Current amp vs Voltage amp

I wonder what happens if one listens to nicely produced music, say a big band with lots of brass and high frequency energy live at 105DB? Is it as comfortable as listening to the no NF tube amp at the same level? Its a fair question, I think.

It is. If you sit close up in a concert hall it will easily be that loud.

So? The amps I'm thinking of are capable of generating these kinds of wattages & sounding musical at the same time. Indeed that's what I was thinking in the 1st place when I wrote that post.....

Its rather obvious from those numbers that the amp is going to be challenged at the least, challenged in the regard that it is likely to make too much power at high frequencies and not able to make enough power at low frequencies. And in practice, that is what you hear with them as well. The feedback is supposed to help the amp with this, but because the model is incorrect (IOW the speaker's impedance curve has nothing to do with box resonance) it does not work.

Often as the speakers impedance changes so does the the sensitivity, and that should correspond to flat frequency response from such a ss amp.

This is true for some box speakers- those that are built with this expectation. But as we saw in the ESL example, the model falls apart. When the Voltage Paradigm was being developed (in the late 1950s and early 60s EV and Macintosh led the way on this) ESLs were not a significant part of the market (and they still aren't). So there was not and still is not a concern to make them work right.

Folks, if you've not picked up on this yet, the Voltage Paradigm is all about marketing and the almighty dollar. The ability to double power as you cut impedance in half has little to do with sound quality. It has a lot to do with looking good on paper. And a lot of audiophiles buy with their eyes rather than their ears. OTOH the Power Paradigm is based on the rules of human hearing, which makes it a lot trickier to execute. The Industry wants something convenient, so you can just plug things in (easier to sell). But our ears are more complex than that.

Its the conflict of these two approaches in audio that generates the equipment matching conversations, the tubes vs transistors conversations, and the objectivist/subjectivist conversations. Its really aspects of the same issue. If the Industry was open about talking about this, audiophiles could save a pile of cash and have better sound at the same time. But very little in audio occurs for the sake of better sound. Mostly its about cashing in.

05-10-13: Atmasphere

I wonder what happens if one listens to nicely produced music, say a big band with lots of brass and high frequency energy live at 105DB? Is it as comfortable as listening to the no NF tube amp at the same level? Its a fair question, I think.

It is. If you sit close up in a concert hall it will easily be that loud.

I once sat in the very first row at Tanglewood for a performance by the Boston Symphony Orchestra of Prokofiev's "Romeo and Juliet." I have no doubt that peaks reached at least 115 db, perhaps even 120 db. I would have to say that it came close to the point of being uncomfortable, but for me didn't quite cross that threshold. There were a couple of times, though, that my wife briefly put her hands over her ears.

I've measured the Sheffield direct-to-disk recording of that work as reaching about 103 to 105 db at my listening position. The acoustics on that recording are dry and excessively bright, though. If it had a tonal balance that is more typical of well engineered minimally mic'd orchestral recordings, I suspect I would be setting the volume control such that peaks would approach 110 db.

Out of curiosity, a while back I examined the waveforms of that recording on a computer, using an audio editing program. Its dynamic range, the difference in volume between the loudest notes and the softest notes, was around 55 db!

Best regards,
-- Al

But as we saw in the ESL example, the model falls apart.

nah! your ESL example, I think, is a bad one. There are several SS amps manuf that have ESLs in mind & they do sound very good with ESLs. Yes, if you pair a SS amp not designed to take a high capacitative load then it will destructively fail immediately/over time. Your example assumes that one would take a SS amp not designed for high capacitative loads & pair it with an ESL & then complain about the sonics. Give both the manuf of ESL amps & the listener the benefit of doubt that they will be using an ESL amp for an ESL speaker & then compare tube vs. SS power amps for ESLs.
Maybe there is another example that you could cite where the voltage paradigm fails? Thanks.

Bombaywalla, actually that example is excellent. I have yet to hear a transistor amp that can play bass on a full range ESL, assuming the ESL is set up properly (at least 5 feet into the room).

Horns are of course another example with the only exception I know of being the Avantgarde Trio, which is (or was) designed for transistors. One of the reasons horns got a reputation for being 'honky' is the fact that a crossover designed for an amplifier with a high output impedance will not work right with an amp that has a low output impedance. As a result the horn is trying to play material that is out of its passband.

Full range single drivers are yet a third example. You will find that the users of such speakers are usually using a low power tube amp, usually one that has no feedback.

A 4th example is the very first acoustic suspension loudspeaker ever made, the original Acoustic Research AR-1. This speaker was designed for an amplifier with a 7-ohm output impedance, and would not play bass right with most solid state amps as a result. With such amps a simple solution was to put a resister in series with the output of the amp, simulating a higher output impedance.

I can also refer you to this:
http://paulspeltz.com/tomcik/index.html
This article shows that just simply having a high damping factor does not always do the trick. Some speakers want a 10:1 damping factor, and others want 0.1:1 (and yes you read that right- such a speaker might be designed for open baffle operation).

I did not make this stuff up BTW, it was well-known back in the 1950s when the industry was trying to sort out what to do about it. Tomcik, in his article above, proposed a solution that was also used by Fisher. Here is a google search on the Fisher A-80 amplifier:
https://www.google.com/search?client=ubuntu&channel=fs&q=fisher+A-80+amplifier&ie=utf-8&oe=utf-8

Take a look at the first hit. Its a YouTube image of a Fisher A-80 tube amp from the 1950s. Take a look at how the damping knob is labeled: "Constant Voltage" at fully counterclockwise, "Constant Power" at 12:00 and "Constant Current" at fully clockwise, where the amp is using current feedback.

I have to agree with Bombaywalla. Some manufacturers of ESL's specifically made/make ss amps for use with their speakers, Acustat and Sanders come to mind. Many ESL manufactures use ss amps when demonstrating their speakers. I remember a particularly fine demonstration of Martin Logan's with Threshold amps.