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My Large Advent Econo-Waveguide Build Thread

MWalt

MWalt

Super Member
After a lot of reading and a few PM’s to a couple of our speaker building experts, I finally decided to try building a set of wave guides my self. Now, mind you, I am technically challenged in this venue, so this is a large undertaking for me. Hell, I can’t even spell “capacitor”, much less install one. So, after a lot of deliberation, I figured to go with the old adage, nothing ventured, nothing gained. It was time to break ground on the project.

I looked at my meager stock of speakers and chose a pair of Original Large Advents that weren’t quite “original” anymore. I had bought these a couple of years ago for $50 on that auction site that was advertised as “works great”. Like many before me, big mistake! Both tweets were bad, both woofers were bad, and the crossover was burned up. I decided that I really liked the sound of the large advents when I was a teenager in the late 70’s and decided that they were worth restoring. The walnut cabinets weren’t in bad shape, so why not?! I found some functional fried egg tweeters, replaced the woofers with replacements from AB Tech Services, and had the crossovers completely rebuilt by a local shop. They still just didn’t sound as good as I remembered so, wave guide here I come.

Here is what I started with:

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I went ahead and ordered the parts that I found were necessary after reading the original econo-waveguide thread as well as the Bauhauslers OLA thread. Since the waveguides and selenium drivers were on backorder, I went ahead and started the disassembly process.

Here is what I did:

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Nice fiberglass batting, eh! Then I removed the plastic border around the perimeter of the baffle.

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Pulled the rebuilt crossovers. Hey, I can salvage that 1.5mh coil!!:banana:

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OK, time to start hacking away at the cabinets! Measure twice and then...voila, ready for the waveguides!

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Not much to do but wait for parts at this stage of the pro:scratch2:ject
 
Good news...The parts arrived from Parts Express. Time to do a little more on these puppies. Let's see if I can actually cut a hole that will work for the waveguide...

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Not bad. A perfect fit for the waveguides. Hey Ross, on this pair of OLA's, I actually did not have to shave anything off the waveguides:thmbsp:
 
Something for all of you that are really serious about trying this project but are afraid of the crossover part of this; get the PC boards that were outlined in the original thread. It makes the project way easier! The instructions that came with the boards are first rate. Here is what they look like:

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Now, it’s time for the fun stuff. It’s time to build the crossovers. Take your time and read the instructions at least two or three times before you start. Here is what mine came out like so far:

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Damn, I knew things were going too good. I see that I forgot to install the friggin jumpers. No big deal, I'll get em when I start this up again here in the near future. Until then, I'll catch you all on the high ground!:D
 
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Sir.Byrd said:
Wow! This is impressive. Don't forget to enlarge the tweeter holes on the grills!
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I am going sell the original grills on that auction site. At this stage of the game, I am not real sure about how I will tackle the grills. Let's see how they look when I am done and we'll go from there:thmbsp:
 
Mark Walters said:
I am going sell the original grills on that auction site. At this stage of the game, I am not real sure about how I will tackle the grills. Let's see how they look when I am done and we'll go from there:thmbsp:
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I recommend getting some nice cloth from acoustimac.com and making a frame from plywood that's magnetically attached.
 
Sir.Byrd said:
I recommend getting some nice cloth from acoustimac.com and making a frame from plywood that's magnetically attached.
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Good idea. I was already thinking along those lines, believe it or not. I am thinking of using black crinkle paint for the baffle and not having a grill at all. I guess it really depends on how the finished product comes out. Plus, I have a seriously busy life, so this project has been moving very slowly. I have lots of time to contemplate it.
 
I think PE sells neat little grill kits for cheap. Aren't the air cores suppose to be standing up?
 
Sir.Byrd said:
I recommend getting some nice cloth from acoustimac.com and making a frame from plywood that's magnetically attached.
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Harbor Freight sells packs of 10 rare earth magnets for under $2. These babies have a very strong magnetic field and are in the shape of a very small puck, similar in size to a pencil eraser, a little flatter and slightly larger radius. Counter sink and hot glue.
 
tensleep said:
Harbor Freight sells packs of 10 rare earth magnets for under $2. These babies have a very strong magnetic field and are in the shape of a very small puck, similar in size to a pencil eraser, a little flatter and slightly larger radius. Counter sink and hot glue.
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Exactly. For a even better look, drill the holes about 1/16" deeper than the magnets, and fill over them. Sand smooth and when you paint over the baffle in black you will not be able to see them.
 
Mark Walters said:
Pardon my ignorance, but what are air cores?
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The big copper coils of wire in your crossover are air core inductors, as opposed to the red ones, which are iron or steel core. The air core inductor orientation is important because the electrical current through the coil will set up a strong magnetic field; the same thing happens to any inductor. Minimizing the influence of these individual fields on each other is very important in crossover design. Flux line influence becomes even more important when working with heavy transformers in tube amplifiers. Any unwanted or unplanned change to the magnetic field of a component can induce unwanted current flow in the affected inductor, resulting in a form of distortion, or deviation from the original signal.
 
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tensleep said:
The big copper coils of wire in your crossover are air core inductors, as opposed to the red ones, which are iron or steel core.
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Thanks. What did he mean by "standing up". I just went with pics I had seen on the big e-wave thread.
 
Mark Walters said:
Thanks. What did he mean by "standing up". I just went with pics I had seen on the big e-wave thread.
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You have them laying on their side, so to speak. He means that they should be stood up, like a tire, so that you can see through the hole. Not only that, there is probably a "right" way to have the coil turned on it's vertical axis in relation to the other coil. Usually the coil wraps should be perpendicular to each other.

I do want to say that your crossover looks fantastic! I wouldn't sweat it too much.
 
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