Zaph ZDT3.5's finished

[phidauex]

Just completed a set of Zaph's ZDT3.5s, and thought I'd share the results. The design was fun to build, and they have turned out fantastic! All respects to the designer for the good documentation, and impecable crossover design.

My one addition to the project was to build a set of chip amps directly into the lower enclosure, making the speakers a bit taller to accomodate the equipment. My modest HT receiver has poor amps, but good pre-outs, which I wanted to take full advantage of.

Amps - The amps are built with the dual mono boards from chipamp.com by BrianGT. They were insanely easy to put together. I went with a 200VA 120/20V toroidal transformer due to the 4ohm load.


A pair of LM3886s by phidauex, on Flickr

The cabinets are a modification of the standard cabinet - the baffle is unchanged, but the cabinet pushes out beneath the baffle, giving it a recessed look. I also changed the size of the lower enclosure (not an acoustic enclosure), and made some small internal tweaks. Cabinets were cut on my CNC router (a fantastic tool).


CNC cutting baffles by phidauex, on Flickr

The cabinets were assembled and glued (no screws), then after rounding the edges over, I primed and sanded endlessly. The order of events was to sand the enclosure as smooth as possible while still bare MDF (to 220 grit). Then I filled a few areas with Bondo, and sprayed 4 coats of high build urethane primer. After blocking the primer down with 220 (using guide coats to ensure flatness), I filled a few low spots with glazing putty, and shot 3 more coats of primer. After that was sanded flat again, then sanded progressively up to 800 grit, I sprayed the final paint, using 4 coats w/ 5 minute flash time between coats to achieve the color and thickness I wanted.

A discussion about paint, since it comes up a lot in questions... This was my first project using an automotive paint system. Getting into it can be quite the daunting task, but I'm glad I took the time.

I have a 208V 3hp compressor, and an Astro Euro HTE HVLP gun (with 1.3 and 1.9mm nozzles). The biggest issue with HVLP spray guns is the quantity of air they need - not pressure, but volume. 13-15CFM is a minimum for many guns, beyond what most 120V compressors can do. The Astro Euro HTE uses slightly less, and they make a LVLP gun that uses as little as 7CFM called the EVO. Both guns are less than $150 and are well regarded as "cheap but reasonable quality" - a good place to start.

The paint I chose was a high build two-part urethane primer, Finish Line FP411, with standard hardener. The paint was Sherwin Williams 3rd Dimension single stage urethane (as opposed to two stage, meaning base coat and then clear coat), Rouge Sevillian color (originally a Peugeot color, I learned). Single stage urethane paints are still mixed with multiple parts (paint, hardener and reducer), but are less expensive since only one layer is being sprayed. The look is not any worse than base/clear, just different - older cars tend to have single stage paints, newer have base/clear. In my case I wanted the slightly richer color of single stage. If you like a more modern look, or want to use pearls or metallics, look to base/clear. It isn't any harder to spray, it just takes a little longer. Base/Clear is also more forgiving with runs and sags in the paint, since those can be easily sanded out of the clear, without affecting the color.

Here are a few little things to remember when buying automotive urethanes:
- Stay in one family of paints for maximum compatibility - most major brands are good quality
- Work with a local supply shop that knows their stuff - they can recommend a lot and answer your questions - seriously do not bother with online ordering, at least for your first few rounds.
- Do not bother with acrylic enamels - they are a bit cheaper, but it is NOT worth it for a project you've spent a lot of time on
- Single stage urethanes are great for solid colors, but very tricky with metallics - if you want a metallic color, use base/clear
- The paint is very toxic - build a spray booth to ventiliate to the outdoors, and wear a good 3M respirator with organic vapor cartridges (your paint supplier can sell you one for less than $20). Safety is not black magic - just read up on proper mixing and ventiliation, and ask your paint supplier if you have questions.
- When you pay a lot for paint, make sure your prep work is impeccable. Sand primer to 800 before spraying on top. Any blemishes won't be hidden by paint, they will be magnified. Read about "guide coats" to help with primer sanding. Use Bondo (or equiv.) for larger blemishes (deeper than a penny), and "glazing putty" for smaller low spots, or pinholes.
- It is worth it! This was my first urethane paint job, but I've painted a lot of things before - this was by far the best finish I've ever gotten, and with a little practice, I know I can do even better next time.


Cabinets, bondo'd and primed by phidauex, on Flickr


Cabinets with final primer coat - back by phidauex, on Flickr


Completed cabinets by phidauex, on Flickr


Completed speakers - rear by phidauex, on Flickr

The paint on the baffles was Rustoleum Fine Texture, available at Lowes. It has a finish that is very similar to the finish on the speaker frames, and looks great contrasting with the shiny depth of the paint.

The amplifiers are in the lower case, and work great - the 68W/ch output is well matched to these speakers - they sound good all the way up to full output (which is far louder than I can listen to in the living room).

The speakers themselves are a great design - certainly the best I've ever owned, and among the best I've ever listened too. A true pleasure!

Let me know if you have any questions, and I'll try to answer.

-Sam

[kmibb]

Those look really good. Very nice job. I'm jealous of your CNC.

[cwad8505]

These are just absolutely, ridiculously, incredibly beautiful!! Very nice work.. ditto on the CNC envy! WOW! Thanks for sharing.. Chris

[phidauex]

Those look really good. Very nice job. I'm jealous of your CNC.

If you ever feel like a fun non-audio project, I recommend a CNC router! Mine is a Hybrid CNC from Joescnc.com - I paid for the plans which gets you into the web forum, which was worth every penny.

-Sam

[kmibb]

If you ever feel like a fun non-audio project, I recommend a CNC router! Mine is a Hybrid CNC from Joescnc.com - I paid for the plans which gets you into the web forum, which was worth every penny.

-Sam

Would you mind ballparking about what you paid to complete it? Also, how long did it take you to make?

Kevin

[phidauex]

Would you mind ballparking about what you paid to complete it? Also, how long did it take you to make?

The machine has a 4' x 4' x 5" envelope, a 2.25hp router spindle, and a large steel table. The main beams are 80/20 extrusions, which are amazingly straight and rigid. The design isn't the cheapest way to build a CNC router, but I feel it is the best bang for the buck. I'm probably about $3500 in on the project, but that was with a few mis-steps. People usually fall in the $2800-$4000 range for this size of machine. You can go cheaper by making smaller machines, such as 2'x4' sizes. If you have a computer with a parallel port you can dedicate to the router that will save money as well.

If you are doing a lot of MDF, don't sacrifice on router HP or machine stiffness - MDF machines well, but is dense.

I spent about 3 months building the router, working on it most evenings and weekends - with good plans and a good support forum I didn't have any major hiccups. Cnc-zone is a good forum, but I got the most use out of the Joe's CNC forum (joescnc.com, which you get access to if you buy his plans). It was worth it, and Joe is a good guy (just a hobbyist making some of his huge expenses back).

Software matters too - I use Vectric V-Carve Pro for the CAM portion (converting lines to actual toolpaths), and Mach3 for control of the machine (translates gcode (motion code) to actual stepper motor pulses). That combo is about $700, but was worth it for me. There are open source alternatives like EMC2 for machine control that work well, just take more time to setup properly.

All told it was a big project, but for the last two years I've made a tremendous amount of stuff on it - speakers, a bed, signs, tables, boxes, jigs, guitar bodies, etc. Lots of fun. Plus, it is totally hypnotic to watch.

Here is a time lapse video of it running, and that set on Flickr has a number of other pictures, including some of the router in construction.

http://www.flickr.com/photos/phidaue...7620745231773/

-Sam

[arlis_1957@yahoo.com]

nice report thanks. good looking build. love the cnc.

[Wolf]

Saw these also on DiyAudio.com...

What color is the paint? I like what you have there.
Nice job!
Wolf

[phidauex]

Paint was Sherwin Williams 3rd Dimension, solid color single stage urethane, "Rouge Sevillian" color, which when looked up on their computer, comes up as a Peugeot color for 2003!

The color is even better in person - the color is rich and deep, and very glossy.

-Sam

[Paul Carmody]

Yow! Nice work. Beautiful finish. I wish I had the patience for that kind of prep work (and also a safe place to get rid of toxic fumes)

Also, is your screenname a Frank Zappa reference?

[phidauex]

My trick for getting into long stretches of hand-sanding? Audiobooks! Listened to a good chunk of the Song of Fire and Ice series by George R.R. Martin ("grown up" fantasy - among the best ever written in my opinion) while building these speakers. 6 hour runs of listening, sanding, and sipping microbrews can be very relaxing. Makes you actually WANT to go sand for a few hours - you won't be disturbed, and you can really zone into the book.

As for the spray booth, it is a simple configuration. I have a few bamboo poles setup in my workshop, forming a square with the backside against the garage door. I tape 6 mil plastic drop cloths up on the three sides, leaving the top open. I open the door a few feet and have two powerful fans blowing out, sealing the rest of the open door space with chunks of plywood leaned against it. Air flows over the top of the plastic, down, and out the door.

I know you are supposed to have explosion proof fans, but considering the high volume of air movement and the small scale of my projects, I think I'm relatively safe. Dust isn't a big problem as long as the rest of the workshop is fairly clean, and I haven't swept yet that day (don't want to knock a bunch of dust into the air!). The whole thing packs apart in 30 minutes when it isn't being used.

-Sam

[GTB]

Impressive! Thanks for sharing.

[mattp]

Very nice work, I love the addition of the amps. I'm suprised no one has caught this, any reason why you didn't mirror the baffles?

[johnnyrichards]

Very, very well done. I am going to go out in my garage and weep a little bit now, looking over my meager collection of tools

Seriously though, lovely job. Love the colors, love the design.

[phidauex]

Very nice work, I love the addition of the amps. I'm suprised no one has caught this, any reason why you didn't mirror the baffles?

I'm under the impression that acoustically, the baffles do not need to be mirrored, and aesthetically, I liked the asymmetry... I know it isn't usually done that way, but I like it!

-Sam

[violaplayer]

Wow. You're an inspiration. Fabulous work!

[gabel87]

Those are awesome! Excellent work indeed. I like the way you did the baffle, I might borrow that for my za5.3t build.

[poochieone]

WOW!
Fantastic workmanship there!!
Wish I had someone local I could hire to work up a pari of enclosures like that!!

[phidauex]

Glad you like them! The cabs did turn out quite well, though I hope my next set are even better. Don't sell yourself short - craftsmanship is just patience applied to materials.

It's not the same as entire cabinets, but if anyone has baffles, back panels, etc. that they'd like to have cut on the CNC, I offer pretty competitive rates to help pay for my costs of operation. $80/hr for machine time + materials + shipping. For comparison, it took about 25 minutes to cut one of the ZDT3.5 baffles, including all the driver recesses, drilled holes, etc., but not including the roundover (that is done with a hand router). All I would need to cut would be a vector file (autocad, adobe illustrator, inkscape, etc.). If all you have is a napkin with a sketch on it, I'd ask for a few bucks for design time.

-Sam

[RINNAV]

...craftsmanship is just patience applied to materials...

Very true..!


Excellent work and your choice of color is exquisite!

Jason