Sovereign C60 S7R & LE85 Diaphragm Advice Needed

[indyaudio]

Good Afternoon
I was fortunate to purchase this pair of Sovereigns from the original owner who bought them new in 1968. A picture is attached. The woofers were reconed and foamed by JBL back in '89, and I've pulled the LE15A's to refoam again. Unfortunately I'm getting nothing from one of the LE85 tweeters. I've swapped it with the good speaker and also ran some tone sweeps, it's dead. I just cracked open the body (hated to disturb the original JBL red wax plugs) and I believe I'm seeing a damaged diaphragm. I'll post a couple pics here next and have a couple questions for the experts here, thanks!

[indyaudio]

I see what appears to be small hole and some damage to the outer edge of the diaphragm, look at the pics about 1 o'clock position, agree? Everything was very clean inside when I removed the back cap, but the foam damper pad is cracking and starting to break down. I've read a couple of other great threads here about cleaning the gap and installation which I will follow religiously including running a test signal sweep. Here are my questions:

>Do I need to remove the Phase plug in the middle to clean the gap, if so, how?
>What diaphragm would you suggest using since this original is no longer available? Simply Speakers has a decent looking replacement around $40, but please let me know your thoughts
>I should replace the pad while I'm in there - haven't looked yet, but a source you recommend?
>What do you think about the LX5 crossovers? They are untouched and original since '68. These are kind of a mystery to me. I"m going to pull one and open it up. Should I recap them both or?

Thanks guys! I am excited to own these and get them back up and running again. A decade ago I had a pair of these with the bullet tweeters and extra crossover, guess that was the S8R. Loved them and can't understand why I sold them LOL. These will take front and center in my audio room powered by a pair of Mc MC30 mono block tube amps.

Thanks again for any advice or thoughts here!

[ATTACH]

[Earl K]

With the non-existent availability of the original ( tangential ) spiral-surround diaphragm, I would recommend the Radian 1225-16 aluminum diaphragm.

These are good sounding diaphragms ( & the dome is aluminum ).

It's always best to replace in pairs ( btw ).

Cleaning the drivers gap does not require removing the phase plug ( good thing, because it's not removable ).

I would replace the foam pad with cut up felt ( felt winter-boot liners are a source in the north ).

[indyaudio]

With the non-existent availability of the original ( tangential ) spiral-surround diaphragm, I would recommend the Radian 1225-16 aluminum diaphragm.

These are good sounding diaphragms ( & the dome is aluminum ).

It's always best to replace in pairs ( btw ).

Cleaning the drivers gap does not require removing the phase plug ( good thing, because it's not removable ).

I would replace the foam pad with cut up felt ( felt winter-boot liners are a source in the north ).

Awesome Earl K - thank you sir!

[indyaudio]

Pulled one of the LX5 crossovers. Need to clean the pot as caked in white powder, but otherwise looks OK for being so old! It appears to be "potted" guts encased in what looks to be wax.

Any thoughts on what to do with these? Option 1 - clean pots only; Option 2 - replace caps; Option 3 - install a new crossover inside the cabinet and bypass these.

Anyone have experience with options #2 or #3? Thanks in advance, look forward to your input on what to do with these as part of my refresh, thanks!

[Earl K]

Here's the schematic.

I would replace the 16.5 uF cap ( in the HF section ) with a 15uF industrial type motor run cap ( not motor start ), plus another 1uF Film & Foil Polypropylene paralleled onto it ( an esoteric type of your choice ), with another .5uF cap of something really Hi-End ) preferably Polystyrene ​ ( for "air" ) .

This cap setup will give you a good ( affordable ) clean top-end ( & reasonably deep mid-range ).

I use Mallory Motor Runs ( unfortunately they are NLA ) implementing this same "cascading" formula for my 1st serial cap.



In the woofer section I would also use similar motor runs ( of the correct value if you track them down > on eBay for instance ).

Cascading ( or simple bypassing the woofer caps is up to you > it won't hurt > that's for sure ).

[indyaudio]

Earl K - thanks very much for the crossover information! I will need to study and understand this a bit more - newbie to some of what you mention. Thanks again!

Are the original caps electrolytic?

[indyaudio]

Awesome Earl K - thank you sir!

I cleaned the gap today with tape and blew out with compressed air lightly. The gap was very clean to begin with. Mine are 8 ohms and found that version of the Radian on Parts Express.

Question - can the original JVL 21956 be repaired?

[Earl K]

I cleaned the gap today with tape and blew out with compressed air lightly. The gap was very clean to begin with. Mine are 8 ohms and found that version of the Radian on Parts Express.

Question - can the original JVL 21956 be repaired?

Whatever it is, that's the dcr ( of the replacement diaphragm ) that you need to buy/match.

If the 21956 has a hole in it, it can't be fixed.

[indyaudio]

Whatever it is, that's the dcr ( of the replacement diaphragm ) that you need to buy/match.

If the 21956 has a hole in it, it can't be fixed.

Thanks Earl, wishful thinking LOL! I'll be purchasing the Radian tomorrow.

[Earl K]

Make sure you match dcr values ( new to old ) / I sense that you're likely going to buy the wrong diaphragm.

[indyaudio]

Make sure you match dcr values ( new to old ) / I sense that you're likely going to buy the wrong diaphragm.

Before disassembling any drivers - DCR on both speakers at the crossover terminals was 10.6 and 11.5 ohms.

DCR on the bad diaphragm has no reading. I have not pulled the good LE85 to test it.

The woofer pair and the bad LE85 I removed from the cabinet are all marked 8 ohms.

Is there other testing I should do before ordering the replacement? thanks!

[Mr. Widget]

I cleaned the gap today with tape and blew out with compressed air lightly. The gap was very clean to begin with. Mine are 8 ohms and found that version of the Radian on Parts Express.

Question - can the original JVL 21956 be repaired?

No LE85 was ever produced with 8 ohm diaphragms. JBL changed the way they labeled the LE85 and a few other drivers of this era. I’ve heard claims this was due to changes in rating systems, my feeling is that it was also likely due to changes in the market from mostly tube based amps to solid state amps and the fact that solid state amps in general work best with an 8 ohm load. In any event you should use 16 ohm diaphragms if you do not want to design new crossovers.


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[indyaudio]

No LE85 was ever produced with 8 ohm diaphragms. JBL changed the way they labeled the LE85 and a few other drivers of this era. I’ve heard claims this was due to changes in rating systems, my feeling is that it was also likely due to changes in the market from mostly tube based amps to solid state amps and the fact that solid state amps in general work best with an 8 ohm load. In any event you should use 16 ohm diaphragms if you do not want to design new crossovers.


Widget

Thanks very much for the reply and info.

I took reading on the good LE85 that is still installed in the other cabinet - disconnected the leads from the rear of crossover and wired directly to the driver - it comes up as 6.9 ohms.

I took readings on both woofers - 10.8 and 12.3 ohms.

The bad LE85 still had all 4 red wax seals in place before I opened it up this weekend. I don't know about this one, but owner said they had never been touched and I"m assuming it's got the red seals in place with an original JBL diaphragm in place, but inconsistent with your history of LE85 noted above.

What are your thoughts? Thanks again for the help here!

[Earl K]

Thanks very much for the reply and info.

I took reading on the good LE85 that is still installed in the other cabinet - disconnected the leads from the rear of crossover and wired directly to the driver - it comes up as 6.9 ohms.

I took readings on both woofers - 10.8 and 12.3 ohms.

What are your thoughts? Thanks again for the help here!

Those readings are correct for the goofy way JBL labels their impedance.

Your 6.9ohm reading for your le85 translates into you needing to buy the Radian 1225-16 ( as mentioned at the beginning of this thread ).

Please read the Radian tech sheet