# Zaph ZDT-3.5 Build



## bigbugberg (Jan 12, 2009)

This is my first DIY build. I searched the web for months trying to decide which build would best suit my needs (80/20 HT/Music). I was most impressed with John Krutkes site because he shows both modeled and actual response from his designs. I modified the cabinets keeping the same internal volumes and driver alignments but changing the overall appearance. I call these my ZFMs (Zaph Faux Magicos). I took the internals of Zaphs ZDT 3.5 and imitated the Magico Mini 2 cabinets.

John warned that these speakers may dip into the 3.2 ohm range. I seem to have no problem driving them with my Denon AVR 2802. My ZFMs replaced my Mirage FRx Ones I used as front mains and some old Polk center channel is now unplugged as well.

I hate high end audio reviews because of their use of seemingly incoherent descriptions (i.e. a review of Pear D'anjou cables claimed they were "Danceable." Obtuse yet Fragrant might be equally as descriptive!) however I will try without the nonsense...

My ZFMs bring new life into a tired HT setup. The Mirage FRx1 (2 way) seemed to be constrained in their output. They acted like they were holding something back or that I had this full range of sound coming into them but they were filtering what was coming out. My ZFMs are just the opposite. Them seem to let everything out. The highs (using the 1.5ohm in the tweet xover) reveal the the ringing in triangles as if I were the the one playing them! Mids are clear and precise, vocals no longer sound muffled or like peoples mouths are covered. And the lows are equally precise.

Some ZDT builders claim the 1.5ohm tweet xover is too bright. I have found the brightness comes more from the source than the tweeter. If the source sounds good, the speakers will play well, if the source is bad, well you know, "Garbage in, garbage out!"

The cabinets are baltic birch plywood, mdf, and african mahagony. 

Please feel free to contact me with any questions.


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## JCD (Apr 20, 2006)

Wow.

And as a first post, you've set a very high standard for all further posts.

Wow.

Those are really pretty. I love the mahogany. And an excellent job for a first time build.

Have you taken any measurements yet?

Great job.

Oh, and have you started thinking about your next build? :devil:


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## Mario (Jun 2, 2009)

I've been lurking on the forum for awhile, but had to register after seeing this post. I'm also a fan of John's work and finished a set of 3 ZMVs just a few days ago. As my first DIY project it took quite a bit of time and effort and I just feel those entry level speakers weren't really worth it. If I'm going to sweat over something for several months the end result should be something more substantial. So the ZDTs along with ZD3C are the natural choice. I'm still in the planning stages and trying to figure out the building process before I start hammering and run into some unexpected problems. I like what you did to John's design although I want to leave them floor standing, just change the dimensions a bit.

One thing I had problems with while working on ZMVs was the crossovers. I just zip tied the components to a piece of pegboard and soldered them together on the other side. I'd really like something more neat looking for the next project and if you don't mind sharing your advanced crossover building technology with the backward natives I'll be sure to improve my production line. Also, can you post a picture of the speakers' internals ? What dampening material did you use? I noticed you only have three sets of screws holding the baffle instead of four as in the original design. Is that because you have fewer braces?

Anyway, great job on the speakers. Hope to have something similar looking in my house one day.


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## bigbugberg (Jan 12, 2009)

I'm glad you like them!!! But I bet I like'm more!!!

For the xovers I cut pieces of melamine coated 1/4" mdf and just placed the components where I thought they looked good. I then drilled holes placed the leads through the holes and clinched the leads. I then cut jumpers for all the leads to connect everything all together. Once the components were soldered, I came back with a hot glue gun to keep the parts from rocking on the mdf. Soldering all the parallel leads together was somewhat hard but not insurmountable. Next time I would make a positive and negative punchblock bus and connect leads that way. That would make tweaking waaaaaaayyy easier.

Because the the BB plywood ripped and reglued is considerably more rigid than mdf, the only bracing is the chamber separation.

I used PE Sonic Barrier on the insides with dacron fill.

The front baffle has 6 1/4-20 screws into Tnuts with 1/8" speaker gasket to keep it sealed.

I found learning Sketchup (free download) very helpful in designing the cabinets.

I think my next build is a center but I'm limited on space. Currently researching low profile CCs but have found one worthy.

Also, I have moved the ZFMs off the tv stand away from the tv and on their one stands about 10" off the floor.

Hope that helps.


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## Mario (Jun 2, 2009)

Hmm I think I'm gonna follow your crossover building technique , except I'll put the components closer together to cut down on the number of jumpers required. 

I used PE Sonic Barrier in my ZMVs and was hoping to find something a bit cheaper for my next project. 

I'm not sure about skipping bracing completely, whether it's MDF or plywood. With ZMVs I used a simplified bracing technique where I used a forstner bit to cut half way into both side walls of the cabinets and then sticking a piece of one inch dowel inside. Much easier than messing with rectangular braces. 

You say you used 1/8 inch speaker gasket to keep the cabinet sealed. I was thinking about that, but am worried that it would create a visible gap between the baffle and the cabinet. It's kinda hard to see it on your pictures, but I assume it's there.


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## bigbugberg (Jan 12, 2009)

I like your bracing idea! The dowels will probably also deflect internal waves better as well.
As for the front baffle, yes, there is a small gap. My center channel design has a dado half the thickness of the gasket.
Another technique for the front baffle might be similar to a jewelry box where the entire box is made enclosed and a band saw is used to cut the top off the box. This ensures perfect alignment of the front baffle. If you apply a vernier of some sort you can make through dadoes and cover the ends with the vernier. You could also make stopped dadoes with a router but the setup takes longer. This would eliminate the gasket gap. But if the front baffle is not square, flat, and secure, you may get leakage or the baffle might vibrate against the cabinet.

Being this was my first build, learned a lot and I definitely will do things differently on my center channel!


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## Mario (Jun 2, 2009)

This is probably a stupid question, but why do the Zaph's plans show 100 mm port for 41Hz tune? According to port size calculators ( such as inside sonosub.exe) port length for .69 cu ft enclosure and 1.5 inch port width, should be closer to 3 inches, not 4. Do I need to know the exact value of empty volume (by subtracting drivers and crossovers) to figure out the required port length?


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## bigbugberg (Jan 12, 2009)

I loaded the values in both LSPCAD Lite and WinISD and got different results but they only varied about 3Hz at f3. I know I can't hear that small of a difference.

I still haven't measured my speakers. I will post results when I do. I have some issues with the size of my room and the hardwood floors and bare walls; that needs fixing before an honest measurement can be done.


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## Mario (Jun 2, 2009)

I simulated RS180 in WinISD using measured T/S params from Zaph's site and it looks like 41Hz is the best tuning frequency. Now the problem is that I need to know the exact volume of the enclosure to calculate the port length. Zaph's plans show 19.5 liters per chamber, but that's not accounting for braces, drivers and crossovers. I guesstimated the volume of all three at 1 liter tops. Entering 18.5 liters in WinISD I get 3.22 inches port length for 41Hz tune. To get 3.9 inches (100 mm) of port length I have to enter 16 liters, which is not realistic. The two flares could account for the missing .7 inches, but I'll need to make some measurements to confirm it.



bigbugberg said:


> I still haven't measured my speakers. I will post results when I do. I have some issues with the size of my room and the hardwood floors and bare walls; that needs fixing before an honest measurement can be done.


I'm not an expert, but I think you can still do pretty accurate nearfield measurements of individual drivers. I'd be very interested in seeing the response of RS180 with Zaph's suggested port length.


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## XxxBERRYxxX (Sep 13, 2007)

I keep looking at all these fine creations in the DIY sections and it's like I open one thread and go, "Wow, thats nice!" Then I open another do it all over again. You guys are VERY talented. You make me want to go build something. Nice work on those, they look very nice.


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## Mario (Jun 2, 2009)

I hope the OP doesn't mind me hijacking his thread to post an update on my slow (but steady) build of my own set of ZDTs. I decided to stick with what I know, using the tried and true method of pegboard+zip ties for the crossovers. Not much to look at, but easy to put together with the minimum number of jumper wires. I also used terminals for the padding resistors to make tweaking easier. The enclosures are pretty close to the original plans except for some minor tweaks and the use of 1-1/4 inch dowels as braces.


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