Pencil Tower

[jhollander]

This is the project that won third place in the Dayton category at MWAF 2012. I'll post the details in this thread.

The design goal is a narrow tower for LR mains in a 5.1 home theater system. The configuration is mmtmm with 4 of the Dayton ND90-8 and the Dayton ND20FA-6 tweeter.

The design began life as a cascaded 2.5 with a double chamber reflex enclosure. The design morphed into a simple 2-way reflex design.

The enclosure is 20 liters.

The tweeter to mid is crossed at 3,800 Hz.
The tweeter has a second order filter.
The woofer has a 3 order filter with an RC shaping circuit, corrected damped 4th order

More to come
The response was designed to be flat.

[jhollander]

Re: Pencil Tower

I think this is the right pic of the response over simulated. I went through at least 6 x-o’s before settling on this one. Note the SPL is not accurate.

The PCD three panel is also shown.

[jhollander]

Re: Pencil Tower

Here's unibox and the x-o drawing. I'm pretty happy with the number of components.

The inductors are all 20 gage. Film and foil cap on the tweeter, electrolytic on the low pass.

I'll post some construction pics

[jhollander]

Re: Pencil Tower

This cabinet is a pain so you’ve been warned.

The cabinet is solid oak with a removable back. The back is gasketed with weather stripping. The weather stripping held up better than the speaker gasket foam-tape material.

There is a middle window brace. There are corner braces and cleats for the removable back. The back is held in place with 14 recessed black pocket screws.

The drivers are recessed and mounted on a poplar mounting plate. The mounting plate is relieved in the back with a 45 degree chamfer. This is a required step. The mounting plate is covered with felt before being held in place with cleats.

The ports are mitered 2 inch PVC mounted in PVC flat trim.

The finish was easier than the cabinet.

[jhollander]

Re: Pencil Tower

More construction pics

[jhollander]

Re: Pencil Tower

OK last group of construction pics

The finish will be another day

[6thplanet]

Re: Pencil Tower

I really liked the finish you put on those cab's, very nice! They sounded pretty good to...

[greywarden]

Re: Pencil Tower

Yeah you really nailed that finish, it really looks awesome!

[Wolf]

Re: Pencil Tower

Oh- YOU'RE jhollander! I gotcha now!!!

You did a nice job on the finish, and they sounded pretty good too.

FYI- that is technically a damped 4th order electrical on the ND90's.

You did much better than last year's horn thingy!
Congrats!
Wolf

[Paul Carmody]

Re: Pencil Tower

That's a clever way to hide the pincushion frame. I never would have thought of that.

[jhollander]

Re: Pencil Tower

Thanks all.

Last years was an experiment. I mistakenly thought that MWAF was a listen-around, talk, get advice, etc. It's much more intense where you need to bring both a good sounding and good looking speaker.

John H

[John_Frum]

Re: Pencil Tower

That is a beautiful finish, I love em. Great work on the construction as well. All this with a modeled response that audiophiles love and doctors hate. Great work man.

[greywarden]

Re: Pencil Tower

Why do doctors hate a flat response? Oh haha nvm...

[skinney6]

Re: Pencil Tower

i'd like to finish my baffles like this.
would you tell me how you got this beautiful finish?

[ReissM]

Re: Pencil Tower

You knocked this one out of the park.

Very cool.