Chorus 1 tuning?

[Onform]

I have read numerous times about adding 7" ports to tune the cab lower. I have managed to get hold of 4 tubes but they are just shy of 7", am I right in thinking being slightly shorter they will just tune the cab slightly higher? Also I would like to brace the insides with some 2by1, not very subtle but they will certainly do the job. One more thing would adding some stuffing inside lower the resonance?

[moray james]

Yes you are right. You can experiment using some thin cardboard sheet to roll up into a tube and hold it together with a little tape. You can take a look at the link below to get an idea of what I did with a Quartet cabinet. Also bracing the magnet structure to the rear baffle will stiffen things up a lot. You can add stuffing high density fiberglass is the best material you can use like the kind found in acoustic flexi tiles. You would only want to damp the walls and the top most portion of the cabinet as damping the lower section or the full body with dacron or polyfill will prevent the woofer from generating a good strong resonant coupling with the vents which is how they work together. You have to have a good volume of air resonating in the lower half of the cabinet. Good luck and have fun and welcome to the forum this is a great place. Best regards Moray James.

http://www.audiokarma.org/forums/showthread.php?t=372783&highlight=klf20&page=3

[lyfguard1]

I decided to try this trick about a month ago, even though I was satisfied with the Chorus I's bass already. I picked up a couple of 4" tubes from the UPS store (they don't have them laying about, but if you ask they should have them in the back somewhere). They were too big and sturdy to shove in as is, so I cut them to 7 inches then used a ruler and a sharpie to make a line from end-to-end and cut them lengthwise with a jigsaw. This allowed me to fold them in to get them in place and then spread them back out to make a tight fit.

The tubes do lower the bass noticeably. My initial impression was that the bass sounded lower but not quite as natural sounding. I guess it depends on what kind of music and voicing you like. For now I'm leaving them in as I've gotten used to them. I'd like to do more experimenting with lengths when I get more time. But this is a cheap and easy mod to try, so I would recommend it for anyone with Chorus I's. I spent maybe $10 on the tubes.

I saw a photo of someones speakers where they only had one tube in one of the two ports in each speaker and am curious if that was how they are running them. I guess I could pull one out of each speaker but they are in there nice and tight now, so I figured I'd ask first.

[Tobi]

You would only want to damp the walls and the top most portion of the cabinet as damping the lower section or the full body with dacron or polyfill will prevent the woofer from generating a good strong resonant coupling with the vents which is how they work together. You have to have a good volume of air resonating in the lower half of the cabinet.

Let me get this right. I don't want foam in the lower part of the speaker?

[moray james]

Correct.

You would only want to damp the walls and the top most portion of the
cabinet as damping the lower section or the full body with dacron or
polyfill will prevent the woofer from generating a good strong resonant
coupling with the vents which is how they work together. You have to
have a good volume of air resonating in the lower half of the cabinet.

Best regards Moray James.

[pzannucci]

You can use dampening in the lower portion of the cabinet so you will have less likelihood of standing waves, as long as you keep the ports open to the woofer cavity. This will clean up the bass somewhat but you have to be very careful not to over dampen the enclosure because that will suck the life out of the bass. Do it small amounts at a time to "tune" the cabinet for the best non-smeared, less sloppy bass without going overboard.

Overdamping may tighten things up and make it sound like there is better extension so it really will be to each his own.

Underdampened cabinets also have their issues where they will usually sound lively but too lively and not true.

There used to be some old books that pointed out that you were real close when you heard a quick thud (not boing) with no additional ringing when doing something like a 1.5 volt battery click test on the woofer and enclosure. A click when doing this test might be too damped.