Should I build University Classic or La Scalas?

[D-MAN]

I follow you now. Interesting. Let me chew on this for a bit.

At first glance, I like it.

DM

[ajsons]

At first glance, I like it.

DM

(Whew! I was worried that you won't!)

Maybe one of my ideas will get me a patent, too.

Hey what's the word on yours?

[D-MAN]

More waiting. You get used to it.

DM

[ajsons]

I'm glad you clarified the single path with a divider issue. I can use all those info.

[Quisitive]

I personally would only change the reflectors to optimize the response for upper bass bandpass in the Classic. Other than the throat reflector in the Dean, there is little or no enhancement needed.

DM

Dana,

I 'm still woking on the cad drawings for the Classic with the added reflectors, just like we talked about. I think I'll start a new thread on driver specs, construction details, and mods. I'll post the cad drawings for the reflector mods there.

Armando

D-Man -

Thanks for the input regarding the throat reflector of the Dean. I had been wondering if a similar implementation on the rectangular Classic would be of value, but I'm far out of my depth on the theory of bass horns.

ajsons -

If you want to start a Classic builder's thread I would be an active participant and contribute what little knowledge I have to the common good. I am a fairly decent amateur cabinet maker. Perhaps that would help.

I am also interested in WAF, but more for myself. That extends to wondering how you might be able to construct 30"x40" speaker grilles that can handle being repetitively installed and removed, yet still be fairly acoustically transparent. I don't think the orginal designs would work. they look awfully bulky and have those cross-basrs, but they may not have that much influence on large bass horns and stand-alone mid- and high- horns that are suspended in the bass mouth. Again, an area I have no experience in.

Another thought is the "shelf" created by one side of the doghouse at the bottom when the Classic is in the vertical position. Strictly for appearance sake, what would happen acoustically if it were enclosed?

The last thought I had was if the Classics were going to be redrawn, are they currently optimized. I may have missed something, but D-Man's comments lead me to believe he thinks they're fine the way they are. Also, as Q-Man suggested, you can start with the drivers originally specified and then go from there.

I suspect my 50'ish ears will probably be happy with the originals.

Chris

[ajsons]

I've been looking for info on the Gately Super horn. TNX for the post. I've never heard of the Rice's.

Do you have anything on the Drisko horn?

[ajsons]

Chris (Quistive),

We're still with you. It might have appeared that we were going in unfamiliar territories, but we're still with you.

Classic or La Scala?

Or maybe both in a single enclosure..

[Quisitive]

Chris (Quistive),

We're still with you. It might have appeared that we were going in unfamiliar territories, but we're still with you.

Classic or La Scala?

Or maybe both in a single enclosure..

Oh, not a problem at all. I'm soaking up as much of this stuff as I can.

Our posts most have passed each other. I definitely like the direction the conversation is heading, especially with your innovative design.

If there was a way to shrink the depth, even at the cost of a little height, I would be all over it due to my dimensional constraints. I'd still like to use my set of University drivers, but if push came to shove I could always eBay them and get what's best.

You guys are really something else, you know it?

Chris

[ajsons]

"If you want to start a Classic builder's thread I would be an active participant and contribute what little knowledge I have to the common good. I am a fairly decent amateur cabinet maker. Perhaps that would help."

What I really need is a fairly decent cabinet maker I can team up with to build folded horns! I wish I live in Texas, right now. Or maybe in Washington state. BTW, my beautiful sister-in-law lives in Whidbey.

"I am also interested in WAF, but more for myself. That extends to wondering how you might be able to construct 30"x40" speaker grilles that can handle being repetitively installed and removed, yet still be fairly acoustically transparent. I don't think the orginal designs would work. they look awfully bulky and have those cross-basrs, but they may not have that much influence on large bass horns and stand-alone mid- and high- horns that are suspended in the bass mouth. Again, an area I have no experience in."

The Classic's speaker grille construction really impresses me, it is well-made, very good joinery and can handle repetitive on-offs . Joinery on all exterior pieces is pretty good. It is in the inside pieces where craftsmanship is sloppy. I had to take off the grill this weekend and drew it in AutoCAD. The grille cloth looks acoustically fine, but man, I hate that color. Did the drawing of the base, too, but that was the wimpiest part of the enclosure. I took that off and when the weather gets better, I'll use 2 x 4's . Right now, my Classic has no base.

"Another thought is the "shelf" created by one side of the doghouse at the bottom when the Classic is in the vertical position. Strictly for appearance sake, what would happen acoustically if it were enclosed?"

I'm not sure which area you're referring to, but if it is the bottom unused section around the throat pieces, that's the one I was referring to that needs to be enclosed and sealed with an additional piece in front, holes made through the motorboard to make it a part of the rear chamber to gain cubic inches a necessity to my EV driver, or any driver that needs it.

"The last thought I had was if the Classics were going to be redrawn, are they currently optimized. I may have missed something, but D-Man's comments lead me to believe he thinks they're fine the way they are. Also, as Q-Man suggested, you can start with the drivers originally specified and then go from there."

I am sticking to the original dimensions of the Classic with the exception of the reflectors angle at the throat, first bend and the large one.

The last change I made at the throat Dana said is fine. At the first bend I saw it as 42+degrees, he saw it at 47+, but we're using opposite references. It is the same thing. It equals 90 degrees. The large reflector has to be adjusted by a couple of degrees. These were discussed through emails and were not posted.

"I suspect my 50'ish ears will probably be happy with the originals."

Most likely you will. Out of the three changes though, I think the reflector at the first bend is a necessity. And if you don't want it you can take it off. The reflector in my Classic is screwed with no glue.

I like the C15W. I was lucky to have EV spares to compare woofers performance. If I were you, I'll use the components that you have now, then try different drivers as you get familiarized with the sound. I have 5 pairs of midrange drivers, but prefer the EV 1824M.

BTW, I don't have an HF-206, and have no intention of getting one, unless the price is right. (Yes, I'm el-cheapo). I need to draw it in AutoCAD. Can you take dimensions for me, if you don't mind? I'll send you some pictures via e-mail, and you can write down the dimensions on them, or whatever works.

Armando

[Marvel]

Dana,

John Albright emailed me about his Peavey FH-1 horns. He said those

actually get up close to 1Khz. Still lack in the bass like the LS do

though. The design is simpler as the doghouse is a simple three sided

affair compared to the LS doghouse.

Bruce

[D-MAN]

Armando, I like the University Belle design!

It sure increases the complexity, doesn't it?

I imagine that you will pick up a couple of inches of length that the Classic doesn't have. However much area you pick up means you can make the mouth that much smaller and still retain the performance that you currently have. There is a suprizing amount of leeway on mouth size, but I'll save that for later!

The issue is expansion rate; should be approx 18" doubling point for 50 Hz. The cross-sectional areas need to be checked along the "new" pathway for this rate. Some variation is allowed.

Note that the stock Belle/LS has a 60Hz throat expansion rate. I would go with a 50Hz one for your purposes.

For a quikie lesson on horn design, download and read all of Edgar's "Show Horn" which is another 50Hz bass horn and Dinsdales "Horn Loudspeaker Design" articles (3) from

http://www.volvotreter.de/dl-section.htm

DM

[ajsons]

It sure produces some compound cuts, the good news is they will not be large pieces, and will be easy to make on a table saw. And they're just repetitive cuts.

As far as the expansion, I thought of dissecting the Classic's expansion and copy it, say every 6 inches. It is not that long. So it stays a Classic with a different doghouse. But I'll try both ways.

I'm glad you like that design. I'll post more tonight.

[D-MAN]

Here's the specs as I figure them on the University Classic horn:

It's a 1/4 wavelength in pathway length (good) as I figured 66 inches center-of-channel (5.5 feet) which is 1/4 of the wavelength of the Fc of 50Hz (22.5 feet).

This corresponds REAL close to the overall length of the Khorn, except the Khorn is a 1/8th sized 40Hz horn and the Classic is a 1/4 sized 50Hz horn. The Khorn therefore has a much smaller mouth comparitively (632 sq. in. -vs- the Classics 1080 sq. in.). For example the Khorn in a corner (1/8th space) is 4 sq. feet x 8 = 32 sq. feet which is the wavelength of 35Hz.

The overall mouth of the Classic is 1080 sq. inches in area (7.5 sq. feet), which is more than the calculated value of 735 sq. in. (or 5 sq. ft) used by Edgar in his 50Hz "Show" horn, but he calculated for 1/8 space (corner use), and the Classic mouth is appropriately sized for 1/4 space which is wall and floor placement, more or less. The Edgar "Show" horn has a longer horn length (71") comparatively. Typically, the longer the horn length, the better the bass, and 1/2 wavelength horns sound better than 1/4 wavelength horns, etc. However, it should be realized that the Khorn is far less than 1/4 of a wavelength long, yet it produces rather awesome bass IMO, so there you go! The only way to really figure these things out is to actually hear the differences oneself.

50Hz exponential expansion rate doubling point is 18". That means that it doubles its cross-section every 18" of pathway length from any point along the horn.

Means you've got some leeway to make "adjustments" to the cabinet if you wish. Do not shorten the horn length any more, although PWK states that if the woofer is properly matched to the horn, it can be as short in length as 1/12 of a wavelength (fc) in the Little B***ard patent, per Thuras.

The 78 sq. in throat (St) is fine and is actually the same as the Khorn, allowing the K33E to be a viable alternative, as would be the Altec 515, JBL 145, etc. I would use a narrower slot for the K33E based on my experience with the K33E in my corner horns, though.

If you lengthen the horn and increase the expansion doubling point to 22 inches, the horn mouth sized as it is, if left alone, could support 40Hz as the overall Fc. I think 45 Hz is completely doable, 40 might take some work, though.

Also note that any changes will make the horn more complicated, of course. That is part of the beauty of the original Classic design - its about as perfectly simple as it gets.

The more I elaborate on this stuff, the more confusing it is going to become, because there are simply no hard-and-fast rules to follow that meet every condition.

DM

[ajsons]

Dana,

I wasn't sure what kind of conclusions to draw from the size versus flare vs mouth size comparisons that you did, but now I think that's what you probably meant, there is no conclusion to draw. There are too many variables, compromises, etc. , so it is now all preference in my opinion.

I believe the Show horn has a 12" driver with a smaller throat size, that's why it is longer. A 15" will terminate with the same mouth size using the 50hz flare rate, 1/8 size, but it will be shorter.

Let me do this. I'll draft one using the Classic's original expansion as a "gobee" (term we use at the office, after go-by, "go by this"), then do another one using a 50hz expansion flare rate. Then we'll compare them , maybe I'll send them to you for redlines. (Why do I feel like I am at work? This is exactly what happens there).

But I enjoy doing it, why not.

[ajsons]

Here's another variation, this time top is now bottom, with a 511B horn, and a C15W woofer in one. (I really should stop playing with this and get busy). Overall height about 49", can be lowered to 47 or 48.

[ajsons]

Q-Man,

Do you have a picture of your Dean in the new configuration, i.e. with legs?

I think that's a clever idea, although now you can't push it in a corner unless you remove the legs.

Also, the Classics built in the 60's have braces (two inside the doghouse, and one rear of the doghouse. It also used glue blocks and glue wedges. 1 x1 strips of wood to support joints. Mine (built in the late 50's) does not have the braces and has too much panel vibrations. Do you notice that in the Dean?

[TRiv]

Question, I would like to build Classic cabinets and transfer 1977 Cornwall components (cabinets are in fair cond. parts like new), all stock except for 511B horn, any problem here? The Khorn using the K33E woofer uses 3"x 13" slit on compression chamber, would this be used in the Classic design (opposed to the 6"x13"). Would also use the Cornwall type B crossover, then upgrade to type AA crossover, thoughts?

Slow down.

The Classic bass horn is only good to around 350Hz. I measured it once, but I don't remember the exact number. That information is with my old notes. I also believe that the University crossover is also at 350Hz. The Cornwall midrange horn won't go that low. I think the Cornwall had a 700 Hz. crossover point. The Corbreflex midrange horn in the Classic is a 250Hz. horn.

Slowng down to a halt here, I am going to go back to other plans of mods to Corns, as of now the cabinets are inverted and raised 11" from ground with k55v/511B on top, and k77 verticle between 511 and k33e, really like they way they sound like this, imaging (height) of voices much more stage, performance straight in front, just dropped a bit in bass due to port/k33e being 36+ inches off floor. Was thinking of adding a single K horn/EV106 bass bin crossed about 200hz with separate amp to augment bass lost and go a bit lower, and/or get second bass bin later and transfer Corn componets/511's to them and type A crossovers.

Since the forum search feature doesn't work as well as before, I can't find many earlier posts, are you the one with K horns and the 311-90 Altecs with tweeter below them? If so was wondering how well you like the false corner set ups you used ( I think that is what I remember), having both K horn cabinets facing forward? I would have to use false walls in my situation, though I had one thought if using just one with the CW's, laying Khorn bin on side (vertical) and use floor and back wall as the corner, in between the CW's. I need to add a drawing here to show this but, with the Khorn bin as above, I would build what essentially would look like a 38" wide desk using appro 28"x28" side panels, and a top and front panel 38" wide x approx. 20" deep that would form a 90 degree peak over the front 38x31 panel of the khorn. The sides would be for function and peak would be for a furniture look, the Khorn bin should function the same just using different orientation. I do wonder if a peak (like LaScala) in the center of the Khorn would have any acoustical benefit, it sure would in aerodynamics, actually a must in that flow direction. The false corners of course would be the next option.

[ajsons]

Question, I would like to build Classic cabinets and transfer 1977 Cornwall components (cabinets are in fair cond. parts like new), all stock except for 511B horn, any problem here? The Khorn using the K33E woofer uses 3"x 13" slit on compression chamber, would this be used in the Classic design (opposed to the 6"x13"). Would also use the Cornwall type B crossover, then upgrade to type AA crossover, thoughts?

Slow down.

The Classic bass horn is only good to around 350Hz. I measured it once, but I don't remember the exact number. That information is with my old notes. I also believe that the University crossover is also at 350Hz. The Cornwall midrange horn won't go that low. I think the Cornwall had a 700 Hz. crossover point. The Corbreflex midrange horn in the Classic is a 250Hz. horn.

Slowng down to a halt here, I am going to go back to other plans of mods to Corns, as of now the cabinets are inverted and raised 11" from ground with k55v/511B on top, and k77 verticle between 511 and k33e, really like they way they sound like this, imaging (height) of voices much more stage, performance straight in front, just dropped a bit in bass due to port/k33e being 36+ inches off floor. Was thinking of adding a single K horn/EV106 bass bin crossed about 200hz with separate amp to augment bass lost and go a bit lower, and/or get second bass bin later and transfer Corn componets/511's to them and type A crossovers.

Since the forum search feature doesn't work as well as before, I can't find many earlier posts, are you the one with K horns and the 311-90 Altecs with tweeter below them? If so was wondering how well you like the false corner set ups you used ( I think that is what I remember), having both K horn cabinets facing forward? I would have to use false walls in my situation, though I had one thought if using just one with the CW's, laying Khorn bin on side (vertical) and use floor and back wall as the corner, in between the CW's. I need to add a drawing here to show this but, with the Khorn bin as above, I would build what essentially would look like a 38" wide desk using appro 28"x28" side panels, and a top and front panel 38" wide x approx. 20" deep that would form a 90 degree peak over the front 38x31 panel of the khorn. The sides would be for function and peak would be for a furniture look, the Khorn bin should function the same just using different orientation. I do wonder if a peak (like LaScala) in the center of the Khorn would have any acoustical benefit, it sure would in aerodynamics, actually a must in that flow direction. The false corners of course would be the next option.

Can you slow down some more? (LOL!)

[D-MAN]

Armando, the version# 3 is too cool.

I have not calculated the Vb which is going to be the make-it-or-break it as far as selecting the appropriate driver. But using a horizontal "shelf"; i.e., enclosing the void space made by the slant with a horizontal shelf and sealed area and adding that to the overall Vb would allow for increased back chamber area if needed (and would allow for a separate top, too). I like the versatility of separate units, personally.

The rest is simply a matter of arriving at the proper cross-sectional area at the exit from the bifurcated "section".

It looks very good. Makes me wish that I had come up with it!

DM

[ajsons]

Thanks, but I'm not done yet. Wait till you see the next one. This next one will blow the JBL guys away. I'll probably post it under Upgrades & Mods.

As far as the calculations, I'm not really worried.

I was taking programming lessons when the Show Horn article came out. I took Edgar's formulas and wrote a Qbasic horn program. Then wrote a "how to use a program" write-up for my English class. I submitted the software and the write-up to Audio Amateur. Edgar reviewed it, got published and got paid (5th issue of 1995 Speaker Builder). Back then , I hardly knew anything about horns. I still don't, but I am learning a lot from you. I wish I know as much as you do on horn design.

The program is in ancient DOS. It will calculate throat area, mouth area for 1/8, 1/4, 1/2 size or infinite horns, Vb, mass roll-off frequency, expansions for a single path horn or bifurcated horn. It will also calculate expanding dimensions between parallel sidewalls (my idea, and somebody copied it) if you enter the constant dimension. The M parameter is manually inputted, so you have control of expansion choice, i.e. exponential, hyperbolic or catenoid.

Printing using today's computers is its biggest problem. It looks for a dot matrix printer at the old printer port. But there are ways around it.

I'm going off line to draw my next posts.