Advice on building some SPL sub boxes

[acarmody]

Cheers Holdenboy, I'll let you know how I go in the comp, assuming its still on, registration numbers were very low, which is surprising considering how many retard have their subs cranked at midnight in the middle of an estate.

Wanna play a game, see who can guess my reading. I say 143dB.

EDIT: That test CD is exactly what I needed. With a bit of work I created a 40hz-50hz track that plays each frequency for 3 seconds before going up 1hz, so 40hz for 3sec, then 41hz for 3sec, then 42hz for 3sec, etc. I'm hoping that this will give a better reading than a sweep.

 

[acarmody]

Shattered, only 2 people pre-registered so they called it of due to lack of number, but at least 20 cars rocked up, idiots. Including 2 'teams' and some of thier cars are awesome, including this one guy with an old early 90's Holden Barina with 3000wrms in a custom box, he said he scored 149.9dB last time, and he is looking at buying a 12kW amp, insane prick.

They took all our names down and will scheduler the comp in a few weeks.

On the positive side I got the oscilloscope on my amp and the gain is up higher than I've ever run it, set to about 3-3.5V for a 5V preout from H/U running at 30/35 volume.

 

[holdenboy]

Ahh thats a pain.....sorry to hear they called it off, 20 cars is a better-than-average turnout for most SPL comps.

Yeah being up there you'll run into a few hardcore SPL guys at the more serious comps...big numbers are much easier in a small hatch, only downside to a small car is exactly that.....its small haha.

Most monos these days can be taken to around 2/3rds gain on a 4v input at a few notches below max vol without clipping.

 

[acarmody]

On the positive side I should have the boxes fully fiberglassed and painted for the rescheduled comp in a few weeks.

 

[acarmody]

OK I don't want anyone to think I've given up on the boxes, its just that I have bigger priorities and these are just for whenever I get some spare time (barely any). But progress is being made. I have big plans still, still going to fiberglass them and paint them, I was thinking a two-tone paint job, metallic blue over metallic black with a silver stripe separating them.

My (slow) progress so far.

 

[acarmody]

OK well I haven't had much time lately so only a small amount of progress on the boxes.

I wish I had thought of this earlier as it is much easier than my old method, it also give a much 'tighter' fit to the sub. Basically I have some 2-sided tape along the edge of the sub and then the dyno sheet stuck to that, the body filler won't stick to the laminate (too smooth) but it still has about 3 layers of PVA mold release anyway.

 

[acarmody]

Meh I'm probably wasting my time but screw it, it gives me something to do. Coming along though.

 

[AmmoJammo]

Wanna play a game, see who can guess my reading. I say 143dB.

I would say you're aiming too high.

Maybe 140, on the dash, with the doors closed.

obviously more if you drop the sensor down to the kick panel, and open a door.