Help me design a DIY midbass horn? (long)

[pdq2]

If you try it again with a temporary baffle around it / cardboard wings, you'll probably get a smoother result. Post 26 here is where I discovered how, even for nearfield tests, you need a ~infinite baffle to see how good the driver can be.

Measurement based cone damping / treatment

Thanks. I mounted my eventual midrange (K53/K700) and tweeter (K77) in a scrap-dryboard baffle today along with a space for the midbass I'm working on. (I may need to extend the baffle a bit on the sides - it's currently about 3 ft wide and 4+ ft tall.) I'm going to repeat the measurements above in this setup and do some listening tests. Among other things, I'm curious what effect the cross-sectional shape of the throat has on the response.

 

[hollowboy]

I'm curious what effect the cross-sectional shape of the throat has on the response.

I think it's important for HF bandwidth.

My tests have been far from rigorous (I vary more than one characteristic between each build), but I get much better HF smoothness and extension when the throat is asymmetric. A slot-shaped throat (eg 4cm wide, 8ch high) had smoother / more extended HF than an round throat (axisymmetric horn), when using the same 4" driver.

On one axisymmetric horn, I improved HF bandwidth by adding a few tiny bits of foam to throat, thus breaking up the symmetry of the void between the driver and the horn throat.

Mounting the driver off-centre may help for similar reasons.