My new GPA drivers and cabinets

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

They look really nice. Good project and a lot of hard work went into these. It seems to me that the 399 and 902 overlap a little on the high end. Curious on the value of having both?

Thank you. The tweeters just balance the high end out a little more than just the 399's. If I had an equalizer I think I could match the 902's output with just the 399's. The 902's add a little more output up top. Both drivers probably go up high to the same frequency, don't know for sure just guessing.

Kenny

i wonder if you have to shelve the horns down due to the efficientcy of the horns? looks great, now its time to start playing with that active crossover. do you have specs on that mid horn? i know that woofer will play clean out to a 1000 cps

Nice job Kenny - and thanks for sharing your project with us. I liked your story about the GPA tour - that would be cool to do - I bet they have some stories they can tell! Are you crossing the 902s at 500 Hz?

valhallax, I had them crossed over at 750hz for a while but liked 500hz better. I didn't go up to 1000hz or 1200hz. I also tried the tweeter at a lower crossover but liked 7000hz better. And I tried without the tweeter and I could live without the tweeter just fine, I just like the sparkle the tweeter gives the system, not really a sparkle per say but the highs are higher in volume. The highs are duller without the tweeter. The 902 they say will go to 20khz and the 399 to 15khz. I never liked the 902 crossed over at 500hz on 511b horns but liked the JBL LE175 crossed over at 500 hz on the 511b horn. But the LE175 needed a tweeter. The Faital LTH142 they say will go to 18khz and go down to 400hz. I will play around some more and see what I get and like. I can hear to 13khz but not above that. That maybe why I like the tweeter as my hearing is not what it used to be. But I can clearly hear the difference without the tweeter. Maybe if I cross the 399's over at 1000hz or 1200hz I could eliminate the tweeter. I will try it.

Here's some sites to look at on the Faital LTH142.

Cornscala Style D | Critesspeakers.com

FaitalPRO - Professional Loudspeakers Made in Italy

Beyma - Faital Pro Speakers, Faital Pro Speaker Parts, Faital Pro bass speakers, Faital Pro speaker upgrades. Faital Pro woofers, crossovers, horns, drivers, etc. Faital Pro has some of the finest speaker parts. ARRAY HORN

http://www.lautsprechershop.de/pdf/f...tal_lth142.pdf

Thanks Allen, I am crossing the 416 to 399 at 500hz and the 399 to 902 at 7000 hz.

Kenny

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Originally Posted by valhallax

i wonder if you have to shelve the horns down due to the efficientcy of the horns? looks great, now its time to start playing with that active crossover. do you have specs on that mid horn? i know that woofer will play clean out to a 1000 cps

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Here is a few sites on the Faital LTH142s

I tried 750hz and liked 500hz better. I tried below 7000hz and liked 7000hz better. I also tried the system without the tweeter and liked the tweeter added better. I didn't try 1000hz or 1200hz. Will try it and disconnect the tweeter and see if I like it that way. They say the 399s go to 15khz and the 902s to 20khz.

FaitalPRO - Professional Loudspeakers Made in Italy

Beyma - Faital Pro Speakers, Faital Pro Speaker Parts, Faital Pro bass speakers, Faital Pro speaker upgrades. Faital Pro woofers, crossovers, horns, drivers, etc. Faital Pro has some of the finest speaker parts. ARRAY HORN

Cornscala Style D | Critesspeakers.com

Kenny

http://www.hostboard.com/forums/atta...ts-gpa-002.jpg

Thanks for the pic Kenny ( gives me a really good idea how the Faital 142 would look over my ( SR employed ) 15 inchers .

:)

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Originally Posted by Kenny Brant

Thanks Allen, I am crossing the 416 to 399 at 500hz and the 399 to 902 at 7000 hz.

Kenny

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i've read of folks who used the 802 (small format altecs) instead of JBL 075s in what is called a "z-array" configuration...
a'la Richard Long (a noted early nightclub installater/icon)...

it was supposedly very, very sweet sounding.... (as I imagine you are hearing for yourself)

but I think you are right, they probably don't hit 20KHz with any authority....

Earl K, the LTH142s are really good horns. Reply to just me now post, I can't hear over 13khz anyway but adding the 902 did make a difference and I like the addition of them.

The picture stretched the image, the speakers are a little wider than they appear to be in the picture.

Kenny

I brought the low crossover from the 416-8c to the 399 up from 500hz to 750hz to see how I like it. It seemed to have a distortion in voices that seems to be eliminated by going to 750hz.

I will listen more and see. Will play with the 399 to 902 crossover and see what it is like. Also will take the 902 off and see if I like the 416-8c and 399 only. Time will tell.

Kenny

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Originally Posted by Alien_Shore

Nice job Kenny - and thanks for sharing your project with us. I liked your story about the GPA tour - that would be cool to do - I bet they have some stories they can tell! Are you crossing the 902s at 500 Hz?

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Yes nice job Kenny, Thank You for sharing this build with us.

GPA will give anyone a tour of their facilities if you go there in person and ask.Very Cool ! And they are gentleman as Kenny pointed out...