John Curl's Blowtorch preamplifier part III

[PMA]

Max, you are talking only.

 

[Max Headroom]

How does that work exactly, the confidence thing?

The amplifier works according to spec sheet.
Dan.

 

[billshurv]

I say $100 worth of impedance eq is good engineering and economically solves problems that are far more costly to solve otherwise.

With as ever zero measurements from you OR Joe to actually back this up.

 

[scottjoplin]

What spec sheet?

 

[PMA]

Anything can be said, flat earth, class AB inability to drive complex load, voltage and current to be in phase. Absolutely anything can be said without any proof and with equal importance. Such is internet.

 

[Max Headroom]

Max, you are talking only.

Pavel, what is that intended to mean ?.
I have spoken from experience and I also asked you a polite question, your polite answer would be appreciated.


Dan.

 

[scottjoplin]

And such is this forum where some members with businesses and power can change thread titles without justification

 

[Max Headroom]

What spec sheet?

The typical Yamaha, Sony, Pioneer amplifier/receiver etc.


Dan.

 

[PMA]

No interest in playing word games.

 

[scottjoplin]

Then why talk to him?

 

[Max Headroom]

With as ever zero measurements from you OR Joe to actually back this up.

Yeah, take an oscilloscope and take a look at OPS transistor bases...or you could sim with resistive or reactive/resonant load.


Dan.

 

[scottjoplin]

The typical Yamaha, Sony, Pioneer amplifier/receiver etc.

Meaningless, only a with and without test would have any value, presumably these have been done, and there are results to be viewed to inspire confidence in potential customers?

 

[Max Headroom]

Has anybody here ever actually impedance compensated a loudspeaker and compared to matching but non compensated loudspeaker ?.


Dan.

 

[Evenharmonics]

There is nothing that would persuade this guy that he is wrong, not speaking about the fact that he is unable to place any measurement supporting his pseudo-theories.

Isn't that the standard pattern of behavior by those in audio business who shill online?

 

[john curl]

I'm for all new ideas in improving audio design. There is NO exact solution. Amps need to be better, and to do that, we have to better understand their problems (that we have not fully discovered). Take that from someone who designs amps for a living.

 

[billshurv]

Has anybody here ever actually impedance compensated a loudspeaker and compared to matching but non compensated loudspeaker ?.


Dan.

Clearly YOU haven't yet you claim it improves things.

 

[Evenharmonics]

I'm for all new ideas in improving audio design. There is NO exact solution. Amps need to be better, and to do that, we have to better understand their problems (that we have not fully discovered). Take that from someone who designs amps for a living.

In improving audio design, shouldn't the first step be the weakest link in the chain? I'm sure you would agree that amp isn't the weakest link in audio replaying electronics.

 

[31697B]

As I understand it Joe is advocating impedance eq across loudspeaker input terminals causing loudspeaker to appear as 'clean/flat' resistive load. This eliminates harmonic/circulating currents which means amplifier is not having to output harmonic currents in order to satisfy constant output voltage condition. In the case of 'perfect' amplifier reactive load of no importance but in the case of typical 'consumer mid-fi' reactive load is of strong importance and this is what Joe is addressing.

Dan.

Ok Joe has also published amplifier circuit using an R as i originally showed for motional feedback.

A couple weeks ago I and Demian1 said we did this parallel R approach commercially from my suggestion from an experiment I did myself to flatten speaker resonance peaks and see if there was an audible effect. Thus, making the load more benign and resistive.

The sound character change could be due to change in amp distortion but seems unlikely until your Rp is very low, comparable to speaker Z. Seems effect of speaker resonances on amplifier are audible.

The derivation came from flattening high freq Z rise with a series RC across the speaker terminals. I decided that removing the C would include Z changes at any freq (esp bass resonance of driver/box).

The effects of Z/resonances are also manifest with motional feedback. Either/both are audible depends on OPS..... single, double or triple.

IMHO all amplifiers should have the simple Rs (0.1-.33) added to lower driver audio distortion. Its a no brainer and like dc servo can be applied to most all design topologies.

THx-RNMarsh

 

[john curl]

Amps are very limiting when you already have a good enough loudspeaker.

Loudspeakers, because they operate open loop, SEEM to be much more important than almost any amp, static measurement for static measurement, BUT low distortion in amps is usually achieved by adding negative feedback, AND this does not seem to improve the sound much, if any. A good 'open loop' amp with modest distortion (compared to others) might sound better than a 'zero distortion' amp. That is our experience, and has been for more than 50 years.

 

[scottjoplin]

Amps are very limiting when you already have a good enough loudspeaker.

Similar to what merrill said earlier, is it true though?