mo' better bass: any substitute for watts?

Atmasphere ;
So synergy is the only constant and wattage takes a backseat to circuit design for both amp and speaker . Is this a correct summation ?

Up for some more questions ?

Are global feedback , negative feedback , loop feedback , and zonal feedback all names for the same thing ?

How close to zero should we get ? I noticed that you offer up to 2? of feedback adjustability on your amps .

And what is your opinion of the use of 'autoformers' to achieve the higher speaker resistance that the amplifier will see ?

Thank you .

Saki70, I don't like the word 'synergy' as it suggests that we are going to balance one defect against another, and I think that in the case that we are talking about, the word is 'compatible' and the answer is 'yes'.

Loop and global feedback are the same thing. Zonal is usually the same as 'local' and may or may not be loop feedback, it could also be degenerative feedback. They are all forms of negative feedback, and there is a lot of verbal shorthand around, so you have to be careful.

I think what is important if you use feedback is that a) the amplifier must be fast and low distortion to begin with and b) the feedback be low enough that the odd-ordered harmonic enhancement is kept out-of-band. That really does not allow for very much feedback in practice.

The ZERO is the only autoformer I know of (we used to make a similar product called the Z-Music autoformer years ago). The concept is all about problem solving- this or that amp can't drive a speaker load that low so here's a solution to that problem. Given that that is the case, they work very well indeed. But if you had a 16 ohm speaker to start with that would be better :)

Atmasphere,

Thanks so much for taking the time to share your insights in this discussion.

My question is how can I tell by listening to a system whether use of negative feedback is having a noticeable negative effect on what I hear short of an a/b regression test between two comparable amp designs, one with and one without?

Also, as with most technology solutions, aren't some negative feedback implementations done better than others? Are there any that do it right to the extent that the negative effects are minimal or non existent?

Saki70, FWIW Steve McCormick, who has been making solid state amps for years, reports that his amps sound better driving a 4 ohm load though the ZERO, such that the amp is loaded at 16 ohms. His amps easily double power- they have no problem driving 4 ohms. I interviewed several solid state amp manufacturers at CES this year, and independently of each other they all concurred that while their amps easily **drive** 4 ohms, that due to effects withing the transistors themselves (which are exacerbated by more current) the amps **sound** better on 16. So much better, that using a set of ZEROs to do that is effective.

Transformers are inductors and so they ring if improperly loaded. Putting a 16 ohm speaker on an 8 ohm tap will mean that the transformer is going to add some distortion due to ringing, but the tubes otherwise will see a higher impedance load. Quite often, although they will make slightly less power, the distortion will go down too.

Mapman, you bring up a good point- feedback as a design issue can be tricky to sort out. Its the sort of thing that a designer or DIY person might tinker with and compare. There are so many variables that go into an amplifier/preamplifier design that it would be hard to ascribe something you hear in such a product to any one thing. You do have to work with the designs a bit in order to begin to sort out the sonic artifacts that different design considerations bring.

However we do already know that negative loop feedback contributes to odd-ordered harmonics in the regions that the ear uses as loudness cues. The contribution is slight- 100ths of a percent- but human ears are very sensitive to that sort of thing. We perceive this as 'brightness' or 'hardness'.Conversely, even ordered harmonics can be several orders of magnitude higher and our ears don't seem to mind.

I feel we are getting OT. If you wish to continue in this direction, let's start another thread :)