Epic CF3 Bracing & Damping Project

[kapsnb01]

More stringer bracing

[wuzzzer]

Great project for such a beautiful weekend! []

[kapsnb01]

Yeah...hard to stay inside on a day like today, huh? [um]

[kapsnb01]

Well the bracing is complete. Ran a couple more side to side stringers and also a couple down from the top to the factory installed brace. Looking forward to putting them back together tomorrow for a listen. Thanks to Moray James for the road map and advice on how to do this project!

[kapsnb01]

Through tweeter opening

[kapsnb01]

Upper woofer opening

[kapsnb01]

Down through the upper woofer

[Fizzlemizzle]

Great work, that looks awesome! I'd like to see the original insides before the bracing, do you have pictures? Also, you wouldn't happen to have exact inside dimensions would you? I'm not sure how you're supposed to measure. Here's a pic of factory KLF-20s

[kapsnb01]

Great work, that looks awesome! I'd like to see the original insides before the bracing, do you have pictures? Also, you wouldn't happen to have exact inside dimensions would you?

The first couple posts in the thread have the before. I had already taken out the factory damping material, so it was just the empty cabinets. Not the best pictures, but those are what I have for 'before' type pics. Side to side measurement was 15 1/8", Front to back was 15 1/8" and the top to bottom was just a shade over 39"...I think it was 39 1/16". Best advice, it's always better to have it be a little long than too short. If it's too long, you can always shave it dwn a bit to fit right. I always cut one 'test' board first and fit it into place just to make sure the measurements were right.

Spent a lot of time today with the Eagles Farewell Blu Ray. All the work paid off in spades. I couldn't be happier, just a nice tight and very detailed sound. Just awesome in my opinion and well worth the time and effort! [H]

[moray james]

Just a note: I believe that it is a mistake to cut braces and stringrers so that they are a "wedge in fit" this leads to a number of problems and can cause problems for you. If all your joints in a retro job like this are that tight then you are not going to have adequate adhesive in the gap and you don't want dry joints. There is zero advantage to making joints tight fitting. Remember that white glue fills gaps just fine. White glue and yellow glue are both types of PVA adhesive only with different set times and concictency. PVA adhesive is a better choice than urethane adhesive for work like a retero brace job. Hope this helps and is of interest. Best regards Moray James.

[moray james]

If you are interested you can take a look at the thread link posted below there are some pictures on the second and third page of two different cabinet jobs. The KLF20 was a fast and dirty brace job with both front and back baffles removed as they were all loose and I wanted to move the vents from the rear to the front inthat case. The job actually turned out very well and they soumd excellent. The Quartet brace job is the better of the two but is also a lot more work but very much worth the effort. as Brian will confirm. This style of brace job results is an extremely rigid cabinet with minimum cabinet volume use.You can also take a look at a very similar brace job on a pair of Heresy 3 which follows the style of the Quartets, very rigid. Once you hace addressed box talk with a solid brace job then you are in a position to address other speaker modifications and actually be able to appreciae them as they will be clearly audible once the boxis made secure and quiet. Hope this is of interest. Best regards Moray James.

http://www.audiokarm...ghlight=klf20 KLF20 brace job/Quartet brace job

http://www.audiokarm...php?t=438234 Heresy 3 brace job

[kapsnb01]

Just a note: I believe that it is a mistake to cut braces and stringrers so that they are a "wedge in fit" this leads to a number of problems and can cause problems for you. If all your joints in a retro job like this are that tight then you are not going to have adequate adhesive in the gap and you don't want dry joints.

Great point. All braces should fit in easily with enough of a gap for the adhesive. My point was only that if you're going to miscut a brace, better to do it on the long side, as that can be fixed versus the short side which really can't.

[kapsnb01]

If you are interested you can take a look at the thread link posted below there are some pictures on the second and third page of two different cabinet jobs. The KLF20 was a fast and dirty brace job with both front and back baffles removed as they were all loose and I wanted to move the vents from the rear to the front inthat case. The job actually turned out very well and they soumd excellent. The Quartet brace job is the better of the two but is also a lot more work but very much worth the effort. as Brian will confirm. This style of brace job results is an extremely rigid cabinet with minimum cabinet volume use.

http://www.audiokarma.org/forums/showthread.php?t=372783&highlight=klf20 KLF20 brace job/Quartet brace job

http://www.audiokarma.org/forums/showthread.php?t=438234 Heresy 3 brace job

Highly recommend looking at the threads. The Quartet was the basis for everything that I did and it is 100% worth the effort. Definitely more work and not always easy, but well worth it in the end.

[wuzzzer]

My Chorus' don't have any bracing in them at all. Might be a good project for me at the end of the month when I have some time off of work.

[moray james]

When you install a brace it should rest or sit upon a bracket like a
shelf/ The bracket should be installed first that way you are bonding
the brace to the bracket not directly to the cabinet wall. The little
bracket adds a tremendous amount of additional stiffness and strength to
the brace. If you want you could add additional bracket to the brace so
that it is supported on both sides, but this is likely sliding into the
realm of overkill. Best regards Moray James.

[wuzzzer]

Good to know. What would you recommend as far as a bracing project for my Chorus? I don't want to go crazy, just have at least some bracing.

[moray james]

Well a chorus is more or less like a Quartet of Forte ll only larger and hat mens that the rear baffle is especally weak. f you take a look at the pictures of the Quartet brace job you can see the small braces added to stiffen around the woofer and the passive. toy can install a number of those easily and quickly and then as as many front to back stringers as you can fir in and two or three side to side stringers as well and if you can cotrice to have the stringers connect to one another that helpd also. You could do this in a day and it would help a lot. A small block right behind the mid driver on the rear baffle and a piee of that cell rubber insole material fitted so thatthe driver copresses the gel rubber on install and you hace a nice solid ftont to back brace for the rear baffle very easy and cheap to do. The more you stiffen the baffles the better especially the back as it is getting the lions share of the flexing at the lowest frequency. That should do it for a fast easy dirty but effective job. Hope thias helpd Best regards Moray James.

[kapsnb01]

Spent some time over the weekend damping the cabinets. Haven't had a lot of time to listen to them now that both are done, but I did do one cabinet at a time and did some A/B testing. Clarity is the word that I keep thinking of. Little details seem to pop more easily, especially noticeable in tracks that I've listened to many times. Was very noticeable when I popped in Hotel California...heard many secondary guitar chords & notes that I had not heard prior...and I've definitely listened to that track a ton. Here are a few pics...

[kapsnb01]

2

[kapsnb01]

A look at the rebuilt crossover from Bob Crites.