University Speaker "Dean" similar to "Classic" 3D Model and Build

rustnrot · Jul 9, 2011

Hi all, I've been working up a model to allow me to CNC the panels to construct a University Dean which is similar to a University Classic speaker enclosure except more dimensionally suited to a corner.

Posted below are plans, an picture of an original, and a picture of my 3D model in Google Sketchup. The horn is a P.Audio PH4525 2" horn which is exactly the same as a Goldwood GM-450PB horn. The high frequency driver will be a P.Audio BM-D750. The woofer will be a Eminence Legend CB15.

That said, notice in the original how they position the mid and high frequency horns inside the mouth of the bass bin. Mine is a 2 way so there is only one horn.

How bad of an idea is it to mount the horn inside the mouth of the bass bin?

Thanks!

68custom · Jul 9, 2011

I know nothing about those sorry, however that is a cool looking design, and I would think that you can leave it on the left side and tune them to the room by changing the position. maybe mirror one for true left and right.

Tom Brennan · Jul 9, 2011

rustnrot said:
How bad of an idea is it to mount the horn inside the mouth of the bass bin?

Not bad at all.

AFP1 · Jul 9, 2011

Dean/Clssic

Good day. I, too, have been mulling over a Dean clone for some time. Like you, I have considered a two way design with the horn/driver mounted inside the bass horn. I have not been advised that it is a bad idea or that it would cause problems in any way. You seem to have done your homework, so I have a few questions for you. Regarding your woofer selection, why did you choose the Eminence woofer over the original University C15W, what makes it a good substitute? Also, the original crossover point to the mid-horn was 350 or 375 Hz, at what frequency will you be bringing in your horn/driver? Keep up the good work and I look forward to your reply, Andrew.

rustnrot · Jul 10, 2011

My criteria were:
1. Two way horn design
2. No vintage drivers; all newly available stuff
3. No bass bins requiring corners of a room as final flare
4. I do not want to run a separate subwoofer (with attendant amp) nor do I want to biamp. I have a tube amp and want to keep things simple.

Turns out the Eminence CB15 is a good choice for a horn loaded bass bin, is cheap, and I even found a pair of "barely used" on ebay. Refer to this thread over at the Klipsch Forum:
http://community.klipsch.com/forums/t/64694.aspx?PageIndex=1

Furthermore, a crossover was designed for this woofer as used in a horn loaded bass bin as referenced in the thread above that I intend to use, "extreme slope" crossing at 600 Hz.

AFP1 · Jul 10, 2011

University

Rustnrot, thanks for responding. I like your design criteria, I have been following the same relative path. My choice of drivers, up until this point, have been the electrovoice DH1A compression driver and HP940 horn. I had not decided on a bass driver. My major stumbling block was the woofer. The low crossover point (350hz) of the original design worried me because I did not know if it was a function of the original woofer used, or if the bass horn was limited in upper end response (like the KHORN) by its very design. I know you guys are pretty busy over there on the Klipsch forum (I should visit more) but are you sure that the University/Eminence combo will make it all the way up to 600hz? Thanks for responding, Andrew.

automojo · Jul 10, 2011

Nice!:thmbsp:

rustnrot · Jul 10, 2011

No, I am NOT sure the eminence woofer, CB15 will make it to 600 Hz in this bass horn. I am not sure if the original 350 Hz cutoff was due to, like you said, the University woofer used, or the limitations of the horn itself, or a third possibility -- that was brought up on one of the University Classic threads at Klipsch -- the same crossover WAS used for other speakers in the University lineup. It could be possible they selected that particular crossover simply for commonality of parts.

I argued with myself that at least the Eminence CB15 performed up to 600 Hz in the horn I referenced above on the Klipsch forum. I realize, of course, that the horns are not the same but the University Dean to me does not seem to have a very tortuous path compared to other horns. This horn, for example, goes to "500 hz" and appears to have a more tortuous path.

http://www.egbeck.de/15bhorn0.htm

I am not familiar with hornresp. Does hornresp, for example, even model accurately the high frequency response of a woofer in a given horn?? If anyone wants to model the University Dean in hornresp, I can easily provide accurate linear and area measurements via the Sketchup model to plug into it.

AFP1 · Jul 10, 2011

University

Thanks for your thoughts. Other than having a basic understanding of how and why things work, I do not have the ability to model or design. If someone here would like to provide assistance, feel free to step in and contribute, Andrew.

rustnrot · Jul 17, 2011

Cut out half the panels for the first speaker. Will take two 4x8 sheets per speaker. All panels interlock with rabbet except for angled sides. Cannot do angle on shopbot so cut oversize then trimmed with table saw to correct angle. Rabbets a little narrow so will increase width 30 thousandths next cut to compensate.

Reinforcement panel that also holds mid-high horn goes in the center slot. Mid High horn captured with bracket so speaker can be mounted either side up. Rabbets are wider where inner panels intersect with sides at an angle.

tensleep · Jul 17, 2011

Is that one of those homemade or kit CNC machines you are using to cut your panels? Duly noted and impressed! I have a pair of the C15W and I believe they are capable of crossing over quite high. I'll look it up.

EDIT: According to University literature on Hi-Fi Lit, the C15W could be crossed over as high as 2,000 Hz. I am planning a big monophonic econowave, driven with a tube amp, based on the C15W. I would suspect that the original University Dean could have been designed as a two-way system. I realize you are planning modern drivers - I am just adding a bit of trivia.

AFP1 · Jul 17, 2011

University

Very nice work indeed! Andrew.

rustnrot · Jul 20, 2011

That is a Shopbot CNC machine.

The CNC machine cannot cut the angles so I have to do those on the table saw. I cut each panel oversize on the Shopbot so this can be accomplished. It is easy to make a cut wrong and that is what I did on the motorboard that I will recut; it came up short as you can see. In the meantime, I need to make the boards for the throat which are angled on all sides. The angles and dimensions on the original plans are not exact. But doing a 3D model you can read the dimensions and the angles directly.

Once I got everything cut correctly, it literally "snapped" into place. It is holding itself together in the pictures. It needs to be taken apart, glue applied then all glued together in one motion with the top on, not shown.

Note: These speakers are being used in the garage and will be mounted just below the ceiling. The pic of the speaker shown will be the right one and is upside down of the 3D model pictured earlier. The high freq horn is suspended just under the reinforcing panel on the right.

Turborusty · Jul 20, 2011

was that original mid a folded horn as well?

it looks like the driver could be in the front and the horn(s) makes a 180* turn.

Turborusty

rustnrot · Jul 20, 2011

The original Dean had a CobreFlex mid horn which is a folded horn. From what I understand it is an aluminum casting that is folded in cross section. You can still buy it new but it may be plastic now.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-155

tensleep · Jul 20, 2011

Brilliant mount for the horn! I love the hanging slot idea. FYI, I have an original CobraFlex in a University system, just like the one in the pictures of your Dean. In fact, I have that exact same load, including all horns, drivers and crossover, in a big, ported three way cabinet. It is going to be part of a killer tube based monophonic system. Down the road, I intend to cut a new baffle board and try out the C15W in a MonoWave system. I really wish I had your woodworking skills - that cabinet is looking beautiful! I have a pair of grills to make and the aforementioned baffle.

rustnrot · Jul 27, 2011

Some progress pics. Keep in mind that no fasteners or glue hold any of the panels together in the pics below (just one piece of masking tape). It will be disassembled and glued together all in one motion in probably 20 minutes or less.

wilberforce · Jul 27, 2011

rustnrot said:
No, I am NOT sure the eminence woofer, CB15 will make it to 600 Hz in this bass horn. I am not sure if the original 350 Hz cutoff was due to, like you said, the University woofer used, or the limitations of the horn itself...

My guess would be the limitations of the horn itself. The Jensen designed rear loading horn you see in my avatar puts out 300 hz through the horn mouth, according to the Jensen plans on hi-filit. Will the driver and horn you're using play nicely lower than 600 hz if you need to adjust the crossover down?

The Eminence woofer itself is rated to 3000 hz, and this is a front loaded design, so your mileage may vary. Great project! You must spend a lot of time in the garage...

kfa888 · Jul 27, 2011

Awesome build, nice work. :thmbsp:

fergs · Jul 28, 2011

Greetings Wilber, how are your stereo Jensens going. A final analysis? Did you end up corner loading them or not? I have been tossing between the Jensen and the Classic or Dean for about 6 months.Rust, is thee any chance you could share your cad drawings as a friend has a cnc machine and this could be the deal breaker as to which one I build. By the way there was a thread on the classic on repositioning the internal corner reflectors to allow the horn to play clean up to about 500 hz. Did you see it cheers fergs

University Speaker "Dean" similar to "Classic" 3D Model and Build

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