The JBL PRX735 midrange covers 480Hz-2kHz using the 6.5" JBL 196H on the JBL 5024540 PRX735 horn you purchased.
There would be no requirement for a phase plug using the B&C 6MD38 on that horn, though it could improve the upper axial response.
The shallow horn will probably increase its on axis sensitivity about 3-4dB in the 500-1kHz range, so should keep up to the 15".
I went looking for some photos and I found some from the first plug I made for the 8PE21.
This is a ring and a plug. It was basic and limited, and was based on the idea that a 2:1 compression ratio tends to act like a phase plug in and of itself. This is the rear chamber..
An early screenshot of the process of comparing distances.
This is a ring and a plug. It was basic and limited, and was based on the idea that a 2:1 compression ratio tends to act like a phase plug in and of itself. This is the rear chamber..
An early screenshot of the process of comparing distances.
Thanks, that is helpful.
I guess the phase plug has to be taken into account in the calculation of the compression ratio ?
I guess the phase plug has to be taken into account in the calculation of the compression ratio ?
The phase plug is what produces the compression ration. To a first order, it can be ignored in a model by just inserting the area change, albeit, the gap is critical as this forms a volume that is a shunt-like capacitor to ground yielding a LP limitation. Which could be part of a LP total filter including the electrical LP.
Thanks Gedlee, that is a very interisting post.
Anyway, I tried to connect a BC 6MD38 to a JBL Mid waveguide.
I routed a 10mm board of wood at 45° and then plastered a little bit. So the angle goes towards the suspension. So for a 10cm JBL throat I have something which tangents the suspension.
I also have my empirical waveguide I made prior to buying the JBL waveguide it has almost the same dimensions.
First what is funny is that raw without Eq I got the same peaks at 500 and 1 khz on both speaker-horn combo.
Then with a little bell EQ they look quite the same.
Phase seems better on the PHL - DIY waveguide.
I understood why crossing this at 400hz was too low, I am now crossing at 500hz and 2khz for the STH100 which also seems to loose control below...
The mic is about 80cm behind and in the middle of the mids and highs. I guess this is why it is weird around 400 hz. it is smoothened farther.
Anyway, I tried to connect a BC 6MD38 to a JBL Mid waveguide.
I routed a 10mm board of wood at 45° and then plastered a little bit. So the angle goes towards the suspension. So for a 10cm JBL throat I have something which tangents the suspension.
I also have my empirical waveguide I made prior to buying the JBL waveguide it has almost the same dimensions.
First what is funny is that raw without Eq I got the same peaks at 500 and 1 khz on both speaker-horn combo.
Then with a little bell EQ they look quite the same.
Phase seems better on the PHL - DIY waveguide.
I understood why crossing this at 400hz was too low, I am now crossing at 500hz and 2khz for the STH100 which also seems to loose control below...
The mic is about 80cm behind and in the middle of the mids and highs. I guess this is why it is weird around 400 hz. it is smoothened farther.
