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Romy wrote :

"...This BTW expanse what we have such a differences in assessment of leaking he the S2’s back chamber. (It was somewhere in past)..."

I would just the same like to confirm my findings one more time in the new room; I will run the test again once I have the system back on the long wall with mid-bass horns in place (had to move it out of the way to make space for bass horn fabrication)

"...As I told before: the decision to go for 180Hz was very good on your part and now you are benefited...."

And as I mentioned before, you can credit yourself with that "right decision" (I made this decision based on Romy's experiences and confessions while adding and integrating the 250 Hz horn to his system)

"...What would be VERY interning is to run S2 and S3 in 150Hz horn and to see if it possible to load them down to 350-400Hz..."

Y E S ! This I would love to try.
Is the S3 as sensitive as the S2?

I keep telling myself that I am almost done making horns, but I keep having ideas to try additional horns (more on that when I finally decide to do it).

"...I have seen an S2 go apart at 450Hz in open air as the diaphragm-pressing plate is not good in S2. With S3 the diaphragm-pressing plate looks much better and it decoupled from the back of the driver – so I think the S3 will go lover, with no mechanical stress..."

Hm... It would probably become clearer to me if I had an S3 to compare with the S2. The diaphragm clamping plate of the S2 is very stout, but yes it is mechanically coupled to the heavy body of the driver (bolted right into it actually) as well as the rear cover.

"...1)    The Fundamentals Channel at 2kHz with first order pass too much directional HF. Since the 180Hz  is relatively large (twice larger then 250Hz for instance) then the Fundamentals Channel axis will be higher and consequentially the mid lime of the system will be risen at 2kHz much more then at 1kHz. I personally would recommend of lower upper knee crossover point if you drop the lower knee crossover point, but it is only in the case if the minimum integration distance is important. With 80m² room I doubt that it is critical for you..."

With the mid-bass horn construction taking so much space, I am forced to sit closer than normal; like about 8 ft... Surprisingly image height has not been as much an issue as I would have thought. But yes, in this configuration the system is more prone to presenting a spacious image. Image height was definitely an issue when I was really "misusing" the fundamentals channel, and running it up a lot higher in the frequency range. The final (in this room) set up will allow something like a max of 16 ft between the listener's head and the mouth of the upper-bass horns.

"...2)    If the upper knee of your Fundamentals Channel is at 2kHz then you might not use 450Hz for MF Channel but go for 700-800Hz. This would add some HF extension to your MF channel and will make them MF less beamy..."

If I understand correctly : With an upper knee of 2 KHz, you are suggesting that I try narrowing the band pass by moving the lower knee up to around 750 Hz (?) Hmmm... Yes I can try it, but it seems more logical to keep the 450 Hz lower knee (I like the body it adds) and to drop the upper knee a bit as you suggest above. As for beaming, I know how unlikely it seems, but I don't have beaming issues.

"...3)    The biggest this that I see is the flatness of Vitavox drivers over the 1250Hz. Running the driver flat you will have let say  109dB at 500hz and 2kHz but you will have 113dB at 1250Hz. How do you deal with it? Using impedance compensators? Any other means?..."

You are saying that the S2 has an increased output around the 1250 Hz range. I don't contest this, but at the same time, I have not measured what exactly the channel is now doing. The current configuration (450 - 2 KHz), was arrived at one night while woking... I just dropped everything and swapped caps and coils in a sort of gut reaction to something I had been trying to identify, which that instant became more clear to me. In the same little frenzy, I brought down the upper knee of the upper-bass horn. The result felt immediately right ... Again, I have not yet taken out the RTA and measured what either channel is now doing. When I do, I will most likely confirm the increased output of the fundamentals channel around the 1250 Hz range, at which point I will of course immediately perceive it as "problematic".

jd*

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