Khorn bassbin polars? Anyone with Khorns and an RTA setup?

[jwc]

Been doing some fiddlin here at the house...

Curiousity has me on something. I've never seen polars published for the Khorn bass bins. Anyone have them?

If there is anyone that could do some experimenting for me...that would be great. This would be to run an RTA curve of one Khorn bass bin in a corner. Start with the mic on axis about 6 feet away. Then start to move it off-axis horizontally a little at a time to see what happens.

My curiousity is can the bin hold up off-axis after 300Hz?

I've had a look out for Khorn beater bass bins on the bay....no such luck.

jc

[Restoman]

This is the perf sheet from EV K-horns. I am assuming you are looking for the big corner horn bass bins or maybe build them your self. Also included a pic of my bass bin which is being rebuilt.

[Restoman]

Sorry--only 1 pic uploaded----I think you are wanting the big bass bins ??

[mikebse2a3]

My curiousity is can the bin hold up off-axis after 300Hz?

Hey jc.....hold up in what way and up to what frequency? Once interference from the bifurcated mouths start to show up off axis things just get worse as frequencies go higher.

From an anechoic response point of view because of the bifurcated mouths there will be interference nulls that should begin to affect response in the lower 300hz range with the main on axis lobe's -6db points progressively narrowing as frequency goes up from there.. The nulls deepest points will of course shift with frequency and I believe will be found in the range of approximately (20 degree - 35 degree) off axis. This is one of several reason why IMO even though the Jub's LF can play higher than the Khorn's LF it also being of a bifurcated mouth design is better whenever possible to cross to it acoustically by 500Hz or lower.

The RTA in room response that you are asking for is a much more complicated matter since it will be effected by the distance from the source and walls as it is moved around and will also include room mode interferences as well and thus will be very unpedictable from one situation to another IMO.

mike tn

[jwc]

Yes Mike...aware of in room difficulties....but was wanting someone with the equipment to share what was going on in their room. I can gather some info from that.

I didn't think of the bifucation and the description you just described.

Roy had stated once that the MWM's get "beamy" after 300Hz and worse after 400Hz. Although we all see these wonderful curves shown here and everywhere else of on axis of certain speakers..

Well, just tinkering with my own designs....I'm just wondering this...? How hard is it to get "good polars" over 300Hz from a "complex folded" bass bin? The MWM has no fancy reflectors at all. The Khorn and Jube have some...but not necessarily full reflectors....and they have more folds/turns.

I put together my own folded horn that I'm messing with....complex folds for sure....and see to get inconsistent "response" after ~350. This can be outdoors sittin in the middle of the yard.

I'm making a second version that is a little more forgiving with the folds but is "bigger"....allowing for less "aggressive" folding. Soory for the vague descrptions but hopefully you can get my point.

So...after so many folds and such with a low Fc design....I mean how well are the polars to be expected after ~300Hz....as the wavelengths gt shorter and more susceptable to "loss".

jc

[PrestonTom]

JC: The anomalies in the polars are going to be due to the bifurcated mouth (as mentioned above). In the Jubilee article (JAES, 2000), it is couched in the discussion about "splay angle".

I don't believe the folding and refelectors will directly impact this. The main variable seems to the distance between the two "mouths". The greater the distance, then the lobing anomalies will occur at progressively lower frequencies. Although once you get down to 200-400Hz or so, then room modes may become the dominant problem with peaks and dips in the SPL as you transverse the room.

It may or may not be helpful for your application, but I have been fooling around with applying a few inches of absorption on to the baffle between the "mouths" of my Jubilee-clone. My intention was to measure the polars with-and-without the treatment. Such measures made indoors are probably not very meaningful, but my "corner" (ouside in my patio) is currently not usable and the weather is getting colder. So I don't when, or if, the measures will get done.

[jwc]

Yes....remember the part about the "splay angle". Also in that earlier build in the AES article...there is a sharp turn not in the final prototype.

So....anyone out there want to take a stab at axis and off axis of their Khorn.....?

Or....anyone have any published material on the khorn with such specs...

thanks

jc

[Edgar]

I'm a little reluctant to post this, for fear that it will be misinterpreted. The attached graphic is the result of simulation, not measurement. It is not a polar plot, but instead it shows what the actual waveform might look like at an instant in time if the sounds were waves in a water tank, and you were looking down at the tank from directly above. The speaker is located in the upper right corner. The red areas are peaks and the blue areas are valleys. The simulation takes into account side wall, front wall, floor, and ceiling reflections, but it does not assume that those reflections are perfect (reflection coefficients of 0.7, 0.7, 0.7, and 0.5, respectively).

This particular simulation shows 300 Hz, but I can simulate any frequency.

Greg

[Coytee]

The conversation is over my head...but I wanted to say that is pretty cool [Y]

[Edgar]

The graphic format is intentionally similar to that shown here. To me it is more intuitive than a polar plot.