Thicker baffle for Pensil 12.2P

[zman01]

Given the 11.8mm thickness of the A12P frame, a 19mm front baffle piece should ideally be made thicker by adding a layer of 4mm or 6mm material.

In my previous Pensil12 build, I had added a 6mm layer of ply from the top of the front baffle roughly 16" down. I did not run it the full length, as I suspected that would result in increasing port depth from 19mm to 25mm and affect tuning.

I am in the process of building a Pensil 12.2P and this time would prefer a flat front baffle - hence am planning to add the layer on the inside. I have attached an illustration of what I want to do - run a 25" 6mm thick piece from the inside top; cross section is maintained throughtout this length, and the layer ends roughly 8" away from the port (resulting in this last part having a slightly greater internal depth of 260mm instead of 254mm).

Hope I am not affecting the line in any way?

Thanks,
Zia

[planet10]

If you want to be anal you could add a few mm to the depth.

dave

[zman01]

Originally Posted by planet10

If you want to be anal you could add a few mm to the depth.

dave

Dave,

Please elaborate! More mm to the depth? Where exactly?

[mp9]

Originally Posted by planet10

If you want to be anal you could add a few mm to the depth.

dave

Originally Posted by zman01

Dave,

Please elaborate! More mm to the depth? Where exactly?

...would have to be to the rear panel, i.e. rather then 254mm inner front to inner back, + 6mm = 260mm front to back, simpler to stick with the plan and add the 6mm sheet to the outside, also i'd go full length with the additional 6mm to the baffle panel and not worry about the additional 6mm changing the tuning Fq. I'll guess you could probably just increase the openings top and bottom edge radius from (10mm) ~1/2" to 3/4" to compensate for the thicker baffle.

[planet10]

Originally Posted by mp9

I'd go full length with the additional 6mm to the baffle panel and not worry about the additional 6mm changing the tuning

Vent depth is specified 18-20mm... the 6mm less depth will have almost no impact,

dave

[zman01]

mp9, thanks for your thoughts - btw, what did you end up building?

Dave,

Sorry, if I have confused you - I don't have less depth (I think).

Plan says internal depth should be 254 mm throughout.

I have 254mm internal depth for top 25" of the cabinet (as per plan)

I have 260 mm dept for the remainder (~10.5") - resulting in slightly larger cab volume; I shall be using bracing and cleats though.

Port size stays faithful to plan at ~19mm.

[mp9]

Originally Posted by zman01

mp9, thanks for your thoughts - btw, what did you end up building?

I'm embarrassed to say i haven't yet:| Got wrapped up going to physical therapy for my banged up arm twice/week and trying to maintain over all fitness on the other days that i let it go by the wayside:\

I'm ready to build now but can't decide between the Standard Pencil or wait to see how topsy's MLTL turns out leaving it as a option. The two are so close in size and probably suited to similar listening environments that i wouldn't want to have both if the MLTL ends up besting the Resonant Air Coupler Pencil's in overall refinement.

I do however have all materials and tools ready to go.
Was disappointed with the Jasper jig so sent it back and built my own circle cutting jig out of a scrap sheet 3/8" plexi i picked up for $6

[zman01]

Hey, that jig looks smart. You need to publish plans for that!

Colin's MLTL also looks good - also designed by Scott. Look forward to his listening impressions once he's done with the build.

You take care of your arm and self. Nothing to be embarassed about - some of these builds end up spanning over long periods. I have an unfinished build on a FAST design provided by Dave which had I started in Feb or March but never got to mounting the drivers!