New Dipole Project

PWRRYD

I was impressed with Andy's dipole project in Iowa last weekend.  The dipole bass was really impressive.  It was smooth and natural, and it didn't change much as I moved around the room.  Not long after it played I started discussing project ideas with John Hollander.  We've emailed back and forth a bit since then and I started building some prototype test baffles today.

I went to Menard's this morning and found a couple of 2'x4'x3/4" particle board handi-panels that had their corners bashed in.  I talked to the store manager and was able to buy them for $2 each 

Anyway, here is the beginning of my first prototype:




I free handed the curved cuts with my saber saw so they aren't exactly perfect.  Good enough for getting some test measurements and listening impressions.

PWRRYD

Cut the woofer hole free hand with the saber saw too:

PWRRYD

Here is the Lab15-4 sitting in the hole:

PWRRYD

I bought a pair of 5" Gradient mids from JR last weekend that will be my first test for this project.  I don't know what I will try for tweeters yet.

tajanes

Your putting a smile on my face....   see the minidsp in the background.

Don't forget to try a deep and very narrow cut at the speakers fs in combo with the low shelf / eq for the front to rear cancellation...

PWRRYD

tajanes said:

Your putting a smile on my face....   see the minidsp in the background.

Don't forget to try a deep and very narrow cut at the speakers fs in combo with the low shelf / eq for the front to rear cancellation...

Oh yeah Andy!  I was taking in what you were saying Brother

Nicholas_23

Is it beneficial to have a narrow or wider baffle for the mid/top end?

tajanes

my 2 cents: could go either way, but in any event helps to measure mid and its low end rolloff (mounted on baffel) in determining the woofer slope and cut frequency - I know, dah    ...but OB provides challenge and opportunity to manage baffel step / OB rolloff thru balancing W and mid transfers   (and no box for mid/vocals... if you have ability to place speakers out a bit more into the room)

jhollander

A narrow baffle moves the dipole higher in the FR. this is generally preferred if you want constant directivity, or smoother off axis response. 

PWRRYD

I think I'll start my experiments using a pair of RS28AS I have on my shelf.

Tom_S

I'll be watching with great interest. I know almost nothing about dipoles, but have been sifting through the Linkwitz site a bit.

PWRRYD

Good thing these are only cheap $2 particle board prototypes...

I started to router the tweeter rebate and ran into the mid rebate.

Like John Hollander says he does, I will have lots of blue painter's tape, cardboard, and whatever it takes to arrive at a good baffle. 

jhollander

don't forget the bondo...

PWRRYD

I hate the smell of Bondo...  probably fill in my mistake with drywall mud.

jhollander

That Elmer's wood filler was pretty good.  It almost looks like MDF when dry and shaped.  I hate Bondo, but I have no patience for stuff to dry.

PWRRYD

My little save.

PWRRYD

I've purchased and used that Elmers wood filler twice.  I really liked it.  But both times the second time I went to use it the entire container was dried out.  I even put the container in a zip lock bag and forced all the air out.

Wolf

Dap PlasticWood has been good to me. Store it upside down though.

S7910

PWRRYD said:

I've purchased and used that Elmers wood filler twice.  I really liked it.  But both times the second time I went to use it the entire container was dried out.  I even put the container in a zip lock bag and forced all the air out.

I've used the Elmer's wood filler and like it as well. When it dries out, what I've done is add a very small amount of water, let it sit a minute or so to soak in, and stir, repeating the process until it is back to the proper consistency for use.