# Zaph ZDT3.5 Build



## watson b (Feb 18, 2013)

I am in the process of upgrading the fronts of my system and have settled on replacing my DIY Dayton TMs and Onkyo HTIB center channel with Zaph ZDT3.5 fronts and center. They are run by an Emotiva UMC-200 and XPA-3.

For background, they will be located in a 13.5'W x 22'L x 8.5'H HT. They will be used 70/30 music/movies. For now, it will be used with the Onkyo HTIB sub (10" x 220W max) until I replace it with one or two ported Stereo Integrity 15s and few thousand watts (once the wife stops noticing the endless parade of UPS trucks at the house and the assault on the checking account). I imagine I would cross the sub and fronts at 80 Hz.

Parts Express arrives today, so my first question is what should the Zaphs be tuned to? The plans allow for 41, 46 or 51 Hz depending on port length. Given where I'm headed on the 15" subs, anyone have any thoughts?


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## dougc (Dec 19, 2009)

I just finished these for my dad, but used the standard crossover for the center channel instead of the different option for the center. I tuned all 3 to 41hz and use a single sealed SI 18D2. You will love how they sound! I like them so much I am thinking of building another set for my 2c system, and stacking them on top of a ported SI 15 or 18 for each enclosure. I have yet to ask the gurus here on the forum about that plan. Have fun and take lots of photos of your build.


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## fusseli (May 1, 2007)

watson b said:


> I am in the process of upgrading the fronts of my system and have settled on replacing my DIY Dayton TMs and Onkyo HTIB center channel with Zaph ZDT3.5 fronts and center. They are run by an Emotiva UMC-200 and XPA-3.
> 
> For background, they will be located in a 13.5'W x 22'L x 8.5'H HT. They will be used 70/30 music/movies. For now, it will be used with the Onkyo HTIB sub (10" x 220W max) until I replace it with one or two ported Stereo Integrity 15s and few thousand watts (once the wife stops noticing the endless parade of UPS trucks at the house and the assault on the checking account). I imagine I would cross the sub and fronts at 80 Hz.
> 
> Parts Express arrives today, so my first question is what should the Zaphs be tuned to? The plans allow for 41, 46 or 51 Hz depending on port length. Given where I'm headed on the 15" subs, anyone have any thoughts?


I don't think that any of those tunings will make much of a difference since you are crossing them into a sub, they are all pretty low. Try the lowest port tuning if you ever think you'll use these without a sub. I think planning to cross at 80Hz is a great place to start. Those speakers are big enough that you could also experiment with crossing even lower, like 40 or 60 Hz, if you wanted.



dougc said:


> I like them so much I am thinking of building another set for my 2c system, and stacking them on top of a ported SI 15 or 18 for each enclosure. I have yet to ask the gurus here on the forum about that plan.


That's a great idea :dumbcrazy:


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## watson b (Feb 18, 2013)

Thanks for the input so far. Trying to understand the difference, I modeled an RS180 in a 0.69 cf box and the various vent combinations in WinISD. I couldn't duplicate the tuning frequency; it runs about 10-15% lower than the design.

For the same size box, though, it seems that the shorter vent or higher tune gives a little more extension before it rolls off but rolls off more quickly when it does. The difference is only about 1dB anyway with a 60dB crossover point and even less with an 80dB one. Bottom line, I'll probably go with 46 Hz because the curve looks better to me. 

I know little to nothing about what I am saying, so feel free to say I have completely misunderstood this.


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## fusseli (May 1, 2007)

I think that what you think about your thinking is fine. A slight change in port tuning like the three choices wouldn't be huge anyways, and yes once you factor in a crossover to the sub it becomes a fairly mute point. As far as matching Zaph's stuff goes keep in mind he measures the parameters of all drivers in-hand, which will vary slightly from both manufacturer's specsheets and other people's measurements due to atmospheric conditions and manufacturing tolerance in the driver itself. Something like 10% isn't a cause for concern.


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## gottavtr (Oct 24, 2011)

I would run those full range or a crossover right at or just below tuning frequency when watching movies. Therefore the tune become important. Have you measured in room response and then the response of your current speakers outside? I would also start with a lower crossover for 2ch like 50-60. Those mains will sound great so why stunt them. 
Zach


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## fschris (Oct 31, 2009)

watson b said:


> I am in the process of upgrading the fronts of my system and have settled on replacing my DIY Dayton TMs and Onkyo HTIB center channel with Zaph ZDT3.5 fronts and center. They are run by an Emotiva UMC-200 and XPA-3.
> 
> For background, they will be located in a 13.5'W x 22'L x 8.5'H HT. They will be used 70/30 music/movies. For now, it will be used with the Onkyo HTIB sub (10" x 220W max) until I replace it with one or two ported Stereo Integrity 15s and few thousand watts (once the wife stops noticing the endless parade of UPS trucks at the house and the assault on the checking account). I imagine I would cross the sub and fronts at 80 Hz.
> 
> Parts Express arrives today, so my first question is what should the Zaphs be tuned to? The plans allow for 41, 46 or 51 Hz depending on port length. Given where I'm headed on the 15" subs, anyone have any thoughts?


subscribed... i built a pair of zaphs and i love them. I hope we see some build pics!


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## watson b (Feb 18, 2013)

Here's what one and a half sheets of mdf and a few hours look like. Cutlist is really good (and free) program. So far I've only had one mess up due to not doing the take-off right on one piece. Also, the obligatory clamping and glue-up picture. I do not have enough clamps; this is not going to work when I build a sub.


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## watson b (Feb 18, 2013)

To my original question regarding tuning, I think I'm going to go with 46Hz. After modeling in WinISD, 41 rolled off more steeply and 51 had a hump before it rolled off. If the plot printed correctly I would post it. In any case I don't think there would be much, if any, noticeable difference. When in doubt, split the difference.

My next question is regarding lining. The Zaph Audio image (linked below) shows carpet pad lining on the interior surface, but does not mention fill. What effect would lining versus no lining have? I am not currently considering fill.


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## fusseli (May 1, 2007)

Any full range speaker design really need lining to damp the back-wave of open backed midwoofers, otherwise you are sure to get muddier midrange. It also helps to dampen standing waves.

Fill is usually for sealed designs, AFIK you can risk reducing the performance of your port using fill instead of lining.


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## dougc (Dec 19, 2009)

I used some polyfill sheets to line the sides and back of mine. As far as tuning goes - they can handle more than the standard 80hz THX setting, but I would be careful with full range tuning if you like to listen at reference levels and you are using a sub. They are strong little drivers, but they are still only 7" and they will try to play 20hz if you feed it 20hz with the full range setting, and you risk damaging them because they will offer serious volume with clarity, which makes the volume knob easy to turn up. I think 40-60hz with a sub is the sweet spot, 60hz if you like symphony or dubstep. Low to medium level listening - definitely full range.


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## watson b (Feb 18, 2013)

fusseli said:


> Any full range speaker design really need lining to damp the back-wave of open backed midwoofers, otherwise you are sure to get muddier midrange. It also helps to dampen standing waves.
> 
> Fill is usually for sealed designs, AFIK you can risk reducing the performance of your port using fill instead of lining.


Thanks, I'll go with a heavier carpet pad since it is locally available. My other question, and it may be a stupid one, is the crossover specific to the upper and lower woofer? In the crossover schematic below, is W21 or W24 top, or does it not matter? Also it appears the notations C19 and R20 are swapped, and I assume C19 is connected to the ground side.


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## watson b (Feb 18, 2013)

Here was my first (and hopefully last) major screw-up. Cutting the vents for the backs of the towers, I accidentally grabbed the center and cut it, too :rant:. Choice words were thought. Sometimes I am amazed at my own stupidity.

It was a relatively easy fix, though. I set up the circle jig 1/2" larger, got a plug and hammered it in - very tight fit. I can't imagine doing all these cutouts without the circle jig.


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## fusseli (May 1, 2007)

watson b said:


> Thanks, I'll go with a heavier carpet pad since it is locally available. My other question, and it may be a stupid one, is the crossover specific to the upper and lower woofer? In the crossover schematic below, is W21 or W24 top, or does it not matter? Also it appears the notations C19 and R20 are swapped, and I assume C19 is connected to the ground side.


Yes, it matters! The .5-way is the lowest woofer in the baffle and it's the one that has the extra coil in front of it (L22).


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## watson b (Feb 18, 2013)

fusseli said:


> Yes, it matters! The .5-way is the lowest woofer in the baffle and it's the one that has the extra coil in front of it (L22).


Thanks, I did a fair amount of researching and couldn't find any direct references. I assume the RC part of the circuit referenced above has the resistor on the signal side as well?


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## watson b (Feb 18, 2013)

The (unfinished) LR boxes are done.

Also finished the crossovers. I put woofers on one board and mid and tweeters on another. They aren't a thing of beauty, but I kept the inductors as far apart and oriented as the space allows. Both are located in the base of the cabinet.


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## watson b (Feb 18, 2013)

I've spent the last few days listening and tweaking. This is a really good sounding design/drivers, although I don't have much frame of reference.

I don't have another three-way to compare it to, but the mids sound exceptional; it's obvious what does most of the work. The mids, though, did sound a little too bright so I ended up with a 5.1 ohm resistor instead of the 3.3. 

I think I'll spend a a few more days listening before I move on to finish. I'm looking at maple veneer for the cabinet and black-painted baffle.


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## fusseli (May 1, 2007)

Looks like they are coming along nicely! And don't worry, your xovers looks nicer than some that I've cranked out in the past  As far as inductor spacing, they can be closer together than you have them though distance helps. You don't want them in the same plane either, so good job rotating them as needed.


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## fschris (Oct 31, 2009)

they look great! i like your table saw set up


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## fschris (Oct 31, 2009)

i used some knock down hardware to secure my baffles....i used some nice flat black ones from woodcraft

http://www.woodcraft.com/category/2001045/knock-down-hardware.aspx


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## watson b (Feb 18, 2013)

fschris said:


> they look great! i like your table saw set up


Thanks, on the table saw I still have to finish the drawers, router table, fold-up out feed table and dust collection but now I have a mobile platform to accurately cut full size sheets with no problems. I love it.


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## watson b (Feb 18, 2013)

Build is complete. Thanks to everyone who answered my questions (especially fusseli). I am pretty happy with my 2nd speaker build.

I finished the towers with maple veneer (2x8 sheet for less than $10). I used leftovers from my kitchen cabinets: wipe-on Sherwin Williams stain along with one coat each of Sherwin Williams Kemvar sealer and catalyzed lacquer. If you use an HVLP on this lacquer, it can turn out like glass and with a few coats is almost bulletproof. 

Baffles are just flat black from a can (being near the screen I didn't want something too reflective). Next time I will probably try automotive paint and use the HVLP. The center channel and base are the same paint.


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## Owen Bartley (Oct 18, 2006)

Great work, Watson, they came out looking really nice. I'd be very proud of those as your second build project. And don't worry, nobody's going to see the back of the centre channel anyway!


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