Another Cornscala is born

[dls123]

Hi all,

Just thought I would post a couple of shots of my new CornScalas. Just completed them, they started life as a consecutively numbered pair of 1975 Cornwalls in pretty nice shape. Interiors were spotless. Klipsch certainly builds speakers that hold up! I used the gothover horns and a modified version of the ALK universal XO that gothover recommended as his favorite in this speaker. I built the XO's with Solens air core coils on the squawker and tweeters and an Erse coil on the woofer, Dayton 1% caps and a Jantzen 33 uF on the woofer. Cabinets were lined with B-quiet that I had laying around leftover from a car project. I also put some B-quiet on the woofer frames. Used a pair of the Crites tweeters as well. The result....well, the caps have about 5 hours on them and the speakers are really opening up. While I liked the original Cornwalls, these are so much better in every way that it is not the same speaker. Everything you have read about the CornScalas is true in my opinion. Stunningly good speakers! And the crossover caps aren't even broken in yet. Sound wonderful with my Citation V and Citation I. I will have to try them with the Citation II later this week. I have never heard a pair of speakers this good. Warm, rich, yet fully detailed. Bass is far better than the original. Don't know how much of that is the cabinet tweaks, or the improved XO......but it is great!

Hope the photo comes through!

cheers,

Don

[Pete H]

You can't go wrong with a Cornscala, I love mine too. I did a split version with one of Dave's larger horn and the difference in the mids is incredible. Nice job and welcome to the forum. What part of the country are you in?

[dls123]

Hi Pete,

I am in Nelson, BC, Canada. Have been lurking here for a while gathering info. Was thinking about doing a pair from scratch, but then a pair of pretty minty walnut 75 Cornwalls showed up about 3 hours away for $600. So I decided to do this project instead. Pretty stunning improvement across the board. The original XO had CDE poly caps from a previoius owner and upgraded binding posts. Original other than that. While I enjoyed listening to them, this is an entirely different speaker. It goes much lower with more authority and clarity and yes, the difference in the mids is startling; a whole different animal. The tweeters are pretty good too, and since they have the most caps in the XO they need another 10 or 20 hours to fully show their colors. I was thinking about mounting them flush on the front, but I quit here for now and will live with them a bit. I just wanted to quiet and listen to them! Dispersion seems more than adequate.

Yeah, a split version with a larger bass bin would be fun. Or I was thinking about making a cabinet about the same size as the original with no parallel surfaces, and just large enough for the Beyma tweeter. Also possible time alignment. But these are incredibly good speakers and I am not sure how much difference all that would make for the effort. At some point the sound is so good it is time to work on something else. Maybe in a year or two when I need another project!

cheers,

Don

[Pete H]

I use the Beyma's and really like them, but the difference between them and the original K 79 isn't earth shattering, meaning that when I listen to the original Cornwall 2's, it's not like they sound bad, but they will be getting a conversion to a Cornwall also and I will be using the same type of mid horn that you are using to keep everything in the original cabinet. Currently I'm using Bob's cast woofers and Atlas mid drivers in my split Cornscala and picked up some 15" Kappalite's that I will be testing in a DBB build based on Rudy's build and impressions of those woofers. It's a fun and enjoyable hobby.

[Guest David H]

"Another Cornscala is born"

Don, your Cornscala turned out very nice, I am pleased you like the results.

Dave.

[REN]

do you have a diagram for that xover i am interested in trying it with my cornscalas

[dls123]

Hi,

Dave has the schematic posted on his site:

http://mysite.verizon.net/res12il11/id92.html

I used the bigger one on the bottom left - a modified ALK universal with the 33 uF cap off the woofer to the mid and tweeter and the 1.5 mH inductor on the woofer. The picture on the top left is of Dave's layout. Mine was pretty similar. I used Solens air core coils (Litz wire) on the tweeter and midrange. This is what Al recommended in the original. Dave used copper foil here. Both are probably good. If you email me I can send you a photo of the crossover. Dave would be happy to send you the layout I am sure.

cheers,

Don

[hklinker]

Don,

Very nice. I have an almost identical pair that I finished a couple of months ago and love them! About the only difference is that I used Sonicaps and foil inductors on the squawker and tweeter in the crossovers.

You will hear things that you never heard before in the music!

Enjoy them.

Herb

[dls123]

Hi Herb,

Thanks. Yes, I think the advantage to making this mod is that it still looks exactly like a Cornwall with the grills on. I hope to sneak them out of the basement and into the living room to replace my Josephs which are taller and thinner. I might be able to ease the transition if I keep the grills on for a while, you know the drill about sneaking rather large speakers into living rooms and spousal approval. I know they sound better with the grills off, never heard a speaker that didn't. I think any good cap will make a great speaker with this design. There are so many to choose from. I have used the Daytons before in several projects and they are really cost effective for a 1% matching cap. I am sure you could fool around with a dozen different caps and change the sound slightly, same with inductors. Dave said he has never heard a bad sounding pair with any of the crossovers, but that the ALK universal modded for 600/6000 was his favorite. He has built and modded quite a few so I went with his recommendation. They sure are nice, and it is a lovely crossover. I did all the mods at once (horns, cabinet tweaks, removal of bug screens on K55, new XO) so I cannot comment on what mod improved what aspect of the speaker, but it is so much better than the stock Cornwall that it isn't even close. Better at all frequencies, better clarity. They match my Josephs upstairs for clarity (driven by my fully modded Citation II), but the Josephs (and I do love them) just don't have that Cornwall slam. Once you get used to hearing it then you just don't want to give up that dynamic range. The bass on these is different than the Josephs, but very musical. Really, while I expected them to be better than the originals I had no idea they would be this good! I guess all those of you who built them know. I cannot say that I have ever read a bad review of a Cornscala! Now I know why!

cheers,

Don

[REN]

i was wanting it to be crossed at 400/4500

[Guest David H]

i was wanting it to be crossed at 400/4500

Ren, I believe ALK has that crossover schematic, I dont reccomend the 4500 for use with Tractrx horns, only if you want to use the K-400 lens, and you will also have to use Bob Crties CT-125 tweeter or another that will run down to 4k or better.

I also prefer the 600hz for the lf, because most mid driver do not perform well at 400hz and the K-33 or Crites CW1526 both play well above 600hz.

If you feel you need to run to 400 but are ok with 6000hz, I reccomend the ALK universal with tweeter attenuator. Al sells a universal kit at a reasonalbe $300 and I think $90 for the attenuators. He may even get you the 4500hz mods.

Dave

[hklinker]

When I built my crossovers, I originally wanted to cross them over at 4500 Hz, but Dave talked me out of that and I'm glad he did.

The beauty of the Fastrac horn is it's ability to make vocals (especially female) and horns sound so natural and realistic. Reducing the squawker down from 5800Hz to 4500Hz detracts from it's very strength. Just because the Crites driver (APT-150) will go down that low doesn't mean it will do a better job than the K-55 matched with the wooden horn. The great JBL tweeters are crossed at 8K to 10K so that tells you something.

Tonal quality is different than frequency ability ...that's what living in the midrange is all about!

Herb

[MechMan]

Don, Welcome to the Cornscala club.

I too have just recently finished my Cornies and they do indeed sound fantastic. I seriously doubt you could buy a speaker that does what the modded Cornwall does for the price of the upgrades.

Bob, Dave and Greg all have a direct hand in mine...and many others here have givin their thumbs up along the way. Cant go wrong!

Enjoy your music collection all over again...I know I am.

[handrewmoore]

Guys, I just got some 79br cornwalls with the intent of modding. I'm wanting Gothover's fastracs, Crites' cast woofers, and it has the ct125s already. I've been looking at crossovers and this is where I need help making a decision. The crossovers I'm looking at are Crites' cornscala crossover and Al's AP12-600 + ES5800. Does anyone here have any experience with these crossovers and the fastrac? Would the ES600 + ES5800 that AL offers yield a better result? With the drivers I've mentioned above, which crossovers are going to perform the best?

I'm not an engineer by any means and a lot of what I'm reading is over my head, but AL's site is full of easy to understand writing. His descriptions of extreme slope crossovers make a lot of sense, I just don't know how it plays out with cornwalls. I understand the XO frequencies of the ES XOs, how do the other crossover's frequencies interact? I'm just not informed enough to make a decisioin. Hope you guys can help me out.

I know I'm asking quite a bit here, thanks for the help.

[handrewmoore]

It seems to me that the extreme slope XOs would protect the drivers in the long run as they would be operating within a smaller range. But, then again, what the hell do I really know...haha.

[dls123]

Hi Rick,

Thanks. I just brought my fully "McShaned" Citation II downstairs to try with them. Even better. You are right, the midrange is pretty amazing. With the II, the clarity is astounding. Yet it is never harsh or ringing at all. With the stock cornwall there was just the slight honk in the horn at certain times. Also, with the new XO and the CT125 tweeters the highs are far more extended. I was considering mounting the tweeters on the front of the board, but it seems they are fine where they are. Astoundingly good speakers for the $1400 I have into them. Plus I love a good stereo project. I have rebuilt about 40 amps and preamps (all tube) in the past few years. I always end up listening to the Citation II though....you just get hooked on that clarity. I have to say that a Citation II through a pair of CornScalas is pretty darn good! Dave's comment about crossovers was that he never really ever heard a bad CornScala regardless of crossover choice as long as the parts used were good. So I just built his favorite design, but my guess is that yours is every bit as good as mine and probably not all that different sounding. The bass takes a little getting used to. Prominent, and not the tightest, but very, very musical. A string bass sounds like a string bass. Mine still only have maybe 10 - 12 hours on them so the caps are still changing. It is mainly the highs that are changing and becoming more extended with time. The tweeters are the only new drivers so they are probably breaking in a bit along with the caps. If these things get much better it will be spooky! Plus they look cool. Dave's horn looks like it came from the factory. At some point the sound is so good it isn't worth splitting hairs trying to get better....

cheers,

Don

[handrewmoore]

Don,

Your posts are getting me jazzed up to cut into my "new" Cornwalls. How difficult was your crossover build? I've never done it, but think it's within my capabilities.

[hklinker]

If you can solder and have a little patience it's a piece of cake. The hardest component to obtain is the autoformers.

Dave's horn comes with a template to mount on the inside of the motorboard and it's a five minute job to route out the opening.

Go for it!

Herb

[handrewmoore]

Well, I think Crites' cornscala crossover is set at 500 and 5000. I think that would be the easiest route for the crossovers. From what I've read, the CT-125 easily goes down to 4500 and the fastrac should be able to handle 500 well with the k55. The consensus seems to be between 500-600, I wonder if Bob can set the crossover at 600 and 5000, if that would be better?

I think I'm going to put out a bulletin for anyone in Arkansas to help route the opening for the fastrac. I have access to a router, but have no experience using it.

hkliner, your build is what initially got me motivated to do this. Any advice you can give from your experience is appreciated.

So I've got the K55 and CT-125 in my 79 cornwalls.

Next to get is Crites' cast woofer and cornscala XO. Then match these with Dave's fastrac.

Am I missing something, or anything I need to amend in my plans?

[hklinker]

I tried both 400 and 600 for the lower crossover and liked the 600 better. It just seemed a little boomier at 400 because the woofer doesn't change, it's controlled by the inductor. So dropping the squawker down to 400 gave me a "hump" in the 500Hz range. I don't have the analyzer to confirm this but I just liked it better at 600.

As for the higher crossover, I go back to what I posted earlier and reiterate the strength of the Fastrac is it's ability to reproduce the warm, natural vocals and horns. Dave's testing shows the K-55/Fastrac strong up to 6kHz. It's not that the Crites won't go down there, it's just a matter of which driver you want to produce that range of music, and for me there is no comparison between a K-55 and the APT-150.

I have a pair of JBL L-65 Jubals with the 2405 tweeter, which is highly sought after by the Japanese, often selling for $300 per driver! They cross the tweeter at 6500 and it's presence is mainly to provide the harmonics and percussion. If I disconnect the midrange driver I can barely tell they are playing.

In a stock Cornwall I would go with 4500, but with the Fastrac for me it's 5800! I am very satisfied with the Sonicaps, which you can purchase from Bob. I have the tweeter attenuator on the board but I don't use it in this configuration. ALK was critical of it and I tend to agree with his contention that it would affect the overall impedence. Al prefers Litz air core inductors over the foil but I am very impressed with the foil. I think that the real difference is in using the right capacitor.

I hadn't used a router in years, but the template Dave provides makes it easy. The key is to go slow and use a sharp flush bit. I used a cheap, 1-1/2HP Ryobi router and it worked great. Try practicing on some scrap pieces of wood to get the feel of the router. Once you do it you will wonder what you were afraid of, go for it! The screw holes you use to mount the template are exactly the same as mounting the horn. It truly is a piece of cake!

That's my two cents worth! If you want to talk, send me a PM and I'll give you my number.

Herb

Herb Klinker