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ZRT speaker build

Engelhorn

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Having been stimulated by the Gov't, I decided I'd use the money to build a pair of Zaph Audio ZRT towers. I have a small, bright room, short ceilings, highly reflective walls and floors, so it'll never be a perfect environment - but this design seemed like I could make it work. I'm forced to shove the speakers right against the wall, and I figured the xovers could be easily tweaked to compensate.

I built my own cabinets, and used Makore (African cherry) veneer, which has a wonderful deep color and some nice mottling, but nothing too crazy. Baltic birch, otherwise, and to the sizes recommended by John. Got the kit from Madisound, and was really hoping they'd perform - because these aren't cheap components!

I'm very pleased with them so far, haven't tweaked anything yet, as the response is surprisingly close! Plenty of base, an awesome transparent quality, and a surprisingly good soundstage - even in my stupid room. All the crap on top is simply to keep the cat off of them. Driving them with a Bob Latino ST70 "Dynakit", and my old noisy Carver preamp. I'm eagerly awaiting new input selector, tone control, and phono preamp from Schiit audio (months of waiting, grrrr).

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Gorgonzola

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I also make the Zaph Audio ZRT (Zaph Revelator Tower) speaker -- I absolutely love them: possibly the best audio investment I ever made.

Since my woodworking skills are minimal plus I had no table saw, I bought knock-down tower cabinets from Parts Express. These are slightly smaller than Zaph spec, (which were based on Madisound cabinets not longer available), but I was able to calculated a revised vent tube length. I place my vents at the back of the cabinet, (not sure this was the best idea but plenty good enough). I fabricated my own bases, (black in this pic).

gi.mpl
 
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Engelhorn

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Excellent, and I'm glad to hear you love them. I've listened for several hours over the last two days - everything from Abbey Road to Handel's Messiah to Rush and Tom Petty... They have a clarity that's a joy to listen to, and so far, seem very non-fatiguing.
 

antennaguru

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Jun 16, 2021
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They look very nice! Have you tried bringing them out a little further from the front wall?
 

alex-z

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Building some mineral wool absorption panels is easier than building speakers, and even a handful can turn a bad room into something palatable.

Last time I priced them out you can build 2x4ft panels at 3.5" depth for $25 a piece.

Also, a drop ceiling is an asset because you can throw some 6" insulation up there and turn the whole ceiling into a moderately effective bass trap.
 

xarkkon

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really beautiful speakers, well done!
 

AudioAaron

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Mar 2, 2021
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Great looking build.

What adhesive you use for the veneer?

How do you trim the veneer? The top piece looks perfect.
 
OP
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Engelhorn

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Because the room is so tiny, I can't walk past them if they come out from the wall... more than an inch or two. But they sound pretty damn good even pressed up tight. I'll spend a few weeks playing with placement etc...

I have "acoustic" ceiling tiles, better than drywall.. but shy of a bass trap for sure!

I used Heatlock from Veneersupplies.com. I have a veneer vacuum bag press, but these shapes are tough to do, so iron on is the way!

I glued the front and sides, let it dry, and ironed on the veneer. I then applied two coats of General FInish seal-a-cell before gluing the top, so my top glue didn't absorb into raw veneer and mess up the finish. All trimming was done with a down cut 1/4" bit from Whiteside.
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Gorgonzola

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Because the room is so tiny, I can't walk past them if they come out from the wall... more than an inch or two. But they sound pretty damn good even pressed up tight. I'll spend a few weeks playing with placement etc...

I have "acoustic" ceiling tiles, better than drywall.. but shy of a bass trap for sure!

I used Heatlock from Veneersupplies.com. I have a veneer vacuum bag press, but these shapes are tough to do, so iron on is the way!

I glued the front and sides, let it dry, and ironed on the veneer. I then applied two coats of General FInish seal-a-cell before gluing the top, so my top glue didn't absorb into raw veneer and mess up the finish. All trimming was done with a down cut 1/4" bit from Whiteside.
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Really gorgeous. What method did you use to round the edges?
 
OP
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Engelhorn

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I used a 1" radius router bit to round the edges. I have a speed control, so slowing that gigantic bit down a little is the key to safe and clean cuts. I also clamped a board to each end of the cut (at the top and bottom of the speaker) so I could ride past the ends without rounding over the top and the bottom. That large radius is both nice looking, and large enough to solve some diffraction issues. Unfortunately, my veneer plan killed my ability to round the edges on the top. I think, honestly, I could have built a false top and rounded the edges, but I don't really know how much impact that might have. I'm currently listening to The Wall on my old vinyl version from High School, and I'm extremely, extremely pleased.

Front baffle is 2 1/2" layers of baltic birch glued in my vacuum press. Sides and back are 3/4, FYI. Leaves enough structure under that giant radius. Also, I used materials leftover from other projects as I really spent quite enough already on the kit and the veneer!
 

Jim Matthews

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Nicely done. You have achieved something few ever manage; make something beautiful with your own hands, for your own use.

Kudos
 
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Engelhorn

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Just replaced my noisy old Carver "Sonic Holography" preamp with a few pieces from Schiit audio. The Saga+ for preamp/volume control, the Mani for a phono preamp, and the Loki for tone control (as my room and speaker placement is definitely not perfect). Power comes from my new Bob Latino VTA ST70 Tube amp (KindaDynaKit).

I'm nearly blown away. DEAD quiet and incredibly responsive and transparent (for want of a better word). I guess my old Carver was even worse off than I thought it was. Welp, it's going up on Ebay immediately, with a giant bag of fresh electrolytic caps to help with the noise and the key bounce etc.

I cannot say enough about these speakers, they are certainly the best I have ever had. I can't stop listening to them, my vinyl collection is coming to life again, and John Krutke deserves a round of applause for this design, IMHO.

Cheers!
 

gfinlays

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May 30, 2020
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I completely missed this thread earlier. I knocked up a pair of the ZRTs in a ~20 litre sealed enclosure made from 18mm birch plywood with a 36mm front baffle. Crossovers are Ampohm FP-CA-AU film caps and precision air cored inductors, with the exception of the 2.7mH woofer coil which is a high quality ferrite cored inductor. I went with the sealed box this time - despite its diminutive proportions, my prior experience with the 18W8531G00 tells me that it can be very 'bass heavy' for a 7". A previous bottom ported tower build with this midwoofer used to rattle the windows......

Yeah, I'm a sucker for Neutrik Speakons. I wish more manufacturers would fit them to their amps.



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I'm currently contemplating retiring this old girl for a pair of seriously good Class D monoblocs:

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Matthew

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May 4, 2018
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Having been stimulated by the Gov't, I decided I'd use the money to build a pair of Zaph Audio ZRT towers. I have a small, bright room, short ceilings, highly reflective walls and floors, so it'll never be a perfect environment - but this design seemed like I could make it work. I'm forced to shove the speakers right against the wall, and I figured the xovers could be easily tweaked to compensate.

I built my own cabinets, and used Makore (African cherry) veneer, which has a wonderful deep color and some nice mottling, but nothing too crazy. Baltic birch, otherwise, and to the sizes recommended by John. Got the kit from Madisound, and was really hoping they'd perform - because these aren't cheap components!

I'm very pleased with them so far, haven't tweaked anything yet, as the response is surprisingly close! Plenty of base, an awesome transparent quality, and a surprisingly good soundstage - even in my stupid room. All the crap on top is simply to keep the cat off of them. Driving them with a Bob Latino ST70 "Dynakit", and my old noisy Carver preamp. I'm eagerly awaiting new input selector, tone control, and phono preamp from Schiit audio (months of waiting, grrrr).

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Nice looking veneer!
 

egellings

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If those speakers sound as good as they look, you should have some real winners there.
 
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