Building a set of O-3's

bryede · « **on:** 22 Dec 2006, 01:50 am »

Hello,

I currently have a mostly Polk HT system (RTi28's w/Dennis Murphy X-overs, a CSi30, and Velodyne 10" sub), but I've been itching for better 2-channel performance so I emailed Danny about the A/V-1 and he told me about the A/V-O and O-3. After much deliberation, I've decided to give the O-3 a try. I'll post updates as I go along.

I'm extremely tool deficient at the moment, but I'm managing to keep the tolerances fairly tight using a circular saw and a small finishing router with circle jig. Plus, one of the pre-cut sizes of MDF at Home Depot (12" deep) makes building the sides a snap!

Wish me luck!!

-Bry

edit: Sorry, I originally got Danny and Dennis' names mixed up. Breathing too much sawdust.

bryede · « **Reply #1 on:** 22 Dec 2006, 03:24 pm »

Can anyone give me a few veneering/finishing tips? I'm thinking of going with ebonized oak. I've read the stuff about making an iron solution and brushing it on. Does this look best with white or red oak, and should I use a particular veneer cut? I assume I can just use wipe-on-poly over it. I had originally thought of doing a navy blue dye (after seeing the A/V-4 pic) but my wife talked me out of it.

I also read about the flex-pro glue, but I don't really want to buy a gallon of it.

Danny, how much NoRez should I order with the kit? I assume I need to cover all surfaces except the ones with holes?

-Bry

Daygloworange · « **Reply #2 on:** 22 Dec 2006, 04:31 pm »

Quote from: bryede on 22 Dec 2006, 03:24 pm

Can anyone give me a few veneering/finishing tips? I'm thinking of going with ebonized oak. I've read the stuff about making an iron solution and brushing it on. Does this look best with white or red oak, and should I use a particular veneer cut? I assume I can just use wipe-on-poly over it. I had originally thought of doing a navy blue dye (after seeing the A/V-4 pic) but my wife talked me out of it. I also read about the flex-pro glue, but I don't really want to buy a gallon of it.

Danny, how much NoRez should I order with the kit? I assume I need to cover all surfaces except the ones with holes?

-Bry

The iron solution thing is outdated. To get that bluish black you can use an aniline dye ( aka NGR ), to get the same results. An iron solution reacts with the high tannin levels in oak to make it go black. If you use a water based finish on top of it, you could actually get rust spots in the finish from little bits of iron oxidizing. Same thing with using steel wool on wood and then using waterbased finishes.

Quartered oak or ash is a really nice veneer. It doesn't look the same as flat or rotary cut. Quartered or rift cut ash is beautiful, quartered oak can vary wildly, so you can't just order some and be sure what it 's going to look like, you have to hand select it to be sure.

As for glue, some people do the iron on method, where they cover both the veneer and the MDF with carpenter glue, let it dry, then use a hot iron to reactivated the glue and bond the two. I would recommend contact cement. Use a disposable roller and work quickly and don't go over and over the glue. Make sure you get good coverage, ( sometimes requires 2 coats) apply lots of pressure, and you'll be fine.

Cheers

bryede · « **Reply #3 on:** 22 Dec 2006, 11:53 pm »

Maybe I'll try Quartered Ash. Are quartered and rift the same thing? Looks like I'll need a 4x8 sheet to cover both. Should I go with 10mil paperbacked, and should I dye it on the cabinet?

-Bry

Daygloworange · « **Reply #4 on:** 23 Dec 2006, 12:00 am »

Quote

Are quartered and rift the same thing?

Technically, no. But a lot of times in practice, they end up as each other.

Quote

Should I go with 10mil paperbacked

The 10 mil paperback is fine. It's what is most common.

Quote

should I dye it on the cabinet?

Yes, dye it on the cabinet. Cool thing with the aniline dye is, is that it's alcohol based, you can start applying a finish almost immediately after. The alcohol evaporates almost immediately, and there is no binder that has to dry, the alcohol is just to dilute the powdered dye and a vehicle for application.

Do not use aniline dye powder with water as a solution, it'll raise the grain and then it's a pain to try and get rid of that.

Good luck.

Cheers

bryede · « **Reply #5 on:** 23 Dec 2006, 03:35 pm »

I've ordered my kit. Danny was very helpful. It's nice to have these kinds of people in this hobby!

Denny, thanks for all the advice. Two quick questions and then I think I'll be ready when the veneer gets here. First, the reason I was interested in iron treated oak was this picture:

The upper right photo has sort of a two-tone appearance that I've seen in cabinets before. Do I get this same effect with dye? And secondly, in some places I've read that contact cement has a tendency to let-go after a period of time. Is this something I need to be concerned with?

Umm.. maybe a third question too.

What is the best way to paint a solid black base piece (foot) using MDF?

-Bry

RAW · « **Reply #6 on:** 23 Dec 2006, 04:07 pm »

http://www.audiocircle.com/index.php?topic=27065.msg240571#msg240571
Here is a idea for glue.

For those who have not see my post before on veneer glue I wanted to bring this in as a thread for those to try this product and get away from contact cement

Yellow glue doesn't fully harden even after several years. This softness allows the veneers to "creep" or move on the substrate (caused by seasonal humidity changes) which can lead to edges lifting and occasional bubbles.

Heat Lock has a cross linker in it. After 48 hours, the cross linkers have locked together and the veneer will not creep. So panels that are veneered correctly with Heat Lock veneer glue do not come apart.

Thick consistency helps prevent "bleed through"

Daygloworange · « **Reply #7 on:** 23 Dec 2006, 05:39 pm »

What Al says about the carpenter's glue is true. PVA ( polyvinyl acetate) dries by polymerization, and never does fully cure. We use tons of it,(ok, pails of it, not tons) and sometimes apply it by roller, we pour it onto a sheet of lexan, load up a paint roller and apply. When it hardens, you can peel the glue off the lexan, and re-use the lexan, the glue can be paperthin, and will remain flexible for years. You can actually fold it.

There are warnings of some instances of it not performing well with veneers. It use to be a source of worry for me, but I've never had it fail. I don't doubt the claims, but have never seen it fail.

I have heard the same about contact cement, and I have seen failures. I went to look at a potential job yesterday as a matter of fact, and they had a bunch of reception desks with the laminate peeling off. I believe it has more to do with them not applying enough glue more than anything. Over the years, there have been a few instances where we've had to remove laminate from a piece that's over 10 to 15 years old, and it was a bear to get it off. So much for that theory.

Every material has it's shortcomings, and nothing is perfect. I've never used the glue Al is talking about, but I'm sure it outperforms PVA glue. So would epoxy, but that starts getting very expensive, and it starts to get into overkill. I might try some and report my findings on AC.

Your question about achieving the look you want with the stain is doable with aniline dye as a base color, then seal, then apply a glaze (stain) that seeps in the pores to achieve the look of the picture. The iron solution method can be blotchy, and leave tiny little dark spots all over. It's a chemical reaction with the tannins in the oak and can be inconsistent. If you have a few pieces of veneer left over, test it out on them first. You cannot get the iron solution effect out. It is a chemical reaction and it's permanent.

Your last question about painting the MDF bases can be answered here:

http://www.audiocircle.com/index.php?topic=33185.msg295590#new

Good luck,

Cheers

bryede · « **Reply #8 on:** 23 Dec 2006, 07:06 pm »

Okay, sounds like the iron stain thing isn't worth the risk. Sure sounded cool in a Mr. Wizard sort of way, though.

Thanks!

-Bry

bryede · « **Reply #9 on:** 25 Dec 2006, 11:56 pm »

Getting closer! Just need to fill some screwholes, cut out the back panel holes, and make the pedistals. Once the No Rez and wire is installed, I can seal 'em up!

-Bry

Hank · « **Reply #10 on:** 27 Dec 2006, 06:15 pm »

Here's what I used on some oak bases for a customer: TransTint concentrated black dye:
http://www.woodcraft.com/family.aspx?familyid=171
Note that it can be added to either water OR alcohol as the solvent. For the bases I did, I diluted it VERY little. Also, a professional woodworker shared a 'secret' with me: India ink. I haven't tried it, but it sounds intriguing.

Al: that iron-on glue looks interesting. I have not used the PVA iron-on method - just something in the back of my mind told me to stick

with contact cement.

santafefrank · « **Reply #11 on:** 29 Dec 2006, 04:25 am »

I am curious about this design. It states that it is a full 3-way, not the usual 2.5 way one typically expects with dual woofers. What is the goal then? To relieve the mid-woofer of bass duties? An increase in output around the crossover point? To increase the flexibility in room placement?

Thanks for any insights.
Frank.

bryede · « **Reply #12 on:** 29 Dec 2006, 01:03 pm »

My kit arrived! UPS can sure beat the heck out of a box! More pics when I get a chance.

Frank, From looking at the crossover, it appears that the front woofer is bandpass filtered, while the rear woofer runs through a single inductor.

-Bry

ryno · « **Reply #13 on:** 29 Dec 2006, 05:36 pm »

A quote from Danny about the xover in his intro thread for the O-3

What measures flat with these speakers is not necessarily what you get as an in room response. The 180 dispersion of the lower frequency ranges can load rooms a little differently than most speakers and cause a little bit more room gain in some rooms. What measured flat with the mic at a meter or a meter and a half was actually a little bottom heavy in my room. So that first order crossover (big cap bundle) on the front woofer used to pull the lows off of it is made up of several different smaller values. By adjusting the values on the front woofer you can adjust how much bottom end that it will be allowed to play and how much it can overlap onto the rear woofer. This allows the speaker to be easily dialed into any room. If you need more bottom end than increase the cap value. If you need less then decrease the cap value. It worked great in my room.

Danny Richie · « **Reply #14 on:** 29 Dec 2006, 10:36 pm »

Quote

To relieve the mid-woofer of bass duties?

Yes it does.

Quote

An increase in output around the crossover point?

Not really.

Quote

To increase the flexibility in room placement?

Yes it does.

bryede · « **Reply #15 on:** 1 Jan 2007, 02:23 am »

Almost ready to put the backs on!

Happy New Year!!

-Bry

bryede · « **Reply #16 on:** 1 Jan 2007, 06:22 pm »

Crossovers (front & back)

-Bry

Danny Richie · « **Reply #17 on:** 1 Jan 2007, 06:43 pm »

Judging by the size of those mounting boards it looks like it might be a tight fit.

I mounted the tweeter network on one board, the front woofer network on one board, the high pass portion of the front woofer network to another board and then screwed the inductor (rear woofer network) right to the wall.

Typically I would advise to cut the leads of the inductors down to about 3/8", solder your wire to it and seal it with heat shrink.

Heat shrink was provided in the kit (I hope). It is needed to seal all the connections where the OFC wire is used. This will keep it from oxidizing and degrading the upper frequency ranges over time.

bryede · « **Reply #18 on:** 1 Jan 2007, 10:05 pm »

Danny,

Yeah, that is a better way to do it.

Well, I went back and used liquid electrical tape rather than try to put heat shrink on everything. The board fits nicely. The mounts for the bottom plate aren't in yet, but they should fit too.

The board is on plastic stand-offs made from small plastic pipe adapters.

-Bry

Danny Richie · « **Reply #19 on:** 2 Jan 2007, 12:12 am »

Quote

Well, I went back and used liquid electrical tape rather than try to put heat shrink on everything.

That will work just fine.

It all looks real good too.