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RichK
02-20-2010, 08:16 AM
Hi Guys,

Me and my father have been getting his original S8R system up and running again. His LE15A's needed both foaming and reconing, as one of the voice coils were toast.

We are still getting the rest of the system back in order. We used to have an SA600 integrated amp driving the system. It seemed to match the system very well. Now we have a Marantz 7T and 15. I have fond memories of the SA600 driving the speakers, and the 7T / 15 sound well, but the low frequency stuff seems too prominent, especially in a certain area 20 - 25 feet away from the speakers...like it hits a resonance or something. If I place the 50 hz filter on the 7T in line, it doesn't help much, but if I place the 100Hz in line, it does get better.

Just wondering if by having to recone LE15. is the PR15 now out of tune with the cabinet? How about the crossovers? Or, do you think the 7T/15 has flatter response further down low when compared to the old SA600. Wish I could just try the SA600 to compare, but it's caps are all dried out.

7T and 15 were just gone thru and returned to OEM spec by a Marantz expert, so they are up to date.

Regards,
Rich

Mr. Widget
02-20-2010, 09:44 AM
Can't help about the electronics, but I would get both of your LE15As reconed and then your speakers should be good to go. The PR15s are tuned to that cabinet. Their tuning should not be changed.


Widget

Audiobeer
02-20-2010, 09:57 AM
Looking forward to you telling us how great they sound! :applaud:

RichK
02-20-2010, 10:10 AM
Thanks Widget. Sorry if I wasn't clear... they are already reconed and refoamed. I'm wondering if the recone is somehow causing the extra boom down low. I remember these from my childhood being fantastic.

Regards,

Rich

Doc Mark
02-20-2010, 11:23 AM
Hi, Rich,

Sounds like you and your Dad have a fine project in the works. Where, may I ask, did you get your woofers reconed? If you didn't use an authorized JBL Service Center, and the wrong parts were used, that would very probably change the TS parameters of the woofers, and then the entire tuning would be off, hence a possible source of your booming bottom end. Since you are in Southern Cal., I hope you used our own Edgewound, who is an authorized JBL Service Center, or maybe Orange County Sound. Good luck with your system, and have fun. Take care, and God Bless!

Every Good Wish,
Doc

RichK
02-20-2010, 01:09 PM
Hi, Rich,

Sounds like you and your Dad have a fine project in the works. Where, may I ask, did you get your woofers reconed? If you didn't use an authorized JBL Service Center, and the wrong parts were used, that would very probably change the TS parameters of the woofers, and then the entire tuning would be off, hence a possible source of your booming bottom end. Since you are in Southern Cal., I hope you used our own Edgewound, who is an authorized JBL Service Center, or maybe Orange County Sound. Good luck with your system, and have fun. Take care, and God Bless!

Every Good Wish,
Doc


Hi Doc,

I in fact used a local JBL Authorized... OC Speaker. I wasn't aware of Edgewound. We were very concerned about who did the work. Dad has been stressing over getting it done for years (not playing it either) - I finally took them out and had it done. I hope it works out OK.

I think I should assume OC speaker did their job, right? We used the JBL factory parts, or so I paid for.

Regards,
Rich

Audiobeer
02-20-2010, 04:38 PM
What do you mean by boomy. Is the bass muddy and not very pronounced? Before you look at the speakers try another amp in the mix. Sometimes the older amps can have a significant deteriation to the signal going to the speakers due to old caps going bad. Try another amp with a good solid 100 + watts and see if that changes things a bit.

RichK
02-20-2010, 05:38 PM
What do you mean by boomy. Is the bass muddy and not very pronounced? Before you look at the speakers try another amp in the mix. Sometimes the older amps can have a significant deteriation to the signal going to the speakers due to old caps going bad. Try another amp with a good solid 100 + watts and see if that changes things a bit.

I'm going to try another amp, although the amp is freshly done. I wouldn't call it muddy and not pronounced. On the contrary it seems too pronounced, and resonate the house. It used to not do that with the SA600, at least I don't remember it.

Rich

mech986
02-21-2010, 03:25 AM
If you were comparing the JBL SA600 with the speakers before refoaming to the Marantz 15 driving the refoamed speakers, the comparison is not valid.

The unrestored speakers without foam would have had little to no bass output due to the woofer being completely unloaded without the surrounds. With the new surrounds, the woofers will work properly into the cabinet. However, all bass reflex systems may have a prominent resonance that may be the problem.

A way to test that is to stuff the port with a towel and see how it sounds. Sometimes closed box bass is subjectively an improvement compared to a ported system.

You should look carefully at the crossover and consider rebuilding with new caps and resistors. The inductors will probably be Ok unless damaged.

BTW, if you still have the SA600, its well worth rebuilding/repairing. I would recommend Tom Ishimoto at Northridge Electronics or Fred Longworth at Classic Audio Repair in San Diego. Both are top notch repair shops that know what they're doing with vintage gear.

Bart

RichK
02-21-2010, 05:36 AM
Thanks. The Olympus cabinet with the S8R package doesn't have a port - I don't think any of the packages have a port but could be wrong. It does have a passive radiator.

I'm very on the SA600. It may be on my deck to do, or I have someone in mind that knows the unit well. It will be a while tho.

And good point on the cross overs. That may be the next lil project.

Regards,

Rich


If you were comparing the JBL SA600 with the speakers before refoaming to the Marantz 15 driving the refoamed speakers, the comparison is not valid.

The unrestored speakers without foam would have had little to no bass output due to the woofer being completely unloaded without the surrounds. With the new surrounds, the woofers will work properly into the cabinet. However, all bass reflex systems may have a prominent resonance that may be the problem.

A way to test that is to stuff the port with a towel and see how it sounds. Sometimes closed box bass is subjectively an improvement compared to a ported system.

You should look carefully at the crossover and consider rebuilding with new caps and resistors. The inductors will probably be Ok unless damaged.

BTW, if you still have the SA600, its well worth rebuilding/repairing. I would recommend Tom Ishimoto at Northridge Electronics or Fred Longworth at Classic Audio Repair in San Diego. Both are top notch repair shops that know what they're doing with vintage gear.

Bart

Mr. Widget
02-21-2010, 09:10 AM
Thanks. The Olympus cabinet with the S8R package doesn't have a port - I don't think any of the packages have a port but could be wrong. It does have a passive radiator.Functionally the PR15 acts like a port, though with a bit of added upper bass warmth. This is why I said that the number of discs on the back of the PR15 were determined at the factory to properly tune these cabinets for a properly functioning LE15A.

I doubt the crossover will "fix" your bass issues. Not to say that the crossovers couldn't be out of spec, or improved upon even if they are still in spec.

What threw me off was your saying reconed and refoamed. Which was it? Or did you recone one and refoam the other? I would recone both.

Is it possible that you slowly got used to the less and less bass output these speakers created over time, and now that they are back to normal you realize you are not happy with them?

A couple of points. I assume these speakers are up against a wall. If your listening position is up against the opposite wall, you are going to be experiencing generous bass gain in a very narrow band of frequencies. This is the physics of it... and can't be helped. There are two fixes, move your room around or use speakers with limited bass output. The fist choice is the better one, yet not always possible.

Secondly, what are your expectations? While these speakers have excellent components, the design is dreadfully dated. JBL (and everyone else who are serious about this stuff) has learned a hell of a lot since 1962.


Widget

RichK
02-21-2010, 10:24 AM
Functionally the PR15 acts like a port, though with a bit of added upper bass warmth. This is why I said that the number of discs on the back of the PR15 were determined at the factory to properly tune these cabinets for a properly functioning LE15A.

I doubt the crossover will "fix" your bass issues. Not to say that the crossovers couldn't be out of spec, or improved upon even if they are still in spec.

What threw me off was your saying reconed and refoamed. Which was it? Or did you recone one and refoam the other? I would recone both.

Is it possible that you slowly got used to the less and less bass output these speakers created over time, and now that they are back to normal you realize you are not happy with them?

A couple of points. I assume these speakers are up against a wall. If your listening position is up against the opposite wall, you are going to be experiencing generous bass gain in a very narrow band of frequencies. This is the physics of it... and can't be helped. There are two fixes, move your room around or use speakers with limited bass output. The fist choice is the better one, yet not always possible.

Secondly, what are your expectations? While these speakers have excellent components, the design is dreadfully dated. JBL (and everyone else who are serious about this stuff) has learned a hell of a lot since 1962.

Widget


Widget,

Sorry, I may have been being redundant. I did say we reconed and refoamed, and I did mean it. I realize now that may be silly to state. Regardless, the foam and cone is new JBL on both speakers - done by the authorized service center. My real worry was the recone and non-Lansalloy foam caused a significant change in spec., but I'm feeling better now because.... I think you're on to something. The position in the room where the bass is very prominent IS up near or against the opposite wall of the speakers. Fortunately, that is not the listening location. I was just walking thru that area (there's a doorway to another room) when listening, and freaked a bit. It seemed to be really resonating at said location.

I think you fixed "the problem". :applaud: YAY!


Now onto the crossovers. Any recommendations on resistors and caps? :p (sort of a joke LOL ... but not really)



Regards,

Rich

RichK
02-22-2010, 11:38 PM
Cabinets needs some steel wool and JBL oil mixture...otherwise in very nice shape!

http://rrichk.smugmug.com/Other/Audio/11325866_qzwxS#795173881_5QQwm-A-LB


http://rrichk.smugmug.com/Other/Audio/11325866_qzwxS#795174597_7z35m-A-LB

Rich

Mr. Widget
02-23-2010, 08:09 AM
Very nice! That design with the fretwork grilles are near the top of the list of the JBL's with magnificent industrial design... in my book.

Your speakers look very nice and really do deserve to be kept up.


Widget