really!?
I want more.
Maybe I just need another tuba. I went to a dudes house. He had twin PB13 ultra's. That started all this. I don't get the tightness I desire from the tuba. I have a sealed 10 in my CRV it sounds very good. powering it with about 500 watts.
I'm wondering if you built that horn correctly. In particular did you use the correct driver which is the
Dayton RSS390 HF4 driver?
If you use the wrong driver then the design will not work. Horns usually have a very tight bass. However they are reliant on room loading more than other designs. In some positions in some rooms the room loading can be excessive.
The other issue that you need to consider, is that is what is perceived as bass is largely well above sub range. It is that area between 80 and 400 Hz that is perceived as bass. So the quality of the main speakers is of overriding importance. If the bass in that range is of poor quality no sub will rectify it.
Your speakers are from the eighties and never much good despite what you might read on line.
The speaker has a bunch of small drivers, which if I remember had an interconnecting cable between the outer set of drivers to modify the sound stage.
However the real problem is the small drivers have a high free air resonance. This determines how low they will play. Adding a bunch of small drivers does not give you any more low end extension than a single driver. It just gives more power handling and requires a larger cabinet. Size of cabinet has to be doubled every time you double the number of drivers.
This speaker is tuned by the passive radiator lower front. This is no different than a tuning port. The speaker was miss tuned to give the impression of bass. In other words you create a hump to give a false bass.
If you are suffering from lack if a tight bass, then I'm sure it is your Polk speakers to blame and not the horn sub.
I think you need much better mains before changing your sub.