T48 Build Thread

[miked]

Got the first 3 sides sanded down. I'll only have to repatch a handful of the holes, so I'm happy about that. I have a feeling if I had let the spackle dry longer than 3.5 hours, I would've had less tear-out, but oh well, it's done.

I got the other 3 sides including the front patched. They'll get sanded tomorrow morning, then I'll repatch whatever needs repatching, sand that tomorrow evening and hopefully Monday is leak testing...if I don't get antsy and start it tomorrow night. We need a "whistling emoticon."

[miked]

Wattage awaits. This is my amprack. It's very heavy, but I like having all my amps in one rack.



Top to bottom:
DriveRack PA+
Berry A500
QSC GX5
QSC PLX3602
Berry EP4000

I'll only be using the two QSC amps for now. At four ohms they kick out more than enough wattage for my four OTops and four T48s. The other amps are spares or if I need to run monitors or something.

I tell you, sanding spackle is a very messy task. Good thing I'm doing it in the street in front of my house. I got the cabs completely sanded down and then repatched/final patch touchups, yesterday. Today I will sand them down and clean them up real good. I hope to do leak testing tonight. At that point, the drivers will stay in the cabs and I'll cover them up with plastic real good and the painting can begin. Getting closer!

[miked]

The Four Horsemen...without their clothes on.





I thought I was finally done patching and sanding, but when wheeling the cabs back into the garage I spotted a few things I missed. Of course. So, to patch 6 or 7 little spots, I'm delayed another day. If I didn't patch them, I'd always know they are there and it would bug me. So leak testing will be tomorrow. That's OK as I have a lot of work to do getting my rig setup. Gain structure, limiter, etc. In the past I wasn't as good about setting limiters properly as I should have been. I was using all direct-firing cabs and if I heard something amiss, I'd just turn it down. Can't do that anymore.

[hifibob]

Your neighbors must think your a lunatic lol.. Cabs are looking sweet, you gotta be anxious to fire these beauties up. I'm excited for you..

[miked]

Two neighbors have actually stopped to ask what I was building. They both said "It doesn't look like a speaker", so I showed them the Sketchup drawing, explained how it worked, etc. One guy was interested, the other, his eyes glazed over halfway through my 2-minute speech.

I am definitely excited. Now that the edges are rounded over and the holes patched, the cabs are starting to look and feel "like cabs." When you've got a lot of holes to patch, the finish work takes forever. Spackle has to dry before you can sand it. Time+time+more time...it gets frustrating.

Even though I hit them with a leaf blower, there's still a lot of dust clinging to them. I think I will wipe them down w/a damp rag before priming. That's after mounting the driver and leak-testing, of course. And I still need to drill the pilot holes in the access cover flanges, for the access cover screws. But these are the fun steps in the build. Getting there!

As for what the neighbors think...wait until I fire up the whole rig in my backyard. I'll do it at least once immediately post-build and of course, again, when and if you make it here, Bob after the Texas Mile. I like everything from EDM to Motown to Aerosmith to Iron Maiden. I'll be sure to hit all the high points when testing for max SPL.

[hifibob]

Two neighbors have actually stopped to ask what I was building. They both said "It doesn't look like a speaker", so I showed them the Sketchup drawing, explained how it worked, etc. One guy was interested, the other, his eyes glazed over halfway through my 2-minute speech.

I am definitely excited. Now that the edges are rounded over and the holes patched, the cabs are starting to look and feel "like cabs." When you've got a lot of holes to patch, the finish work takes forever. Spackle has to dry before you can sand it. Time+time+more time...it gets frustrating.

Even though I hit them with a leaf blower, there's still a lot of dust clinging to them. I think I will wipe them down w/a damp rag before priming. That's after mounting the driver and leak-testing, of course. And I still need to drill the pilot holes in the access cover flanges, for the access cover screws. But these are the fun steps in the build. Getting there!

I hear ya there's always a few more step then a few more before you can fire them up.. I was loosing sleep thinking about it..

[miked]

I neglected to break in the drivers in free air, so they are breaking in right now. They are mounted in their cabs. Even with the access panels and terminal cups off, there's still a whole lot of sound being made. 10v to all four cabs was vibrating the walls in the house. Not like an earthquake, but bad enough that I feared for some of the more delicate things on the shelves. I had to turn it down to about 6.5-ish volts. They're running at 30Hz, so 8-10 hours will do.

I finished (finally!) sanding the cabs down early this morning. Then I drilled the flanges for the access panel screws, vacuumed out the driver chamber to operating-suite cleanliness and mounted the drivers. All of the t-nut prep work; running each screw totally in/out/in/out thru each t-nut, keeping the threads clean etc really paid off. 31 of 32 went in like buttuh. One required a bit of torque, but it's in. I did the leak test with the hose and not a puff of air to be found around the drivers. The driver gaskets squished way down with a lot less force on the screws than I thought they'd need. The baskets are not bottomed on the spacer rings, but they are close. Before sealing up the boxes after painting, I'll give each screw another 1/4 turn or so.

Pics or no progress! First and foremost: Racheting, bendy interchangable bit screwdriver thingee, I LOVE YOU. Chucked the right size allen head bit and I was off to the races. No L-keys here.


The keen-eyed will notice that I removed the rear gaskets. Messy business, doing that. The gasket comes off fairly easily but it leaves behind a lot glue/fuzzy material that you have to remove, lest it start flying around in the chamber.



All four cabs w/their backs to the bench. Note the small amprack behind them. My electric bass/testing rig.


Super advanced tone generator rig thing.


Highly-technical wire binding apparatus for driver break in.


Tomorrow starts the painting. Not looking foward to painting the mouths. I'll probably duck tape a small roller to a piece of scrap to make a handle...or something like that. I can't wait to close these things up and throw about 20v into each cab.

[David Raehn]

Hey,

A lot the rollers are threaded to accept a broom handle. Cut one down and GO!

[Bruce Weldy]

Did you do the break-in while they were in the cabs?

[miked]

Did you do the break-in while they were in the cabs?

Yeah...it's going on right now. At 6 volts my whole garage is vibrating and that's w/the access covers and terminal cups off. For giggles I raised the frequency to 70Hz. Bad idea...everything in garage vibrated off the bench/walls. This isn't optimal, but over the past weeks, between the mess in the garage and the mess in my office, there was just no room to spread everything out and do the break in like normal. So be it. The garage is clean now; all the tools put away, etc. Tomorrow I paint...assuming the garage is still standing by then. LOL!

[hifibob]

Did you do the break-in while they were in the cabs?

Yeah...it's going on right now. At 6 volts my whole garage is vibrating and that's w/the access covers and terminal cups off. For giggles I raised the frequency to 70Hz. Bad idea...everything in garage vibrated off the bench/walls. This isn't optimal, but over the past weeks, between the mess in the garage and the mess in my office, there was just no room to spread everything out and do the break in like normal. So be it. The garage is clean now; all the tools put away, etc. Tomorrow I paint...assuming the garage is still standing by then. LOL!

OMG you broke them in, in the cabs lol.. Your house is probably falling apart! Good news it looks like my car will be done for Texas mile! I'm dying to hear these beauties!

[miked]

I had to shut it off at about the 6 hour point. It was just too much. Again, this was at 6 volts with no access covers on. During the first hour or so of testing, I flirted with up to 20V and varied the frequency from 30 to about 90Hz, just to mess with it. Hopefully that makes up for the "missing" 6 hours. That said, the first time I fire them up, I'm not going for max SPL (seriously), so they will get played in with normal music for the first few hours of their young lives. Then I wanna hear them put their money where their (horn) mouth is.

I'm very much looking forward to hearing these T48s with my OTops. I was very impressed by my OTops, even running with the cheapie 18" ported subs I have. The OTops outran them by a country mile, but damn if the OTops didn't just sound smoooooooth doing it. The first two tracks I will play at decent volume are Tracks 4&5 from Disc 1 of The Wall. Hint: They run concurrently and were made to be played together. If you can't figure it out, I"ll tell you the track names. If you listen to them, and imagine sitting in front of a great PA and feeling that "whomp" in your chest, you know what I'm waiting for.

And Bob: As the time gets closer, PM me so we can exchange info, etc. When is the Mile again? The cabs should be done in a weeks' time if not sooner. I'm setting up my rack, but that's another thread.

[Radian]

For break-in with the drivers installed....place two cabs mouth-to-mouth and wire the drivers out of phase. That'll shut 'em up by quite a bit. No need to piss off the entire block for something that should've been taken care of well in advance of final assembly.

[miked]

Oh sure, NOW you tell me. After I've dislodged every speck of dust in the garage and pissed the wife off. Eh, it's done. Besides, with the garage door closed, you could only hear the rumble from around the corner...about 200 feet away. No farther than that.

[Tom Smit]

Mike, the drivers may not have fully bedded in yet since you mainly used just 6 volts. However, with time, they will, and you'll notice the fuller sound emanating from your cabs.