dating my new c51 apollo s7 speakers

I bought a pair of c51's with the LX5 crossover (pictures attached). I read that the older ones before ?1973 with alnico drivers were better. The serial numbers on the cabinets are 53154 & 53155. The serial number on one of the LE15As is 16387. They look great, really beautiful covers. I think they could sound better though.

It seem like the mid lows are kind of muddy. They've been sounding better, but I'm not sure if it's the surrounds starting to loosen up from having sat for years, or if it's my moving the speakers around. They probably need surrounds. And I probably need to see if I can test the specs on the crossover components. If I get to dumping money into the crossovers, would that money be better spent replacing the crossover with a more modern design?

I also have a pair of L55's the are a little rough looking, but they sound very good. The LE14As in those also need new surrounds.

Thanks,
sidney in Chandler AZ

Attachment 77566Attachment 77567Attachment 77568Attachment 77569Attachment 77570

Welcome!

Definitely need new surround. Maybe, eventually, a UHF driver. The Lansaloy surrounds you have on the LE15 will not loosen up by playing it. Some have dabbled in carefully coating the surround with brake fluid which has been known to restore some flexibility, perhaps temporarily. New "foam" surrounds from Rick Cobb is probably a better longterm solution.

Yes, welcome to the forum. Neat speakers!

Others may be able to give you a more accurate date, but I'd suggest early '70s due to the LE15A being gray and saying it is 8 ohms. The earlier versions of the exact same woofer were called 16 ohms and later ones were also 8 ohms but painted black. In any case I think the more desirable vs. less desirable woofers came much later in the decade when JBL and everyone else had to rapidly switch over to ferrite magnets.

Yes, you definitely need new surrounds as the bass will be anemic with those stiff old surrounds. Unfortunately the less than stellar midrange is part of the design and new surrounds will make little or no difference. Every design is a compromise and that is one of the compromises of the S7 system.


Widget

Thanks for the welcome, and I think Widget answered my question about date. There is a surround guy in the Phoenix area, and years ago he told me that he refuses to put foam surrounds on the back of the cone as the lansaloy surrounds are installed. He said the new surrounds are engineered to be installed to the front of the cone. He said some people feel this reduces the value of the speakers. So he wanted to make me aware of that before he worked on my LE14A's.

So are you guys, the some people he was talking about?

sidney in Chandler AZ

Quote:

---

Originally Posted by sidney8151

There is a surround guy in the Phoenix area, and years ago he told me that he refuses to put foam surrounds on the back of the cone as the lansaloy surrounds are installed. He said the new surrounds are engineered to be installed to the front of the cone. He said some people feel this reduces the value of the speakers. So he wanted to make me aware of that before he worked on my LE14A's.

So are you guys, the some people he was talking about?

---

He's the kind of guy we talk about. Find someone else to do the work, or do it yourself. I certainly wouldn't use whatever surround he would supply. Contact Rick Cobb for the correct type. Google is your friend.

Quote:

---

Originally Posted by sidney8151

The serial numbers on the cabinets are 53154 & 53155. The serial number on one of the LE15As is 16387.

---

In the registry there are some entries for the cabs but no dates were provided.

The LE15A was likely produced in 1971-72, per the few registry entries with nearby serial numbers.

Registry: http://www.audioheritage.org/vbullet...8-JBL-Registry

I have seen lots of LE14As that have the lansaloy surrounds glued to the front of the cone from the factory. You can re-foam those with the foam on the front of the cone, it comes out OK.

Hi Sid. Depends on how involved you want to get, but if you are going to be repairing components, etc., one other notion (beware, writer was an experimental engineering technician in a former life) you might think about doing a major upgrade. L300 has better woofers, crossovers plus an 077 UHF transducer - it sounds significantly better overall. It wouldn't quite fit but, you know, nothing is impossible. There are a couple related threads in the data base. Anyway, this would be the time to do it - sell the LE15s and buy a couple 2235, etc. Not exactly easy but worth a thought. MM

Is it generally accepted that the 136a and 2235 woofers are superior to the LE15A?

I need to start a new thread on c51 modification. I will restate this question there, and see you all there, this thread is completed.

sidney in AZ