Project Phoenix (or what to do with my Dayton RS621s)

[RickS]

Back in the heyday when Parts Express was still offering some nice finished cabinets, was just starting into speaker DIY and thought these looked really promising…

I also bought some of the cabinets for the day when I wanted something nicer than my usual DIY cabinets. Anyway, bought and built the RS621s but was not that impressed with the sound. Was prepping to sell them when I realized the cutouts were almost identical to Directiva 2.0 drivers. After checking, all that was needed was to gut the crossovers and deepen the recesses for the drivers.

I slipped up routing the tweeter recess and had to repair that and found the DXT tweeter also needed larger terminal cutouts. After some paint touch up for the front baffle, they now look like this…

They are sealed for now but vented will work too (already modeled). For now is good enough to do some spins and design crossovers.

 

[RickS]

Vented box modeling...

f3 is around 60 Hz and f6 closer to 38 Hz. Sealed box f6 is at 60 Hz before any eq boost.

 

[Arindal]

f3 is around 60 Hz and f6 closer to 38 Hz.

As the port tuning seemingly is around 32Hz, I would conclude that the enclosure volume is a bit small for a vented design using the bass driver in question. It basically leaves the choice between an unusually high port tuning freq, or going for the low one as in your simulation, leading to very little output from the port around tuning freq and relatively high f3 point.

I would suggest a compromise between the two, i.e. simulating a different port design closer to the high tuning freq variant. Something closer to 50Hz, like approx. 48Hz, might be giving nice results, but you have to ignore basic rules of vented designs, particularly aiming for textbook impedance.

 

[RickS]

As the port tuning seemingly is around 32Hz, I would conclude that the enclosure volume is a bit small for a vented design using the bass driver in question. It basically leaves the choice between an unusually high port tuning freq, or going for the low one as in your simulation, leading to very little output from the port around tuning freq and relatively high f3 point.

I would suggest a compromise between the two, i.e. simulating a different port design closer to the high tuning freq variant. Something closer to 50Hz, like approx. 48Hz, might be giving nice results, but you have to ignore basic rules of vented designs, particularly aiming for textbook impedance.

Thanks, but have plenty of experience with box tuning and the above is just an initial modeling. VituixCAD allows a wide range of tunings to be applied and the cabinet is actually bigger than standard alignment tables would suggest. Was just showing the results from one potential vented alignment. Since this is custom design, any other alignment would be tailored to the speaker application and target bass preferences.

That said, your suggestion is essentially correct if a lower f3 was the only target.