Jubal woofer fubar?

[DanMan]

Question about my L65's, and before you give me grief, lansing heritage automated email sent me my birthday greeting today.... so thanks and be kind ;-)

I bought these Jubal L65's on ebay long ago, so I'm way over the 30 day return policy... ;-)

It appears to me that the woofers were refoamed incorrectly - I added my comments in red in the pics below > I'm used to seeing my JBL woofer surrounds glued to the other side of the spacer onto the basket. (pardon if my terminology is incorrect).

Are these surrounds indeed on incorrectly?

The ohm meter shows 7.7 ohms across the woofer - what does that mean?

The speakers 'sound' 'ok' up to about 85db, but I wont turn it up louder than that in fear of harming either the speakers or the amp.

I bought these for the sound quality not quantity.

Am I in fact getting distortion throughout the volume range or only at the new peak excursion limits?

Is there a different mix of frequency response if they're on incorrectly?

Should they be refoamed?

Thanks.

[Zilch]

Yes, they should be refoamed.

That's REALLY stupid what they did there. It's supposed to be UNDER the gasket at the edge, on the metal frame.

At the cone, it should be on the rear, but that takes effort by someone who knows what they are doing.

If the cone kit is available, have a full recone done by a pro.

You were screwed by an idiot....

[grumpy]

ouch. clench your buttocks before pricing a recone... it would appear that an OK set
of L65's might go for about the price of a pair of recones for this driver. Think I'd be looking for either
a re-refoam (bastard side or not) or a functioning set of bass drivers that someone else
has pulled. Someone else check me on this. -grumpy

[DanMan]

thanks guys. recone it is.

i guess that just leaves two questions that at this point are really more theoretical than functional -

1- Am I getting distortion throughout the volume range or only at the new peak excursion limits?

2 - Is there a different frequency response curve if they're on incorrectly (I'm assuming weaker in the bass region)?

[grumpy]

thanks guys. recone it is.

i guess that just leaves two questions that at this point are really more theoretical than functional -

1- Am I getting distortion throughout the volume range or only at the new peak excursion limits?

almost certainly throughout... it appears you're already about 1/2 way out of the gap one way
(harmonic distortion, which you may or may not pick up as sounding "bad")

2 - Is there a different frequency response curve if they're on incorrectly (I'm assuming weaker in the bass region)?

I would -expect- so, and level dependent. One could look up studies on dynamic offset
for characteristics that would be mild in comparison.

Way to buck up for the recone... best way to go if these are keepers. -grumpy

[Robh3606]

almost certainly... it appears you're already about 1/2 way out of the gap one way
(harmonic distortion, which you may or may not pick up as sounding "bad")

Hello Grumpy

You really don't know that as these are probably the wrong surrounds as well. The foams relative position has changed you need to look at the driver as a whole to determine what's actually going on. What you need to do is see where the spider is at rest. If it's flat he may not have as much of an offset issue as you would think.

Rob

[JBL 4645]

Yes, they should be refoamed.

That's REALLY stupid what they did there. It's supposed to be UNDER the gasket at the edge, on the metal frame.

At the cone, it should be on the rear, but that takes effort by someone who knows what they are doing.

If the cone kit is available, have a full recone done by a pro.

You were screwed by an idiot....

Yes underneath the gasket whoa I wouldn’t be surprised if the (voice coil) is rubbing against the core, yikes.

[markd51]

Hello Folks,
Sorry that I'm coming into this thread late, but I'd like to re-hash what's been written, and have some curious questions of my own.

Being an owner of four original L-65's since new, (You gurus know how long that is) my questions are, since the re-cone kit for the 126A Driver is no longer available, what options are there should one hypothetically blow a Driver?

An unlikely event that I'd blow a Driver, and most likely would need re-foam in the future. To inform all, my four 126A drivers were totally reconed twice in the past 34 years, never just re-foamed. They were done twice by authorized JBL repair centers, and thus as you all know, they would never just re-foam these Drivers.

So then, what would be one's option? Can the 126A be re-coned with another model # Re-cone Kit? If so, then what changes if any, are needed to be done to the X-Overs? (inductors-Caps-etc)

As you can see in my particular example, if a change would be needed to another driver, that would no doubt mean a minimum of at least both drivers in a pair, or perhaps even "times four".

Would I then have to convert to all different Drivers, L-65A, or L-65B drivers, which I assume it the 122A, or 129H? Or? Mark

[SEAWOLF97]

they are wrong. I wud have them refoamed.

Z gave a better answer, while I was looking/typing.