Dr. Toole's - A Rational Approach To Calibrations

[dualazmak]

The most important point IMO is that the non-minimum phase response should not be corrected. @Curvature made a very important point - automated software removes your control of what should/should not be corrected. IMO it's a good crutch for beginners, and it will produce acceptable results for some people. But there is a strong likelihood that it will do something inappropriate and degrade the sound.

(I added bold and underline.)

For myself at least, I agree with your points.

I have always been hesitant to depend on “blackbox type” (to me!) automated software for room mode and other corrections. I would prefer to use tuning procedures (in digital domain, analog domain, and room acoustic treatments) that are "understandable" to me who have rather naive and limited knowledge of audio science...

 

[Justdafactsmaam]

I can't see how that has anything to do with the point i raised, that speakers are not anechoically measured and tuned to a one 1 meter distance...(again unless very small).

Oh right. The exception would be electrostatic speakers. They sound the same from 1 foot away as they do 10 feet away other than the uniform attenuation

If anything, for a highly directional speaker, it is even more important to measure in the acoustic far-field.
because a highly directional speaker inevitably requires a wave guide of some sorts, which means it's a multi-way needing further driver sections.....

Not all of them. See above.

 

[gnarly]

Oh right. The exception would be electrostatic speakers. They sound the same from 1 foot away as they do 10 feet away other than the uniform attenuation

Aah, electrostats ...good point/example.
I've never really figured out what's the right way and distance to measure them. In fact, I've had to measure them up close to get sensible readings.
As they obey line array math in both the vertical and horizontal dimensions, I guess we need some "plane array" math lol.
I see them as highly directional, but from every location on their planar surface, radiating perpendicularly out.
I think the perpendicular HF/VHF phenom occurs, because only a continuous planar diaphragm (or a ribbon), has the tiny c2c spacing necessary for HF/VHF to behave as a true line source.

Line arrays without a ribbon section, that reply on conventional HF/VHF drivers, are also a problem to measure vs distance, ime.
Multiple arrivals independent of coherent summations,

Circling back to my opening point....all I was trying to say is that I think it's a big mistake to believe measurements are routinely made at 1m.
Measurements, for all types of speakers, are much more complicated than they appear on the surface, imho.

 

[DavidMcRoy]

Aah, electrostats ...good point/example.
I've never really figured out what's the right way and distance to measure them. In fact, I've had to measure them up close to get sensible readings.
As they obey line array math in both the vertical and horizontal dimensions, I guess we need some "plane array" math lol.
I see them as highly directional, but from every location on their planar surface, radiating perpendicularly out.
I think the perpendicular HF/VHF phenom occurs, because only a continuous planar diaphragm (or a ribbon), has the tiny c2c spacing necessary for HF/VHF to behave as a true line source.

Line arrays without a ribbon section, that reply on conventional HF/VHF drivers, are also a problem to measure vs distance, ime.
Multiple arrivals independent of coherent summations,

Circling back to my opening point....all I was trying to say is that I think it's a big mistake to believe measurements are routinely made at 1m.
Measurements, for all types of speakers, are much more complicated than they appear on the surface,

Aah, electrostats ...good point/example.
I've never really figured out what's the right way and distance to measure them. In fact, I've had to measure them up close to get sensible readings.
As they obey line array math in both the vertical and horizontal dimensions, I guess we need some "plane array" math lol.
I see them as highly directional, but from every location on their planar surface, radiating perpendicularly out.
I think the perpendicular HF/VHF phenom occurs, because only a continuous planar diaphragm (or a ribbon), has the tiny c2c spacing necessary for HF/VHF to behave as a true line source.

Line arrays without a ribbon section, that reply on conventional HF/VHF drivers, are also a problem to measure vs distance, ime.
Multiple arrivals independent of coherent summations,

Circling back to my opening point....all I was trying to say is that I think it's a big mistake to believe measurements are routinely made at 1m.
Measurements, for all types of speakers, are much more complicated than they appear on the surface, imho.

Even among electrostatics there are variations with regard to radiation geometry. The Acoustat Spectra series are among a number of ESLs with electrically curved, as in their case, or more commonly physically curved diaphragms.

 

[Justdafactsmaam]

I don't want headphone effect, keeping it in order with good clarity and RT60 decay times is fine with me. I initially forgot to mantion ISO 3382-1 (back to front refractions ratio) importance which are also very hard to improve in normal environment (small to medium sized room).

I don’t want a headphone effect either. Thankfully Im not getting it

 

[AudioJester]

I don’t want a headphone effect either. Thankfully Im not getting it

Yeah, but you had to use a very expensive solution to get there......

 

[Justdafactsmaam]

Yeah, but you had to use a very expensive solution to get there......

Yes. I’m aiming at state of the art. I wish that came cheap. I take it where it does

 

[AudioJester]

Yes. I’m aiming at state of the art. I wish that came cheap. I take it where it does

I guess thats one of the problems with DSP, we often try to correct things rather than address the underlying problem.

While a realise it does more, spending another $6-7k to fix a headphone like sweet spot for speakers seems absurd to me.
But then again, if your happy, thats all that counts. However, i would talk others out of going down that path and pick speakers that can be polished by dsp but not be critically dependent on dsp, particularly when spending $10k plus for speakers.

 

[Justdafactsmaam]

I guess thats one of the problems with DSP, we often try to correct things rather than address the underlying problem.

While a realise it does more, spending another $6-7k to fix a headphone like sweet spot for speakers seems absurd to me.

I’m not sure I follow you.

But then again, if you’re happy, thats all that counts. However, i would talk others out of going down that path and pick speakers that can be polished by dsp but not be critically dependent on dsp, particularly when spending $10k plus for speakers.

My speakers are not dependent on the DSP. However they are state of the art when used correctly and synergistic with the specific DSP that is also IMO state of the art. It was a cohesive plan of a speaker/room/DSP system that all push the envelope individually and work ideally together. A different speaker with a wider radiation pattern would have been inferior.

 

[ZolaIII]

I don't use anything special, average bookshelf's with plane silk tweater and usual problem with not great crossover and usually bad ported design. I use them with port's plugged, close to back wall and with two 10" closed box sub's. They stand on each other's and are separated and isolated from each other by thick silicone seaters. Room is relatively small and half treated. Signal processing is done on PC in 64 bit FP base is JRiver added with plugins (MConvolutionEZ and MFreeformPhase along with PTEq-X) all free. Rest of the system also ain't anything special a mid range Yamaha and calibration mic. So it's how I do it respecting physis, placement and doing DSP-ing comprehensive and If I can do it so can you.

 

[gnarly]

"Even among electrostatics there are variations with regard to radiation geometry. The Acoustat Spectra series are among a number of ESLs with electrically curved, as in their case, or more commonly physically curved diaphragms."

@ DavidMcRoy,

Yes, for sure. So many designs have tried to change the flat panel perpendicular radiation pattern, huh?
I still have a pair of Acoustat-X with the 3 angled sections, and the ML CLS.
Damn I love 'stats"....with a love not way far behind my DIY synergy/unity horns..

 

[Justdafactsmaam]

"Even among electrostatics there are variations with regard to radiation geometry. The Acoustat Spectra series are among a number of ESLs with electrically curved, as in their case, or more commonly physically curved diaphragms."

@ DavidMcRoy,

Yes, for sure. So many designs have tried to change the flat panel perpendicular radiation pattern, huh?
I still have a pair of Acoustat-X with the 3 angled sections, and the ML CLS.
Damn I love 'stats"....with a love not way far behind my DIY synergy/unity horns..

You still have the CLSs? I miss mine. Best looking speakers of all time. And enjoyable sound to boot

 

[gnarly]

You still have the CLSs? I miss mine. Best looking speakers of all time. And enjoyable sound to boot

Yes, although in a closet.
With the right material in the right room, they do have a bit of magic, huh?

 

[krabapple]

So, I have my own take-away from Dr. Toole's advice. Buy good speakers. Or if your wife won't let you, do your best with your existing speakers. Apply a broadband low-Q equalization to the upper frequencies if necessary. Pay attention to the off-axis response. And finally, do not correct for a single point in space.

I would only add to this excellent summmary that if you have 'good speakers' but because of distance issues still need to apply high frequency EQ -- if you use one of the most popular speaker correction DSPs (Audyssey) , you actually can't do it because the DSP shuts off the broadband/low Q 'tone controls' of the AVR. This also means that a per-song/album adjustment of the (often wonky) recorded treble or bass is out of the question (a state of affairs Dr. Toole laments), by that means, at least.

 

[ooheadsoo]

I would only add to this excellent summmary that if you have 'good speakers' but because of distance issues still need to apply high frequency EQ -- if you use one of the most popular speaker correction DSPs (Audyssey) , you actually can't do it because the DSP shuts off the broadband/low Q 'tone controls' of the AVR. This also means that a per-song/album adjustment of the (often wonky) recorded treble or bass is out of the question (a state of affairs Dr. Toole laments), by that means, at least.

You can use tone controls if you turn off Audyssey DEQ.

 

[dualazmak]

You can use tone controls ....

Yes, as for safe and flexible tone controls (or I can say "relative gain controls among the multiple SP drivers"), my stance (policy) at least, is that we are encouraged to utilize the "best combination" of "DSP configuration in digital domain" and "analog domain tone controls using HiFi-grade preamplifiers and/or integrated amplifiers".

We need to note (and to respect for) that analog domain tone controls (relative gain controls among the multiple SP drivers) give no effect nor influence at all on the upstream DSP configuration (XO/EQ/Gain/Phase/Polarity/Group-Delay). I myself believe that this is a great merit of flexible tone controls in analog domain. We know well, on the other hand, in case if we would like to do the "tone/gain controls" only within DSP configurations, such DSP gain controls always affect more-or-less on "XO" "EQ" "phase" and "delay" of the DSP settings which will leads you to possible endless DSP tuning spirals every time; within DSP configurations, XO EQ Gain Phase and Delay are always not independent with each other, but they are always interdependent/on-interaction.

Just for your possible reference, my DSP-based multichannel multi-SP-driver multi-amplifier active system (ref. here for the latest setup) has flexible and safe analog level on-the-fly relative gain controls (in addition to upstream on-the-fly DSP gain controls) for L&R subwoofers, woofers, midrange-squawkers, tweeters, and super-tweeters, all independently and remotely. My post here shows you a typical example case for such safe and flexible on-the-fly analog-level tone controls. This my post would be also of your interest.

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