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jessie.dazzle wrote:

I really appreciate the result of the 180Hz horn with the S2... Particularly in terms of "texture". It is responsible for such an important range...

Well, if you appreciate the lower knee of the S2 driver then wait unit you hear it’s perfomance with reduced dumping of the cone.

I have been trying to solve the dilemma why my 250Hz Tractrix does not allow itself to be loaded too closer to the horn rate. I was not able to go lower then 600Hz and their order (!!!) and it is not where I would like to be. When I was dropping the crossover point I was loosing the cleanness of S2 tone and it became muddy and nasal. I was and still am planning to do some modifications of the horn; I will post the pictures later on.

However, in addition to it, last nigh I decided to experiment with the damping of the driver’s cone. How pleased I was when with redaction of dumping I got instant improvement in the very direction I would like to have improvement. The channel began to response much lower and the most important the tone (with lower response) become absolutely free from any nasal colorations and from any dynamic congestions. I was listening again and again and was very pleased with the result (I was listening juts one Fundamentals channel).

I did not figure out how much the back chamber should be extended, my preliminary assessments that it should be for my horn made 4 times larger. I am seriously contemplating that if I will be ordering from my machine shop the extended S2 back chamber’s cover then to make it with adjustable volume (proposals are VERY welcome). As you can see on the picture the back plate should have larger (adjustable) chamber….

Well, this post would not be complete if I did not measure the thing, of course I did. I measured the lower knee of the S2 response in the Fundamentals Channel, way off the axis (~45 degree off). The channel is high-pass with one 25uF cap that makes around 400Hz, first order. In this animated image you will see one measurement (closed back) as a default S2 driver and another “with crack”. The crack was make by screwing off the back plate of the S2 drive for 1 turn and introducing (juts from one side) a  little, <1mm  crack between the diaphragm’s plate and the back chamber’s cover.

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