Amiga build -- crossover mounting & veneer questions from a beginner

[early rejecter]

Hi all,

I'll be starting my first speaker build soon with a set of Amigas. I've done a ton of reading and think I have a pretty good handle on things, but have a couple of questions to start:

- From the build threads I've found, it seems people generally mount the crossover at the bottom of the cabinet. I do intend to test everything before I seal it all up, but especially given that it's my first time I'd like to keep the crossover accessible just in case it ever needs attention. Is there any harm in mounting it on the back of the cabinet directly behind the woofer? I imagine I'd need to find a way to cover the crossover with the damping material in that case, but anything else to look out for?

- I've read a ton about veneering and the various methods available. I'm planning to have a continuous sheet running from one side, across the rounded baffle, and over to the other side. From the research I've done I think I'm most comfortable working with Titan DX contact cement and paper-backed veneer, and have seen/read some great tutorials. The one thing I'm not clear on is what sort of finish is compatible with this method -- apparently you need to be careful not to use a finish that could penetrate the paper backing and react with the contact cement? I imagine Joe Woodworker can provide some guidance here when I order my supplies but curious to hear any experience from speaker builders.

Thanks!

[fpitas]

A lot of people here put the crossover external, usually so they can tweak it endlessly lol. Some even put it in its own enclosure and connectorize it to the main cabinet. Otherwise it can go anywhere in the cabinet. The bottom is just the most convenient.

[joshshetter]

I mounted mine behind the driver because I mean, putting it at the bottom means you can never touch it again. Mine are built to spec but they have some sort of cancellation at 550hrtz. Not sure if this is because of the lack of foam behind the woofer or just a product of these speakers. Pretty sure I'm the only person who's done measurements on these.

Are you dead set on them and have parts ordered? If not I'd suggest something else with less issues. I had to eq back in the mid range dip and take out some of the ~4k-6k region for them to sound good. Without EQ they're pretty meh.

[early rejecter]

Thanks -- yep, pretty set on these, parts already on their way. I do remember coming across your build thread when I was researching, seems you've had a bit of a roller coaster ride with them? In any case these fit the requirements I have at the moment (floorstander, price point, parts availability, flat pack option, mostly good reviews) so I'm going to give it a shot, and not opposed to EQ if it comes to that.

[djg]

Well known forum member John Hollander put the XO on the back of this design, along with an external port.

Many people have been very happy with the Amigas. I have built 4 of Mr. Carmody's designs and find them to be quality speakers. I have never heard the Amigas.

I have used shellac, Danish oil and Minwax wipe on Poly finish on paper backed veneer with no problems. I use PSA veneer.

http://projectgallery.parts-express....ojects/bmr-3l/

[Paul Carmody]

Yeah definitely mount your crossovers where you can get at them, in case of goofs.

I just made a pair of Classix IIs for a friend out of some spare parts. And as soon as I played a few notes out of it, I realized I wired them wrong. I dunno, maybe some guys have better luck than me, but I'd estimate that I make at least one wiring or polarity mistake 75% of the time when finishing a pair of speakers. Don't skip the QC Speaking of which, I like your screenname.

[Geoff Millar]

I put the crossovers onto the bottom of the cabinets but make the backs removable, doesn't seem to affect the sound although it detracts from the appearance with a very visible join. It would be better to inset the rear panel but that would require more precise wood working skills.

Geoff

[tomzarbo]

If you have not yet ordered your contact cement from Joe Woodworkers site, may I suggest putting another of their products in the cart? I LOVE the Heatlock veneer glue. You'll need to get one of their rollers to distribute the glue, it makes a big difference so it's needed.

You apply to both surfaces, the enclosure and the veneer, then wait until it's just stopped being tacky, then just place it on the enclosure, in your case, probably on the front, then place an old 100% cotton T-shirt or piece of cotton sheet or something like that, then set the iron to 2/3rds to 3/4 of full power. It's very therapeutic to do, and you don't have the added stress of making sure the pieces don't touch unless you are 100% ready for them to touch.

I have a video that shows a little on how I do this... https://www.youtube.com/watch?v=e3U6EWnfuMg The veneer part is a little ways in. Here is an older video that I did that is longer and boring-er, but it shows how to get things covered over a radius. https://youtu.be/Wqwvbla7D-g

I've used Titan DX before as well, but the heatlock method is just so easy to get right, I'd recommend it if you are still open to suggestions.

Best of luck with your build! Please post pictures if you can, we'd love to see them.

TomZ

[joshshetter]

Yeah definitely mount your crossovers where you can get at them, in case of goofs.

I just made a pair of Classix IIs for a friend out of some spare parts. And as soon as I played a few notes out of it, I realized I wired them wrong. I dunno, maybe some guys have better luck than me, but I'd estimate that I make at least one wiring or polarity mistake 75% of the time when finishing a pair of speakers. Don't skip the QC Speaking of which, I like your screenname.

I have a question, is the amiga supposed to have a cancellation at 550hz? Both of mine have it but were built exactly to spec. I'm unsure what to do to alleviate it.

[fpitas]

That sure seems like a bounce cancellation. Have you tried playing with the gating? Sometimes also I have to put an absorber on the floor to suppress floor bounce.

[joshshetter]

I'm not referring to in room measurements but outdoor ones, with the speakers mounted on a tall ladder well away from any boundaries. You can see it here, although it is smoothed, the dip goes quite deep. This is a gated measurement btw.

https://imgur.com/sGjMvV1

[fpitas]

Very odd...

[early rejecter]

I have a video that shows a little on how I do this...

Hey Tom, thanks for the reply, I came across your videos during my research and watching you wrap that subwoofer convinced me that I could do this. I haven’t ordered any of the veneering supplies yet; speaker kits should be arriving today but it’ll probably be a week or two before I can really get into them and will take some more time to ponder my finishing options. I came across a few comments from people who used the iron method and had issues with the veneer lifting at the baffle roundovers — I wonder if it’s easier to get a good bond on a larger radius like you had with the subwoofer vs the tighter radius on the baffle? In any case haven’t made a definite decision on that yet so taking your advice into consideration; thanks again!

Will definitely post progress pics once I get started.

[tomzarbo]

Hey Tom, thanks for the reply, I came across your videos during my research and watching you wrap that subwoofer convinced me that I could do this. I haven’t ordered any of the veneering supplies yet; speaker kits should be arriving today but it’ll probably be a week or two before I can really get into them and will take some more time to ponder my finishing options. I came across a few comments from people who used the iron method and had issues with the veneer lifting at the baffle roundovers — I wonder if it’s easier to get a good bond on a larger radius like you had with the subwoofer vs the tighter radius on the baffle? In any case haven’t made a definite decision on that yet so taking your advice into consideration; thanks again!

Will definitely post progress pics once I get started.

Okay, gotcha.

Since the knockdown kit is 3/4" material, from the pic it looks like a 1/2" radius roundover. Being able to get the veneer to comfortably go around that small of a radius will depend a little on the species of veneer. Burls and some specific types of wood with harder/softer areas of grain will tend to want to crack at a radius that small, even when backed. You'll be able to know for sure once you get the veneer in hand.

Another thing you might want to consider is using 'Veneer Tamer' or a similar veneer softening product on the finish side to soften the veneer to make bending easier... I'd do it a day or at most two before you plan to apply it to the enclosure. It will make the veneer more pliable and less likely to crack when pulled around the curve.

There are (kind of) two ways to apply the veneer with the heatlock... I usually leave it just ever-so slightly tacky in a few places on the veneer and box. If you do that and touch the veneer to the box it can be stuck there pretty much for good just like contact cement so you have to be a little more careful if you apply it in that manner.

The second way, and most guys I think will follow the directions to the tee, and wait just a touch longer until it's basically 100% non-tacky, then you can basically reposition it at will until it's where you want it, then iron it down to lock in place.

But If you do it while it's still a tiny touch tacky in a few places, you would be able to put the veneer face down, marking center top and bottom for placement, then place the enclosure face down on the veneer... then 'roll' it over the roundover while applying pulling pressure (you would tape down the ends of the veneer sheet) to basically stick the veneer to the enclosure ever so slightly, and repeat on the other side, then iron on as usual. As long as you are 'pulling' the veneer tight in this way, it should work fine. The process of ironing it and curing the glue actually shrinks the veneer ever-so-slightly, so it should be tight when cured as well. The cube subwoofer video from several years ago basically looks like what I'm describing... though it will be harder to do with a tallish tower type speaker.

Just a thought though... I'm sure you'll get a method that you like and dial it in so it works. It sounds like you're put some real thought into this and how to do it. That's the important thing... do it in your mind, then dry-fitted to make sure you not having an issue when the glue is setting up.

TomZ

[djg]

You might want to try a small test setup to see if your chosen veneer will do the bend. Imagine the mess a failed veneer install would leave.

Another approach, if you have the tools, is to cut the baffle sides and install solid wood corners after veneering the flat surfaces. Flush trim then round over.

[early rejecter]

Yep, will definitely do a test run on the veneering! I’ve seen some projects with the solid wood corners; looks really nice but that’s beyond what I have available in the workshop.

[early rejecter]

Finally had some time to get into these this weekend! The cabinets went together nicely and I’ll be working on the crossovers today. I’ll get some photos posted so you guys can let me know what I’m doing wrong.

Two quick questions:
- All along I’d been planning to hot glue the crossover components as that’s what I’ve seen in most of the tutorials, but suddenly seeing lots of comments about hot glue getting brittle over time. Especially since I’ll be mounting the crossovers vertically I want to be sure things are secure, so picked up some E6000 which gets a lot of praise. I guess that’ll make things more difficult if I need to replace any components in 20 years, but otherwise any reason not to use the E6000 instead? (I’ll be using zip ties as well.)

- Should I be making some sort of gasket/seal when fitting the port to the cabinet? If so any recommendations?

Thanks!

[tomzarbo]

Finally had some time to get into these this weekend! The cabinets went together nicely and I’ll be working on the crossovers today. I’ll get some photos posted so you guys can let me know what I’m doing wrong.

Two quick questions:
- All along I’d been planning to hot glue the crossover components as that’s what I’ve seen in most of the tutorials, but suddenly seeing lots of comments about hot glue getting brittle over time. Especially since I’ll be mounting the crossovers vertically I want to be sure things are secure, so picked up some E6000 which gets a lot of praise. I guess that’ll make things more difficult if I need to replace any components in 20 years, but otherwise any reason not to use the E6000 instead? (I’ll be using zip ties as well.)

- Should I be making some sort of gasket/seal when fitting the port to the cabinet? If so any recommendations?

Thanks!

E6000 is great stuff. Hot glue just works instantly so it's what a lot or even most of us use for crossover parts.

So anything that is heavier, like coils, and maybe bigger, heavier caps should be fastened down with an additional method anyway, usually zip-ties like you mentioned. So the glue is just helping it stay put.

For me, I've just always used hot glue for crossover components and have never had a single failure, some speakers going on 20+ years. Honestly, the wiring of the parts together actually gives some measure of 'securing' the components as well -- thinking resistors and small-medium size caps here which do not weigh much -- so usually not too much of an issue as far as things moving around a lot in-cabinet. Basically, the glue/adhesive isn't really doing much heavy lifting and isn't stressed much at all.

I'm not saying hot glue won't get brittle in a few decades time, but it just hasn't been any issue for me.

The vent, yes, you want to make the junction between that and the cabinet air-tight or you will hear the leak. I usually use ABS pipe from the hardware store for my vents, epoxy it in place, then veneer over the flush vent and use a roundover bit to create an easy transition for the air moving in the vent. The epoxy gives me my air seal in that case.

If you're using a pre-built vent with a flange, then some gasket tape or even a dollar store piece of 1/8" thick craft foam cut to the correct shape will work fine as well, done that many times. Hot glue or E-6000 will make removal difficult if you ever need to replace or remove for some reason.

Glad you're still going on this!

TomZ