what determines the cut off for khorn woofers?

[DAX616]

What is the weak link? Why won't they go down past 40hz? Is it the horn or the woofer, etc?

[Deang]

Placed correctly, and in a room large enough to allow the waveform to complete -- they'll do 33Hz. The "weak link" is the room, not the Klipschorn.

[bcs]

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On 3/29/2005 7:11:45 AM DAX616 wrote:

What is the weak link? Why won't they go down past 40hz? Is it the horn or the woofer, etc?

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If there is a weak link, it is the horn. A horn's cutoff frquency varies with the horn length and mouth area. To get a lower cutoff frequency would require a longer length & a bigger mouth. That is, the box would have to be bigger. Much, much bigger to get a fairly small improvement.

I say enjoy them as they are: Fantastic.

Rob

[Deang]

"To get a lower cutoff frequency would require a longer length & a bigger mouth."

It's a 50Hz horn, and when loaded in 1/8th space as specified by design -- it goes below 35Hz.

[DAX616]

I have heard the woofer flutter when pressed not above it's limit or even at. I would say the k33 is fine for normal listening. With synthetic bass, the bass is absent in the low low regions. Is it the crossover protecting the speaker. Is it not possible to have 15" subs with these cabinets down to at least a low b what keeps the cabinet from reproducing even lower?

[Frzninvt]

What the hell do you think a good subwoofer is for, get with the program! If you don't like the bass your getting, sell them and buy some Cerwin Vega's for crying out loud.

[sunnysal]

to answer his question...it is the horn...no matter what driver you put in there you will not get it to go lower...it is an almost magical trick it pulls to get horn loaded bass that low from such a compact cabinet...truely one of PWKs greatest legacys! tony

[3dzapper]

In speakers as in life there are trade-offs invoved. It is impossible to get super low frequencies, low distortion and high effeciency without trade-offs. PWK designed the Khorn for low distortion and high effeciency to 35Hz although there is usable output to 28Hz at the -10Db point. That is where many other speaker manufacturers claim their LF cutoff. -10Db that is.

If you are hearing a "flutter" I would assume that you are listening to a 20Hz tone. At that frequency, the woofer is moving but the horn and room are not big enough to develope a wave. It can be felt but not heard.

Sub woofers are designed to produce low frequencies by sacrificing effeciency and distortion with long cone excursion and powerful built in high distortion amps utilizing class "D" amps (not Digital). They only amplify a small portion of the waveform relying on large cone excursion to fill in the rest. The ears are far less sensitive to distortion at 20Hz than 200Hz. If one were to use a class D biased amp for higher frequencies the distortion would send him running!

[DAX616]

I'm asking a question, personally I think with 2 15" folded horns you should'nt need a sub. What the hell do you think this forum is for? I am not passing judgement or commenting on the bass of a khorn. I like my speakers. I do have some cerwin's if any ones interested.

[DAX616]

thanks for the intelligent responses. Great explanation to all except.

[sunnysal]

"personally I think with 2 15" folded horns you should'nt need a sub"

dax, horn design is a well known and developed science, folded horns have limits dictated by various factors.

without going into too much detail horns need to be very long and big to handle lower frequencies, folding helps keep diomensions compact but they cannot work miracles.

you CAN build a folded horn to go down to 20hz but it would have be be MUCH bigger than a klipschorn bass bin. so the phrase "there is no free lunch" is applicable here.

the fact is the klipschorn bass bin cannot go lower, no matter what driver you put in there. you COULD design a folded horn bass bin to go to 20hz but it would be BIG, if you are interested in finding out how to build a 20hz bass horn let us know and we can give you some links to see what they look like.

regards,

tony

[Frzninvt]

"Sub woofers are designed to produce low frequencies by sacrificing effeciency and distortion with long cone excursion and powerful built in high distortion amps utilizing class "D" amps (not Digital). They only amplify a small portion of the waveform relying on large cone excursion to fill in the rest. The ears are far less sensitive to distortion at 20Hz than 200Hz. If one were to use a class D biased amp for higher frequencies the distortion would send him running!"

Don't assume all subs use Class D amplification and are unclean! My Velodyne's use AB amplification and accelerometers to measure cone movement thousands of times a second so there is NO distortion or incoherent response out of the drivers, just clean ultra low bass response and lots of it, and to below 20Hz I might add!

[DRBILL]

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On 3/29/2005 9:55:07 AM 3dzapper wrote:

"If you are hearing a "flutter" I would assume that you are listening to a 20Hz tone. At that frequency, the woofer is moving but the horn and room are not big enough to develope a wave. It can be felt but not heard."

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Sez the Irishman at the pub, "Is this a private fight, or can anyone join in?"

Klipschorns do not cut off sharply at 40Hz but follow a rather gradual slope down as low as 16Hz. I demonstrate this to myself almost every night when I end my evening with one of my excellently recorded pipe organ CDs, of which there are available at least eight that I know about. I have successfully demonstrated this to at least two other forum members -- Daddy Dee and RDmarsiii. And yes, I have also connected my audio generator and produced pure 20Hz tones. What did I hear? Nothing! But I could feel my internal organs being re-arranged and by touching the wall could feel the sheet-rock trying to work the nails out! This is exactly the same feeling that I have had while tuning a 32' high-cut E.M. Skinner pedal Bourdon. Those grave pitches were not meant to be "heard". Instead, they contribute a powerful emotional impact to the music. "Visceral" is the word often used. If you have not experienced it in a large stone church, it would be almost impossible to explain.

Having said all of that, I need to tell you not to bother trying to reproduce my experiment with your mincy little SET's.* It isn't going to happen. And when listening to organ recordings, don't expect to keep your preamp controls in the "flat" position. (You can see, below, my gear.) Also, I wouldn't leave the 20Hz tone on at high power for more than 30 or so seconds. You wouldn't want to open or deform your woofer voice coils.

*Nobody is more enamored with the "first magic watt" of SETs than I. But this is a job for Mark III's and KT90s!

Now I've done it. Be merciful.

DR BILL

[sunnysal]

no argument from me dr. who you are right, of course k-horns have some output down ultra-low...but it is many, many dbs down by 20hz (or even 16hz)...you could sweep tones down to those levels and get some output I suppose but it would be useless in a music listening envrionment at anything close to safe listening volumes...if we use -5db as the accepted reference the best you can do in normal music situations is 35-38hz...regards, tony

[D-MAN]

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On 3/29/2005 9:08:57 AM DeanG wrote:

"To get a lower cutoff frequency would require a longer length & a bigger mouth."

It's a 50Hz horn, and when loaded in 1/8th space as specified by design -- it goes below 35Hz.

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No bisquit for you this time, Dean!

The 1945 patent Khorn (describing a 12" driver embodiment and a "rubber throat") is specified as using a 47 Hz Fc., but this is not to be confused with the "current" Khorn using a 15" driver and NO rubber throat, which employs a 40Hz. Fc. Granted that horns DO produce an audible output below their respective cutoffs, but the output fall off is very steep as compared to other types of loudspeakers below their respective cutoffs. That's the price of horn-loaded efficiency within the band pass of the horn itself. Outside of that specific bandpass, the horn increasingly impedes the futher transmission of the frequencies being "attempted" outside of the specification.

If you don't beleive me, do the math: Khorn 78 sq. in throat x approx. 65 in. overall horn length, exponential expansion rate with an area doubling length of every 21.7 inches (40Hz), terminating in an approximate mouth size of 4 sq. feet, which is 1/4 sized for corner placement (1/8th space), resulting in a 32 foot waveform (40Hz) using an apparent mouth with 16 sq. feet of area, the apparent throat area also appearing to be 3 times larger than the actual throat area. This is assuming, of course, that you have a room large enough to accept a 32 footlong waveform propagating into it without encountering an obstruction...

Most likely most of us never actually get to hear a fully developed 40Hz waveform in our listening spaces.

Additionally, putting a speaker in a corner DOES NOT LOWER the Fc of the enclosure! It does ENHANCE the AVAILABLE bass by virtue of reflective reinforcement from a trihedron, but it does NOT GO ANY LOWER. The structure of the horn remains fixed and CANNOT go lower than its structure dictates, regardless of placement.

All horns designed for corner placement are smaller than the free-standing counter-part of the same Fc would be due to the reinforcement of the reflections of low frequencies produced in a corner. But it will NEVER, EVER go lower due to placement. Rather the capability to go as low as its respective Fc is ENABLED by corner placement. That is built-in to the design as dictated by the throat size, expansion rate, overall length, and size of mouth of the horn. Corner placement will reinforce the AVAILABLE bass response but NOT produce a frequency response that is not actually there in the first place, NOR EXTEND the available frequency response in any way.

If putting speakers in a corner actually LOWERED the respective frequency response, hey kids, Bose would rule the speaker world by now, wouldn't they?!

DM

[sfogg]

"This is assuming, of course, that you have a room large enough to accept a 32 footlong waveform propagating into it without encountering an obstruction...

Most likely most of us never actually get to hear a fully developed 40Hz waveform in our listening spaces."

Please tell me you aren't suggesting that a wave must be able to 'fit' into a room for it to be able to be reproduced in it.

Shawn

[DAX616]

In your opinion how tough is the k33 with in its rated capability? I do know there is an "industrial" model but it seems to lack the grace according to earlier threads.

[D-MAN]

"Please tell me you aren't suggesting that a wave must be able to 'fit' into a room for it to be able to be reproduced in it."

That's EXACTLY what I'm saying.

If not, you are only hearing a section of the waveform and its folding back and reflecting around you before the end comes by - and guess what- the END (phase)that is 1/2 of it MAKES it a 40Hz waveform. What most of us hear that ain't a 32 foot soundwave. That's an in-and-out-of-phase waveform in sections, due to the effects of reflections, refractions, difractions causing canceling and peaking (modes) in in an audible but distorted manner than the waveform actually produced.

Essentially, the ROOM is an enclosure with its own Fc determined by its dimensions.

DM

[sfogg]

"If not, you are only hearing a section of the waveform "

And?

Exactly how is a person hearing a total 40' waveform at any instant in time anyway? Even outdoors you are only hearing a section of the wave at any instant in time.

That a wave can't be reproduced in a room that it won't fit in is an audio myth that just won't die.

How big is your ear? Can't you easily hear sounds below the wavelength that can fit entirely in your ear?

Put on a pair of headphones (maybe an inch from your ear) and you will hear bass well below that point.

How could a passive radiator system work if the bass can't be reproduced inside the enclosure which is FAR FAR smaller then the bass it is reproducing.

Go fill your tub with water. It is a trivial matter to setup a wave that has a wavelength well beyond the length of your tub. That is no different then in your room.

"and its folding back and reflecting around you before the end comes by - and guess what- the END (phase)that is 1/2 of it MAKES it a 40Hz waveform."

And that happens well above that frequency too, most music isn't just a single peak and trough.

All you are describing is roughly where room gain starts to kick in, not some low frequency limit in a room. See the link below...

http://sound.westhost.com/subcon.htm#5

Anyone with an RTA (or other suitable measuring equipment (not just a SPL meter, they can be misleading)) can easily see they have bass reproduction well below the frequency that a wave will entirely fit in their room. I get good response into the teens easily (measured)... my rooms longest dimension is about 17' long.

Shawn

[D-MAN]

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On 3/29/2005 5:38:50 PM DAX616 wrote:

In your opinion how tough is the k33 with in its rated capability? I do know there is an "industrial" model but it seems to lack the grace according to earlier threads.

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By "tough" you mean it's wattage rating? that's 150 watts.

The Fc of the K33E is 34 Hz, I believe according to Marvel's posts which I consider the most reliable.

The K43 is the professional version with a higher wattage rating, but a slightly higher Fc.

I agree that the K33E has a nuance to it that lends a certain transparency to the sound, which is particularily conducive to high fidelity use, where the higher wattage version is possibly better used in a PA or live music venue, of course this is only my opinion.

DM