Hi,

I'm curious to know if anyone has experienced any lobing issues with dual driver midbass horns like Altec 817 or JBL 4550, in relation to the midrange horn they cross over to.

I see lots of DIY guys also building dual stacked midbass horns. I guess the reason for this is to get the efficiency high enough to avoid padding down the midhorn in a passive system.

My own experience tells me that lobing is a huge issue when using dual 15" drivers on an open baffle, I just did this with 2 x Faital 15PR400 per side.
The problem is the distance between the lower woofer and the midhorn, hence the use of MTM/D'appolito configuration to remedy this issue.
Another way around this is 2.5/3.5-way systems, where both woofers are used for bass frequencies but only the upper woofer is used to cross over to the midhorn.

So I don't understand why this wouldn't be an issue with the dual driver bass horns as well, or maybe it is?
Or do the two drivers 'blend' together to act like one driver at the mouth of the horn?

I have been thinking about this for a while, so hoping to get lots of responses here