My 4520 project

[Eaulive]

I started a set on flickr, for whoever's interested.
I'm not to keen on finishing but I'm making a big effort. When I see the craftmenship of some forum members here I feel very ashamed

Basically I'm gonna build a set of 4520 with a completely home brewed midbass horn and 2370/2426 as HF.
It's gonna be triamped with eventually a good digital processor but for now all I have is an old DOD

The midbass horn will house a B&C 12PE32 but I will eventually get some E120 or similar.

http://www.flickr.com/photos/eaulive...7626260334894/

[more10]

Nice project!

The 4520 have an ugly dip at 150 Hz from first out of phase interference. How low will you let the E-120 horns go?

I have never heard the 2370 horns, but I believe that a tractrix or lecleach will sound better. Why use 4?

[Eaulive]

Nice project!

The 4520 have an ugly dip at 150 Hz from first out of phase interference. How low will you let the E-120 horns go?

I plan to start them at about 125~150 but before I'm gonna measure the 4520 to see exactly what response they have and how to work around the flaws.

I have never heard the 2370 horns, but I believe that a tractrix or lecleach will sound better. Why use 4?

Because I have them and because stacking 2370s vertically increases the gain significantly and narrows the vertical pattern at lower frequencies.
And also because this setup will also be used for high SPL from time to time

[Eaulive]

I'm leaving now for Champlain NY to pick-up my four C8R2225

[Lee in Montreal]

I'm leaving now for Champlain NY to pick-up my four C8R2225

Wished I had ordered two from you. I have an installed pair of 2225h with cones that look and measure exactly like original JBL parts but lack the bass the other pair has. I switched amps, channels, wires. It remains the same. To make sure the problem is not a nearby wall, even with my head inthe scoop, one side is missing the lower bass. I suspect the cones are JBL, but from another driver with different coil depth...

[Eaulive]

Wished I had ordered two from you. I have an installed pair of 2225h with cones that look and measure exactly like original JBL parts but lack the bass the other pair has. I switched amps, channels, wires. It remains the same. To make sure the problem is not a nearby wall, even with my head inthe scoop, one side is missing the lower bass. I suspect the cones are JBL, but from another driver with different coil depth...

Last test is to try them in the other cabinet.

[Lee in Montreal]

Last test is to try them in the other cabinet.

Indeed. But I doubt there woud be such a difference. Boith 4520s were the same. And I used the same sound damping in both units (Walmart egg crate shaped mattress foam - $5.00 for 18" x 24")

[Eaulive]

I'm uploading the pictures of the day on flickr.

http://www.flickr.com/photos/eaulive...th/5581194522/

[maxwedge]

Looking nice!

[Eaulive]

I have an installed pair of 2225h with cones that look and measure exactly like original JBL parts

By look is hard to tell, do you have markings on the back of the cone that says what cone it is?

[Lee in Montreal]

I'm uploading the pictures of the day on flickr.

http://www.flickr.com/photos/eaulive...th/5581194522/

Your set of 4520 is definitely not the same construction as mine.

[Eaulive]

Your set of 4520 is definitely not the same construction as mine.

I took the first two next to the door, but I noticed the scoop was different.

[Lee in Montreal]

I took the first two next to the door, but I noticed the scoop was different.

I suspect that yours are made from 3/4" presswood, not 5/8" as mine, as your framing seems thicker than mine.

[John]

I suspect that yours are made from 3/4" presswood, not 5/8" as mine, as your framing seems thicker than mine.

Do any of these 4520 cabinets have a cut out on the top surface of cabinet near the front center with a recessed terminal plate with 2 pairs of JBL style terminals?

[Eaulive]

Do any of these 4520 cabinets have a cut out on the top surface of cabinet near the front center with a recessed terminal plate with 2 pairs of JBL style terminals?

No, those are not made by JBL, but by a local sound company that made tons of them in the 70s, 80s.