That would be nice to see. Perhaps it would be a great start for a new thread on "my greatest tech fail". I have a great one to be proudly ashamed of too, but it needs a lot of digging up. Has to do with sound but no audio.
You are missing time. You can home in on the right target a lot more quickly in the digital domain*. For prototyping it wins hands down. As for cost, miniDSP and their ilk are remarkably affordable these days. Of course depends if you are making one, 10 or 10,000.
Aside: 5 years ago Linkwitz reckoned that DSP was no where near as good as an analog crossover. Now he no longer supports his analog units and only supplies miniDSP files. I cannot find an explanation for this on his website. My suspicion is that it vastly reduces his tech support burden. I also realise that his approach to active cross-over design is not the same as many others.
*I realise that there are those with the requisite experience who can home in on the answer quicker than us mere amateurs having put in the blood sweat and tears over decades.
But agree with you on the op-amps 🙂
Do we have any hope that one day we'll be able to manufacture "linear speakers"? If not, why do we keep polishing "linear amplifiers"? 😕
Nope. Physics is going to take a lot of exceptions with "perfect" speakers. Much less their interaction with the world around them.
It's a heck of a lot easier to swap a opamp than it is to design a quality speaker. Geddes makes some good evidence towards why the sins of loudspeakers are less noxious than that of electronics. So it's probably good to pick and choose one's preferred "sound" or at least push the errors of our electronics into oblivion (not too hard to do).
It's a heck of a lot easier to swap a opamp than it is to design a quality speaker. Geddes makes some good evidence towards why the sins of loudspeakers are less noxious than that of electronics. So it's probably good to pick and choose one's preferred "sound" or at least push the errors of our electronics into oblivion (not too hard to do).
This is (roughly) similar to the question "How can we hear 0.1 percent distortion in an amplifier through a speaker that has 10 percent distortion?
The answer is that speaker distortion is generally in the lowest harmonics, and drops off dramatically for higher harmonics Much like in (many) tube amps, distortion only in the first few harmonics isn't easily heard. Modern amplifiers have lots of negative feedback, which pushes the total distortion numbers down, but it also this pushes the "balance" of the distortion into the higher harmonics, which are more easily heard, and even worse, are more annoying.
The second and third harmonics are on the musical scale (thus they are often masked by a real musical note at the same frequency), but the 7th is not. Some musical instruments (such as piano by the placement of the hammer hitting the string, and Hammond organ) are designed to not generate the 7th harmonic.
It's harder to put a driver in a feedback loop and keep stability. It's been done with "servo drive" for woofers and subwoofers, but the phase shifts and such for drivers reproducing higher frequencies are apparently too hard to deal with.
It's a heck of a lot easier to swap a opamp than it is to design a quality speaker. [/QUOTE]
Now I'm imagining people doing "driver rolling." You read it here first!
Harman M2, Kii, many Genelecs, these are linear speakers, there are others too, but none of them is perfect in all regards. By the way, none of these work with "linear amplifiers". So that is where the fun is.
One area that I want to exploit in the future are the possibilities for pre-distorting the amp feeding a driver so that the distortions thereof are compensated. In effect making the amp even more non-linear. This will require the capability to measure level and phase of all relevant driver distortions in a matrix related to input power, and secondly the ability to design a trinket which produces the adequate counter-distorted signal. I can't do either at the moment, but this is the direction I would like to follow.
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Pre-distortion is a very interesting field. We used to do it with wideband power amplifiers back when I had a real job. I've always been wary of it with speakers as I can't see how you deal with cone modes, so seems only beneficial when the cone is being purely pistonic. But that might be me viewing the problem the wrong way.
Reminds me must (finally) get my servostatic sub working. Been malingering for nearly 20 years. no excuses left.
Reminds me must (finally) get my servostatic sub working. Been malingering for nearly 20 years. no excuses left.
I think Klippel does this, I was at a demo several years ago where they showed a prototype. The driver was characterized and the signal predistorted. The goal was to get lots of sound out of a small box with a small driver, but as linear as possible. Also incorporated limiting and protection with soft clipping.
Jan
Yes. Something I agree with!
Heh.
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No opamp content:
Anyhow, you have the sub from Infinity Servostatics?
Now that's funny/interesting!
A good friend had those in 1973 or so with Audio Research D-76 amps, SP-3A preamp.
A fairly horrific combination, but impressive to look at - he had stacked ESL
modules. Fwiw.
You'll want to reverse engineer that, and build it with a real amplifier...
...that was a pretty awful subwoofer, fwiw. Nice box - if you have the Rosewood, they polish with some hard wax wonderfully! That may be the best part - the shiny Rosewood.
Where's the rest of the Servostatics??
Hello Vac,
FIY. Below is the approach you mention described: feedward error correction in loudspeakers. Dunno, maybe the Kii follows that approach.
The Schurer Thesis is based on the Klippel work.
http://doc.utwente.nl/13925/1/t0000002.pdf
http://etd.dtu.dk/thesis/185888/imm3871.pdf
The real challenge with the feedforward process, as described by Schurer, is the accurate establishment of the non-liniar parameters of the speaker ( read : woofer) in question. Not two drivers seem to be alike. Also, an amp that is really fully dc coupled and can actually deliver the feed-forward dc pulses to the speakers, is necessary. Schurer, Aemics b.v. and YT tried, but gave up in 2004. Fine for a lab, but too labor intensive for series production. This might be an explanation for the limited application of the Klippel concept.
Eelco
FIY. Below is the approach you mention described: feedward error correction in loudspeakers. Dunno, maybe the Kii follows that approach.
The Schurer Thesis is based on the Klippel work.
http://doc.utwente.nl/13925/1/t0000002.pdf
http://etd.dtu.dk/thesis/185888/imm3871.pdf
The real challenge with the feedforward process, as described by Schurer, is the accurate establishment of the non-liniar parameters of the speaker ( read : woofer) in question. Not two drivers seem to be alike. Also, an amp that is really fully dc coupled and can actually deliver the feed-forward dc pulses to the speakers, is necessary. Schurer, Aemics b.v. and YT tried, but gave up in 2004. Fine for a lab, but too labor intensive for series production. This might be an explanation for the limited application of the Klippel concept.
Eelco
electronics some stuff on kii. Bruno has taken things to the next level, at least for speaker control.
From the diagram, it seems it is still feedback instead of feedforward. But apologies : this is off topic..
Well I wasn't trying to suggest that the amp should compensate the loudspeakers, that is rather complicated and would work only with a particular make of speakers.
I was thinking on lines of "how about we look at it from the same perspective as (good) speaker makers". I.e. instead of trying to minimize several (or a total of) "distortions" at once, concentrate on the most unpleasing ones and leave the innocuous ones alone.
I was thinking on lines of "how about we look at it from the same perspective as (good) speaker makers". I.e. instead of trying to minimize several (or a total of) "distortions" at once, concentrate on the most unpleasing ones and leave the innocuous ones alone.
Audiphools spend their life trying to get synergy, and matching amps and cables to speakers (or even matching speakers to their amps). Why not take a systems approach and try to make things actually better!
Thanks Eelco, to learn is the main reason for me to be on this site and these are very helpful links.
Bill, afaik know there is no feedforward in the Kii. The two, for a domestic speaker revolutionary technologies are 'beam steering' of the lower frequencies to get a cardoid pattern that holds to about 80Hz, and the split current/voltage feedback for drivers. The former works, the latter I had already found from private experiments to be of limited use to reduce driver distortion. Watch out for AudioXpress to find out more.
Edit: and yes, it has op-amps.
Bill, afaik know there is no feedforward in the Kii. The two, for a domestic speaker revolutionary technologies are 'beam steering' of the lower frequencies to get a cardoid pattern that holds to about 80Hz, and the split current/voltage feedback for drivers. The former works, the latter I had already found from private experiments to be of limited use to reduce driver distortion. Watch out for AudioXpress to find out more.
Edit: and yes, it has op-amps.
Seems like a worthy topic - are there any threads on this?
Suggest someone start one, link it from here...
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Suggest someone start one, link it from here...
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