Paul Speltz to show you that letter from Steve McCormick.


More challenging impedance loads would seem to go hand in hand with getting a more full range sound out of a smaller speaker design that will fit in well to most user's living/listening space.

For less full range applications especially in smaller rooms, there would appear to be more viable/affordable options in well designed higher impedance speakers.

However, the trend over time for most things is to become smaller and more efficient and also usually more cost effective and usable accordingly. The old paradigms have their strengths, but do not hold up well from an overall end user perspective these days. Too big, too expensive, and more maintenance required to keep things running well over time. But they can and often do sound really good. As do a lot of voltage based systems that leverage modern technology.

Its not valid to base decisions today on technology from 40 years ago. It is a different story now. THough I do love nostalgia including tubes and even Victrolas and have the Victorian styled home to potentially put these things in to prove it, the game continues to change, so one has to keep an eye on the ball!
Mapman, I'm not sure where you are holding with SS vs tube amps. But I think it's important to restate for emphasis sake that what Al and Ralph have been trying to explain all along is IME accurate.

If you read my posts about the SS/tube amp Paradigms and varying speaker impedances, I think Al was spot on when he said that an important factor, maybe the most important factor, is a tube amp's output impedance. The lower it is, the more "SS-like" it will perform.

I posted bench test reports from Stereophile and Soundstage for the ARC Ref 150 and ARC VS-115 (my amp). I found John Atkinson's comments quite interesting. He said that the FR output performance of the Ref 150 significantly "flattened" when driving a simulated speaker load off the 4 ohm taps as compared to the 8 ohm tap. Atkinson measured the Ref 150's output impedance to be lower off the 4 ohm taps as compared to the 8 ohm taps.

That result is consistent with what AL said about tube amps having low output impedance performing somewhat "SS-like" when driving speakers that were designed and voiced to be driven by a SS amp -- like mine.

Of course the reason the Ref 150 and VS-115 have low output impedance attributes is likely because of NF, which as Ralph says introduces odd ordered harmonics. So in the end, I guess it comes down to design trade-offs, with respect to both speakers and amps.

Bottom line: My Paradigm S8s have an impedance peak of 28 ohms at 2.2K Hz, which corresponds to the midrange/tweeter x-over point. In contrast, there is an impedance "saddle" of 4 ohms at 100 Hz. Paradigm advised me that the S8s were designed and voiced to be driven by a high current/high output SS amp. Ooopps.

I always thought the S8s sounded a bit "forward" when driving them off the VS-115's 8 ohm taps. At Al's and Ralph's suggestion, I tried the 4 ohm taps. I had to get used to the change in presentation, but now I like it better. Less listener fatigue, less forward, slightly crisper bass, and so forth. My anecdotal experience is consistent with what Atkinson predicted when he bench tested the Ref 150.

Not sure what else to say. Seems to me that if one can pick up a great speaker with relatively flat impedance and phase angle plots, the issue of tube versus SS amp compatibility will be largely mooted. But based on my read of reviews on some of the "big boy" speakers out there, like Magicos and Revel Salons, you are looking at speakers that need to be driven by some monster SS amps to sound their best. But don't take my word for it. Pull some of the bench test reviews and see for yourself.

Cheers and thanks again Ralph and Al for your patience and help.
Bifwynne,

What you relate sounds fine and does not surprise me. Whatever the details, paying attention to impedance matching between components pays off. Its a fundamental thing to get right, sometimes harder than others.

I just do not buy into the assertion that power paradigm and no negative feedback is the only way to make music sound real. It is based on sound theory perhaps, but in practice is not consistent with what I have heard in both cases over the years.

Cheers!