I started this project by reading on Bob Crites Website about the Cornscalas and then on the Klipsch forum. I was going to use the CW1526CF woofers and Faital LTH142s. Then I discovered the Eliptrac 400. I didn?t think I could afford the built ones but could afford the flat pack kit. I stated putting together a parts list with prices and thought I should scale back a little and went with the LTH142s.
I went a different direction with the woofers and went with GPA 416-6C?s. I couldn?t decide to go with the GPA 515-8LF or GPA 416-8C, but after talking to Steve at GPA he right away steered me to the 416-8C?s. I knew the 515 worked better in horn loaded enclosures than in ported enclosures. I couldn?t decide on a mid driver and was going to use the Faital Pro HF140 but decided to try the GPA 399-8A. I talked to Steve about using the 390?s but he said to go with 399?s. He said he would sell me either one just whatever I wanted. I drove down to Oklahoma City (I Live in Wichita) and picked up the woofers and drivers. I toured the GPA facilities and meet Bill, Steve and the crew. Never saw so many 604?s in my life in one place. A true experience and the guys at GPA are true gentlemen and treated my ignorance with respect.
I looked at the LTH142?s and the 399?s and I thought I could mate them together as they both are 1.4 inches. I had to grind 4 notches into the back plate for the 399?s to fit.
I knew I wanted to use active crossovers and separate amps so I bought a used Rane AC23b 3 way crossover off of e-bay. I heard that this was a good crossover and didn?t introduce any nasty sounds into the audio chain so I went with it.
I already had a pair of Altec 902-8T drivers that I had taken the back cap off of and lined the back cover with felt and I wanted to try them for tweeters. I looked at Fastlane Audio and they had a recipe for a Cornscala parts list. They recommended using B&C ME-10 horns. I ordered a pair from Parts Express. To adapt the 902?s to them, I had to drill the mounting holes on the horns a little bigger to accept the 902?s.
I knew I wanted a separate woofer enclosure and not mount the horns in with the woofers. I wanted the horns at ear level so I had to have a bass enclosure no higher than what the horns could set on to make them at ear level. I also wanted to use the acoustic golden rule for the bass cabinets. So I designed the cabinets and added the bracing and woofer volume and what I could stand size wise in my little stereo room. I came up with 5.65 cubic feet. Then I went to WinISD Pro and started playing around with alignments.
I decided to use a 5.65 Cu. Ft. with 2 each 4 inch dia. Ports 7 inches long. That put the box tuned at 34.68 Hz. I made the cabinet outside dimensions 19.75 in. wide X 24.25 in. deep X 48 in. tall. The woofer box inside dimensions 18.25W X 22.75D X 28.5H. WinISD Pro says -3db at 48Hz, -6db at 36.6Hz and -10db at 31 Hz. That?s about right as in my room I get strong tone to 40Hz and a dropped tone at 31.5Hz and 25 and 20Hz. So I think I get probably down to a usable 34 or 35 Hz. Good enough and if I need lower will use a subwoofer.
I had three 5? by 5? sheets of Baltic Birch ?? plywood I bought like 15 years ago waiting for that perfect project and this was it. Now I am retired and 62 years old so I don?t have the strength I had when I was in my 30?s or even 40?s, but I man handled the sheets and cut them down on my table saw. Glad that was over with I though until I started gluing them up and the more panels and bracing I glued together the heavier the cabinets got. Working out in the garage and sweating in 90 plus heat got me toned up fast. I thought walking 4 miles 3 times a week was enough but I found out I was wrong. Hah. Reminds me of a co-worker that biked like 30 miles 3 times a week and walked 4 or 5 miles 3 or 4 times a week and he was in great shape and liked to tell everyone how he eat the right foods etc. blah blah blah. Well he helped a friend roof his house one weekend and when he came to work on Monday he could hardly walk or stand up. He couldn?t figure it out. I said you were using different muscles. He had a new appreciation for roofers.
I settled at 500Hz and 7000Hz crossover with a .6 ms delay on the woofer. I am using a Magnavox 6BQ5 push pull amp for bass, APPL 6BQ5 single ended pentode amp for mids and Magnavox 6V6 push pull amp for highs. I also tried the 399s without tweeters and they sound nice and really need no tweeters but are just a little dull or laid back on the highs and the 902s give a triangle or cymbal a little more shimmer and clearer and cleaner sound. What I did notice about only using the 399 and LTH142 is the lower mid range is a little more intimate and romantic sounding. So you have some tradeoffs to consider. I could take either if I had to, but like the tweeter added a little better. The sound once you get everything balanced is good, very good. A drum sounds good and a guitar sounds like a guitar, well as close as a reproduced sound can I think. It will never sound like live. The voices are clear and the sound is balanced from top to bottom.
Here are some pictures of the cabinets and what I am running them with. This is in my clapped out room. I am getting ready to move everything to a little bigger room and am going to build a new stand for all the components. I wanted to hear the speakers before veneering them and besides I can?t afford the veneer right now. That will come later. It took me two weeks to build the cabinets. Most of the time it took was gluing the wood, as I didn?t have enough clamps and straps to do more than one panel at a time.
Kenny
Originally Posted by Alien_Shore
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