There is a hole in my system

[djnagle]

I'm sure this has been covered here but I can't find anything. I have A7 cabs with 515G drivers. 1505B horns with 288C drivers, and Beyma supertweeters. I am crossing the horns at 500hz and 5000hz. I have closed the vents on the cabs down to 90 Sq.I. The system sounds great. Extremly detailed with great imaging and a sense of presense I have never heard....however, the mids are there in spades and the low, lows are there in spades but the low mids (I do not have the equipment to measure) like from 500 to 100 are down by 5 to 10 db (by my ear) then the low bass pickes back up and sound great. There seems to be a big difference between the horn section of the A7 cab and the bass reflex sectioin. So if I turn up the bass amp to get the 500 to 100 matched to the mid horn, the below 100 is way to loud. What can I do about this. I love kickbass and everything else in that region. Thanks.

[stpower]

Igor,
You don't metion how you crossover your system, but I suspect that may be where the problem lies.
The A-7 cabinet is usually very good at projecting
the region you mention with no holes. I would suggest borrowing an RTA and mic and measuring the hole to see what is going on. While you are at it, try moving the horn forward and back as mentioned in Altec application notes #9.
This can help a lot.

stpower

[Wagtbtoobz]

Hi Igor, for sure your Xover may produce the hole . Are you passive or active filtered ? Wht kind of Beymas do you use ?

Cheerz
Pierre

[djnagle]

I am using a Rane AC23 to cross all three drivers. The problem seems to be with the cabinet. The freqs coming out of the vented portion are up 5 to 10 db then then freqs produced by the front horn of the cab. I played with the crossover but no matter where I put it, the vented portion of the cab is always louder than the front horn. For the supertweeter I am using the Beyma CP25. Cheers.

[Steve Schell]

A bass driver that has been partially demagnetized will be deficient at the upper end of its response range. You might try substituting another driver that you are fairly certain has a full charge, i.e. ceramic or field coil.

[dhook17322]

Aren't 515G's all ceramic?
You might find a Rane analyzer on ebay. I got one fairly cheap, but had to get the mike direct.

[stpower]

Igor,

Your A-5's should excell in this region you mention, the woofer is horn loaded down to about 160. Your Rane is ok, so I would next ask; are the cabinets factory 825 or 828's? Do you know the history of the 515-g's? At some time were they possibly reconed with aftermarket kits? You can check with Bill at GPA for the correct cone number on the back of the cone. As Steve Schell mentioned, maybe they got partially demagged by rough handling in road PA use.

stpower