mo' better bass: any substitute for watts?

Saki70, as Bob pointed out above, it takes both voltage and current to make power. The issue is that if we are to make 200 watts into a set of Ohms which might be 3 ohms, the voltage and current can be easily calculated (assuming for the moment that there is no phase angle which there always is in inductive devices).

So you can also look at it as being able to make the Voltage into a load like that- which will only be possible if you can also make the current.

The use of the term 'voltage source' I think can be dangerous without the understanding of the accompanying engineering principles for which the term is a sort of shorthand. You have to keep in mind, IOW, that regardless of the amount of current or voltage that you are making, that the end result is power which is composed of both.

Low impedance amplifiers (Voltage source) *can* make constant voltage with respect to the load. Not all do.

Higher impedance amplifiers (Current source) *can* make constant power with respect to the load. Not all do.

You **must** match such amplifiers with speakers that are designed with intention to work with that particular kind of amplifier that you are using. If you do not tonal aberrations will occur.

It is true that some constant voltage amplifiers can deliver lots of current. It is not true to say that that is the same thing as having lots of bass authority. IOW any kind of amplifier can be perceived as being wimpy in the bass if not set up properly. OTOH, some amps will not play good bass no matter what you do.

In my personal case, because I like amplifiers to be relaxed at all volume levels, I will not use one that has negative feedback, as that design element adds loudness (harshness) cues. So I work with speakers that are designed for amps that have a higher output impedance. So on my speakers there are no 'voltage source' amps that will play the speaker with the authority that my 60 watt triode amps will. But that could be very different on other speakers- my bone of contention is that because the use feedback, as far as I am concerned they will never sound like real music, so who cares :)

Atmaspere ;
First off...I would like echo Bob's accolades and offer our thanks to you for your patience and diligence in this thread ! You are one of a very few gentlemen that would not only offer some input but also stick it out for a myriad of questions as we try to learn a thing or two . A true industry leader !!!

I understand that it takes both voltage and amperage to make watts (E x I = W). And that you can have different kinds of watts ie. "voltage source" and "current source" depending on the impedence of the amp .

Can you tell us if the 'ratio' of volts to amps is the same for both types ? IOW do the watts from a "voltage source" amp generally contain more volts , than the watts from a "current source" amp ? And conversely do the watts from a "current source" amp generally contain more amps , than the watts from a "voltage source" amp ?

Or...

As you stated , "It is true that some constant voltage amplifiers can deliver lots of current." Would this be an example of a ratio difference ?

Thank you .

Rja
I will one up you.. I have gone from a Class A solid state power up to a percentage then it would switch to clas A/B in Mono block which was 300 watt peak with VEry high damping factor to a
20 watt S.E.T. Class A amp and it stomped the crap out of the 300 watt in bass! Go figure :-)

Saki70, thanks for your comments.

What we are talking about is 2 things: 1) output impedance as an actual raw impedance, not complicated by negative feedback (IOW 'open loop') and 2) servo gain- the amount of negative loop feedback employed.

A lot of designers see these two as the same, but they are not. A variety of Voltage Paradigm speakers *require* that the amp have some sort of feedback to accommodate the otherwise improbable impedance curves that have resulted. The feedback is part of mechanism that allows the amplifier to accommodate peaks as well as dips in the curve. You can do this with raw impedance alone, but feedback makes it easier- your amp does not have to have such a low open loop impedance.

With higher impedance amplifiers, in order to get flat frequency response on such speakers, the role of feedback becomes more prodigious. However, many of these amplifiers are probably tubes, and often tube designers will eschew large amounts of feedback as the amplifier will often exhibit some linearity without, something that is rare in the transistor world. Their hope is that you will do the right thing and use these amps on a speaker that has a higher impedance. FWIW the thinking here revolves entirely around sonic performance rather than the ram ability to simply drive a low impedance, something that usually has little to do with overall sound quality.

So we are talking about a spectrum- as output impedance is increased and servo gain decreased, the voltage/current ratio that describes the output of the amplifier changes with it. So there is not a hard and fast rule.

In the past I've seen a lot of DIY hobbyists try to add loop feedback to a 'current source' amplifier with the hopes of getting it to play a four ohm load better- with more power. It does not work. That is because the open loop impedance of the amplifier is too high to be adequate for four ohms. You can reduce distortion and flatten the frequency response using servo gain, but you can't change the power. That is why I say that open loop output impedance and servo gain are different phenomena.

The pity of this whole thing is the idea that the ability to drive 4 ohm loads is a sign of being 'beefy' or 'gutsy' (somehow better anyway) in the amp. The fact of the matter is no transistor amplifier sounds right on 4 ohms, nor does any tube amp. If you want to really see what either one is really capable of, you need a higher impedance -16 ohms is nice- to do that.

At higher impedances speaker cables are far less critical in the overall sound and all amplifiers will exhibit less colorations due to reduced distortion. Transistor coloration BTW is the harshness caused by odd-ordered harmonics at very low levels. Tube coloration is the added 'warmth' or 'bloom' that is a product of even-ordered harmonics that are at a more pronounced level. So transistors will sound smoother with more detail and tubes will sound more neutral with more detail. Win win.

Sorry there was not a simple answer to your question!