Bass reflex port in early Opollo enclosure?

[JRL]

I just purchased a pair of early S7/Aplollo's (ebay #5706599654). Are the cutouts shown in the photos bass reflex ports or tweeter cutouts?

[Don McRitchie]

Here's a definitive answer - I don't know. The system you purchased appears to be an early version of the Apollo given that the drivers are painted blue. The first versions of the Apollo were all two-way, with no provision for an 075 tweeter. Therefore, I am inclined to think that the cutout is intended as a port. However, this has to be balanced against the fact that the first LE15 based systems were meant employ sealed enclosures. The fact that the cutout has provision to be blocked makes me think that it may have been intended to be blocked when used with the LE15A and open when used with the 130A or D series woofers.

I would suggest calculating the internal volume of the enclosure, determining the port area and running some calulations to determine the response. Given the relatively small size of the enclosure, I would guess that a sealed configuration would result in poor bass extension. However, given that the port appears to be one size fits all (the Apollo could be orderd with a D123, D130, D131, 130A, LE8, or LE14), there is likely some optimization you could do by changing the port area or going to a ducted configuration. If you don't have the ability to do this, just provide these dimensions on this forum and I am sure there are other members that would be willing to run this for you.

You should be aware that the LE15A in your system likely has stiff surrounds due to aging and this will change the response. Do a search on "Lansaloy" on this forum for techniques to restore the surround to its original compliance. As an alternative, you may want to consider having the surrounds replaced or even reconing to ensure operation at factory specs.

[Lawrence HF]

Not sure about your model, but my experience LE15A between 3.5 to 8 cu/ft is bass reflex tuned to 32 Hz. 5cu/ft would be very good. I can't get at my orginal JBL system now, LE15A, LE85 LX-5 is about 3.5 cu/ft tuned to 32Hz.

[Don C]

I once saw a set of Olympus with a bass reflex port. But that set had a 130A woofer. It could be that this set was made to accomodate the 001 system as an option.

[Lawrence HF]

From what I understand Olympus and Sovereign were about 26X38X20 LE15A and PR15. What I have I think is Apollo, but it's buried behind other things and can't look at it now. Wood fret removable grill. LX-5 on rear, and closed opening on rear for JBL dedicated Amp. On front rectangular port, not on bottom, but off to the side of woof and horn lens. I know it's tuned to 32Hz. Some increase in low freq enjoyment could be had with larger cab., but very well coupled in this about 3.5cu/ft size. Harder to destroy woofer in this size cab, and amazing amount of clean bass if not afraid to turn it up, surround must be good, or you will be sorry. Also I beg to differ with the people here that said no 8&16 ohm versions of LE15A. My 2 original 5.5 Ohms on meter, when reconed I said I want the same, got C16R2215 which show about 9.2. I was not happy, told take it and pay or we will be happy to keep them. Same thing with LE85's.

[Zilch]

Olympus S7 (no "R") came as closed box. I updated a pair with 2235's and dual 4" X 9-1/2" ports. Fretwork grilles kinda defeat the biradial tweeters, but they're still mighty sweet. I stripped, repaired, and clear-lacquered them grilles; they came out a nice warm honey shade....

Interior dimensions are 34 X 13.5 X 22.5" extrapolated from the actual exterior, i.e., 6.0 cu ft. There's overhangs everywhere, so the published dimensions are deceiving. WinISD says I have them tuned to 30 Hz.

2426J mids are still too "hot." I've been meaning to attenuate them more (another 3 dB, maybe) for about 10 years now. The 2370A horns were a tight (albeit satisfying) fit, as you can see below....

Most Apollos I've seen have also been closed boxes. I was suprised to see the rectangular port; looked more like a cutout for the crossover, but those were usually on the rear.....


[Kindly EXCUSE the dust.... ]