Audio Artistry CBT36K kit

[agarwalro]

hey man that sounds like a last name, would you prefer to be called by your first?

They call me "Tater Salad" . Nah, I go by, 'Ro', short for Rohit. It is no biggy, Agar, Agarwal, Ro, Rohit, whatever. Thanks for the concern and a tip of my hat for great etiquette.

This speaker is meant to be standing (or hanging) above (or below) the floor (or ceiling) in order to act as a line source. If you block off half the speaker's output with drywall, then you're effectively messing with the design.

The CBT builds on the line source concept. It is half arc length of the semi-circular Legendre shaded array. It needs the floor bounce to compete the desired response.

 

[GranteedEV]

They call me "Tater Salad" . Nah, I go by, 'Ro', short for Rohit.

I was close. I figured it was short for Rohan

 

[Velcrofly]

Thanks for the thread

Benbodtke,

Thanks for starting this thread. I am an avid DIY'er. mainly 2ch tubes. vinyl. and a passion for all things audio. I'm looking for a new project and while researching vertical line arrays for my next design I found the CBT36. I am seriously concidering "pulling the trigger" on a pair. Like many others finding threads on the 36'es are far and few in between. paticularly anyone with an independent listening experiece. I am looking to experence a pair connecting them to a quad of home built KT-88 set mono block amps and an analoge active crossover. Again Im looking forward to following the thread.

 

[agarwalro]

I was close. I figured it was short for Rohan

Hey that was a good guess. I'm assuming you have someone by that name in your circle .

 

[benbodtke]

BTW, Ben, I would try to avoid having any 90 degree corners if you do end up with a falsewall. Try to have large format 45 degree bevels where possible.

Don't discount the possibility that maybe you don't even need a center. Perhaps stereo is perfect for your needs. Build the speakers first and then decide on the rest. I know I don't particularily care for center speakers, at least until I can do the whole AT screen thing myself.

I dont plan on having any 90 degree corners, I will find the pic of the soundstage/falsewall that I am contemplating and post it here. I usually like center speakers but I need to hear these first to decide on whether I need one or not. Like you said, I may not need one.

I am having a sample of that screen sent to me, should be here in a couple of days. Another DIY screen, I am going to be busy.

 

[benbodtke]

Benbodtke,

Thanks for starting this thread. I am an avid DIY'er. mainly 2ch tubes. vinyl. and a passion for all things audio. I'm looking for a new project and while researching vertical line arrays for my next design I found the CBT36. I am seriously concidering "pulling the trigger" on a pair. Like many others finding threads on the 36'es are far and few in between. paticularly anyone with an independent listening experiece. I am looking to experence a pair connecting them to a quad of home built KT-88 set mono block amps and an analoge active crossover. Again Im looking forward to following the thread.

I am just now getting the painting close to being done now. But I have been going through the manual and it doesnt seem to hard. I initially thought I would have to solder each tweeter to the driver, but they came attached already. That made it a ton easier.

I am just using a couple of Crown amps, which I received today. Also going to set it up using the DCX2496, comes in tomorrow. I may change the stuff later on but for now I want to keep the cost down to please the wife.

It has been a fun project so far, but its really just started. I will post some pics soon of the speakers, they are not the greatest, and if I am not satisfied with them when I am done, straight to the automotive shop for painting.

 

[agarwalro]

Hi Velcrofly, welcome to the forum.

and an analoge active crossover.

You will need a DSP processor (like the DCX2496, DEQX or mini DSP) in which to implement the 16 filters per channel. Combined they constitute the crossover, constant directivity shelf and response eq, all the while keeping phase fairly constant across the board. Most likely, the analog crossover by itself will not work for the CBT 36.

 

[GO-NAD!]

As has been mentioned by agarwalro (hey man that sounds like a last name, would you prefer to be called by your first? ) you'd be blocking off half the speaker. This speaker is meant to be standing (or hanging) above (or below) the floor (or ceiling) in order to act as a line source. If you block off half the speaker's output with drywall, then you're effectively messing with the design.

Line sources are best when vertical, as they minimize offensive vertical reflections while maximizing desirable horizontal reflections. That is why we want it be behind an AT screen, as flipping it on its side would probably have ill effects on the perceived multichannel soundstage (though probably not the timbre, luckily).

BTW, Ben, I would try to avoid having any 90 degree corners if you do end up with a falsewall. Try to have large format 45 degree bevels where possible.

Don't discount the possibility that maybe you don't even need a center. Perhaps stereo is perfect for your needs. Build the speakers first and then decide on the rest. I know I don't particularily care for center speakers, at least until I can do the whole AT screen thing myself.

Whoa, hold on!

We appear to be talking about two different things. Perhaps I should've been more clear about what I consider to be a false wall for an AT screen. I consider - by default - that a false wall for an AT screen to be acoustically transparent as well. Just framework covered by speaker grill cloth. I certainly wouldn't use drywall!

I thought that was a given, but I guess I shouldn't assume that everyone is on the same page as me. My apologies.

 

[Velcrofly]

Center Channel and Surround Alternatives

Okay I'm just spit balling here and a 2ch guy so don't beat me up to bad but, I had a moment.
What if rather than using 1 whole speaker for the center channel cut it into 3 equal segments. Each having 6 speakers and 18 tweeters. The center channel would have no power tapering because if mounted horizontally you want off axis symmetry and the rear or surrounds in a 5.1 system could be hung from the ceiling. The smaller segmented speakers would still maintain the same arc and use the ceiling rather than the floor for the reflective properties. This in someway resembles a free standing vertical line array much like you see at a concert. I know you can't buy just one speaker so if you had a 2nd pair some subset of the 2 could complete a 7.1 system.
Again just a thought.
As far as painting I did send a project to the body shop once. A pair of Lynn Olsen Aerial Mk VI's I built myself in 2003 are now in Cadillac Escalade White Diamond. They really look nice however the horizontal imaging narrowed. The sweet spot became about 24"X24" in an equilateral triangle from the speakers. Each speaker is aprox 135lbs so I don't think the natural freq changed. Probably a standing wave issue with the glossy paint. Not saying this will happen to you. Just my experience and excited to hear about the sound check.

 

[Solid-State]

The first coat of primer just went on the first tower. I hope I get this right. I am going to Hedahls tomorrow to have them shoot my sub for color. Then get them to make the automative paint for that color. A little more expensive but its worth it. I was thinking the sub color which is rosenut for the sides and back, and a high gloss black for the faceplate. Well those are my thoughts, any other suggestions...

you really need to seal MDF!

uhh... one sec I have a post on another thread regarding this stuff.

 

[Solid-State]

I'm curious as to what products to use working with MDF. What is the best glue to use to bind joints. Should I use a biscuit? How should I prep the MDF at the joint. Sand it? As for glues for veneer the local hardwoods shop said use epoxy. I mentioned the iron on glue stuff DIY seem to use but he had no idea what I was talking about and said "no no use epoxy" but this guy knows nothing about MDF substrate. I have heard so many varying opinions on the topic that I'm rather lost as to how to finish the cabs LOL. It seems very little is known in the wood working community how to work with MDF and they all stick their noses up and use baltic birtch. I found some great posts on the shop bot forum regarding working with MDF.

"Sherwin Williams "Promar" E-Z Sanding Lacquer Searler B44FT8" seems to be popular as a sealer for Lacquer top coat.

This seems to be the best way to apply it.

To get the best results, I suggest this procedure and you will get good results and as you refine it you will get perfect results.

1. Sand all edges with 150-180g
2. sand all edges with 200-300g
3. primer using a lacquer based sanding sealer
4. sand whole thing with 300g
5. add another coat of sanding sealer and another if needed.
6. paint as usual...

By using that process you will get a bullet proof finish. Heres why...

first you are sanding to remove any machining marks, then you are "burnishing" with 200-300g.

What this means is you are using the micro dust to seal the edges as you are sanding.

Then by adding the sanding sealer you are in effect making a surfboard type of finish, the sanding sealer soaks into the pores making it one solid surface."

Mdf finishing - Let's Talk ShopBot
Some 2008 PRS Alpha Highlights - Let's Talk ShopBot

And this is an interesting post
Has Anyone Ever Heard Of Using Lacquer As A Primer?? - Painting & Finish Work - Contractor Talk

The top coat is Porter's Glyptex High gloss oil.

This stuff I can easily source.
Sandable Primerrimer | PlastiKote Paint Products

I found some interesting products and I wonder if others have used it with MDF

This looks like a potential FANTASTIC sealer for MDF

MultiWoodPrimeTM CREATES COATING ADHESION

They also make a glue in which the marketing material specifically mentions speaker cabinets.

Star Distributing * Similarities and Differences between Tropical Hardwood Epoxy and Oak and Teak d Glue Information Page

Looks like great product.

veneersupplies.com is a good source for heat lock glue for the iron on method, as well as other glues if you have a vacuum press.

 

[Solid-State]

If you don't seal MDF properly and if you use a latex based sealer it will telegraph and bumb on you BIGTIME and any paint you apply will look HORRIBLE.

I found that using the "burnishing" sanding method on ALL MDF pieces first then I apply MultiWoodPrime and sand it again down to 300g burnished level you can apply something like Porter's Glyptex it comes out looking like glass/liquid "hand rubbed". That MultiWoodPrime stuff is just AMAZING!

Same goes for their glue. The Star Distro glue is the best MDF/wood glue on the market. Hollywood use it for set construction as does luthiers etc for instruments.

 

[benbodtke]

Ok, so its been a while but I finally found some time to get this along. We will be done un under two weeks but here is some progress.

 

[slipperybidness]

Lookin good. Thanks for the update.

 

[DS-21]

Beautifully-done finish.

I would love to hear some CBT's.

 

[Bjorn]

You will enjoy them. I don't think people understand what breakthrough this is in a speaker design. The response is very uniform.

 

[benbodtke]

I am almost all set up, just trying to figure out how to get it all hooked up the way I want it. I have given up with being able to hook it up to my Yamaha receiver. Is there a decent preamp out there this isn't super expensive.

 

[Bjorn]

I am almost all set up, just trying to figure out how to get it all hooked up the way I want it. I have given up with being able to hook it up to my Yamaha receiver. Is there a decent preamp out there this isn't super expensive.

Since you need a crossover anyway, I would get the miniDSP 4x10 Hd. It has a volume control and is very transparent sounding. Much better then the Behringer DCX2496. Costs $399 plus shipping:
miniDSP 4x10 Hd | miniDSP

The CBT36 are trully awesome speakers. My search is over!

 

[benbodtke]

It's been a while since posting but figured I would give an update. I def should have insulated the walls with dynomat or something. Wife does not like the loud music. I have maybe got to enjoy 3 hours on these beauties. Will be putting up for sale as soon as can figure out what I want for them.

 

[GO-NAD!]

It's been a while since posting but figured I would give an update. I def should have insulated the walls with dynomat or something. Wife does not like the loud music. I have maybe got to enjoy 3 hours on these beauties. Will be putting up for sale as soon as can figure out what I want for them.

You're selling them!? After all that expense and effort? That's really too bad. If the music is too loud, can't you just....I don't know...turn it down? What will you replace them with?