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Discussion Starter · #1 ·
Wmax is the author of these guideline and an expert of extreme hi-fidelity DIY audio. He's one of the guys that got me hooked on the hobby.

These mods are Wmax's idea and if he requests they be removed I will remove them. He does have an account with us so if you have more specific questions you might try a pm. Please note the

$70 mod is a guide on how to build a constraint layer dampening system inside a speaker. It's easier than it sounds.

$20 mod:

-Remove front face plate cover and drivers.

-Add in 2" of high density rockwool or high density fiberglass insulation board such as Owens Corning 705. This will provide improved internal acoustic dampening; most speakers have insufficient material and this is no exception.

-Use liquid superglue and apply generously into the crack between the magnet shield can and motor on the woofer. This joint is only crimped and has some slack, causing possible resonance/vibration at certain frequencies. The super thin glue liquid will harden deep in the crack preventing this problem.

-Use rope caulk or preferably Parts Express gasket caulk / mastic and apply between where the tweeter connects to the front face of the speaker. Simply remove the screws, place the putty like material in very thin amount on all opposing surfaces, and re-install tweeter. Use your fingernal to scrap off excess that squeezes through on front side of face around the joint. This will fix an air breach.

-Apply more rope caulk or preferably Parts express gasket caulk around the back edge of tweeter motor and it's own face plate to prevent air leak. Do not remove screws from tweeters motor and it's own face plate. Only apply externally around the edge, including around the metal wire connection terminals.

$70 mod:

-Remove face plate, drivers, crossover, wire connection terminal and internal acoustic dampening.

-Scrape out any residual glue left on walls that was holding the acoustic dampening in place using a chisel or any other suitable flat edge sharp instrument as best as you can.

-Use Peel N' Seal (one roll of 6 inch wide by 25 foot and divide between a pair of speakers) or Dynamat(not more effective - just more expensive) and apply in layers to inside walls to get a 1/8" thick - 1/4" thick layer appliled to walls. Use a hair dryer or heat gun to apply the first layer to the MDF bare walls for maximum effectiveness of adhesion.

-Clean aluminum foil side of Peel N' Seal with brake parts cleaner spray on a rag to clean off residual tar. Score aluminum surface lightly with 60-80 grit sand paper.

-Use solvent based(not water based) contact cement and apply a few coats to the aluminum side of peel 'n seal.

-Apply contact cement to one side of metal window screening material.

-Apply/press window screening material to aluminum side of peel 'n seal.

-Cut out some small pieces of cardboard and use some duct tape to make a small protective dam inside around where the terminal mounts to back of cabinet. This is needed to keep epoxy from spilling/blocking the terminal from being re-installed as will be clear from the next steps.

-Purchase 1 gallon of garage/shop floor 2 part epoxy. Mix small amount at a time and pour into one side of the cabinet - enough to get about 1/2" deep on all sides except sides where flat slot ports sit. Apply more than 1/2" on slot port sides to make sure the gap between port and wall is completely filled. Allow each side to harden enough to not move/shift and then turn over cabinet to do next side. Repeat until all sides are done. Ideally, you would also put some peel n' seal between the slot port and mdf wall - but this is a tight space and not easy. If you do it, the best way would be to apply thick paper to the sticky side of Peel N' Seal for this particular spot and first pour the epoxy and then shove the paper-backed peel n' seal into the space while the epoxy is still liquid so that the peel n' seal will be trapped securely in the epoxy. You will still need to apply the screening to the aluminum side of the peel n' seal.

-Go to $20 mod steps and now apply these to complete modification.

Doing the 70 dollar mod will net you a hi-fi speaker.
 

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In one of WmAx's original list he recommends what is effectively creating a sealed speaker:

"Use a hammer and block of wood and knock out the ports. After you remove them use black silicone and small piece of wood from behind the port openings and block/seal them."

Any opinions on sealing vs. leaving a ported design as you have recommended?

Also, he recommended adhering concrete board to the dynamat, which your epoxy method improve upon in terms of overall surface area coverage. But, he then goes on to recommend using a threaded rod system to further brace the cabinet:

"You can go further and use some 5/8" all thread rod and cut it about 1/4" short of the concrete board to concrete board contact points across the enclosure. Use nuts on both ends of the rod. You will use the nuts to take up the slack and grab the inner walls. Use permanent locktite on the threads to lock the nuts(you will have a few minutes open time) and use high quality metal epoxy to adhere the nuts to the concrete board. If you use the all thread bracing technique in more than one axis, try to have the all thread rods intersect with each other and use more of the metal epoxy to bind them in the middle of the cabinet; this will make the bracing stronger."

Would this additional bracing net any positive results using your epoxy method, or is the epoxy sufficiently rigid as is?
 

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Additionally, if anyone has tried these methods, please let us know your experience. Are you happy with the results? Did you have any tips based on problems you ran into along the way? Suggestions for where to pickup OC 705 in small quantities?
 

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Discussion Starter · #5 ·
In one of WmAx's original list he recommends what is effectively creating a sealed speaker:

"Use a hammer and block of wood and knock out the ports. After you remove them use black silicone and small piece of wood from behind the port openings and block/seal them."

Any opinions on sealing vs. leaving a ported design as you have recommended?

Also, he recommended adhering concrete board to the dynamat, which your epoxy method improve upon in terms of overall surface area coverage. But, he then goes on to recommend using a threaded rod system to further brace the cabinet:

"You can go further and use some 5/8" all thread rod and cut it about 1/4" short of the concrete board to concrete board contact points across the enclosure. Use nuts on both ends of the rod. You will use the nuts to take up the slack and grab the inner walls. Use permanent locktite on the threads to lock the nuts(you will have a few minutes open time) and use high quality metal epoxy to adhere the nuts to the concrete board. If you use the all thread bracing technique in more than one axis, try to have the all thread rods intersect with each other and use more of the metal epoxy to bind them in the middle of the cabinet; this will make the bracing stronger."

Would this additional bracing net any positive results using your epoxy method, or is the epoxy sufficiently rigid as is?
In all honesty, I'd just do the 20 dollar mods unless you are up for some serious work. He's measured the results of resonance reduction using these methods many times and they are very impressive. He goes to the extreme in my opinion. Most of us don't have the passion or drive to do that much work. I've not had the chance to hear his system and prefer to wait until he completes his new mains which will be even better. But rumor has it that it's among the best in the world.

Sealing does eliminate port resonance and is probably necessary with bracing to fix the alignment.

I'd also use some wood on the inside of the peel-n-seal instead of the epoxy. Oak being preferred.

This construction method will be employed in my reference speakers. except I'll be using 4" quarter round on the baffle to fix the baffle issues of a fast turn.

Basically I'll build the exterior with birch ply. Then apply the peel-n-seal. Then I'll build the inner layer with chip wood which will be placed only on the flat panels. 4" of rockwool on the back and 2" on the sides, top and bottom. Bracing is used to prevent the panel resonance coming from the pressure of the back wave. The peel-n-seal kills the resonance coming from the coupling of the driver to the speaker box.

So basically what these methods do is decrease resonant and reflective distortion. The rockwool(705) eliminates the reflective distortion. Which is a major component of distortion.
 
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