Yes you were off on one with your 'power paradigm' which made it very difficult to take you seriously.
MiniDSP. Marvellous device and really winds up the luddites. WNTL? 😀
Age And Listening
Question for folk. How do you deal with how things sound as you age?
I know that today (age 70) what I hear is quite different from what my hearing was like 30 years ago. Tinnitus, hearing loss, etc. now are the way it is. As a result, the sound I like has changed. Does this mean my amplifier, designed by listening, will be significantly different today than 30 years ago? No axe to grind, just curious how age has affected what you hear and how it affects your preferences.
Bill
Question for folk. How do you deal with how things sound as you age?
I know that today (age 70) what I hear is quite different from what my hearing was like 30 years ago. Tinnitus, hearing loss, etc. now are the way it is. As a result, the sound I like has changed. Does this mean my amplifier, designed by listening, will be significantly different today than 30 years ago? No axe to grind, just curious how age has affected what you hear and how it affects your preferences.
Bill
Of course if you have MiniDSP (and the meas gear to be able to use it well) then what the DF does to your frequency response is entirely beside the point.
Apparently you didn't read up. It works; been using the techniques for decades at this point.
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Anyone recall motional feedback where the speaker was either acoustically or mechanically included in the overall negative feedback. Was that not the correct approach, maybe before its time?
Yes, the concept is still alive an in use. But it works well only at lower frequencies (cone resonances make the loop very difficult to keep stabilized) and the amount of feedback that can be applied while remaining stable is rather low. Usually practical (as opposed to short-term in lab conditions) harmonic distortion improvement isn't very large because of the low loop gain as frequency increases. The main advantage is that compression at low fundamental frequencies is reduced.
Yes, but a clean, flat signal from amp makes it a lot easier to deal with speaker anomalies.
Clean flat amplification is a commodity these days, thanks to GNFB. The same cannot be said of clean, flat speakers, (and listening spaces).
I've found reducing the no. of variables I've got to deal with is a Good Thing. [edit] Folk can always dial up some colour they'll allow themselves some EQ.
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So you really didn't follow along! Yes, it's nothing new as I said before, but it's not current drive. Current drive is where the amplifier has an output impedance significantly higher than that of the load. To do this current feedback is often employed.
Power drive OTOH is where the amplifier output impedance is near the same impedance or slightly lower than that of the load. Either no feedback is employed or else current and voltage feedback are used in nearly equal amounts.
And speakers, and the understanding of their interaction with rooms, are getting a lot better these days.
how about comparing fft spectrum taken at ~5W from the output of high DF GNFB amp resistive load vs real speaker?
and then the same with low DF amp?
and then the same with low DF amp?
And speakers, and the understanding of their interaction with rooms, are getting a lot better these days.
Yeah. For more than 20 years I've been thinking the low hanging audio fruit is speakers. But, only if my psychoacoustic knowledge/understanding can be adequate. With regard to the latter, I have to say when I first started looking in this direction, that an awful lot of useful knowledge had only just been found out and a great deal of good research was just getting underway.
Toole's big book is remarkably useful for a critical reader. Huge info mine.
Funny how we hear different. I never could get bass sound right until I went active with high(ish) DF amps. Friend of mine is a professional bass player (electric and acoustic) and he checks everything he records on my stereo as it has, in his words, the most realistic bass representation he has come across.
Check out his open access paper in the latest AES journal too, The Measurement and Calibration of Sound Reproducing Systems. Cinema audio standards in particular are bound to change, and for the better. But I also like his acknowledgement of areas for further research.
That's really true. The room dictates all we hear, nothing new... Measurements and calibration systems, IMHO, are far from giving us the real sound that we hear, but yes, thats what we have, so we have to count with it.
I have some experience with Dirac software, and it's far away of what I think to be a good audio reproduction, it's called Dirac Live, a digital room correction system. To me it sounds like there is a funnel between the speakers and all the instruments are there. The "target curve" you make of your system is very beautiful, but the result is not for me.
I have some experience with Dirac software, and it's far away of what I think to be a good audio reproduction, it's called Dirac Live, a digital room correction system. To me it sounds like there is a funnel between the speakers and all the instruments are there. The "target curve" you make of your system is very beautiful, but the result is not for me.
room correction
Room correction can help at low frequencies, as can carefully-placed multiple subwoofers. Otherwise they are fashionable but not particularly useful, and some are downright awful. As Toole's paper referenced above begins, it has long been thought that a single microphone measurement of a steady-state amplitude response is an important indicator of how a system will sound (paraphrasing there).
It's not. As FT adds, "It is an enticing marketing story".
Room correction can help at low frequencies, as can carefully-placed multiple subwoofers. Otherwise they are fashionable but not particularly useful, and some are downright awful. As Toole's paper referenced above begins, it has long been thought that a single microphone measurement of a steady-state amplitude response is an important indicator of how a system will sound (paraphrasing there).
It's not. As FT adds, "It is an enticing marketing story".
Much has to do with whether the speaker is designed for high DF or not.
If yes, the FR will suffer. If not, the FR might be just fine.
If the speaker is designed to use a higher Source impedance, then the user manual should state so and explain how to achieve the effect that the Speaker Designer intended.
It is not the fault of the amplifier, nor the amplifier Designer, that a speaker does not perform as intended when it is designed to suit a higher source impedance.
It is not the fault of the amplifier, nor the amplifier Designer, that a speaker does not perform as intended when it is designed to suit a higher source impedance.
I was thinking about thd fft, not FR:
compare thd fft resistive load vs real speaker.
if there will be more hf fft peaks with real speaker that means that its coil acts like microphone injecting additional signals to gnfb loop
which should not occure with low df amp