energizer cutout for paragon rearpanel

[Rafael]

Hi all,

I have a newer paragon without the option of installing the SE 408 s transducer energizer in the back panel. Thanks to the marketplace in this forum I now own this amplifer. Since I want to make a new backpanel close to the original, I need the dimensions and the place for the cutout. Comparing a picture of the paragon in the japanese "stereo sound" with the paragon owner´s manual I´m confused if the energizer is located in the left or the right channel. Any help would be welcome.

Thank you and have a nice day,

Rafael

[Don McRitchie]

I can't answer your questions, but I have one for you. Does your SE 408 have the equalizer card for the Paragon? This amp was intended to be sold with different equalizer cards for different JBL speaker systems. I believe there was a specific one for the Paragon.

[Oldmics]

Here is a picture of a Paragon that I sold awhile ago.As you can see there are cutouts on both sides of the enclosure to mount the energizer amplifier.I have never seen a Paragon outfitted with the self powered setup.
I was under the impression that an amplifier was installed into each side of the enclosure.
Let us know how your Paragon sounds,Good luck.
Oldmics

[Don McRitchie]

The Energizer is a stereo amp that is not bridgeable so I don't think it is possible to make use of two of them in a stereo pair. My guess on why there are two cutouts is that it was to reduce enclosure costs, much for the same reason that the large format monitors have two cutouts for the 2405 on each baffle.

[Rafael]

Thanks for your replies,

Don is right (as always): the SE 408´s or the SE 400´s aren´t bridgeable. I don´t think it´s cheaper to construct two cutouts with frames in mirror constellation than a flat backpanel. The only sense could be the same internal volume for both channels. To answer Don´s question: My SE 408 has two EQ boards labeled M 23- but I don´t know if this is the board for the paragon- I tried to get the relationship between the board-numbers and the speaker systems in a former thread- without a solution. Of course I tried the boards in the "equalized position" and the change in sound character is not sooo dramatic, but the idea of fine tuning a speaker through internal EQ boards in the amp is fascinating for me. As with many ideas : JBL did it first.

Regards, Rafael

[Don McRitchie]

I still vote for the reduced costs. I'm pretty sure that the back panels with the cutouts are identical. The resulting mirror image can likely be obtained just by rotating the panel on the opposite enclosure. I just dont see the cutout volume being significant enough to be a concern given the imprecise nature of the empirical design methods of the day. Not to mention, that once you installed an amp in one cutout, the volume would be reduced even further than the enclosure without the amp.

[Harvey Gerst]

Originally posted by Rafael
but the idea of fine tuning a speaker through internal EQ boards in the amp is fascinating for me. As with many ideas : JBL did it first.

Regards, Rafael That was Hank Wolcott's contribution, as well as the design of the original tube amplifier. Hank is still designing premium amplifers, the Wolcott mono block amplifier is his latest. Another amazing person in JBL's rich history.

[Rafael]

The 408´s had no enclosure and the electronic is open monted on the diecast front plate. So it is not only a cutout , but a little chamber in the backpanel to protect the electronic from pressure and vibration ot the woofer. Due to the relatively small volume in the paragon´s woofer enclosure, there could be a difference whether these chambers stole about 8 l of the woofer´s volume.
And when these chambers are mounted in the back panels, there is no difference in the resulting volume whether you install the energizer or not. ´

Regards, Rafael

[whgeiger]

R,

Cutout provided in both panels:

Back Panel for Enclosure Right Half
(as viewed from cabinet rear)

Opening Length: 14-27/32”
Opening Height: 4-3/32”
Opening Corner Radius: 3/16”
Location From Panel Top Edge: 1-7/8”
Location From Panel Left Edge: 4-3/8”
Rabbit Depth on Front Face: 1/2”
Note that Panel Thickness: 1”
Rabbet Width Along Opening Length: 5/16”
Rabbet Width Along Opening Height: 1/4”
Rabbet Corners Chiseled Square
Ref. Rabbit Opening Length: 15-11/32”
Ref. Rabbit Opening Height: 4-23/32”

Back Panel for Enclosure Left Half of Opposite Hand.

Information taken from JBL Drawing C44-39 Rev. B (9-Oct-65)

Regards,

WHG

[Rafael]

whgeiger:

Thank you very much for that perfect information.

Regards, Rafael

[johnhb]

My paragon had an energizer mounted on one side. I have the amp but blocked off the opening. It was on the right side facing the paragon. If desired I can take a picture. It has the cards specific to the paragon.

[Rafael]

johnhb:

I knew there is someone out there with the informations I need and this forum would be the right place. A pic would be just wonderful, do you have the board numbers or even better: the schematic of the boards ?

Thank you very much,


Rafael