The Cornscala Project (or how I became a Klipschomaniac)

[hklinker]

Un Disastro! Took a mulligan.

Not really but still frustating. The top of one of the cabinets had some brush streaks so I decided to take a rag with some denatured alcohol and knock them down. Misstep#4 or 5 I've lost track? Made a mess of the top, all blotchy!

Decided to strip the shellac off and start again, this time using the rag method. This gave a much more uniform finish but still not what I was looking for so I got a can of spray shellac and applied a lightcoat. Now it looks much better but a late downpour kept it too tacky to work on before darkness. Oh well, always tomorrow.

[Tom Mobley]

if shellac gets too old it will do the "always tacky" thing. Real shellac purists buy solid sticks of shellac and make up their own liquid with PGA as they need it. PGA = pure grain alcohol, Everclear works in a pinch but a little spendy.

There's no end of this stuff, did anybody mention that to you?

[hklinker]

if shellac gets too old it will do the "always tacky" thing. Real shellac purists buy solid sticks of shellac and make up their own liquid with PGA as they need it. PGA = pure grain alcohol, Everclear works in a pinch but a little spendy.

There's no end of this stuff, did anybody mention that to you?

I am beginning to learn that;-)

I made my own beeswax from a block of wax and turpentine. I think you are probably right about the shellac, it came from Lowes and the can was dented so who knows how long it was on the shelf?

I will look for some shellac online, do you have a source?

[Tom Mobley]

Look at Lowes or HD, see if there's a date code on the cans somewhere. Look for one that's no more than 6 months old, newer is better. I've never bought this stuff online because of shipping charges.

Is there a Woodworkers Supply near you?

[Groomlakearea51]

hklinker: Check your PM's; I lost your telephone number; need to check something re: the grills.

[hklinker]

A trip to the "Mancave".

You know that you have become obsessed when you drive two and a half hours to see speakers! Go to Yeehaw Junction, hang a left and go about 40 miles!

Groomlakearea51 invited me down to see his collection and workshop. I believe he has more cubic feet of Klipsch per square foot than anyone in the world. The living room has the Wall of Corn, three pair of modified CW's surrounding his flat panel. Talk about surround sound! K-horns and Heresy's (or should that be Heresies?) in the bedrooms. But the highlight of my trip to Klipschmecca came upon entering the "mancave"; a converted Florida Room that featured four pairs of speakers, each connect to it's own Sansui integrated amp. On the opposite wall was the control center which was more complex than the instrument panel of the space shuttle!

The next two hours were spent listening to a variety of tunes, an eclectic mix of old and newer rock and pop. With each song, Groom would jump up like the mad Dr, Frankenstein (that's Fronk-en-steen) and completely change the timber, tenor and soundstage simply by adjusting the gain on one or more of the amps. It was most impressive!

Thanks to Groom, my grills will be professionally rebuilt, and I pickup up a pair of original K-77's. Horns will be arriving on Friday from GotHover!

[hklinker]

The Fastrac Horns arrived Friday afternoon, along with the JWC designed/GotHover built X-overs. Now all the components have been assembled: Woofers that I got with the cabinets, K-55's, Fastrac squawkers and X-overs from GotHover, Eminence tweeters with horns crafted by kg4guy, grill cloth and wire from BEC, and a pair of K-77's from Groomlakearea51, who is re-doing the grill covers for me.

I'm thinking of changing the name of this thread to "The Forum Project". So many new friends, just from building a pair of speakers!

First task, route the new opening for the Fastracs. Piece of cake with the template supplied by GotHover. After sanding the new opening I took a sponge dipped in shellac and sealed the fresh cut. Then I cleaned up the motorboard by removing all the old Velcro tabs and staples. The hardest part was getting all the old adhesive off with mineral spirits.

After a light sanding with 220 paper and a wipe down, the edges were taped. Some like to paint the entire inside, including edges. I left the sides stained. At Groomlakearea51's recommendation I rolled on a latex, black, semi-gloss exterior trim paint made by Ace. It is their best paint and it showed why. Went on like velvet, and I was able to work the roller to get a very consistent finish. The best part was that it dried in about a half hour and by mid-afternoon I was able to move the cabinets into the house for the final assembly.

The moment of truth is at hand!

[hklinker]

The moment of truth. Wired all the speakers to the crossovers and put on the backs. Put on some tunes and sat back to take this project on it's maiden voyage. Sounded very smooth but there was something not quite right. My five-year old grandson diagnosed the problem (yes I'm grooming him to be a junior obnoxious audiophile). He walked over the the MX-110 and thought he was going to be cute and flipped the "phase" switch. At that moment a mono recording was playing and suddenly the sound moved to the middle. AHA, the speakers were out of phase!

I bought red/black wire from BEC, The crossovers were marked with red and black, as were the binding posts on the back panels. Yet somehow I managed to get something reversed?? I still have some work to do on the cabinets. The bass is full but still a tad loose, but the backs are not sealed so that should help tighten them up a little. While I'm in there I will go through all the connections, just to make sure.

So... how do they sound?

I'd like to say they sound perfect, but then I wouldn't be an audioholic would I? First, the Fastrac Horns sound phenomenal. So much more mellow than the K-400's I am comparing the Cornscala's to a much smaller pair of JBL L-65 Jubals. The JBL's have a five inch cone mid-range so they are no match for the K-55/Fastrac squawker combo. The obvious difference is in the vocals, more subtle is the clarity of the mid-octaves instrumentation. Guitar, piano, and cello countermelodies come out from behind the singer and now command attention. All of a sudden a wood block is heard. It was always there before, but now you hear the resonence of the wood being struck. It's a joy to hear the interweaving horn and sax countermelodies on Nelson Riddle's arrangements of Frank Sinatra's classic Swingin Series... far and away the most remarkable improvement in audio!

How bout the low end? Well, you would expect to hear a much fuller bass floor, after all a fifteen-inch woofer moves fifty-six percent more air than a twelve-inch woofer. The bass was room shaking and the woofers went low, actually better than I expected. The JBL 126A woofer is no slacker, and goes as deep as the K-33, just not as pronounced. As I mentioned, the box is still an air sieve, so I have to get it sealed up before making a final evaluation. At least now I don't have to stick a sock in the port to tone down the boominess of the JBL.

The only area that I think there is no improvement is in the high end. The JBL's use the famous 2405 tweeter (the one with the prism) and they are definitely a step up from the APT-50 driver. I am still getting used to less brightness, and as the new drivers break in I expect some improvement. I also have the original K-77s to try if I want a different sound. I still need to spend more time before a make a final judgement.

Still, this is a significant improvement and I am very happy with the outcome.

more to follow...

[bliss53]

Welcome to the party. This is a great sound for not a lot of money. I have another pair to build for a friend.

[hklinker]

Welcome to the party. This is a great sound for not a lot of money. I have another pair to build for a friend.

You got that right, Bliss. What a blast! I have a question for you. I will send you a PM later.

Herb

[bliss53]

You were asking about finishing products. I just saw an article that reminded me that my Dad used to use Briwax. I know it is a little late for this project but here it is.

http://www.woodworkersjournal.com/Ezine/Public/IndustryInterview.aspx

[hklinker]

I live in the antiques capital of Florida and many shops stock either Briwax aor Antiquewax. I made some from beeswax and turpentine which worked great, as long as you could handle the strong scent of turpentine. Took some 600 grit wet/dry and lemon oil to the cabinets. Rubbed until the oil began to emulsify. Now they are smooth as a babies bottom.

Woodworkers Journal is a great resource, Thanks!

Herb

p.s. Great talking with you today. I am going to take your advice and flip the polarity back on the squawkers. HK

[hklinker]

Even a Stradavarius needs to be tuned!

Well here I am, thinking this was a matter of connecting wires, closing the box and connecting my creation to the system and sitting back in audiophonic heaven. Hold on right there bucko, not so fast!

Taking the advice of Bliss and GotHover I reversed the polarity of the squawkers so that while they were in phase with each other they were now out of phase with the woofers and tweeters. This made them less pronounced as they had some cancellation in the common frequency. The horn adaptor had to be cut down to allow the K-55 to fit against the backboard. After receiving the new adaptors from GotHover in just TWO days from CA I was ready to seal up the boxes. I went to Lowes and got some rubber weatherstripping (the smallest they had) and put it around the backs. It was amazing how much the gaskets tightened up the bottom. The boominess was gone and they were now tuned to go down to 38Hz.

While the bottom and middle were coming into tune, the high end still lacked something. The lack of what I call the sizzle of the cymbal was most noticable. I read Bliss post on his project and he tried both the CT-125's and the K-77's and went with the K-77's. So I decided to put in the K-77's just to see what happened.

(to be continued...)

[hklinker]

Even a Stradavarius needs to be tuned! cont.

I am not an electronics expert (nor did I stay at a Holiday Inn Express last night) but I know what I hear, and something just wasn't there in the 125 drivers. It was like the woofer and squawker were at full volume and the tweeter was set at abou 9:00 O'Clock. You could hear the speaker but it did not add enough presence to the top end.

I brainstormed with GotHover and decided to move the tweeter to post #5 on the autoformer (pictured above). We thought this would overcompensate by adding 3 dB, but it made only a slight difference in tweeter output. I really like the sound of the 125 but the K-77 just sounded better, although it was almost too bright and if the recording had a lot of percussion it would grate on the ears. I even tried connecting the 125 directly without the crossover. It was now very loud so something in the X-over is interacting with the 125 to create too much resistance.

As I said, I'm no expert and I am not going to try to reinvent the wheel so my next step will be to reinstall the K-77's and put an attenuator so that I can adjust the output downward with a knob. I went to Radio Shack and bought two mono speaker volume controls for $19.99 each. I will install them in the cabinets between the crossover and the K-77. They are rated for 25W RMS, so putting them after the X-over should not overload them.

After installing the attenuator on the K-77 I was able to bring down the gain in 3 dB steps. This allowed me to "tune" the K-77 to the squawker and took off some of the brightness that I mentioned earlier.

Now we're getting close... Then I had another idea!

[Marvel]

I certainly won't argue with someone who wants to use the K-77 over the CT-125, but I don't see why you would do that. The reponse of the CT-125 is far superior to the K-77, and sounds a LOT smoother. Which is probably why some don't like them. You don't really think they are adding to the high end. I couldn't go back...

meaning there is a pair of K-77s available for sale. No idea of the price, but I don't need them at all. I have two pair of the APT-50 drivers, one pair on the CT-125s and another with some APT-150s (excellent btw).

Bruce

[hklinker]

I decided to put the K-77's back in with the attenuators to bring them down a bit. Before doing that I took out the X-overs just to see if I could get more out of the 125's. Using alligator clips, I set the two tweeters side-by-side and began moving the connection further and further back from the tweeter post, alternating between them at each setting.

At every setting the 125 was smoother and seemed to be nearly as loud, yet when they went in the cabinet the K-77 just was more open and realistic. Electronically, I cannot explain it. The only other thing that I have considered is attenuating the squawker by 3-6 dB and seeing if that creates more opportunity for the 125 to shine.

Finally, I have to consider that I am losing my high end sensitivity and maybe a "brighter" driver is how I compensate???

[bliss53]

You are finding some of the same situations I ran across. My ct125 balance was attained with the tweeter and tap adjustment in alk's apt12-500/es5800 crossover. I found the K77 sounded better with the alk designed cornwall crossover. Trust your ears because the use of your equipment, in your room limits the usefulness of our advice.

[Invidiosulus]

To my ears the harshness of the the K-77 always made it sound somewhat louder than the CT-125's.

Once I installed the Ct-125's and realised I could listen to ACDC's back in black/you shook me all night long 45rpm single at 110+dB without it feeling like a trip to the dentist I was a very happy camper.

I really think the CT125 is superior.

However if it sounds good to you it is good.

[hklinker]

To my ears the harshness of the the K-77 always made it sound somewhat louder than the CT-125's.

Once I installed the Ct-125's and realised I could listen to ACDC's back in black/you shook me all night long 45rpm single at 110+dB without it feeling like a trip to the dentist I was a very happy camper.

I really think the CT125 is superior.

However if it sounds good to you it is good.

The jury is still out for me, although the K-77's attenuated by 6 dB have less harshness but more "sizzle" than the 125's. Maybe thirty years of listening to JBL 2405's has made me think that the tweeter must be bright. I actually hooked up the JBL, and it was a cross between the two, smooth like the 125 but louder like the K-77.

I agree that when you crank it up, the 125's they are much easier on the eardrums!

Herb

[fini]

Our cabinet maker/carpenter at the school where I work uses a beeswax finish on some of his projects. I'll ask him on Monday. It may be Skidmore's, but I don't remember for sure off the top of my head...

Bruce

Bruce, maybe you're thinking of Butch Wax... []