aceinc

Crites bases are an inch "deeper" (front to back) than what comes on a CW III.

Ceptorman yes it was CW III.

mustang, this looks like an interesting mod and simple enough I could do it myself. I will pull the plate off the back and see what I can see. I am not an even an amateur regarding electronics so I will talk here in generalities. Does the current curve at the squawker, tweeter crossover leave a gap, which the suggested modification of reducing the steepness of the slope addresses? One test I did and documented above was to move my testing microphone vertically in three 4" steps. This caused the cutout frequency to shift downward. From what I think I understand, this would seem to show that the the two drivers are cancelling each other out around the crossover frequency and when you change the relative distance between the two drivers it would cause the cancellation frequency to change. If this is true. wouldn't making the slope gentler increase the width of the cancellation and make the cutout wider?

I am not sure I will be able to post additional pictures due to the 2MB limit. Is this limit 2MB per user, or 2MB per thread? Is there a way around this limit? In the meantime I started another thread over here.

The squawker damping was applied to the panels which seemed to resonate in the bandpass. I intended to do the entire woofer in deadening material, but I did every other section first and the sound of the steel frame when struck with my fingernail went from almost bell to somewhere between a tick and a thunk. The angle braces I used were all from various pieces of 1.5" scrap lumber (yellow pine) which I had laying about. They were cut to 1.5"x1.5"x9.5" long and had a 45 degree angle cut in each end. I used 3 up each side and 2 on the top. There was already two 2x4 (nominal 1.5"x3.5") yellow pine braces connecting the baffle (motor board) to the back. The braces in the ports were fabricated out of some primed 3/4" pine I had laying about. These were the most painful to install, I would show a picture those, but I guess the 2MB limit is per user, not per post. I have not listened to the results yet, because the cabinets did have one issue I needed to deal with, the bases. When I purchased them the previous owner showed me the bases had been water damaged, they looked good unless you tuned the cabinets over.. I have fabricated one base and replaced it. The other base is built, but is waiting on paint to dry and holes to be drilled. The new bases are made from 1x3 (nominal 3/4"x2.5") finger jointed and primed pine painted black Duratex which covers my inadequacies as a cabinet maker. This increases the cabinet height by ~1/2" taller. I ran REW on the same cabinet I had run previously (its base was the first one). There appear to be subtle differences in the waterfall plot at frequencies above 120 hz. Some of the slow decay has been reduced in the time domain which I believe will translate into a positive change during listening.

They say it isn't real unless you post pictures. There is a 2 MB total limit to pictures per post so this may take a few posts. Things you'll see in the pictures; (may not be the same order) Squawker & woofer treated to stop ringing. Braces used for one cabinet. Inside of cabinet before & after bracing (after removing foam, and before putting new foam in).

While I know the CCW IV has a much larger horn, what issues do you see with the CW III horn?

The fun has begun. So far I have; Dampened the mid horns with Butyl Automotive Sound Deadener. Dampened one woofer with the same material. Added braces front to rear under the port shelf on one cabinet. They support the shelf and rest on the bottom of the cabinet. Things to be done; Stiffen the sides, top and back. Replace foam rubber stapled sparsely to the interior of the cabinet. Remove and determine if the tweeter can be "lengthened." What are folks thoughts on foam rubber vs rock wool for the interior of the cabinet? I have pieces of a mattress topper which is quite thick I could line the cabinet with. I also have most of a bale of rock wool. The rock wool looks more challenging, as I think I need to trap it behind cheese cloth and staple that to the inside of the cabinet walls. The foam I can either use adhesive, or see whether my staple gun will penetrate the thickness and bite into the wood.

Chris, I would prefer not to either change the aesthetics/cosmetics of the cabinet (moving the tweeter outside & further back) nor bi/tri amp with a DSP. This limits the options. One option might be to lower the crossover freq and steepen the curve, if the tweeter horn can handle that. This would help with the combing artifact caused by the distance of the center of the mid & tweeter horn being longer than the wave length of the crossover frequency introducing cancellation as well. One half baked crazy idea I had is, What would happen if the compression driver was separated from the horn and an appropriate length of pipe were inserted between the driver and horn? Would the pipe act as a Hemholtz resonator or otherwise muck up the sound?

I went looking for freq charts on the K79 which I believe is tweeter horn in the CW III. Couldn't find any.

The tweaking has begun.

I believe I answered the the reason for the cutout at 5 khz. It would appear that it is driver cancellation. The CW has two crossover points, 800 hz and 5 khz. Based on some of the knowledge gleaned from Danny's Tech Tuesday videos I decided to measure a few times from the same distance from the baffle and centered on the horizontal plane adjusting the height in 4" increments from the center of the mid range horn (31") to the center of the tweeter horn (35") to 4" above that. The results show the cutout frequency shifts. Based on Danny Ritchie's explanation I believe this is because the relative distance from the two drivers changing causes the cancellation frequencies to change. It can be seen in the 800 hz frequency range as well. It's really cool to see with my own eyes stuff I learn. Thanks Danny.

I have started the analysis phase of the project. I moved one of the CW IIIs into the center of the room and using REW did a scan. I had the microphone about 39" from the baffle and about centered in the mid range horn. From that I was able to get the following graphs. A few things surprised me; How smooth response was. The boost below 100hz. The dropout at ~5Khz. The waterfall plot seems too clean. The boost below 100 hz is probably room gain/node. I have never worked with waterfall plots, but this one looks too consistent. Either everything is decaying too much at the same rate, everything is perfect, or I don't know what I am doing or looking at. I'm going with the latter.

I became the proud owner of a pair of CW IIIs earlier last year at a great price as part of a larger purchase. Depending on how you value the various pieces I bought, the price could be anywhere from -$1,500 to +$350. They are B-stock and were originally purchased in 2013. I have had them in a 11'x15' den in my home for a number of months and occasionally listen to them mainly with the Mono Block Tube Amps and Tube Preamp they came with. Although I also listen to them with the tube pre & an Adcom GFA 555 Series II I use for testing. Since I have so little invested in them I thought I would have fun with them. One of the bases/risers is water or rodent damaged, other than that they are cosmetically in 9/10 condition. Speaking of bases, Klipsch wants $150 for one base finished in Cherry. Bob Crites wants about half that for a pair unfinished. Unfortunately the Crites pair seems to be an inch deeper (14-12" vs 13-3/8") than what is currently on the cabinet. I have sent an email to Crites, and am waiting a response. Anybody have recommendations regarding a base(s)? My initial plan for the speakers is to make the cabinets more rigid, add additional "insulation/sound absorption" and deaden any squawker horn ringing. During my testing I played various bass/drum pieces to see if the cabinet panels would be excited/resonate. Using touch (not very scientific) I could feel the top sides & back all vibrating during different passages. So I feel some bracing could improve things. Also unscientifically I tapped the plastic squawker horn and the sounds it made seemed like they would be in the midrange (800hz-5khz), so I felt dampening that would be a good idea as well. Here is my testing environment. I close the curtain on the door for testing to help limit reflections.

I need 1 base for a Cornwall II in Cherry. They are available from Klipsch for $150 which is right on the cusp of my budget. I am located in S Florida. When I examined the second speaker, its base was damaged as well. I decided to fabricate a pair of bases. So this is no longer needed, thanks for looking.