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Cornscala build in the time of Covid.


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Hope everyone is safe. Im working 2-3 shifts a week in the ER doing mental health assessments and still doing a full load at the community clinic I work full time.

Both positions are deemed essential due to need for management of emergent mental health needs.

Each day Im getting my tempt checked and asked about symptoms before being let in the door.

I have to say its become more stressful over the past 3 weeks and only seems to be compounding. 

 

With all these stressors cropping up, my mind turns to the long process of building a new set of speakers as an escape. 

About 4 months I reached out to Dave Harris and asked for baffles and horns. Dave was busy and put me in the Que. 

Then about a month ago, Dave was in the Irvine area and came and heard my lasted iteration with his baffles... Faital Horns/Faital & B&C driver combo for compression drivers. 

Its a truly great cornscala, built to the hilt... no screws more braces than you can shale a stick at.. That said, it doesnt have Dave's mid horn and I miss that.

 

So after some repeated requests, Dave cut me some new baffles and horns. Like each before, there a but different; trying a new idea or two. 

The ports are 4" PCV and the baffles are MDF. Ive never built a speaker with the baffle being MDF. The horns and baffles key in so tight. Ill have to clearance them just a bit to get them in. 

The lovely thing with the MDF baffle to MDF horn is just how tight the tolerances are. There will be less fill time.

 

Dave suggested I use a water based Poly to seal them a other products can wick the MDF. Last night I sealed them inside and out. The sealing the inside is likely an error as it has made them harder,but nothing some cut knuckles and sandpaper wont fix. 

 

The plan is highend Ply, lots of braces and everything bolted in place.

Once the ports are glued in, Ill take a 1/2" round over to flare the port.

Drivers and corssovers havnt been fully fleshed out.  

 

Few tid bits... The horns have to be sanded smooth first... then more polly and finishing. The last layer has to be finished separately. Ive pained them together and the paint cracked when they are pulled apart.  

 

 

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  • 2 weeks later...

I’m still mulling if I should laminate a 1/2 ply to the inside. I’d have to route out with a collar and then expand the holes to make large enough to clear the first layer of Dave’s horns. I’ve never had a baffle thicker than 3/4”.  

Might be a good use of energy?

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So I’ve decided to laminate 1/2 ply to the back and rout it out to have the first layer of the horn key into the 2nd layer.  The idea is for constrained layer dampening and increase  Rigidity. I will prime both sides to seal it all up.  
when I finally get to build. I’ll dado in the baffle to some it ever coming lose. 

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  • 3 weeks later...

slow progress but progress none the less. 

 

3/4" CNC cut MDF baffle matted to 3/4" ply and hand cut. The 2nd layer of the horn now will key into the baffle the same way the 1st layer does. 

The hope is that the baffle is more rigid and the the horn is better supported too. 

After my existing Cornscalas are gone, Ill get to the building of this pair... I plan to dado the baffle into place. 

Here are the progress pics. 

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  • 1 month later...

Slow progress but cabinets and finishing will be done by 6-23. The baffle and back brace is dado’d into place.  We did a interesting thing by cutting corner braces at 45deg. Should reduce cabinet residences. Here is where we are so far. 
Drivers are kappa 15C DCM50 and radian 1” for once I’ll have a tweeter that can really carry to 20K. 

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3 hours ago, justinsweber said:

Slow progress but cabinets and finishing will be done by 6-23. The baffle and back brace is dado’d into place.  We did a interesting thing by cutting corner braces at 45deg. Should reduce cabinet residences. Here is where we are so far. 
Drivers are kappa 15C DCM50 and radian 1” for once I’ll have a tweeter that can really carry to 20K. 

 

quick question , why MDF vs BB

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The sides are Baltic 

The rear brace is MDF. 
Dave Cit for me and I didn’t specify. 
The front baffle is 1.5” thick. 
3/4” MDF which is meant to provide the tightest most cohesive fit into the horns which are also mdf. The 2nd layer of the baffle in ply for added strength. 
The rear panel is Baltic. 

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3 minutes ago, justinsweber said:

Also for the corner supports/deflectors have Posstive engagements tying front baffle to rear brace. In general I’m trying to reduce cabinet talk. 

A worthwhile improvement, which has also been incorporated into the new Cornwall IV. I presume WITHOUT extra materials and the, perhaps "overkill" way you did it. Nice work as always.

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Im not sure if Klipsch has incorporated deflectors as integrated bracing or dadoing. Both power on the face of it solid ideas. The 2 places I chose additional material is the back brace. I wanted more than the standard 3/4 mounting face. I have about 1.5” of shared contact face. The back board used 14 1/4-20 bolts to attach. The idea again to snuff the life out of cab talk. The other place was the double thick baffle. The idea is take. From subs I’ve seen built, and by wearing the materials between MDF and ply I should move the breakup nods higher up. I’m getting to a place here I’m less likely to be building a pair a year and so wanted one last big build.  Al did a CSW which should pair well with the eliptrac and the dcm50. 

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  • 2 weeks later...

Did final assembly. 
Tuning questions are left. 
Have the DE10 at -4 dB down. Likely to live to -6 it’s a small room and I want to be able to listen for 2hrs at a time without fatigue. 

Ive ordered an exceptional Faital HF that I may roll in but I intend to having tuning set for each. 
 

The DCM50 is at 9,0... the LF is a bit muted. I will switch to 12,0 and re-Listen. My Guy tell me I’ll be at 12, -1 when all is said and done. 

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