You cleared up a lot of things. Particularly the expansion dimensions. It is a very wide exponential horn indeed. I can only go by what the simulator is showing based on the end results. Your issue may not be the expansion but the Punisher Horn.

Horns are designed to offer a particular frequency range (by the designer) when used in groups of four or eight. Rarely, if ever, in twos. Since you are using six Punisher horns, you are a smitten short of achieving optimum low frequency extension the Punisher can offer which, is why adding an extension offers no significant advantage in the low frequency extension. The results you are seeing would be the end result of adding two more Punisher horns equating to eight bins.

You are already literally flat with six Punisher bins. This basically means you have achieved optimum performance level for the horn from an extension standpoint. There is no where left to go but louder by increasing the mouth size.

I recall when Contour introduced these boxes on Speakerplans. I distinctly remember Contour saying he did not want the boxes to go low based on the type of music he was using. He wanted a very potent attack and, bass extension was not the priority. So the expansion rate of the Punisher Horn is maxmised to a frequency to achieve those results using the Ciare 12 inch woofer.

Unfortunately, it becomes extremely difficult to achieve the low frequency extension you are aiming for when the designer was not on favour of it. Even if you stacked 12 Punisher Bins (6 high Horizontally & 6 across Vertically) standing upright to increased the mouth size, you would not get a lower frequency response.

However, you would get a higher SPL level as the mouth is now bigger horizontally in addition to vertically. That is pretty much how horns work and, why having the extension standing 470 mm tall is more questionable to give you the +3 dB increase terms of SPL you are seeking. Sometimes bass smacking you in the face will do a better job than having all the bass focused on your trousers legs waving them like a flag. Providing you are stacking one extension on top of the other, you should attain more noticeable SPL.

How much SPL? Theoretically, +3dB. Realistically, unknown. This is what happens when you start thinking outside the box. You have to accept there is a 50/50 chance your idea may or may not work. I go through this all the time so I am letting you know in advance.

Is it worth it? At the end of the event, you will be the one that needs to tote the extensions back home so, only you can answer that question.

Bear in mind the width of these extensions would not overcome having the same width using more Punishers from an SPL standpoint. Six woofers can only go so loud even with the extension added on. The coupling affect of multiple drivers working as a team will always win in the end. If you are willing to move 2115 mm in length horn flares then, you can carry an equal amount of Punishers to equate a width of 2115 mm.

Just remember, which ever route you choose to take, you have achieved optimum low frequency extension with your current Punisher Horns.

Best Regards,

Elliot Thompson wrote: I distinctly remember Contour saying he did not want the boxes to go low based on the type of music he was using.

Why is the will of the designer relivent? Will the horn not just follow the laws of physics? Do longer horns with bigger mouths not reach lower frequencies?

The sims support this, look at the one for the Ciare 12.00sw, the efficiency starts to fall off about 7 or 8 hz lower with the horn extension.

Elliot Thompson wrote: How much SPL? Theoretically, +3dB. Realistically, unknown. This is what happens when you start thinking outside the box. You have to accept there is a 50/50 chance your idea may or may not work. I go through this all the time so I am letting you know in advance.

citizensc wrote: Elliot Thompson wrote: I distinctly remember Contour saying he did not want the boxes to go low based on the type of music he was using. Why is the will of the designer relivent? Will the horn not just follow the laws of physics? Do longer horns with bigger mouths not reach lower frequencies? The sims support this, look at the one for the Ciare 12.00sw, the efficiency starts to fall off about 7 or 8 hz lower with the horn extension.

The expansion rate to the mouth plays a factor. If the box is already expanded to a particular frequency at the mouth, adding on an extension to the mouth can just make the box louder without any means of low frequency extension. You need to have pressure buildup in order to achieve lower frequencies at a greater intensity. 

So what happens when there is no pressure buildup below the Punisher's horn cutoff point and, you add a large exponential horn extension in front of the Punisher's horn mouth to extend the low frequency response? Nothing. This is due to no low frequency pressure buildup at the extended frequencies you are trying to achieve. There are principals of a horn you need to follow and, you are just looking at one part of the equation.

citizensc wrote: Elliot Thompson wrote: How much SPL? Theoretically, +3dB. Realistically, unknown. This is what happens when you start thinking outside the box. You have to accept there is a 50/50 chance your idea may or may not work. I go through this all the time so I am letting you know in advance. This bit im not really sure of, I dont think hornresp accounts for directivity (someone correct me if im wrong here) so it wont show the real improvement. The punisher does have a small mouth for a bass horn and is a rather small cab so I would imagine its directivity control is quite bad meaning there is a lot of room for improvement. Would it be naive to have expectations of 3-5 dB improvement measured on axis from 5m away?