New Dipole

[JohnL]

I finally had some time this weekend to cut some wood up, I've had the parts sitting here long enough. OK, I finally took the plunge to full dipole. AMT, PHL 1120 and some cheap IB subs from B&G, with everything being controlled by a DCX. Yeah, the 12s are kinda cheap, but they were designed for IB use so the specs are where they needed to be, and the price was right. I haven't really put a mic to it to measure it, just programmed the DCX with something that should work.

My first thoughts are... nice bass! In comparison to the AMT/RS225 combo I have been using, the bass has much more slam (yeah, 2x12 vs. 2x8, but it's different). The bass is very much of the flavor of the old Hartleys I had in here for a while. The other first thought was, I need to do something in the midrange because something's off. I'll put a mic on it today sometime and figure out what's going on in the midrange. Overall, very positive, as an experiment I can say that with some tweaking I will like the sound of these better than the RS225s.

John

[AJINFLA]

'bout damn time LOL. The response of the mid is highly dependent on the shape of the baffle, its position on the baffle, etc, etc.
The only way to know is to measure it. I prefer only flat baffles for the mid with a minimum fold back, since this effectively creates a shallow transmission line behind the driver. Looking good :T

cheers,

AJ

BTW, if you don't already have it: http://www.musicanddesign.com/measure_dipole.html

[JohnL]

Don't pick on me, I just gave up waiting on the ultimate midrange and picked up some PHLs. :demon:

I didn't get to do any testing yesterday (too much hot dogs and beer), I should have some time to get an idea of what I'm hearing soon. As for the layout, I kinda stole some design ideas from ultrachrome, I just didn't like the idea of edges sticking out in front of the baffle, more asthetically than anything else. I was a little concerned about having even that much folded around the sides in the midrange area, but the AMT needs about 3 inches for its perch. I guess I could mount it differently, this was just the most straightforward way. I wonder if I put some rigid fiberglass board around the inside of the back??? That also begs the question, do you know any place around here that sells Owens Corning 705 or 703 sheets? I can't seem to find any of that stuff anywhere.

And who is this Kreskovsky guy? Never heard of him. :huh:

[MJKing]

JohnL

I finished something very similar this past December.

http://www.quarter-wave.com/Project07/Project07.html

and it works great.

[JohnL]

Heheh... I guess the truth was in the numbers. Once I tested everything I figured out the problem with the midrange. Newly aquired NAD amp has somewhat different gain than the Rotel. Once the midrange gain came up a couple db, everything flattened out and sounded much better.

I never would have considered the RS225s to have sounded 'boxy' (at .58 Qts sealed) until I heard them compared to this. BTW, those PHL 1120s are some sweet sounding mids. I have a B&C 8PS21 here that I was going to try in it's place, but I don't think it's going to sound any better.

Also, for any DCX aficionados out there, should I be putting any delay into this setup?