DR250 + Titan39, some questions

[sykdom]

I finally decided to start a build of some nice loudspeakers after getting tired of either spending a reasonable amount and getting poor quality, or spending a ton and getting reasonable quality. So I'm going for 2x DR250 and 2x Titan 39's. I have a few questions, however....

1) I already own two Eminence PSD2002 compression drivers. I could count it as a loss and go for the piezo array, or get two more and do the horn cabs, however at ~$60/ea and already having to buy at least four other drivers, I'm kind of at a loss as to what to do there...does the piezo array sound better quality-wise? I understand the close-range dispersion is better than the CD's.

2) What size Titans?! Should I build 2 slim's, or one double, or two not-slims? Any experience with widths here is much appreciated....I'm kind of at a loss as to what to do (again).

3) I have access to an XYZ CNC router (4' x 8' blackfoot) . I've never used a CNC router before, but I am very familiar with Solidworks (mechanical engineering student). If I were to use this I'm under the assumption that I can just create a 4' x 8' x 1/2" sheet in Solidworks and then just add in all the cuts. The copy of Solidworks at the shop has a plugin to output the file as gcode for the CNC. Is this assumption accurate, and is it worth it?

4) Related to (3), what would be the best way to arrange the cut sheet in Solidworks? I guess I'll just have to go through and start with the cutlist and then figure out which cut corresponds to parts in the instructions that I can add precision to via CNC, unless there's a better way....

If these questions seem silly, I'm sorry, I'm just really excited.....

Many thanks!

[tomlang]

I am not familiar with Solidworks but I do you use Sketchup and 2.5D CAD to create objects for CNC machining. First off, be sure that the CAM portion of Solidworks isn't outputting a 3D CNC file. In other words, it may not only direct the machine to make the various cuts, it may also tell it to surface the top of the plywood to .5 inches thick. What you want for cutting these panels is known as 2D or 2.5D cutting. In my experience, I explode the Sketchup 3D geometry into the panels I want and import these panels into the 2.5D CAD/CAM software. At that point, the real fun begins creating the various drilling and cutting tool paths.

A complete CNC g-code file not only contains the vectors to tell the machine where to cut, it also should have in its database an entire set of cutting tools, thus allowing for the diameter, geometry and cut feed rate of such tools. On my Shopbot machine, for example, if you specify a 1/4" end mill, it will ask do you want to cut on the vector, or offset to the inside or outside to allow for the tool diameter when cutting as the software takes all into account. If I select a ball nose or 60 degree v-bit for instance, the rendering of the actual cut pieces (does Solidworks do this?) will be exactly what you will get as the rendering depicts the material that was removed by the bit(s) of that actual geometry.

As a quick check, I'd see if SolidWorks has a selectable tool database, a way to adjust feed rates within that database, and if it renders the results so you can see what you are getting when you're done machining the pieces. You will have to know what to set the feed rate for plywood knowing the capabilities of the machine. There is a sweet spot of carriage travel vs tool rpm speed so as to have optimum chip sizes flying off. My CAM software also has a "nest" routine for optimally arranging the panels on a sheet of plywood.

I hope this brief intro helps. Check my Tuba 18 CNC build for some renderings.

[miked]

I can't help you with CNC or Solidworks or any of that stuff...tomlang is doing an awesome job with that, so I'll leave him to it!

You didn't specify what your usage will be. I noticed you used the phrase "build some nice loudspeakers." Is this for use in your living room, or is this for DJ or PA use? Bill has a wide range of designs...he's got all the bases covered. Depending on your desired use, you might be better served by other BFM designs.

A real quick "primer" if you will: Horn-loaded subs work best in pairs. IF you wind up building T39s, build 2 of whatever width, load them with the 3012LF and v-plate them. I'll reserve further comment until you clarify your desired usage. Welcome to the forum, BTW!

ps
There are no silly questions on this forum. We're all adults here...well, most of us, anyway...and we were all newbies once. We learn from each other and trust me that there is a LOT of DIY knowledge here. I've learned tons in my brief tenure. Just read my build threads and be inspired by my growth from Wood Butcher to Elite Butcherer of Woods.

[Tom Smit]

Welcome to the forum, sykdom!

You have selected a great set of cabs. However, are they the right tool? Let us know the intended use of them so that we can better answer your questions.

[Grant Bunter]

Hi sykdom.
Welcome to the forum

Outstanding cab choices for live music and/or DJing if your content is above 45Hz!

You asked about the best width for the T39's.
There are a couple of factors involved:
Driver choice (20" wide is the max for 10" drivers, 28" wide is max for 12" drivers).
Pack space

The usual requirement for dual loaded cabs is, in part, to "manipulate" cab impedance loads to some degree for very large rigs.
2 single loaded cabs half the width of a dual loaded wide cab have equal response.
The 2 singles are much more pack space and handling friendly, so more often than not that will be the recommendation to build.
If you then increase the width of the 2 singles, then you get greater output compared to the dual loaded.

Somewhere from 20 to 24" wide cabs seems to be what many people build.

If you want the greatest output, from the least amount of cabs, then make sure you build with premium drivers and as wide as you can manage in your pack space...

[Chris_Allen]

If you want to reuse the Eminence compression drivers, you could consider the OmniTop12 instead as they only require one each.

[Bill Fitzmaurice]

I'm going for 2x DR250... I already own two Eminence PSD2002 compression drivers.

They won't fit.

[sykdom]

Thank you for all the responses! I guess I forgot the most important part, intended use....PA/loudspeaker use for both live and DJ use.

Starting from tomlang, the tool dia. ends up getting taken care of when the solidworks drawing gets converted. I'll do a bit of research to find the best feedrate/rpm combo.

It looks like two T39's is the answer then. Is the lab12 much better than the 3012? I think I'll build them at around 20-24" as suggested since it seems to work.

If the comp. drivers won't fit....hrm. Bummer. Looks like a melded array then. I think I'll also go deltalite vs kappalite as I don't think I can justify the $65 difference per driver.

Thank you (again) for all of the responses and welcomes! I'm starting on this tomorrow....

[tomlang]

I have a Milwaukee hand held 3.5hp router rigidly mounted to the CNC machine. I used to run it way too fast rpm wise and too slow travel speed wise. I get good results using a 1/4" 2 flute carbide end mill on plywood at about 12-14k rpm at 4 inches per second travel speed.

Edited to include I run .25" deep passes at a time, so 2 passes thru 1/2 ply, 3 for 3/4 ply.

[Grant Bunter]

It looks like two T39's is the answer then. Is the lab12 much better than the 3012?

The 3012lf is king in the T39.
However, if $ are tight, the Lab 12 will do fine, but weighs more.
Response and maximum output will be the same with either driver.

Heads up,you're going to need DSP for brick wall limiting /crossover etc for the T39's to prevent blown drivers.
This can be done via amps with DSP or processors.

If your audience are near to your stage/setup area, you want the wider dispersion of the melded array. If you don't think you can build one (though they aren't that hard), Leland at spekerhardware.com makes them. Leland is your goto guy for what you need...

[sykdom]

I have a Milwaukee hand held 3.5hp router rigidly mounted to the CNC machine. I used to run it way too fast rpm wise and too slow travel speed wise. I get good results using a 1/4" 2 flute carbide end mill on plywood at about 12-14k rpm at 4 inches per second travel speed.

Edited to include I run .25" deep passes at a time, so 2 passes thru 1/2 ply, 3 for 3/4 ply.

Extremely helpful. The router has a 3.25hp Porter-Cable so I'd probably run it around the same, maybe a little slower on the travel speed...3.5in/s maybe.

The 3012lf is king in the T39.
However, if $ are tight, the Lab 12 will do fine, but weighs more.
Response and maximum output will be the same with either driver.

Heads up,you're going to need DSP for brick wall limiting /crossover etc for the T39's to prevent blown drivers.
This can be done via amps with DSP or processors.

If your audience are near to your stage/setup area, you want the wider dispersion of the melded array. If you don't think you can build one (though they aren't that hard), Leland at spekerhardware.com makes them. Leland is your goto guy for what you need...

I may do the Lab12 for $ reasons, unless the sound quality is better in the 3012lf. If it's all the same, I can handle the extra weight.

I'm also planning on ponying up and getting a DriveRack. All I've been working with is a 234s xover and taking care not to run what I have too hard right now.

I can also return the PSD2002's (only recently bought them) which I think I will do in favor of the melded array....if I build another two DR's I'd probably go with comp. horns for a good mix of dispersion distances.

Thanks again to everyone!