Fast, fun, Inexpensive OB project

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#3,641
The lower the DCR of the woofer trap inductor, the sharper and deeper the trap. The main difference between a 20 gauge air coil and an iron core will be the DCR. John built his woofer trap counting on a DCR of about 0.15 ohm. As with all crossovers - especially this one - you should experiment. Start with the published values then tune to your room, your drivers, your ears.
FYI, the trap works at ~2000Hz to kill some noise from the woofer.
 
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#3,644
Tonight I finished the Manzanita build, I think. It's been a long but funny journey.

From day one, the Manzanitas created a soundstage with plenty of width, height, and depth. Unfortunately, they sounded a bit muddy.

Was the integrated Burmester too weak? Well, I ordered a power amp. A 2x350W class D power amplifier based on Hypex NCore NC502MP kept the 15" woofers in an iron fist, but still a muddy midrange...

Tonight I finalized the crossovers with proper inductors and terminal blocks for easy resistor change. The former bass trap inductors (tiny 24AWG, 0.89 Ohm) were replaced with heavy (AWG13, 0.11 Ohm) inductors from Jantzen. Would I hear any difference?
Damned I do! I finally got a clean midrange. DCR matters and the bass trap is a must on the GRS woofer. John was right, no doubt.

These are the resistor values I use for the moment:
R1 8.2 Ohm, R2 6.8 Ohm.

IMG_3044.jpeg IMG_2756.jpeg
 
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#3,647
I have my parts pulled together and will start soon. I'm using the 15" GRS and the TC9 to start. I have read through the updates around #2500. I plan on starting with biamping and using a minidsp to do something quicker. I'm not seeing much on the crossover points using this method and wonder if someone can tell me or direct me.
 
#3,654
My Ultras were made with a double thickness front baffle. My initial build had a few holes cut to open up the back of the Vifa but it turned out to be overly restrictive. There's an old post in this thread that explains how the build got modified and there are a few photos that show various stages of the mods. Opening up the rear of the baffle for the Vifa made a big improvement.

Click on the header to go to the post and see the photos.

B

Post in thread 'Fast, fun, Inexpensive OB project'

This is an example of clearing out the midrange - literally.

TLDR: Cleared out the space behind the Vifa tweeter and greatly improved the imaging and clarity of the Ultras. Changing the feet helped, too.

John mentioned he's working on some new updates to the Manzi design and it got me thinking about taking on a new project. Yet I'd never quite finished the Ultras properly so it was time to get to work on getting them done.

The front baffles of the Ultra's are made up of two boards and my clunky woodworking had left a couple of 90 degree ridges behind the tweeter and another behind the...
 
#3,658
Unfortunately no!. The one pic in there where you see the dowels poking into the interior was taken after I had chamfered the interior (also after the dowel holes had been drilled), but it does look like not much material was removed. A good amount was removed. I was using a chamfer bit with a bearing on the tip, which means you have to have a little lip for that bearing to ride on. If you make an extra 'front' rectangle with a through hole the same size as the through hole for the speaker, stack and fix that to the real piece you need to chamfer, you could use a 3/4"/18mm bit and completely chamfer the real front - a perfect solution. The remaining flange with the long dowels and a good gasket (the 11MS drivers come with a very good gasket) should clamp and seal very well.
 
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