BillFitzmaurice.info

I am not quite half way through building a THTLP. This is my first attempt at building speakers and I've been pleased with how the build has gone so far. However, I have two questions I hope forum members can help me with.

1) I'm using a Dayton RSS315 HF-4 12" woofer (not an extended surround driver like the Dayton Ultimax). When mounting the woofer on panel 6, should the woofer be all on one side of the panel (i.e., front of speaker flange against the panel), or should the flange be on one side with the rest of the woofer protruding through the hole (i.e., rear of speaker flange against the panel)? I looked at the the Sketchup plans but wasn't able to tell.

One image appears to show the woofer all on one side (not the side with the retention blocks) of the panel (i.e., the front of the flange in contact with the panel): Whereas another image (perhaps for an extended surround driver) shows the flange on the other side of the panel (i.e., rear of the flange in contact with the panel):
Currently, I've mounted the woofer so that the front of the flange is in contact with the panel (i.e., all on one side of the panel).

However, because the screws are awfully close to the hole in the panel, I wondered if the woofer should be mounted through the hole (i.e., back side of flange in contact with the panel) to provide more support.

The THTLP build instructions state that the Dayton RSS315 HF-4 needs gasket tape. There is a hard rubber material on the front side of the flange, and a softer rubber material on the back side of the flange.

If the woofer was mounted so that the front of the flange was against the panel, I could see the need for gasket tape. However, the need isn't obvious if the woofer were to protrude through the panel (so that the back of the flange would be in contact with the panel).

I think that the answer is that the woofer should be mounted so that the front of the flange is in contact with the panel (i.e., the speajer is entirely on one side of the panel). But the proximity of the screws to the edge of the cut-out hole has made me wonder.

2) I will be mounting a plate amp (a Dayton SPA250DSP in an enclosure) to the THTLP. Naturally, I'd like to mount it on the back of the subwoofer. I had thought that the side with the notch would be the front, but photos online show it as being the back. Which side is considered the front? Does it matter?

I recognize that these are rudimentary questions, but I couldn't answer them.

Thank-you.

Dave MacKay

This shows a separate driver mounting panel, it's explained in the plans in the topic Extended Surround Drivers.


Technically there is no front or back. Subwoofer frequencies radiate omnidirectionally, so which way they aim doesn't matter.

Hi Dave,

- I'd mount it all on one side with that driver.

- Your cutout appears to be about ¼" oversized. Even if you mounted the driver in the other orientation, the screws would still be the same distance from the cutout. 2 choices... make a new baffle with a smaller cutout or remove the driver, fill the screw holes with PL (let it dry and sand flat), slightly rotate the driver so that new screw holes still go into the same backing block. But, this time predrill holes (slightly smaller than the screws minor diameter) for the screws slightly canted outward so that the tip of the screw angles away from the cutout/edge. The angle doesn't have to be extreme, just enough so the screw stays in the wood without breakout and you can still get a good angle on the head with a screwdriver without it camming out. I'd guess somewhere about 5-10°would be okay. Whatever angle feels right should do. The frame is going to make it difficult to get a screwdriver in there, so don't put too much angle on them.

- Use gasket tape.

- For best performance, the mouth should be facing a boundary. Preferably directed into a corner as the plans state... bottom of page 16/top of 17.


We always enjoy build pics. Got any you wanna share?

-Seth-

If I had to take a wild guess, I'd say maybe you set your circle jig up, measuring center to center? Which wouldn't take into account the diameter of the cutting tool and would make your hole ¼" larger in diameter than intended. I've done similar things plenty of times and will probably do them again.

If that's the case, next time you set it up, subtract 1/8" from your intended radius to account for the distance from the center of the tool to it's cutting edge.

Or, maybe the pivot screw was just simply out too far. Hard to tell in the photo, but looks like that could also be the case.

Cool router BTW. They don't make 'em like that anymore. When men died before their tools.