Kenwood LS-407B Speakers from 1978

[Charlie04SiR]

Here's a pair of vintage beauties I picked up recently. I just finished refoaming the woofers and testing them. I got them with radio shack woofers in them, which when in these particular speakers don't sound very good because the woofer leads are directly to the speaker terminals with zero inductors or crossover points. The original woofers were made with inductance an capacitance built into the voice coils. I had a spare set of original woofers to these models and they finally found a home. The baffles in these are real triple crosslaid lumber core just like how the soundboard in a grand Piano is made! What amazing performers these speakers are, pancake-flat response curve with every detail and every note heard with absolute clarity, without any harshness or shrill. Hands down, utterly amazing speakers! :)

[dakatabg]

Yeah man they look mint! Time to enjoy them! :14:

[thekid]

Looks like a quality job.
Nice looking pair of speakers!

[Charlie04SiR]

thanks dakata & the kid. They're not really all that mint, a few bumps & bruises on the rear edges, but the drivers, baffles and internals are mint :D

Dakata, I love that McIntosh LD player pic of yours. You gots lotsa equipment, man! makes me look like a small fry, heheheh!

[dakatabg]

I work with electronics and and get a lot of stuff! I have had almost everything. I post pictures so when someone searches online, they will appear on the search and give him the info or the picture he wants to see. Another reason is that it makes this site more famous when we have more pictures and discussions and it attracts more people here when they do a search! You know what I mean

[Charlie04SiR]

Yeah heheh!

[ryanguy1990]

i have a pair of these that i got from my old boss along with a set of infinity Qa's very good stuff

[dougmorf]

I'm bringing this back to life with some questions of my own. I have some "new guy" questions.

I just found a pair of ls-407B speakers, but they are pretty rough. My big question is how to replace the woofers, as they currently have KLH woofers directly wired to the terminals. Is it possible to replace them, and incorporate inductance and capacitance? How would I cross them over?

Also, did the woofers originally have baffles on them?

[Charlie04SiR]

Hi Doug, the original wires inside the LS's is silver plated copper core, though I have seen solid silver core in some of the early production ones. It may not be thick like battery cable, but you don't need that thick stuff unless you are planning on pumping 1000's of watts into them. They are not rated that high, obviously, but they will take a good deal more than their rated 120 watts RMS. The silver wire is the best wire as it propagates the signal output with zero degradation. with the purest sine wave from one end to the other. So, try to maintain the original wires if you can because new silver plated copper wire is quite expensive. I do have one more set of LS-407(A or B) 10" woofers, which I need to refoam. I saw a pair of 407's on ebay and was tempted to buy them, just to put them back to original condition with my last pair of OEM woofers. I restored a pair of LS-408B's by installing a traditional 3-way Xover with the usual inductance & caps. I used one with 150 Watt rating, 6dB octave, and 800Hz midrange drop off frequency, and 5000Hz drop off Tweeter frequency. I got it from Midwest Speaker. This one: MX3-85-6: 3-Way Crossover (http://w.mawebcenters.com/midwestspeaker/ecommerce/crossovers-parts/premade-crossovers/3-way/mx3-85-6-3-way-crossover.html)

You can use the wires from woofer and plug them right into the in + & - on the Xover after you mount it on back board right above original terminal plate. Cut the wires for mid & tweeter about several inches from caps and leave original caps in place, that way they maintain their originality, so they can be put back to original condition if you decide to do that someday. Crimp new connectors on mid & tweet wires, and install then on marked terminals on new Xover, taking care not to reverse phase them, however, the mid is originally reverse phased, but with the new Xover, it should be in phase. You can experiment with midrange phasing to whichever way is most pleasing to your ears.

[Charlie04SiR]

Ooops, I forgot to answer your last question. The baffle and woofer are two different things. The woofer is comprised of a cone, voice coil, magnet, spider, pole piece, pole plates, and basket frame. The baffle is the front panel of cabinet that the drivers are mounted into.

[Roger Red Hat]

how much would they of cost back in the day?

[Charlie04SiR]

how much would they of cost back in the day? the 407B's listed for $240 each back then, which was alot of money for the day to the average household.