by erichayes » Wed Mar 08, 2006 7:12 pm
Hi All,
A couple of thoughts . . .
The only "improvement" Bud and I made to the A-25 crossovers was to replace the electrolytic 4.7 µF cap with a Solen 4.7 µF poly. One of the reasons the A-25s sound so good is due to the minimalist first order crossover. When you start throwing inductors and resistors at a crossover to compensate for the mismatching of the drivers, you create more problems than you solve. Seas took great pains to physically match the woofer and tweeter so they'd cross over naturally. The cap's in there primarily to protect the tweeter from excessive low frequency energy burning out the voice coil. If you're interested in experimenting with crossover frequencies and slopes, put a second set of binding posts on the back and wire the tweeter directly to them (the woofer's already wired directly to the existing posts). Now you can hook up passive components or biamp the speakers using an active crossover. I recall seeing a circuit for a tube crossover a couple of years ago on the net, and I'm sure there's probably nore now.
The Brits seem to be fond of using wool for loading speaker cabinets--it's by far the material of choice for loading transmission lines--but there's a downside. Back in the 70s, a freind of mine decided he wanted to build some transmission line speakers, using instructions from England (where XL systems are much more popular than over here). Since the parts list called for so many ounces of wool to load the line, he logically figured he could get some from one of the local 4H kids in the area. Builds the cabinet, stuffs the line with the wool, drags 'em into the living room and fires them up. They had such an effortless and infinite low end that I became an immediate convert. I go home, he leaves town for the weekend, gets back Sunday eve, and I get a phone call: "Can I stay at your place tonight?" Well, he's only 3 doors down, so I walk over to his place to find out what's up. He forgot to wash the wool. It smelled like a shepherd had led his entire flock through my friend's living room.
Needless to say, he spent the night at my place, the speakers were removed to the garage, another pair was eventually built, and this time he used fiberfill pillow stuffing. I'll never forget that smell . . .
Eric in the Jefferson State