JBL 4770A (c. 1992)
The JBL 4770A is a large, professional two-way speaker system from JBL's Sound Power Series, built for high-power work. It was listed at ¥550,000 per unit in Japan around 1992, which puts it in the pro/install market and not the consumer hi-fi line. It's a 2-way, 3-speaker, bass-reflex design. Two 38 cm 2226H cone woofers handle the lows. A 2445J compression driver with a 10 cm titanium diaphragm, mounted on a 2380A flat-front biradial horn, covers the highs. It's bi-amplified, with the low section rated at 4 ohms and the high section at 16 ohms, and it uses Neutrik NL8MPR connectors.
The numbers are big. Playback frequency band is 30 Hz to 20 kHz (-10 dB). Output sound pressure level is 101 dB/2.83V/m for the low section and 112 dB/2.83V/m for the high section, with a 133 dB maximum. Allowable input is 1,200W (AES, 50-500 Hz) for the lows and 150W continuous program for the highs. Recommended crossover is 800 Hz, and the directional characteristic is 90° horizontal by 40° vertical. Each enclosure measures 750 x 1,250 x 533 mm and weighs 110 kg, so this is not a bookshelf speaker. The wedge-shaped cabinet is made to be clustered horizontally, and each additional enclosure extends horizontal coverage by 30 degrees. JBL noted it's optimum when used with the 4788A sub-bass system.
The 4770A is an upgrade of the earlier SR4732. According to forum discussion, the 4732 had only one 2404 driver, while the 4770A carries four. The 2404H is a small high-frequency driver with an aluminum throat piece and the exterior plastic "baby cheeks" horn. A separate chamber in the top of the enclosure isolates the 2380/2445 and the 2404s from the 2226 woofers. Two crossover versions exist: a "bypass schematics" version (40 µF in series with the 2445J and 3 µF in series with the 2404H) and a passive crossover version. One owner on audioheritage.org confirmed, "The 4770A I have is the version with the passive crossover." The crossover network is reachable after removing the upper 2226 woofer.
Owners report that these are workhorses. One listener on audioheritage.org (a forum, not a publication) said they don't kick you in the stomach the way 4311s do on Pink Floyd, but they're far more sensitive, with incredible power reserve and a really clean sound. He found them strong on classical material like Berlioz's Symphonie Fantastique or Tchaikovsky's 1812 Overture. The same owner noted, "I'm enjoying them every evening - I'm rediscovering my old records." Another forum participant offered a caveat: the 4770/4771 is "certainly good enough for hifi, but a lot depends on setting up the right electronic crossover."
Some practical notes for anyone considering a pair. The foam damping material inside the 2445 compression driver can break down into a gooey mess over time and should be replaced. Many of these were driven hard in pro use, so burnt crossover components are a known issue. The 2404H diaphragms are prone to damage. One owner reported two of four with diaphragms in complete disintegration, plus a broken corner on one driver, and replacement diaphragms are the standard fix. Reconing the 2226 woofers is possible, and the original JBL part C8R2226 is available as a separate cone and voice coil. To remove the horn, take off the top 2226, then work a putty knife under the horn from the front while pressing from the back through the 2404H holes.
Production years aren't precisely documented, though the ¥550,000 price point dates to around 1992 and the model is generally placed in the 1990s. One Korean listing notes the early enclosure type was gray fir plywood. The 4770A is closely related to the 4771. A Japanese owner described it as "a speaker like a racing car." A professional audio staff member quoted in a Japanese reseller's blog said that to output enough sound to douse a large stage, it must be JBL.
Known specifications:
- Type: 2-way, 3-speaker, bass-reflex, bi-amp drive
- Low band: 38 cm cone woofer (2226H) x2, 4 Ω, 1,200W AES (50–500 Hz)
- High band: Horn type (2445J compression driver + 2380A biradial horn), 16 Ω, 150W continuous program
- Frequency response: 30 Hz – 20 kHz (-10 dB)
- Output SPL: 101 dB/2.83V/m (low), 112 dB/2.83V/m (high), 133 dB max
- Crossover: 800 Hz (recommended)
- Directivity (-6 dB): 90° H x 40° V
- Connectors: Neutrik NL8MPR x2
- Dimensions: 750 W x 1,250 H x 533 D mm
- Weight: 110 kg
- Original price: ¥550,000 (1 unit, c. 1992)
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