I stumbled over one of the JBL 4530 enclosure at a garage sale a few years ago and didn´t know what to think of it at the time. The JBL 4530 model, nicknamed “Scoop” is a professional single driver horn unit. The enclosure itself (without driver) weighs 120 pounds and measures 48 in x 24 in x 24 in. The speaker is one of JBL´s rear loading horn units, designed for settings where low frequencies are important, rather than highest efficiency or directivity. Rear Loading Horns allow installed speakers to improve the low frequency, maintaining the speakers usual upper frequency limit.
There is not much information about this speaker unit available. However JBL decided to post the specifications of its older professional units online as pdfs. Therefore, I added a link under “Related Links” at the end of the article for more information and details.
The speaker (and enclosure) never achieved a mainstream positioning in its market, as its competitor the Cinerama system remained the market leader. JBL was at the time financially not able to compete with larger competitors in the professional cinema market and finally licensed another company (Ampex) to use the design of the so-called Todd-AO system, including the enclosures 4530 and 4520.
In general I would recommend this speaker unit, as it has lost most of its value. You can pick up one of the 4530 enclosures with a JBL 2225 original speaker for about 200$. The good news is, that people usually don´t want to have such a heavy speaker unit in their living room anymore and will finally sell it for little money, if someone picks them up. However, as this speaker hasn´t been sold in high volumes you have to be lucky to find one of them.
JBL 4530 Price: $200-250
(Depending on overall condition)
JBL Low_Frequency_Enclosures2.pdf More information on JBL enclosures