For anyone keeping track:
1. Got a refund for the bricked woofers and they told me to just keep them instead of sending them back, anything cool I can do with these? Can I fix the magnet? I saw a few threads on realigning magnets, but it looks difficult... maybe use them as passive radiators for a smaller two way speaker project?
2. Buying plywood tomorrow, going with the manufacturer recommended enclosure Vb and Fb, it actually looks fairly close to the 'vintage sound' spec, the port resonance seems a little easier to manage, and the enclosures will be a little smaller/slightly more portable. Also going with two 4" ports
3. I have an interface I can do an electronic crossover on for now, once I find curves I like, how hard is it to turn that into a physical crossover? Resources to learn this kind of thing?
Finally -- a little off topic -- I scored some Fischer XP66s, (late 60s three ways with a high compliance 12" woofer) at the thrift store today for 10 bucks. Not super hifi, but they sound really fun, big gushy low end - listening to some Al Green on vinyl right now, super sweet.
Anyways nice to have a couple wins after the busted woofers.
I'll post pics once I get the enclosures put together for the 811s + Woofers.
1. Got a refund for the bricked woofers and they told me to just keep them instead of sending them back, anything cool I can do with these? Can I fix the magnet? I saw a few threads on realigning magnets, but it looks difficult... maybe use them as passive radiators for a smaller two way speaker project?
2. Buying plywood tomorrow, going with the manufacturer recommended enclosure Vb and Fb, it actually looks fairly close to the 'vintage sound' spec, the port resonance seems a little easier to manage, and the enclosures will be a little smaller/slightly more portable. Also going with two 4" ports
3. I have an interface I can do an electronic crossover on for now, once I find curves I like, how hard is it to turn that into a physical crossover? Resources to learn this kind of thing?
Finally -- a little off topic -- I scored some Fischer XP66s, (late 60s three ways with a high compliance 12" woofer) at the thrift store today for 10 bucks. Not super hifi, but they sound really fun, big gushy low end - listening to some Al Green on vinyl right now, super sweet.
Anyways nice to have a couple wins after the busted woofers.
I'll post pics once I get the enclosures put together for the 811s + Woofers.
Fix the magnet? Are their baskets loose? Or they just need reconing? For PR, best to remove them and cut loose, narrow up the spider so it can move freely.
OK, HR 'says' vents are 10.2 cm/4" long with a 'good enough' ~21 m/sec @ 120 W, > 110 dB from ~35 Hz - up/2 pi, so more if up against a wall or especially if hard in a corner.
Dunno, there's been some discussions, but haven't followed them beyond recommending REW, VituixCad.
OK, HR 'says' vents are 10.2 cm/4" long with a 'good enough' ~21 m/sec @ 120 W, > 110 dB from ~35 Hz - up/2 pi, so more if up against a wall or especially if hard in a corner.
Dunno, there's been some discussions, but haven't followed them beyond recommending REW, VituixCad.
Member
Joined 2009
Paid Member
Well, the technical reason is:
Pg. 76: https://archive.org/details/HowToBuildSpeakerEnclosuresByAlexixBadmaieffDonDavis/page/n75/mode/2up
“A nagging question in the design stage of any enclosure of this type is "How large shall it be?” It was pointed out earlier that the enclosure can be too large or too small for proper bass-reflex action. This implies that an optimum volume exists and indeed it does. This optimum volume does not depend upon the size of the speaker nor its resonant frequency per se but rather on the ratio of enclosure air stiffness to the speaker cone suspension stiffness. This optimum ratio is 1.44 or, looking at it another way, the speaker resonant frequency in the enclosure before porting should be 1.56 times the free-air resonance of the speaker. This size enclosure, when properly tuned, yields at the same time the most extended low-frequency response and a transient response with subjectively unnoticeable hangover, assuming sufficient damping exists. Compared to the entirely closed cabinet, the half-power point (3 db down) occurs at 0.7 times the closed cabinet speaker resonance for an extension of one-half octave."
Pg. 76: https://archive.org/details/HowToBuildSpeakerEnclosuresByAlexixBadmaieffDonDavis/page/n75/mode/2up
“A nagging question in the design stage of any enclosure of this type is "How large shall it be?” It was pointed out earlier that the enclosure can be too large or too small for proper bass-reflex action. This implies that an optimum volume exists and indeed it does. This optimum volume does not depend upon the size of the speaker nor its resonant frequency per se but rather on the ratio of enclosure air stiffness to the speaker cone suspension stiffness. This optimum ratio is 1.44 or, looking at it another way, the speaker resonant frequency in the enclosure before porting should be 1.56 times the free-air resonance of the speaker. This size enclosure, when properly tuned, yields at the same time the most extended low-frequency response and a transient response with subjectively unnoticeable hangover, assuming sufficient damping exists. Compared to the entirely closed cabinet, the half-power point (3 db down) occurs at 0.7 times the closed cabinet speaker resonance for an extension of one-half octave."