The Complex Curve on a Rectangular Horn...

I have had a lot of people ask about making their own midbass horn - PLEASE DO!!!

My method for a quick single or pair is to build rectangular. You can build a horn like this in a very long weekend if all the steps have been carefully planned...

but how to cut that complex curve that is the intersection of the curved wall and the straight wall??? extremely difficult to plot... and even if we can plot it, how many of us have a large CNC 3D router?

so I cut the straight side walls out of 3/4" plywood or even doubled up to 1.5", depending on panel width... I then screw in a brace that is right down the middle... this is easy to plot as it is just the center axis of the horn expansion... you can remove the brace later or keep it in if you want.. your choice..

when you drop a yardstick/meterstick across the face you will instantly see the complex curve... how will you ever get a piece of bending ply to fit properly on that uneven surface? simple. make it flat...

I do this with a "contraption"... that is southern for homebrew tooling... jig... doohickey-thingamajig... whatever... belt sander screwed and clamped to scrap wood... pictures tell it all...

brace in place:



contraption:






I clamped and screwed the sander to a piece of wood:




The actual setup for sanding.. you want this horizontal as your arms will be tired:





check your progress with that meterstick:



not quite:



yep, got it:



close enough.. remember that on a midbass horn, a cm or inch of error is lost to the wavelengths in use... do not go crazy with trying to keep extreme accuracy... quality of build is much more important! stiffen... listen... damp lightly... brace... lacquer... love.. listen... that is how you make great midbass horns.. and do not be afraid to say "that sounds terrible" if it does.. that is only motivation to make it better...


adding layers in the next installment.... i tried to start and finish on Father's Day weekend... I lost... so maybe one late night this week...

Peace,
Me

Smoking in the BP

So we pull in to fuel up and some people will take any chance they have to sneak a smoke.  Even an Alabama action painter.

One Fine 7C

What is that Mike has.

What is inside

Not your average 7C

No time like the present

Noise graded no less...

some of the story

Day one 1:45am... Keychains, Platters and Idlers

The title says it all.  It i now 1:45, about the time I wanted to make the first post but alas It is 1:45pm and win is still sleeping.  I guess that is what happen when the sun tells you it is time to sleep.

301 reasons to come down.

A nice keychain.

 

 Idle Hands

Swarf Rats

sorry to be absent lately... getting ready to head down to the Capital Audiofest to play for a few days.  I'll be hanging out in room 378 "Vinyl and Vintage" with some cold beer and a handful of toys so stop by if you are attending.  When I get back I'll do a mini-show report but until then.... I'll give you the latest script for "Swarf Rats"

The story starts with a money shot of what used to be a 5" chunk of aluminum with a couple of 6" end plates.

In order to get to that point, my fingers were getting very tired of turning the cross slide on my cheap lathe so it was time to get creative,  I looked around and 5 minutes later I had this:

Yes, that is a chunk of 3" firewood sawed off on a bandsaw with two holes attached to a cordless drill.  It also made an incredible power feed for cutting the taper.

Since I already blew the money shot,  i'll end with the title sequence and the net result of the time on the lathe.

Now before you say "well that isn't much"...  I'll assure you I could easily fit two little crackers into the space occupied by the swarf.

Fabulous Furry Freak Brothers...

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I really thought that Joe and I were "on the down low" coming from Amsterdam to Munich. I guess not. Thomas saw right through us from a mile away. He sent this picture around. As Joe said, "Jackson as Phineas Freak? You nailed it."

and JC, on the left, well... he grew up in the village *way* before it was clean... across the street from *the* park.. and I do not mean Central Park... he never had a chance to appear normal... especially not German normal...

but guess what, Mr. Schick Tonearms? I got you, too... remember this?



Peace,
Me

Goto 505 on Le Cleac'h 140 horn - measurements...

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My inbox popped up with more Goto questions... I guess someone started things up at Roman's forum again... one day I will catch up on my reading and head back over there.. I still owe him a phone call or two...


I noticed that there were no measurements at all in any of these discussions... so I figured I would post a few as I am actually listening to them out in the shop... you have to listen and measure and *think* to set up a good horn rig...

Goto 505 free air impedance:


Goto 505 impulse and frequency response on Le Cleac'h 140 horn:


This combination sounds very good... but I will say that it takes up too much space for the range it covers...

oh, and thanks again to the machinist who made these adapters:


and to DC, who sent me that laptop when I was down...

stay tuned.. something curled up is nearly done... lots of midbass compression drivers and cone drivers to test in the near future... something to go *below* this 505...

Me

I need a bigger Lathe.

 

I received this in the mail today as a thank you from fellow lowther enthusiast Matteo in Italy for sending him a lowther reformer.

A few clicks in google brought me to this blog post that had some speakers with his signature on it and some other eye candy.

source

I remember seeing these before and the (blog is now linked) it reminded me when Herb came over to sharpie work the Feral Eye 

give papa $29 for the original art

At some point I need to do this treatment to my bigfuns but where do you find artists that work for free?  Silly me, they all do.  JJ when you heading up this way?