mo' better bass: any substitute for watts?

It doesn't appear to have anything to do with the amp, high impedance or not. What's wrong with this picture?

If you think of the amp output impedance and the speaker load as a very simplistic set of resistors in series then you will see that the output impedance has a big influence on the power ultimately reaching the speaker.

Imagine if you were to increase the output impedance to infinity, then the voltage across the resistor representing the speaker would be close to zero - so almost no power reaches the speaker. Conversely, if you assume the output impedance of the amplifier is Zero, then the voltage across the resistor representing the speaker will be a maximum and it will see maximum power.

In practice, there is no such thing as infinity or zero - typically a rule of thumb is 1 to 10 => if the amp output impedance is a tenth of that of the speaker minimum resistive load then to a first order approximation amp ouput impedance can be ignored and the speaker sees all the intended drive voltage (based on the source signal and your volume setting).

What gives tubes the "punch and body" at lower volumes ?

If you understand the above and you think about a typical woofer with a resonance peak at the low end of the bass response (where the impedance may rise from 4 Ohms to 20 Ohms) then it is obvious why a high output impedance amplifier such as one with an 8 ohm output transformer) will sound punchy in the bass, as more voltage/power will reach the woofer at the resonance frequency than in the lower impedance midrange. So in a relative sense the high impedance points get more juice...

Probably the most straightforward and effective solution to get better bass to your hearts content at low volumes is to add a carefully matched, adjustable sub. ACI and REL are the ones I would consider personally. OR if you are comfortable going used, a second hand M&K might do the job for lower cost.

I cannot live without a full and extended low end and I use a vintage M&K sub for this exact reason with a pair of otherwise fairly bass challenged Triangle Titus monitors positioned way high up in cabinets (~6 feet off the floor) in my 2nd music/A/V system with excellent results. Your system appears much less bass challenged than mine, so I think its a pretty easy, slam dunk solution for you.

Hi Bob, If you've not looked at
http://www.atma-sphere.com/papers/paradigm_paper2.html
maybe now would be a good time.

Of course it is quite true that if you make 100 watts into a given impedance, it doesn't matter what made the power, the current and voltage will be the same.

Where things get interesting is when you have an amplifier that makes constant power, as opposed to constant voltage. What happens here is that as the load varies, the current and voltage both change with it to that effect. This is what I was referring to in my posts above.

It is **not** true that all speakers are "voltage" driven, in fact before the Voltage Paradigm was developed, tubes (and often zero feedback tubes) were the only game in town. Designers had to accommodate constant power so to get flat response; they had to be a little more careful.

Some examples of where constant voltage is not so helpful:
ESLs- Constant Voltage amplifiers have trouble making bass while too bright for comfortable listening due to the impedance curves typical of ESLs: high impedance in the bass, almost none in the highs. You need constant power to make that sound right.

Full-range drivers/horns- Most high efficiency speakers have tighter voice coil gaps (hence their cost) which creates higher reactivity. The reverse EMF thus generated can wreck havoc upon an amplifier with lots of negative feedback. The result is excess harshness (ringing) at high frequencies; the main source of many listeners opinion that horns are brash, honky and the like.

Its not difficult to choose a speaker for such an amplifier with a high output impedance (also known as a 'current source' amplifier to use Voltage Paradigm vernacular). All you have to do is look at the intention of the designer. Some examples: Merlins, Sound Lab, most horns (except Avantgardes), Lowthers, Fostex, PHY and the like, The original AR-1, Audiokinesis, Coincident Technology, Rogers LS3/5A, headphones, Magnepan, Reference 3A Loudspeakers, to name a few.

If the impedance curve operates independently of resonance, you can count on the speaker being a Power Paradigm device rather than Voltage Paradigm. Nearly all planars are Power Paradigm devices. Of course, a smooth impedance curve makes the speaker available to both camps- Avalon is a good example of that.

The two paradigms are responsible for a lot of debate in audio- tubes vs transistors, objectivist vs subjectivist...
What is really going on is that the Power Paradigm nowadays operates around the idea of the rules of human hearing, where the Voltage Paradigm operates around the concept of bench measurement. I hope it is obvious that understanding the rules of these two paradigms creates also a means for using transistors in a musical way- Pass 1st Watt amps and Ridley Audio are good but rare examples.

I am of the opinion that when it is possible to quantify the right measurements on the bench, such as the amount of odd-ordered content generated with a dynamically changing waveform, then a new and encompassing paradigm will emerge. Until then, we are stuck with two schools in competition- and the continuing need to match equipment properly and audition it at home.