New tempest enclosure

[David R.]

Decided to replace my "Cylinder" home sub with a traditional box.. The results:

Images not available

Like most pictures, the finish didnt photograph well.. The color is more even/uniform then the picture shows.

It's a 15" tempest with the DT300 plate amp in a 122L sealed enclosure..

Just need to build a grill for the front.

[Andrew Pratt]

You do nice work David :T

[David R.]

Thanks..

Your tumult project turned out great to.. Not sure if i posted that in your thread..

I will try posting a freq. response chart tonight.. Looks decent other then a drop around 80hz.. possibly a phase problem with the mains.

[Andrew Pratt]

I had a drop off at the XO point too...try inverting the phase and see if that doens't clean it up.

And thanks for the comments on my new unit.

[David R.]

I actually did try adjusting the phase control on the plate amp.. made a 1 or maybe 2 db difference.

Weird thing is that if i disconnect the mains and only play the subs.. The drop out remains.. It almost looks like the recievers crossover is set lower then 80hz, like 65-70hz. But if i move the sub from the front corner location (Shown in picture) to a spot to the side of the couch (Against one wall).. The problem is gone, and the sub is flat to the xover point.

[Andrew Pratt]

What happens then if you move the XO up or down? Its likely just a room mode at that spot that just happens to be the XO point as well.

[David R.]

^ I will have to check again.. But if i remember from my initial testing a week ago, the drop off actually moved when i changed the xover from 80 to 100hz..

i will double check, and post a couple freq. responses tonight.

[Andrew Pratt]

Interesting...which receiver do you have? ( A denon if I recall correctly)

[David R.]

^ Denon 2802..

Im going to do some measuring tonight, and also try moving the meter around to different spots.

[David R.]

So after doing some testing i have indeed found it to be a room node.

When i set the xover to 120hz and retested, the level droped 10+dB at around 100hz, and then jump back up after. I then tested the mains (Sub is placed right next to the mains) by turning the sub off and setting the mains to large.. Yep dropped at 100hz..

Anyway.. I figured i would post a chart.. It includes the mains, xover is set at 80hz.. And im using 6db of boost at 20hz in the amp..

Image not available

When i place the sub next to the couch, its pretty flat to 20hz with OUT any eq boost at all.. But the rest of the response isnt as good, theres a big suck out at 50hz (almost 15db), and a 5db drop at 63hz.

[Andrew Pratt]

Not bad David. You might consider buying RickS's BFD though to dial in a nice house curve and take care of that dip.

[David R.]

I have been thinking about picking up a BFD actually.. Not sure who RickS is though.. is he local or?

[Bent]

Hehehe, maybe we could start a bidding war.

[taz13]

Bfd

if you want to buy new, fleet pro sound and lighting out of Ottawa is pretty decent for prices and shipping in Canada

[Paul H]

I think it's currently cheaper to buy from forum sponsor PE, considering the exchange and $5 border fee. I just ordered one from there myself.

Paul