Polaris - A Return To Home

JasonP

So my last few builds have been kind of crazy, off the rails type of designs, but now I'm taking a break and returning home. Named Polaris for the north star that often guided sailors throughout the ages, these are a medium sized two-way vented design.

Features:

• SB17NAC35-8 6" woofer, XT25BG60 1" ring-radiator. Both drivers are well matched and feature outstanding and similar distortion profiles.
• 4 layer composite panel construction with mass loading (stone insert layer).
• 3/8" wide slot port to increase port friction >300%. Reduces port output, but also increases power-handling below tuning because friction = resistance = resistive = flow resistive vent.

I'll post more details and better pictures on my site with a link added here soon. The camera on my phone can't resolve the three color metal surface at all, its actually a rosemary greenish steel base with gold and darker bronze effects dry brushed. The box came out a little rougher than I thought I wanted at first, but will fit into the final look well. There will be something like raised aluminum rails coming from the SB17 at angles and wrapping around the box. The concept is that it should be like something uncovered right from the earth at a dig. Maybe next to a stargate.

Nicholas_23

Interesting enclosure finish sir. Looking forward to the final finish

4thtry

Nice design.  Excellent picture showing the baffle board texture.  Trying shooting it outside in open shade (a shaded porch area) and see if the colors pop out.

I have to get one of these tweeters.  Every time I have heard these tweeters I have been impressed.  I have a pair of the cheaper XT25SC90-04 units that I plan to use in my auto sound improvement project.  The flange and magnet are much smaller than the G60's, so I can fit in a tight spot up high in the doors.  But it probably doesn't sound as good as the G60's.

Bill 

JasonP

Bill, I love the XT25 tweeter, but they are a pain to work with. I'm not sure what the cause is, but it takes a lot to massage them into shape. I ended up with three resistors in this design, one before the XO, one after, and one across the leads. It needed all that to calm down. I'm not knocking them, but the challenge factor is there for sure.

JasonP

I wanted to wait to post this until after I demo'd them at DDIY, because the voicing is intentionally not flat. Here is a 1/12 smoothed in room measurement at about 10 feet with no averaging, slightly off-axis:



I'm pleased with the sound overall and I am not planning on any more crossover work. The Continuum/LS3/5A sound is something I quite enjoy. In my listening I find the little dip from 150 hz to 400 hz to seriously reduce room effects and make voices far more natural.

kennyk

At ten feet, very nice even with room effects. Good show JP.

4thtry

I really liked the sound of these too.  I also prefer the LS3/5A dip for the same reasons you mention.  If you look at my Plumbers Delight and Dual Exhaust graphs, I am trying to do a little bit of this on my speakers too.  Although, I think my room modes are messing with my measurements somewhat in this frequency range, making it a little difficult to clearly understand what is really going on. 

Bill

ani_101

Hi JP, the squiggles are making it hard to determine the dip. Do you have a more normalized or smoother curve to depict the target response? 

ani_101

a hand drawn ideal response curve?

JasonP

Here is Jeff's more smoothed plot, and a comparison to a stereophile LS3/5A measurement: