4x T48 and 4x OT12 build

[Scott Brochu]

Nice sled! makes life easier.

[dlv]

Things are progressing faster now on the T48s. "Practice" cab #1 is nearing completion and I've got cabs 2-4 started. Ordered the DureTex from speakerhardware.com a while ago and they ordered it drop ship from AcryTex. That was several weeks ago and no sign it's shipped. Getting annoyed about that and may have to call and find out what's up.

Anyway now that I'm getting along with the subs I'm starting to look hard at the OT12 plans and I have a crossover question before I order parts.

I'm going with compression drivers. The recommended Eminence F151M-8 drivers were not available and Eminence seems to be moving away from them so I went with N210T-8 drivers that Eminence is replacing them with.

Bill said these drivers look ok when Bruce asked about them (albeit a bit pricey) but just to be absolutely sure I want to confirm: For a 1.2K crossover are the parts values listed in the plans unchanged with these drivers?

I assume it's the same but that is an assumption. My limited understanding of crossovers tells me the HP filter is about the load impedance and other driver specs don't matter but I could be wrong. I'm really a noob when it comes to crossovers. Any advice on that front is appreciated.

FWIW though I'm using the DeltaLite II 2512 I want the advantages of the wider dispersion for 1-2K and better power handling/sensitivity the lower crossover point gives as mentioned in the plans.

For reference specs on the N210T-8:
https://eminence.com/products/n210t-8#specifications

[Bill Fitzmaurice]

So long as you match the driver impedance with the filter it's OK. I'd use a 16 ohm driver for better level matching with the woofer.

[Bruce Weldy]

So long as you match the driver impedance with the filter it's OK. I'd use a 16 ohm driver for better level matching with the woofer.

I've been running the NSD2005-8 with my 2512 OT12s and haven't ever really noticed any imbalance. The sensitivity of the NSD and the N210T is the same. Maybe I've just EQed it out of there. I doubt there will be a problem......especially since he already has 'em.

[dlv]

Bill and Bruce thanks! I'll get on with ordering crossover components per the specs in the plans.

[dlv]

Well proof you should stop when tired. Set the access cover flanges last night and discovered this morning I managed to be an half inch off center. I know what I did. 7 3/4 to center not 7 1/4. Ugh. Won’t affect sound but I’ll notice it every time I look at this sub. Luckily still room to install braces.

[dlv]

Nothing a bunch of clamps, few cutoffs and some PL can’t fix! My OCD just couldn’t let it go. Yep I checked the driver still fits. Barely

[dlv]

Question: For the T48 square backs I'm building I'm considering pre painting the inside of the cabinet and the face of panel #9 where it is going to be visible through the hand holds. Same for panel #11 at the back/bottom corner.

Will that affect the PL adhesion in any way if it's a painted surface? I'm using flat black exterior latex paint (it was the cheapest) as a primer and would use that in these cavities to black them out.

Couldn't find anything specific about this on the PL data sheet. If that's a problem I can probably tape off where the joint is and keep it bare. But if I don't have to worry about it I'd like to know. Thanks!

Panel #9 dry fit and the space I'm referring to:

[Bruce Weldy]

Put some blue painter's tape on the glue lines, paint it, pull off the tape. Then you have a clean glue line and paint where you want it.

[Tom Smit]

+1

[dlv]

Ya that's what I did.

[dlv]

Haven't updated in a while. Been slowly making progress. Spending a lot of time figuring things out, making templates, dry fitting, and on just overall OCD perfectionism. I get a lot of satisfaction out of a day in the shop. My wife feels a bit abandoned lately but we're about to leave on a 3 week trip around England and Scotland so she'll get some attention there.

Have one T48 cab just about ready to put the final side on. The other 3 are trailing not far behind. I'm definitely glad I'm building one first this way as recommended by Bill and others. I've had to correct several mistakes on the first one that taught me how to do the other 3.

Speaking of templates, thought I'd share a few more I did. Really worth the time to make them!

Cutting the 6/10 braces. The half inch template bit makes a perfect slot!

6/10 brace template

6/10 brace dry fit

I'm using recessed corner casters. The cutouts were tedious with a jigsaw but with a template & router, piece of cake!

caster cutouts and templates

Btw, those are stacks of caster anchor braces there in that last photo. Maybe not necessary but I felt like why not. One of my guys rolls it off a curb or something and there might be some significant impact. Better safe than sorry.

I'm investigating options for grills on these T48s. Leaning towards using flat rolled expanded metal and painting it black. Making a trip to my metal supply house today to see what they have and how expensive it is. I do welding fabrication so might try to trim out the edge of it for a fancy look. The top edge in particular. We'll see.

[Bill Fitzmaurice]

I'd fold the edges, with a brake if you have one, to the outside of the grille.

[dlv]

I'd fold the edges, with a brake if you have one, to the outside of the grille.

I do. But it's only 20" (slightly less actually). However the shop I get my steel from does have a big 8' brake and could do it. Their shop rate is reasonable if I buy it from them.

I just got back from checking and the lightest they have is 13ga, 1/2" diamond. Would definitely add some weight but not terrible. Won't dent easily tho. I grabbed a small cutoff to mess with and see what it looks like.

[dlv]

I found something that may just be the ticket for edging expanded metal grills.

Trim-Lok

https://www.amazon.com/dp/B00NL3Z6Y8

Already has a black pebble finish. I think it would give the grill a bit of a gasket to prevent any chance of vibration noise against the cab too. Not too expensive. Easy to repair/replace if damaged.

I'm looking for a source of 1/4" 16ga rolled expanded metal. The 1/2" 13ga is awfully heavy at 1.68lbs/sqft. 1/4x16ga is 0.86lbs. Though I'm certain the 13ga would not need any center bracing. Another concern though is mice. Little buggers can get through a 1/2" hole so 1/4" is a better option I think. I may have to drive to Phoenix to get it.