Building Zaphs ZA5.2 and ZA5.3c

[impulse]

Hi

This is my build thread of the Zaphaudio ZA5.2 (br-version) and ZA5.3c. I'll give a short description of my impressions of these speakers when finished. I usually build speakers in MDF, but this time I wanted to try something different. The baffle and the removable back panel was made of 19mm MDF (about 3/4 inch) and the rest (top, left, bottom and right panel) was made of 18mm glued joint oak.

I didn't want any end grain in the joints, so I cut all the oak panels at 45 degree. An important side-effect (in addition to the look) is a bigger area of the glued joint (about 40% bigger than a 90 degree joint). Thus the joint will be much stronger.

Furthermore I wanted the wood grain to follow exactly from left panel, over the top and right panel. To do this you have cut all the panels for one speaker form one piece of board and carefully mark every panel in the right order.

From the board cutting:

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There is no room for any errors in the process of cutting these boards. First you have to make sure that the cutting angle is exactly 45,00 degrees. Even a very small error will double up when gluing them together and you'll end up with either a angle that's not 90 degrees or a bad joint where the panels isn't in good contact with each other.

The panels also has to be cut to a perfect rectangle and exactly the same size. Once again, if you screw up any of this you'll have serious trouble with the assembly and end up with a box that is not a rectangle, combined with gaps in the joints.

Be aware of one fact: small enclosures are much easier to build then big ones. Actually, it is the depth of the enclosures that determined how accurate you must be. I started with the 5.2 to get the some practice before the 5.3c.

Finished panels for the 5.2:
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Assembling the panels are fairly easy, but you need to be very accurate. I use a couple of templates to make sure that every thing is at right angles.

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Assembly of the 5.3c:

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Basic enclosures finished:

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[john trials]

Those look really nice!!!! I'm looking forward to seeing your progress.

[impulse]

Baffle

Baffle and backpanel is made of 19mm MDF. I cut the baffle a bit to big, and then let them dry up well before sanding the edge to a perfect fit.

Using a circle-jig its really easy to do all the cut-outs:

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Frontside of the 5.3c:

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Chamfered backside of the 5.3c:

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Closeup of chamfered backside. I recessed the aera where the T-nuts is going to be mounted:

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When doing the roundovers I did screw it up and adjusted the router a bit to deep, see the picture below :M :

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This is what you get when you are in a hurry.... After some initial frustration, I decided to keep it as a design feature. Its not the best solution but I don't think it will increase the diffraction ripple too much. The step caused by the router is less than 1mm.

[Dr.EM]

Looks like a really tidy and well thought out build! That slight step at the edge shouldn't be a problem acoustically, but it may be possible to reduce it a bit with careful sanding if you wished.

I like the use of Oak boards. I've not seen this product before, I assume as it's formed from many smaller pieces laminated together that it is dimensionally stable and not prone to cracking/warping as solid Oak would be? Where did you obtain it from, I've not seen it in the UK.

Look forward to seeing more progress :T

[savage25xtreme]

This is what you get when you are in a hurry.... After some initial frustration, I decided to keep it as a design feature. Its not the best solution but I don't think it will increase the diffraction ripple too much. The step caused by the router is less than 1mm.

hit that with some 220 grit by hand and it will be gone in a flash with no ill effects. I had to do that on my BAMTMs. its tough to get that depth set perfectly with a hand router.

just my .02

[impulse]

Looks like a really tidy and well thought out build! That slight step at the edge shouldn't be a problem acoustically, but it may be possible to reduce it a bit with careful sanding if you wished.

I like the use of Oak boards. I've not seen this product before, I assume as it's formed from many smaller pieces laminated together that it is dimensionally stable and not prone to cracking/warping as solid Oak would be? Where did you obtain it from, I've not seen it in the UK.

Look forward to seeing more progress :T

Yes, the oak boards is formed from many smaller pieces (about 4 cm width) laminated together. This construction is very stable compared with solid oak. They are simular to kitchen worktops, but a bit thinner (typically a kitchen worktop is ranging from 28mm to 40mm). They can be obtaind in many different wood types, most common is probably birch, beech and oak. I don't know where to by it in the UK.

I tried to sand the edges down, but it didn't work out nice. They are going to be spray-painted, so every detail that isn't even will show.

[impulse]

Time for an update

I wanted the back panels to be recessed and removable. The work with recession was indeed time-consuming. I used a normal router to make a flange of 10mm width and 20mm deep (the back panels are made of 19mm MDF). Oak is very hard, so I couldn't take out more the 4mm each round. I also had to go very slow. Sum it all up and you'll see it equals 13 meter of routing to do all three speakers.

Here is a picture of the 5.3c with braces in place. Note a nice method to glue the support braces for the back panel.

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All braces are chamfered or rounded. I have no idea if that actually matters, but id can't hurt anyway.

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I was initially a bit worried with cabinet-resonance. Knocking on the cabinet did indeed create more resonance than I am used with MDF. My guess is that the resonance of oak occurs in a higher frequency then MDF (oak is a much stiffer material and not as "dead" as MDF). On the other hand, high frequency resonance should be easier to get rid of with dampening material then low frequency resonance. I did play with the idea of lining the inside of the cabinets with 6mm MDF. I guess this would reduce the resonance a lot, but also change the tuning (reduction of internal volume of 1.5 liter).

I decided to leave it as i was and use bitumen inside. All the cabinet panels was lined with bitumen.

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The back panel was then lined with acoustic foam. On the top, left, right and bottom panels I used acustilux.

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From inside with the back panel and BR-tubes in place:

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Ready for XO-installation:

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Installing the XO are pretty easy. I mounted it on the bottom of the ZA5.3c:

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One problem occurred with the XO of the 5.2. I usually mount XO in the bottom of the cabinet. The pre-assembled XO from Madisound are HUGE! There was no way to make them fit at the bottom of the 5.2. I had to mount them on one of the side panels. I really can't understand why Madisound mount the XO on such big boards. It is not necessary.

The baffles was finished. I used 3 layers of semi-gloss black spray paint and two layers of semi-gloss lacquer. I will not go into details, but to get a nice finish, takes more time and effort than any other part of the build. The result:

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A detail of the picture above

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[---k---]

Wow. Your efforts appear to be paying off. That baffle looks great. :T

[dmalphur]

Excellent craftsmanship. I look forward to seeing the final result.

-David

[impulse]

Bass tuning and testing 5.2

Back to some basics. Its time to control if calculations and reality checks out. The dimensions of the 5.2 are:
20.4 cm (W outside) - 16.8 cm (W inside)
31.9 cm (H outside) - 28.3 cm (H inside)
21.7 cm (D outside) - 17.8 cm (D inside)

This gives us a volume of 8.5 liter. Zaph has calculated a reduction of 0.7 liter (drivers, XO, port). He is using a port size of 3,81 cm dia and 10,16 cm length. Mine ar 4,3 cm dia and 14,0 cm long. They take up 0,1 liter more. I use brackets to fasten the back panel, so the internal volume of mine version should be about 7,6 liter. WinISD give the following:

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Tuning = 58 Hz


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F3 = 53 Hz

Run fullrange this fellows can't handle much power. The plot below is calculated with 16watts (SPL:98 db):

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Xmax is reached at 80Hz and below F3. A good indication that this should be crossed over to a sub.

Crossed over to a sub at 80 Hz with a signal of 32 watt (LR4):

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I will cross them as low as possible, so I guess I will try 80Hz first and see if that gives me enough SPL.

Rear port air velocity will be kept low if crossed at 80 Hz. Max is reached at 68 Hz and is only 6.5 m/s (32 Watt). Run fullrange air velocity will reach 29 m/s at 52 Hz with 32 watt. But at that level cone excursion is way to big.

I measured some parameters with WT3 and got this result:

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Looks like the theory and calculations are correct. Tuning is about 58Hz and the two speakers are coherent.

I am curious about the little hump at about 48 Hz.

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Does anyone have an idea what this is about?

[nmuntz]

Great pictures. Very nice build so far. That baffle looks fantastic.

[impulse]

The 5.3c has this dimensions:
49.0 cm (W outside) - 45.4 cm (W inside)
20.4 cm (H outside) - 16.8 cm (H inside)
31.4 cm (D outside) - 27.5 cm (D inside)

Internal volume is 21.0 liters. Reduction for braces, ports, XO and driver displacement gives us about 19.0 liters. Calculations in WinISD gives:

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Tuning is 52 Hz, a bit lower than the 5.2. The calculated impedance is wrong in this plot. I have no idea why WinISD doesn't calculate this correct. WinISD use the values of one driver for the impedance-plot, even if you choose 2 drivers. All other calculations is correct (port air velocity, Transfer functions, cone excursion, SPL).

F3 is about 48Hz:

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Measured with WT3:

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Tuning at about 54 Hz is a bit higher then calculated, but the drivers was not broken in so maybe it will change a bit later. Impedance drops to 3.8 ohm at 250 Hz

[impulse]

Pictures of the finished 5.2

I'm pretty happy with the looks of them:

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Closeup of the baffle:

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Woodgrain follows over the edge:

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Backside (with wall bracket):

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[impulse]

Finished 5.3c

Baffle:

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Baffle:

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Backside:

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All of them:

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They will be delivered to my friend tomorrow. Next up is rear-channels to go with them. I think it will one version of augerpro BBv2.

[john trials]

WOW! Those speakers are REALLY nice looking. Your attention to small details really shows. The continuation of the grain around the corners...subtle, but nice. The baffles look really good, too.

[ripcard]

Very nice work and an excellent write up with great pictures.

Not sure what kind of a set up you used for spraying the baffles but I know what you mean about the difficulty in getting a nice finish. Not sure if the satin is a little more forgiving but if I were to do painted baffles again I would get them sprayed professionally. Although I'm happy with my results, it was way more time and effort than I anticipated.

[Dean100]

Those are beautiful! :T

[evilskillit]

Those look awesome. I'm not even really a big fan of oak but they're so well constructed they're a beauty to look at no matter what.

I want to build a box out of ply sometime and try to miter the corners like that. I'm afraid I just don't have the gear for it right now, but maybe some day.

PS. I love the binding posts, those are the only ones I'll probably ever use. Unless something I like better comes along at a similar or lower price point (unlikely).

[Dr.EM]

These turned out great! Really good job

[a-rone]

Nicely done and nice detail in your thread. Congrats on finishing the build.

[Mondo1287]

Great looking build. I am considering building the ZA5.2s or the ZMV5s myself.

What kind of table saw is that? Is that just a sled on top of a normal table saw?

[bbcmp1979]

amazing work.

[krips]

Those look great. How'd you do the back baffle/recess exactly?

[impulse]

Great looking build. I am considering building the ZA5.2s or the ZMV5s myself.

What kind of table saw is that? Is that just a sled on top of a normal table saw?

I used this underhung circular saw. Its a really nice and precise saw.

[---k---]

Those speakers turned out great. I hope you're getting well compensated.

But, your thread loads slow on my cable modem.

[Mondo1287]

Wow that's really nice looking saw that's probably not overly expensive. I haven't seen anything like that available in the US.