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Old 29th September 2014, 04:49 AM   #1
shizzon is offline shizzon  United States
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Join Date: Mar 2014
Default Custom Zaph Audio ZRT 2 way build

Hello everyone,

For the past few weeks I have been working on building an enclosure for my ZRT 2 way kit. I decided to do something a little different and had a custom enclosure designed by Peter Kulicki of PWK Designs; the goal of which was to extend the bass shelf over a sealed design while not going to a full size tower. I gave the information on the Kit/Crossover, as well as a desired maximum external size (keeping the baffle geometry similar to the Zaph Kit), and let him decide what the best configuration would be. I know this is somewhat risky compared to building with the standard enclosure options for the 2 way kit, but I just wanted to see If I could get something fairly small that extends lower that the sealed configuration.

I received the design, and decided to add 5 inches to the bottom of the enclosure to house the crossover network as well as allow for a modular rear panel for binding posts and tweeter attenuation selector. Other than that I have increased the side wall thickness from .75" to 1.25" (double stack 5/8" maple ply), and increased the baffle thickness from .75 to 1.375 (double stack, 3/4" + 5/8" maple ply). External dimensions are 10" X 15" X 30".

Due to the design at hand I had to figure out how to get the speaker cables up through the horn/port. I ended up using 1/4" 101 copper bar laid into 1/4" slots in the left side wall, the bar has Supra classic 2.5 (13 AWG) wire soldered on both ends. The bars were then sealed into the side walls with a clear epoxy resin, it didn't turn out great, some air bubbles were entrapped, but I am sure it will function well and prevent oxidation/discoloration.

The bevels on the sides of the baffle are 1/2" to keep the same 9" baffle width as the Zaph enclosures, as with the thicker side panels the enclosures are now 10" wide. The tweeter sits 1.65" lower than on the Zaph Audio enclosure, so I will create a large bevel to match the distance from the tweeter to the top edge of the baffle on the Zaph enclosure.

The side panels received two layers of Damplifier Pro inside the compression chamber, while the top, back and bottom walls of the compression chamber received a single layer. Two layers of open cell acoustic foam were applied to the back of the compression chamber directly behind the mid woofer, while all other walls received a single layer.

I still have a few more things to do before I glue on the right side, such as add the 45 deg. panels in the corners of the horn/port. Also, I need to cut out the back panel for the binding post plate.

All in all, for my first build things are going well and I am having fun and learning a lot! Hopefully the pictures I have attached work.
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Old 29th September 2014, 08:51 AM   #2
Scott L is offline Scott L  United States
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No pictures have appeared, but I must say you are very detailed oriented especially in light of the fact this is your first time build.

Had you heard a standard version of this design before you decided to build ?

Also, Am I to understand you went with a larger (than sealed version) enclosure, yet not to the full size vented version?
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Old 29th September 2014, 03:45 PM   #3
shizzon is offline shizzon  United States
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Join Date: Mar 2014
I see that the pictures that I attached did not work, I will see what I can do when I get home from work this evening.

To answer your questions Scott, I have not heard a ZRT design in any of the configurations. Im my area I didnt have much of a chance to listen to options before purchase, so after a lot of research I went with the ZRT. Besides car stereo and a little Focal 2.1 setup for the laptop I dont have much experience with high end home stereo, so I won't have much to compare these too.

The goal was to improve the bass shelf withought going to a full size tower, I believe that what Pete came up with is referred to as a folded horn (horn starts in upper front corner and wraps around the top/back/bottom with a 5 degree taper.

Hopefully I will be able to get some pics uploaded tonight to give a better idea of what is going on.
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Old 30th September 2014, 03:21 AM   #4
shizzon is offline shizzon  United States
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hopefully these work...
Attached Images
File Type: jpg slots.jpg (117.7 KB, 584 views)
File Type: jpg slots 2.jpg (90.3 KB, 582 views)
File Type: jpg slots 3.jpg (84.4 KB, 576 views)
File Type: jpg Compression chamber.jpg (117.6 KB, 568 views)
File Type: jpg compression chamber 2.jpg (79.3 KB, 565 views)
File Type: png PWK box.png (62.0 KB, 300 views)
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Old 30th September 2014, 06:46 AM   #5
shizzon is offline shizzon  United States
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I just added the corner braces tonight and glued the right side on. I still have to add the other .75" panel to the front and do the counter bores so the woofer and tweeter are flush with the baffle, plus some additional work to the back panel for the binding post plate.
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Old 30th September 2014, 10:11 AM   #6
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IMHO, you took a risk in modifying the design in some sensible areas. Moreover doing so with an expensive design.
First: changing baffle size (width, and driver positions from the top), means that diffraction related FR will change. You should have at least simulated it before building the cabs for example with BDS (free SW, requires excel).
Second: bass loading. I'm not into horns so I cannot comment on the viability of the solution chosen, but one of the plus of the SS midbass is the bass, and the tower version is designed to take advantage of that. Again, a horn should have been simulated correctly before. What's the tuning obtained?

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Old 30th September 2014, 03:54 PM   #7
shizzon is offline shizzon  United States
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Hi Ralf, thanks for the input. I agree that I have taken a risk by going with unproven design, but I have also tried to mitigate the risk by keeping the same baffle geometry as the Zaph enclosure. The design above is 10" wide as apposed to the 9" on the zaph enclosure, so I will do a 1/2" 45 degree bevel on each side to get the effective baffle width down to 9". Due to the location of the start of the horn, the tweeter location is 4.65" down from the top instead of the 3" on the zaph enclosure, I will account for this by adding a 1.65" 45 deg. bevel at the top above the tweeter.

You will see that I deviated from the mid/woofer location that was recommended in the designs that were sent by Pete, I did this in order to keep the baffle geometry as similar to a standard ZRT enclosure as possible. Pete is well known in the car audio world for designing sub woofer enclosures, and simulates the designs in a program that he wrote/developed. I ordered the "graph pack" when I placed my order, I have attached the simulated Frequency Response and Impedance Profile plots.
He has also done a fair bit of experimentation and design in the realm of two channel stereo systems, ranging from bass reflex, full range horns and dipoles from what I have seen. Here is a link to a build that first got me thinking about having a custom design made (Sculpture 101 HT Monitor ).

With the changes made to the design I have decided that it would probably be best to incorporate the tweeter level/attenuation (R8) as well as the mid-range baffle step compensation (L10). The planned circuit is also attached. The additional resistors and inductor will be selected via the rear panel, so I should be able to adjust for listening preferences as well as for room size or near field listening.
Attached Images
File Type: png Frequency Response.png (99.8 KB, 268 views)
File Type: png ZRT Crossover.png (45.5 KB, 178 views)
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Old 1st October 2014, 03:45 PM   #8
shizzon is offline shizzon  United States
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Join Date: Mar 2014
Now that one of the enclosures is nearly completed and the end of fabrication is in sight (next one should go more quickly I am thinking), I am starting to think about other items for my setup.

I will need a source, Preamp, and Amp/Amps. For the source I am leaning towards the Oppo BDP105, but I am open to suggestions. For the longest time I was looking at Emotiva gear, with a XSP-1 Pre and XPA-1L monoblocks, but now I have the DIY bug and am looking into possibly doing some Hypex nCore 400's.

The hard part to get over would be that the nCore's would cost more to build than I could get the XPA-1L's for right now, but then again there is the cool factor of having a DIY amp. With the nCore's I would probably do monoblocks and make them so that they fit in or under my speakers, keeping speaker wire lengths to a minimum and also cleaning up the install and increasing the WAF.

Any words of wisdom on selecting the rest of the gear that I need to listen to these?
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Old 6th October 2014, 04:06 AM   #9
shizzon is offline shizzon  United States
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Join Date: Mar 2014
hello All,

I have been working away on the first enclosure and have nearly completed the first one; I have gotten it to a stage where it can at least be tested. I borrowed an Onkyo receiver from a friend and have listened to the single speaker a moderate levels for several hours.

At first I was a bit disappointed in the bass output, though overall the sound was great, it was lacking in the lower notes. After several hours of listening, however, the bass has improved dramatically, and the overall package is sounding good. Granted, this is only a single speaker, but so far so good. As of right now I am just using the stock binding posts/terminals as well as the stock crossover (7 ohm resistor on the tweeter circuit and 2.7mH inductor on the woofer). I will probably still buy the other resistors and inductors just to have options, but as is the speakers is to my linking, and I imagine things will only improve when I add the other.
Attached Images
File Type: jpg Front-Back.jpg (61.2 KB, 167 views)
File Type: jpg Speaker Cutouts.jpg (51.0 KB, 157 views)
File Type: jpg Details.jpg (57.0 KB, 155 views)
File Type: jpg test fit.jpg (59.9 KB, 211 views)
File Type: jpg Ready for speakers.jpg (90.9 KB, 217 views)
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Old 6th October 2014, 08:25 AM   #10
Lojzek is offline Lojzek  Croatia
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Originally Posted by shizzon View Post
For the longest time I was looking at Emotiva gear, with a XSP-1
Pre and XPA-1L monoblocks, but now I have the DIY bug and am
looking into possibly doing some Hypex nCore 400's.
Emotiva gear looks good and affordable. One thing bugs me, XPA-1L
specs say 250W/8 0hm and 500W/4 ohm. Being a class A/B amp and
with only 450 VA transformer, I am not sure where the 500 W could
be coming from. Certainly not from the default transformer.
Mankind is created for eternity.
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