K-55 loading in different horns

[3dzapper]

With his horns (K-400, etc) PWK used that red rubber washer with about a 1/2" hole in the center. That would seem, to my pee brain anyhow, to be a pre-load on the K-55 v running it open. Does this lack of or inclusion of the red washer effect the sonics of the K-55 when used with such horns as 511s or trak horns?

I know I shouldn't think but this has been bothering me for a few days.

Rick

[BEC]

Rick,

I will give you all I have on this subject. A couple of years ago, I tested the frequency response of a K-55V with and without the washer on a k-400 horn. The spectrum was a bit different with and without the washer. I concluded at that time that the frequency response looked a bit better with the gasket. Later, I wondered if the difference was the "sealing" effect of the gasket or the hole size of the gasket, but never made it back to test that.

Bob Crites

[3dzapper]

Thanks Bob. Now back to the lab.[]

Rick

[Daddy Dee]

I've been thinking.

Now I'm tired.

[oscarsear]

I've been thinking too. Someone with the measuring do da day stuff should afix a calibrated iris diaphragm to a compression driver and test it at a wide range of apertures.[8-|]

[D-MAN]

Guys, that washer is a somewhat flexible capacitance which would lower the upper frequency response exactly like putting a small capacitor across the terminals. It makes a small-volumed chamber in the throat.

The purpose of adding a capacitance to the throat is to limit the upper corner freq. response by about -3db. The frequency effected is determined by the volume in the cavity.

DM

The compression chamber<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Finally there is a possibility to create a compression chamber (Vf) between the driver and the throat (Ah) of the horn.

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The volume of the compression chamber works like a low-pass filter (6dB/oct.), the higher the frequency the higher the attenuation. The crossover point (-3dB) can be calculated with formula:

Vf is the volume. Note that a larger volume lowers the crossover frequency. The nice thing of these acoustical filters is that the output can be corrected without the use of extra electronics.

Another -3dB "filter" frequency is due the driver moving mass corner of the driver according to the formula mentioned before (Fh).

In any horn system, it is advisable that an exponential design uses the largest possible exit-surface (mouth). The used speaker unit(s) requires a strong magnet (Qts <0.3). The early decline in the low area can be increased actively which works well in the area where the horn is active (>Fg).

[colterphoto1]

Ouch, I don't know if I got all that. How about if I use an adapter for K55 to Altec 511B horn, after the exit of the 55, it's probably another 3/8 inch of adapter before you get to the actual throat of the 511 horn.

M

[Duke Spinner]

don't worry, the adaptor is flared..............

[3dzapper]

D-M that sounds reasonable. Still I wonder what the actual effects are on non-Klipsch horns like Michael's 511.

BTW Michael, What Duke means is that the threads are tapered as pipe threads.

In case anyone wants to know the source of my curiosity, I am nearly done on my first trac horn and will lay up the other starting tomorrow. I already tried the 511 route and was shut down by the bride on WAF.-(

Rick

[JohnA]

I'm pretty sure the washer is there only to prevent rattling and keep

the K-55 from vibrating out of the horn. The hole in the

center of mine is the same size and the throat of the K-400. I

have a few new spares. They have the same I.D. as the K-400

throat.

[djk]

Altec had an application note that showed what happened to the HF response of a 288 without a washer, it looked bad in the top octave.

Without a washer a 288 has a cavity where it mates with the horn, so it is not exactly the same as having the driver mate flush without a gasket.

Without a gasket in a situation where it should be flush with the horn, any bump in the mating surfaces is audible (with a wide-range driver).

"The napkin drawings have been converted into physical reality

(Community-based loudspeakers). They sound quite smooth, however

there is still a little (1 or 2 db peak) problem at 3-4 KHz, which I

think is attributable the the HORN (we are using the Kleitsch 1"

throat horns - the little Altec horns are EVEN WORSE - they have a

10db peak centered around 3.5KHz)... I was able to "get rid" of most

of the problem by crosing the VHF-100's over at about 3.5 to 4KHz.

Unfortunatly, I don't have any other horns to try. The the Kleitsch

ho-made mantaray VHF horns do BEAM, and sort of have a "piezo-like"

problem as I said around 3-4KHz which is measurable (not sure exactly

WHAT is causing it yet). The mids are so smooth and perfect that

nothing can be said about them, they are completely transparent.

The highs, although they do have a slight piezo-like quality down low

(cepstrum distortion!) are MOST interesting in the fact that they (if

crossed over at 3.5-4K) DO measure ruler-flat all the way up to 18+

Khz. There are NO nasty resonances or 20db peaks and valleys, etc,

which AT FIRST makes you THINK that there is "no" high end - it is so

smooth, unassuming and non-zingy it takes a bit of getting used to.

There is NOT a lack of HF though, the highs are completely smooth and

hyper-extended and incredibly DETAILED. I don't know what they will

sound like when a microphone is "plugged" into them...??!?

Sherryl Crow (?) sounds almost exactly like I remeber Bill's "best"

version of the DSP EQ sounding, but I thnk the highs and mids are

smoother and less GLASSY sounding at high listening levels.

Most "normal" (ie: circa 1998 "pop" recordings) CD's sound fairly

marginal, although QUITE smooth and "natural" even though you can HEAR

everything "BAD" that they have done in mastering (ie: insane amounts

of compression and HF boost in vocals, too much compression everywhere

ELSE, artificially lopped off bass, nasty bad corn syrupy sounding

highs, etc).

ie: most of today's pop recordings seem to be pretty BAD quality, not

unlistenable - just not very good. You can hear EVERY wretched

non-deatil of the over processed over compressed

poorly-mixed-on-NS10M's-with-no-attention-given-to-sub-80Hz-low-end on

most of them however most of them DO have "tracks" (on the multitrack)

that appear to have ESCAPED the "attention" of the producers (ie:

everything but the drums and VOCALS on alot of these recording sound

really cool, but when the voals come in they SUCK (over compressed and

over EQ'ed and too lound).

Blah, blah. Anyway, the thing is set up in th barn, and I'm thinking

about hauling it home to play with... We will probably try to install

it on Sunday at the Green Room. Need a tube amp to run the highs off

of (I don't know how bad the Crown D-60 sounds, but it, along with the

speaker calbe and the cheap Sony CD player (and cheap crossover) are

probably responsible for at least part of the non-totally-perfect

highs. -Joe"

I had a problem with the fabrication of the HF horns in the area where the throat joins the mounting flange. After this was fixed the "little (1 or 2 db peak) problem at 3-4 KHz" giving the "piezo-like

problem as I said around 3-4KHz which is measurable (not sure exactly

WHAT is causing it yet)" cleared up.

"We installed the system at the Jazz Club and it sounds glorious! The

midrange and high-end DETAIL and "realness" is uncanny (even WITH the

CRAPPY Ramsa mixer in the signal path - we are going to get RID of it

and use something else - it RUINS the sound). We were sitting there

at their opening party last night for awhile - they were playing

CD's... The sound was completely smooth and natural EVERYWHERE in the

room. Recordings with well-recorded drums sounded like there was a

real drumset in the room - the speakers are extreemly ARTICULATE in

the midrange and highs. Every time I listen to them the word

"seductive" comes to mind. Even the low end has a SEDUCTIVE

SSMMOOOTTTHHH natural sound - although it is slightly "BLOATED"

sounding partly because that's the way the MIXER sounds and partly

because I think I need to rework the low end EQ in the crossover!"

We ended up re-working the TDM 24-CX4 crossover, the Ramsa, and the Crown.

The mid drivers ("The mids are so smooth and perfect that

nothing can be said about them, they are completely transparent")

were the CLS M-200. It measures OK, and it sounds even better than it measures.

The whole point of this was to try and show how the very small problems in the throat/gasket area causing very small (1dB~2dB) problems (in the 3Khz~4Khz area) gave rise to a "piezo-like" sound.

[3dzapper]

Thanks djk. We need to get a little deeper into this "cavity" area.

John, I have never looked into the throat of the K-400 being a leg man myself.[6] That would mean that the K-400 itself, sealed by the red gasket, creates the star chamber reducing HF output?

Rick

[3dzapper]

Thanks djk. We need to get a little deeper into this "cavity" area.

John, I have never looked into the throat of the K-400 being a leg man myself.[6] That would mean that the K-400 itself, sealed by the red gasket, creates the chamber reducing HF output?

Rick