Forums - Poor Man’s ZROB

Hearafter

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Poor Man’s ZROB
01/10/26 at 04:03:00

The Decware ZROB is an interesting design that I have been planning on making a DIY version for about a year now. I am curious how an OB design sounds and the omni flip design peaked my curiosity. Well I just lucked into a new unused pair of Lii Song Fast F-15’s for $250 + $40 shipping. I used scrap particle board etc. at no cost to make a prototype to see if it warrants making one of solid wood. With only 10 hours of use these speakers have some incredible potential. The detail, clarity, highs and upper mids, 3D huge room filling soundstage excel. Bass and lower mids are definitely lacking but the speakers are improving as they break in. I do feel with the size of my baffles that a sub is required,which I have, and was expected. Size of my baffles are 24x18”, they have a 10 degree tilt on standard set up with an adjustable tilt of 38 to 42 degrees on the flipped Omni set up. The 42 degree Omni is currently preferred in my HT room using a Taboo amp with Zrock 3. It’s been a fun project for minimal cost to satisfy my curiosity.

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Hearafter Seasoned Member “In Tubes We Trust” Posts: 329	Re: Poor Man’s ZROB Reply #1 - 01/10/26 at 15:15:34 Question for any ZROB owners or listeners….I am debating whether it is worth the effort to add the Dayton tweeters and caps to my set up. The top end on these drivers seem to be their strong point. What do you gain by adding the tweeters? Is it a very meaningful add? It would double my investment😄
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Tony

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Re: Poor Man’s ZROB
Reply #2 - 01/10/26 at 15:56:09

Tom, nice work on the ZROBs. Your material costs were minimal, and the prototypes look fantastic. It sounds like you have plans to replace the particle board at some point, any idea what kind of wood you might use for a final design? The bottom line is that you like what you've got now, and that's exciting.

Good workmanship and creative.

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Donnie Seasoned Member Why does it hurt when I pee? Posts: 2440	Re: Poor Man’s ZROB Reply #3 - 01/11/26 at 02:30:30 I would think that adding the tweeters would help in getting better spatial cues. They would probably image better and sound more open. That's my guess and I'm sticking to it!
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Hearafter

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Re: Poor Man’s ZROB
Reply #4 - 01/12/26 at 20:44:39

Tony- Thanks for the kind words and encouragement. If these are keepers after break-in and adjustments I have some 3/4 inch Brazilian Cherry floor planks that I could use to do a trim around the sides of this design. I also have leftover walnut veneer from my Sonido speaker build I can use as well. Or if I decide to only use it for omni I might contact Randy to see if he will make one of his standard Caintuck thick baffles with an extended base that I could cut and add hinges similar to my prototype for angle adjustment. So many things to consider. These ZROB-like prototypes seem to amaze me in omni set up and they keep getting better with break-in.

Donnie-Thanks for your words of wisdom and input. Tweeters are probably in my future. It’s hard to stop the constant need to improve. I always value words of advice from experienced fellow Decheads!

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Hearafter

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Re: Poor Man’s ZROB
Reply #5 - 01/25/26 at 03:51:08

These speakers are really improving with break in hours. Bass is just not there but a sub integrates well and makes these drivers sing. Really nice room filling sound. It takes some moving them around and playing with tilt angles to find the sweet spot. I added some leftover 3/4” cherry wood ~4” trim which seems to improve the SQ as a bonus. Ordered a couple tweeters to mount on top and 2 different cap sizes for tweeter protection. No XO’s needed…should be fun to do some more tinkering.

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Bottlehead

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Re: Poor Man’s ZROB
Reply #6 - Yesterday at 06:11:34

Hey HA,

I was looking for this thread when I added the following to the General Topics section:

I see that you built a DIY ZROB, and I’m wondering if you checked out the new Lii Song Ting horn tweeters. They have a crossover that gives you three options for volume attenuation, and are made to add to the Lii full range drivers, esp the F15 and the Fast 15. Randy has pictures on his website, and a little write up in the Speakers section of this forum.

(The Other) Randy

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Hearafter

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Re: Poor Man’s ZROB
Reply #7 - Yesterday at 08:18:00

BH, Thanks for the input. Yes , I have checked those Lii Super Tweeters out and they look great. Just difficult to set up with my DIY ZROB and more than I was willing to spend. I am just now sitting and listening to my GRS RT2.0-8 Neo tweeters with the DIY ZROB’s that arrived today. Wooooh these tweeters really bring extra life to a speaker that were already sounding very good. Just amazed what these add to my DIY ZROB. Should get better with some hours on them and the Caps. My favorite set up is placing them on the floor next to the ZROB aligned with the Fast F15 driver, slightly toed in and set at the same angle up as the ZROB. Once I build a better tweeter box I ‘ll post some pics.

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Bottlehead

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Re: Poor Man’s ZROB
Reply #8 - Today at 05:35:08

HA,

Those tweeters look cool, and I’ve had good luck with pleated diaphram tweeters. As a matter of fact, the speakers that I’m using for my computer setup are Martin Logan bookshelf speakers with pleated diaphram tweeters.

Also, I noticed in one of the earlier threads that you have Alan Eaton 45 monoblocks. I loved mine, and then I found an amp that he built with the power in a separate chassis. Turned out to be quieter than my monoblocks, so I sold them. Can’t go wrong either way.

Randy

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Hearafter

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Re: Poor Man’s ZROB
Reply #9 - Today at 16:35:20

Randy, Sure enough, there is always something better to suck us into an upgrade. Yes, I love my AE 45’s. I just have to rotate 3 amps into two systems…decisions…decisions. Currently, I am really enjoying my Taboo breaking in my DIY ZROB’s. I’m just continually impressed at how well the Taboo sounds with these speakers. Just a really good pairing as are the tweeters I added. As Donnie suggested, the tweeters add “better spatial cues. They would probably image better and sound more open.” Tried two different Jantzen Z Cap sizes (5.6uf same as the Decware ZROB and 10uf) as tweeter protection to compare SQ. With my set up and room the 10uf Cap provided another noticeable level of improvement over the 5.6uf. I added a pic of my rough tweeter baffle prototype. I tried moving the tweeter to several locations including on the top of the ZROB. My preferred location is pictured. Speakers disappear with the best soundstage and detailed clarity that fills the entire room. I plan to make a finished tweeter baffle to mirror my ZROB. The fun continues! Tom

Note: For the budget conscious my total costs for second hand new drivers $300, tweeters and parts $175 is under $500. The wood was on hand from prior projects.

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