I have 2 pairs of custom build cabinets from the 60's / 70's. One is the model C34 (folded horn) and the other is about the same size but has rear ports after passing by several interior mounted baffles . It is very well built and looks to be one of JBLs designs offered for customers to have built but I can not find any literature on it.

Both cabinets are loaded with identical drivers and crossovers:
-Rebuilt LX13 and N7000 crossovers
-2225, 8 ohm woofers, reconed
-2425 compression driver mids, 8 ohm, new diaphragms (C34 use potato masher horns, the other uses H91 horns and L91 lenses)
-075 tweeters, 8 ohm, new diaphragms

The C34 sound great. The others are lacking in that deep bass. My placement of the "not C34" speakers while testing is not ideal as I'm not able to get them in front of a wall to see how much bass that rear reflex port adds.

My plan was to add L-Pads (fixed, not variable) to both the mids and tweeters. I figure if I can get it close I can use the 3 position switch on the LX13 and the variable L-Pad on the N700 to dial in.

My question:
Should I take the time to move these 100 # speakers in front of a wall to have a listen in their proper position before I start playing around with L-Pads? Will it really add that much more bass? If yes, what's the proper distance from a wall? I take it I should be looking for a flat, reflective surface, drywall or wood, no curtins or corners?


Thanks,

Eric M.