Klippel Near Field Scanner on a Shoestring

It is sad that there are still execrable loudspeakers sold!
It's mostly sad how poor datasheets are.
ALL data is available and 90% of all known professional driver manufactures have a Klippel system anyway.
So they even have all data. (sometimes you can get it, when you beg really really really sweet and hard)

Yet, we are left with a piece of papyrus with some cobbled numbers together with less information than tube datasheets from the freaking '30s .
Actually, it used to be better, if you look at old Seas and Dynaudio datasheets, they have a lot more information, incl distortion plots!

Yes, I know I have ranted about this many times before, and I won't stop.
It absolutely annoys the sh*t out of me, as professional and hobbyist.

What's also amazing is that with all these cheap and easy tools there are still brands, able to deliver absolute garbage systems to the market.
I am not talking about taste here, but systems full of issues and problems.

Okay, I will get of my soap box again :D :D :D
 
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Soapbox he, many years ago i did design tubecelectronics, and the document i used was called Tubes and was printed in 1948.
It descibes all possible circuits one could make with tubes. Although i do not have it anymore, i have since not seen a tube circuit that - as far as memory serves me- that was not in that book.

Wrt to speakers the industry has indeed come a long way since, but its documentation is not up to current sota, given the standard being the tooling available to design, measure, simulate and evaluate.

Not only small signal T/S nor large signal , which btw i prefer.

Having said i find that the info Purifi publishes is quite good. So it can be done.
Big difference with accutone or scanspeak or way past with siare, audax, volt, seas.
 
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@Kravchenko_Audio , in a previews post ypu mentioned "Speaking of embarrassed, who taught me about the REW method?" . I probably missed it but what is this REW method?
I am looking for was to reduce room impact on measurements(given my limitations), but sofar found it requiring math, and that i am no longer good in.
I am no longer good in Math either!

The method has been posted, And I am posting it as I learned it!

You need not worry about some of the information. But the basics are there. I have proved this out. You can compare it in posts that I have made. It is not perfect, but so close to ground plane or anechoic that it is plenty good enough.

Mark
 

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An ADC works with 1's and 0's for the purposes of testing this is serious overkill. Be proud you are testing! with very reasonable equipment. When I started out in this to do these types of tests as a independent consultant was not possible. It required a $100,000 in test equipment and we couldn't do much of what is a button press now.

We are well past being able to quantify what a loudspeaker does. It is sad that there are still execrable loudspeakers sold! A $100 UMIL or equivalent is more than enough to measure a great loudspeaker. And the free software tools are many times better than the paid for tools. I happily sent John Mulcahy the Pro fee. Vituix, for crossovers is very powerful. Again a modest fee. I don't do as many crossovers as I used to. Mostly drivers and enclosure/amplifier systems now. But next paying crossover work, Mr. Saunisto will get a license request too!

Speaking of embarrassed, who taught me about the REW method? And thanks for doing so! It has proven to be a most useful tool in measurement and characterization of systems.

The more you dive into a subject the less you know. It is true you know enough to have a skeletal understanding. And even a little more flesh on the bones. But total and complete, that takes a lot of time. Happily we have papers and concerted efforts to understand many of the unanswered questions. Finding the answers is the fun part no?
Thank you for the kind words Mark! :) It really is a wonderful time to be a technically minded, curious but poor DIY audiophile, not only the extremely reasonable cost of hardware and software, but the availability of information and knowledge (like, say, a Polish Professor's measurement method making it all the way to Wisconsin and beyond). Plus, being able to come to understand something is a reward indeed!
 
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Generally two mics close together measure sound velocity rather than sound pressure. Cardioid does not matter much. It is a simple thing to revise the equations to use velocity instead of pressure in the modal expansion. There are advantages to this technique as it is less influenced by extraneous noise.

Taking these measurements on two concentric spheres allows for cancellation of all incoming room reflections as Klippel does (ala Weinreich.) This is basically the same idea.
 
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As this is the Klippel on a shoestring thread I assume we are discussing automation of measurements.

The method of using REW vector averaged measurements with incrementally increasing distance is quite time consuming if one uses 25 samples as @Kravchenko_Audio refers to in this thread. Do not know much about the subject but it looks like one could use the shareware Arta_Tic http://nicholasmart.in/measurement_platform/ as is and combine this with a standard guide rail with a stepper motor like this: https://www.ebay.com/itm/124901880488?hash=item1d14bb72a8:g:BpEAAOSwUFVhQbMk

linear.jpg


For a really long axis a solution with the motor on the slide can give you several meters of action: https://openbuildspartstore.com/nema-17-belt-and-pinion-bundle/

 
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If one wants to use REW for the measurements I think it would be quite easy to use a standard step motor controller to move the mic assembly in the desired increments both fast and reliable. Then one only needs to set the appropriate delay between measurements in REW. With a mechanically robust setup less than 2 sec between measurements is doable I guess. (These things are FAST).

Combining this with a turntable.... Klippel on a shoestring?

On my old laptop REW crashes when I enable the function to make several measurements in a row. I use RME ASIO drivers that normally is as stable as it gets. Any suggestions?
 
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On my old laptop REW crashes when I enable the function to make several measurements in a row. I use RME ASIO drivers that normally is as stable as it gets. Any suggestions?
Use something else than REW. ARTA may have some built-in features for automation of external devices, and MATAA will help you to do pretty much anything you want (as long as it it's about audio measurements).
 
As this is the Klippel on a shoestring thread I assume we are discussing automation of measurements.

The method of using REW vector averaged measurements with incrementally increasing distance is quite time consuming if one uses 25 samples as @Kravchenko_Audio refers to in this thread. Do not know much about the subject but it looks like one could use the shareware Arta_Tic http://nicholasmart.in/measurement_platform/ as is and combine this with a standard guide rail with a stepper motor like this: https://www.ebay.com/itm/124901880488?hash=item1d14bb72a8:g:BpEAAOSwUFVhQbMk

View attachment 1270698

For a really long axis a solution with the motor on the slide can give you several meters of action: https://openbuildspartstore.com/nema-17-belt-and-pinion-bundle/

The second one would offer the stability that you need. First one, not so much.
 
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The software and programming part for me is the more difficult side.

Software and programming is for me too, but in perspective, if someone does the software for free the hardware becomes comparatively expensive. :)

What would the software have to do? Automate some measurements? Do all the complicated math?


This should be, I would think. the ultimate goal. The software is not too hard, but a reasonable cost automated data system would be.

What do you mean with automated data system?
 
What would the software have to do? Automate some measurements? Do all the complicated math?
In a perfect world, it would automate the measurements and do the math. But we don't live in a perfect world. My personal preference would be for software that can do the math, but realistically, at this stage, automating some measurements is a step toward the goal, so I'd be mighty happy with that.
 
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