John Curl's Blowtorch preamplifier part II

[Wavebourn]

Originally Posted by kgrlee

Why do you need to do this 0R1 resistor trick if you have Audyssey? Does the resistor trick provide stuff that Audyssey can't do?

I thought you understand the difference between damping of ringing and equalizing the rest of response that can't be tamed mechanically?
If you equalize the frequency response, no matter how flat is it's 2-d representation (level VS frequency), look at waterfall (time added) and you will see that sharp resonances still produce audible colorations because sounds on some frequencies decay longer than on others. Equalized sh*t sounds like equalized sh*t.

[Joshua_G]

Originally Posted by john curl

Good point Nelson Pass. 100 ohm or so resistors would need to be added, but it still WOULD be quieter than my original design.

Hi John,
Will it work also with JFETs as the folded cascade, like in the attached schematics?

[gpapag]

Originally Posted by Wavebourn

If you equalize the frequency response, no matter how flat is it's 2-d representation (level VS frequency), look at waterfall (time added) and you will see that sharp resonances still produce audible colorations because sounds on some frequencies decay longer than on others. Equalized sh*t sounds like equalized sh*t.

I had indirectly asked SY which resonances are equalizable. He responded there:

Originally Posted by SY

No, that's not minimum phase and it's also not single-valued.

I took the risk to interpret his answer like this:

Originally Posted by gpapag

I don’t know if I guessed well.

George

[Wavebourn]

Originally Posted by kgrlee

I tried optical methods and double coils too but the ACE stuff works so well that I abandoned the other stuff. Also tried current drive but again ACE is superior. See my original post on the subject. I'm sorry Wave didn't see any distortion reduction in his experiments.

Yes, small driver fluttering like a fly in small box would always generate more distortions than bigger driver in appropriate enclosure. Don't be silly, even when joking.

[Wavebourn]

Originally Posted by RNMarsh

Wavebourn -- which Aud auto EQ model are you using. I got hold of their 6 dsp channel PRO model. It works very well for EQ'ing headphones as well... just need a probe mic. -RNMarsh

I have no idea, it's a closed box for dummies, in 5+1 receiver. Calibrated microphone goes with it. It asks to position microphone in 6 different places, does fast sweeps through all channels one by one, calculates levels, delays, EQ. From what it does as the result I conclude that it equalizes mic position - independent things storing results in non-volatile memory.

[PMA]

Originally Posted by Joshua_G

Hi Pavel,
How did you determine the values of those capacitors (which are non-standard values)?

Same ratio as resistor divider. You know, 1/jwC for cap impedance. RC constant to cover low frequencies.

Cheers,

[Esperado]

Originally Posted by Wavebourn

small driver fluttering like a fly

Monacor Carpower Raptor MK1 Funktionstest für Aspirin - YouTube
Diameter 12"
Double spider on each side of the moving coil
Impedance (Z) 4Ohms
Resonant frequency (fs) 43Hz
Power rating (P) 1,000WRMS
SPL (1W/1m) 87dB
Linear excursion (XMAX) ±13.5mm

[SY]

Originally Posted by gpapag

I don’t know if I guessed well.

Very well, but some quibbles: minimum phase can apply to nonlinear systems as well. The only requirement is that the phase be the derivative of the amplitude response wrt to frequency. And single valued functions indeed contain no loops, but if (for example) you have a 2d function unwinding in a 3d space, you can inadvertently have multiple values which are not loops in the 2d representation. Rooms have 3 dimensions (assuming the room size is time invariant!), the signal applied to them has one dimension plus time. So, no minimum phase (there's delays from reflections) and multiply valued (amplitude varies over space as well as time).

[Wavebourn]

Originally Posted by Esperado

Monacor Carpower Raptor MK1 Funktionstest für Aspirin - YouTube
Diameter 12"
Impedance (Z) 4Ohms
Resonant frequency (fs) 43Hz
Power rating (P) 1,000WRMS
SPL (1W/1m) 87dB
Linear excursion (XMAX) ±13.5mm

Everything is relative.

[jneutron]

Originally Posted by gpapag

I read it as a tribune to Ivor Catt.

George

Ya know...it kinda does, doesn't it??

Buuuut...I have experimental evidence...he does not..

jn