2308 Lens

[majick47]

They all look beautiful! Would you have any grill emblems for the 4301B?

[kodomo]

hi majick47,

Sorry. I have only them which is on the list. But if you send me scanned image of original emblem, I will make it. Since initial cost is necessary to make first product, you must buy more than 4 pairs($320). The items is very high quality and recommended. Thanks.

[grumpy]

While over at "toddalin's", Todd was kind enough to let me have a look at
a stock lens. We took some measurements and a trace... thinking I might
follow in JohnW's footsteps regarding a DIY lens. I couldn't leave well enough
alone and fit a hyperbolic curve to the measurements (not everyone has a
lens to trace). Pic attached, ignore the ellipse in the center. Have fun.

-grumpy

[kodomo]

Hi,

The plan of the reproduction of JBL 2308 lens was finally completed. I listed them on ebay.

[Mr. Widget]

The plan of the reproduction of JBL 2308 lens was finally completed.

Funny how a seemingly simple project like this can take so long.


Congratulations! Very nice work!


Widget

[JBL Dog]

I think they will sell quite well at $130 a set. Very nice work!!

[4313B]

I think they will sell quite well at $130 a set.

That's a really nice price. Current JBL MSRP is $193.18 a pair but they are out of stock and something tells me JBL isn't going to bother with another run.

[grumpy]

Look great in the pics, we'll see for certain in a few weeks

[grumpy]

Shipping, notification, and packaging were great.

The units are reproductions to a very high level of detail.

I await a PM response from the manufacturer before posting my own
comparison (stock vs. repro) pictures.

[toddalin]

Shipping, notification, and packaging were great.

The units are reproductions to a very high level of detail.

I await a PM response from the manufacturer before posting my own
comparison (stock vs. repro) pictures.

From the pics, other than the obvious color difference, the notable difference to me is the crispness of the backside right-angle corners. The repops look slightly rounded/beveled there to me in the pics.

I note that there is no picture that compares absolute length back-to-back, but was assuming this would be an easy part.

[grumpy]

The color diff in the photo, I suspect, is more due to lighting and very
minor surface micro-texture differences... the plastic material itself appears
to be very close (at least when the 2308 is clean ).

The corners are as sharp as the original JBL (plastic) version I have on loan
from Todd.

Dimensions of the basic lens plates are identical, with possible exception
of thickness... close enough that I'd need to get out the calipers to be sure.

The hyperbola execution is very close, probably less than 1/32" at any
comparison point... this is only (barely) noticeable when the lenses are
stacked (they fit well enough to do this) and viewed with the profiles
in-line (top view, considering normal use).

I have only one area of comment that isn't "absolutely fantastic", and as
I'd like to see this endeavor succeed, I will wait for the vendor's reply
before elaborating, as it seems resolvable.

[grumpy]

... resolvable or ignorable. My one -minor- concern is actually visible on the
first, vendor provided photo (post #64, above). I did not notice it
initially. Even if you can find it, I still expect you will be very pleased with
the quality of this product.

If you enjoy "Where's Waldo?" books, read no further.


Otherwise, just realize that a very few of the lens plates may not be
-perfectly- flat... a very minor and cosmetic-only issue that is difficult to
spot. It is not worth posting additional photos to highlight the result...
which is a minor variation in lens plate spacing at the front/cutout
intersection. The vendor is aware of the issue and has made efforts to
minimize the problem before (tossing bad plates) and during assembly.

If I can find a method to permanently tweak/adjust the plate spacing
without damaging the assemblies I have purchased, I'll be happy to share
the procedure. I may just leave them alone.

So why mention it at all? The JBL product had no such noticeable
variations, although I'm sure even their initial run had it's own issues to
sort out as the manufacturing and QC processes were refined.

The product remains highly recommended.

-grumpy

[toddalin]

... resolvable or ignorable. My one -minor- concern is actually visible on the
first, vendor provided photo (post #64, above). I did not notice it
initially. Even if you can find it, I still expect you will be very pleased with
the quality of this product.

If you enjoy "Where's Waldo?" books, read no further.


Otherwise, just realize that a very few of the lens plates may not be
-perfectly- flat... a very minor and cosmetic-only issue that is difficult to
spot. It is not worth posting additional photos to highlight the result...
which is a minor variation in lens plate spacing at the front/cutout
intersection. The vendor is aware of the issue and has made efforts to
minimize the problem before (tossing bad plates) and during assembly.

If I can find a method to permanently tweak/adjust the plate spacing
without damaging the assemblies I have purchased, I'll be happy to share
the procedure. I may just leave them alone.

So why mention it at all? The JBL product had no such noticeable
variations, although I'm sure even their initial run had it's own issues to
sort out as the manufacturing and QC processes were refined.

The product remains highly recommended.

-grumpy

Ahhhh,

The spacing between third and fourth is greater than the spacing between the fourth and fifth from bottom on left.

On motorcycle engines, there are sometimes rubber spacers or plugs between the cooling fins to dampen vibration. Something like that could be adapted, though it would place small obstructions in the signal path. The tension of the rubber would hold them inplace. Not original though.

[grumpy]

rubber spacers or plugs between the cooling fins...

Was thinking along the lines of applying fairly localized heat while the
plates were held at the proper spacing (jig or spacers). Getting -controlled-
heat just to the area of interest will be a trick. It would certainly be much
simpler if the plates were not glued together, but it -appears- that the
bonding agent "melts" the parts together... like model glue. I'd be happy
to be corrected, especially if non-destructive dis-assembly is possible.

[Mr. Widget]

Look great in the pics, we'll see for certain in a few weeks

Today I received my pair. The level of professionalism is outstanding. The packaging, the manufacturing, even the label with serial number... very impressive.

I do not have a pair of originals for comparison, but I am confident that when installed no one would ever mind that they were not made by JBL. I am certain that they will be identical sonically, and visually they are very nice. My only criticism is that the mold flow lines in the injection molding process are visible... probably something that most wouldn't even notice. For myself, I'll shoot a quick coat of Kyrlon Semi-Flat black paint on the top vane. It'll take a few seconds and make them look perfect.

I'd recommend these to anyone with a broken or cracked L91 or 2308 lens.


Widget