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  • Legit 70’s Firepower: The Marantz HD-770s

    2015 - 04.17

    Marantz HD-770 top-end drivers and L-pad array

    As posted about previously, I had encouraged my drummer to get the Marantz HD-440 speakers, since I have very much enjoyed owning a pair of their big brothers, the HD-770s. The “High Definition Series” speakers have walnut veneer cabinets and were built sometime in the 70s. In the Marantz 25th anniversary catalog (dated 1978) they are for sale as the medium tier product underneath the “Design Series”. For a mid-tier product though, these are extremely nice. And as an aside, that 25th anniversary catalog is a feast for the eyes if you’re into this kind of thing… here is a link to it at HiFiEngine.  You’ll need an account to view it but it is easy to create one… it’s worth the effort to check out that super sweet catalog.

    It’s clear they put some thought into the design of these units. The most attention-grabbing feature for me was the 1″ dome driver, which is labeled as a tweeter. I’d call that a misnomer though, since the overall frequency response is given as 33-22kHz +/- 3dB @ 125W of “program material”. Crossover Frequencies are 750, 2300, 5000Hz so that 1-inch “tweeter” is handling 2.3k-5kHz.  I have always been a big fan of dome midranges for their lifelike sound, especially on anything of an earthy, organic variety like acoustic guitar, piano, or exposed vocals. Dome mids do a great job of putting those things “in the room” with you. Interestingly the HD-770 has a stated efficiency of 90dB which is very high for a speaker depending on a 12″ woofer to handle the low end, since the woofer is almost always the limiting factor on efficiency and high efficiency woofers are relatively rare in larger sizes.

    marantz HD series lineup... HD-770s are 2nd from the left

    From the factory HD series units were supplied with a “Vari-Q damping acoustical plug” which you could insert to tune the port if you wanted to change the bass response. The trade-off was more definition in the 50-75Hz range, at the expense of anything below. My speakers were bought secondhand off Craigslist and did not come with this accessory. I see some on ebay with the mention that the original foam is long gone… a running theme. Like the HD-440s, the woofer foam on the HD-770s also crumbles away with time. In my case the previous owner swapped out the original woofer for a replacement driver instead of re-foaming it. This can easily be spotted by the convex woofer dustcap; the original was concave. Given the apparent attention that the Marantz engineers paid to driver selection, I wish he had re-foamed the original. If an opportunity ever presents itself, I would like to acquire the original driver and restore these to their intended stock configuration, although the replacement is doing just fine for the time being.  After searching a while on eBay that seems like a pipe dream though, since a pair in need of re-foaming recently sold for $227.50.  That says something though–one, the original drivers were good and two, the market of people out there enthusiastic about keeping theirs in prime condition remains hot.  My set is also missing the metal ring which mounts around the largest woofer, which is too bad because it does look cool.

    The HD-770s have a three-section resistor (aka L-pad) control panel on the front which allows you to individually adjust the volume of the super tweeter, dome midrange and cone mid-bass drivers. When I built the green speakers for my brother I definitely learned that L-pads are a tremendous asset to any speaker design. They really allow you to tweak the “voicing” of the sound to whatever suits your liking. It can’t be over-emphasized just how much of an impact this has on the sound. Put it this way: never again would I built another set of speakers without L-pads.

    These units have a really funky grille, which has brown fabric which comes outward at the center. I can’t decide if they look cooler with out without the grille on, so I keep the one closer to the door equipped with the grille to protect it from passing foot traffic and the one near the window exposed so I can enjoy the neat appearance of the drivers. Hopefully these units will last me a long time. They are certainly ready to pump out some serious dB’s but still have a soft touch for nuance at the same time. That’s a real nice combination.

    no grille... ... or yes grille?

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    One Response to “Legit 70’s Firepower: The Marantz HD-770s”

    1. Ivan says:

      Very nice review

      I bought a pair of those, can’t wait to listen to them

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