Measuring and compensating for woofer Le
- Thread starter Al Klappenberger
- Start date
jwcullison
Active Member
Al. Great. Is that a -18dB network?
What is the 0.2 ohms listed at the bottom?
So for the high pass, it feeds into an autoformer with a swamping resistor?
I take then you can just throw in a band pass of some sort with twweter filter or even use you ESN5800.
What is the 0.2 ohms listed at the bottom?
So for the high pass, it feeds into an autoformer with a swamping resistor?
I take then you can just throw in a band pass of some sort with twweter filter or even use you ESN5800.
Great. Is that a -18dB network?
**It's what is commonly referred to as 18 dB / octave. It's actually a bit sharper than that. It's 3rd order Chebyshev.
What is the 0.2 ohms listed at the bottom?
**This is the source impedance of an amplifier. .2 Ohms is equivalent to an amp with a damping factor of 40.
So for the high pass, it feeds into an autoformer with a swamping resistor?
**Yes, exactly.
I take then you can just throw in a band pass of some sort with tweeter filter or even use you ESN5800.
** The high output would go the input of the ES5800. The low output of that
would go to the transformer and swamping resistor.
**It's what is commonly referred to as 18 dB / octave. It's actually a bit sharper than that. It's 3rd order Chebyshev.
What is the 0.2 ohms listed at the bottom?
**This is the source impedance of an amplifier. .2 Ohms is equivalent to an amp with a damping factor of 40.
So for the high pass, it feeds into an autoformer with a swamping resistor?
**Yes, exactly.
I take then you can just throw in a band pass of some sort with tweeter filter or even use you ESN5800.
** The high output would go the input of the ES5800. The low output of that
would go to the transformer and swamping resistor.
jwcullison
Active Member
Very nice.
Bob, I might build one of these in the future and play with it for awhile and send it to you to hear it.
I have always said the Cornscala is a no brainer. Great speaker.
Bob, I might build one of these in the future and play with it for awhile and send it to you to hear it.
I have always said the Cornscala is a no brainer. Great speaker.
I've been reading up on some of the nonlinear models for loudspeakers by Klippel and came across this picture in one of the articles and thought some might find it interesting as it pertains to the inductance calculations for crossovers:
-http://www.klippel.de/pubs/linpara.pdf
Klippel has a huge slew of articles on the modelling of nonlinear stuff - I don't really understand the math, but the pictures and sound bytes are cool:
http://www.klippel.de/pubs/default.asp
I think there are a few more plots showing changes in the Re and Le of the voice coil in relation to temperature (which isn't a direct result of power levels, but rather the type of source material too). And to think it all changes with frequency too - yikes!
-http://www.klippel.de/pubs/linpara.pdf
Klippel has a huge slew of articles on the modelling of nonlinear stuff - I don't really understand the math, but the pictures and sound bytes are cool:
http://www.klippel.de/pubs/default.asp
I think there are a few more plots showing changes in the Re and Le of the voice coil in relation to temperature (which isn't a direct result of power levels, but rather the type of source material too). And to think it all changes with frequency too - yikes!
jwcullison
Active Member
Purchased another pair of Bob Crites CW 1526-stamped drivers.
These are to emulate pre-1984 K33.
Well. All principles hold here.
Alk quotes 6 ohms impedance in series with 1.0 mHy inductor for the older K33.
OK. I have a pair of Bob's woofers horn loaded in one bass bin cabinet wired parallel.
I have a nice flat impedance from 400hz - 845 Hz. 3 ohms in series with 0.53 mHy.
Bob. Nice job. AlK...I'm still amazed with this technique.
Bob...I am going to do this test in "free air" eventually to see what I get for this driver.
I need to let you all know that I need to repeat my testing on the new K33 as I noticed a slight inaccuracy in my technique when I last did it. Back later.
jc
These are to emulate pre-1984 K33.
Well. All principles hold here.
Alk quotes 6 ohms impedance in series with 1.0 mHy inductor for the older K33.
OK. I have a pair of Bob's woofers horn loaded in one bass bin cabinet wired parallel.
I have a nice flat impedance from 400hz - 845 Hz. 3 ohms in series with 0.53 mHy.
Bob. Nice job. AlK...I'm still amazed with this technique.
Bob...I am going to do this test in "free air" eventually to see what I get for this driver.
I need to let you all know that I need to repeat my testing on the new K33 as I noticed a slight inaccuracy in my technique when I last did it. Back later.
jc
usedto
Lunatic Member
I hope someone can help you. I seem to remember reading awhile back that he got irritated of people plagiarizing his work and selling it as their own, so he removed the info from his site. I could be mistaken. Good luck.
Brinkman
Analog loyalist
I can recall some details, such as using a function generator running at the crossover frequency through a power amplifier and the need for a dual channel oscilloscope and an RC bridge. Anything more detailed is a bit foggy.
klipschorn
Klipschorn
While reading the paper published by ESP, an innocuous error was noticed. The link to the paper was given by DrWho in message #26 and is http://sound.westhost.com/tsp.htm
ESP gives the formula for the volume of a cone V=pi*r^2*h/3 and while that formula is correct in and by itself, it is improperly used here. The reason, the volume in the loudspeaker cone is a frustrum of a cone, not a cone. The correct volume is h(B+b+sqrt(Bb))/3, where B is the large area of the cone, b is the smaller area at the dust cap and sqrt is square root. The volume of a cone can be re-written as V=Bh/3.
The difference is about 28% in the volume of a 15 inch cone which will have no effect on the calculated Thiele/Small parameters but shows that one can't always trust that which is written in so called 'white papers'. A 28% error in Re or Fs would have more serious consequences.
Such errors are not uncommon. Some are actual errors on the part of the author and some are the result of the typesetters, the latter showing that proof reading is mandatory.
Many years ago, in 1975, an error in a paper published by none other than Paul Wilbur Klipsch was noticed. Upon meeting Mr. Klipsch, I approached him with that discrepancy, to which he chuckled and took my paper upon which he made a note. The whole story can be found in the following link of which there are two pages, the second being accessed by the famous Klipsch BS pin. http://www.ln271828.net/exponent.htm
As stated earlier, this error is of little consequence and I am no exception to the rule. Even something as innocuous as a misplaced decimal point can have catastrophic consequences. My dad was a mechanical engineer and as a kid, I had a habit of nibbling on erasers. To cover up my habit, I'd smooth the eraser on something rough but my dad noticed my pencil erasers were prematurely worn. I told him I made mistakes to which he replied, "If I made that many mistakes, the bridge would collapse."
ESP gives the formula for the volume of a cone V=pi*r^2*h/3 and while that formula is correct in and by itself, it is improperly used here. The reason, the volume in the loudspeaker cone is a frustrum of a cone, not a cone. The correct volume is h(B+b+sqrt(Bb))/3, where B is the large area of the cone, b is the smaller area at the dust cap and sqrt is square root. The volume of a cone can be re-written as V=Bh/3.
The difference is about 28% in the volume of a 15 inch cone which will have no effect on the calculated Thiele/Small parameters but shows that one can't always trust that which is written in so called 'white papers'. A 28% error in Re or Fs would have more serious consequences.
Such errors are not uncommon. Some are actual errors on the part of the author and some are the result of the typesetters, the latter showing that proof reading is mandatory.
Many years ago, in 1975, an error in a paper published by none other than Paul Wilbur Klipsch was noticed. Upon meeting Mr. Klipsch, I approached him with that discrepancy, to which he chuckled and took my paper upon which he made a note. The whole story can be found in the following link of which there are two pages, the second being accessed by the famous Klipsch BS pin. http://www.ln271828.net/exponent.htm
As stated earlier, this error is of little consequence and I am no exception to the rule. Even something as innocuous as a misplaced decimal point can have catastrophic consequences. My dad was a mechanical engineer and as a kid, I had a habit of nibbling on erasers. To cover up my habit, I'd smooth the eraser on something rough but my dad noticed my pencil erasers were prematurely worn. I told him I made mistakes to which he replied, "If I made that many mistakes, the bridge would collapse."