GM-416-8B MLTL Corner Cabinet

[srivenkat]

You should really use biscuits all along the angled edges.. It is the only way to ensure an airtight strong glued joint...If you don't have a biscuit joiner you can rent one at Home Depot.Or any similar lumber yard.

AB,

Thank you.

I was able to glue few boards and filled the small gaps I noticed with PL-400/saw dust, I didn't know about the biscuit, I will look into it for the remaining boards.

Also see folks suggested the following, "Bondo", "DAP acrylic caulk", "DAP Silicone" to apply from interior for better sealing. Any thoughts?

Appreciate your input on this.

Thank you,
Sri

[GM]

Yes, biscuit or dowel joints are preferred, especially if both sides of the panel will be exposed, but my 'el cheapo', quick [my operative word WRT woodworking] sawdust/PL400 or similar appropriate bonding agent for the material[s] + internal reinforcement does just fine even on the outside as long as it's not going to be a stained or similar finish.

That said, when making any kind of seamed joint it's best to back cut them a degree or three more than the mathematically 'ideal' angle depending on how accurate the tool gauge and/or one's measurement capabilities are, so that the finished side makes a 'seamless' joint [or in this case a 'knife edge'], then just the bonding agent can be the [ backside/internal] joint 'filler'.

GM

[srivenkat]

Yes, biscuit or dowel joints are preferred, especially if both sides of the panel will be exposed, but my 'el cheapo', quick [my operative word WRT woodworking] sawdust/PL400 or similar appropriate bonding agent for the material[s] + internal reinforcement does just fine even on the outside as long as it's not going to be a stained or similar finish.

That said, when making any kind of seamed joint it's best to back cut them a degree or three more than the mathematically 'ideal' angle depending on how accurate the tool gauge and/or one's measurement capabilities are, so that the finished side makes a 'seamless' joint [or in this case a 'knife edge'], then just the bonding agent can be the [ backside/internal] joint 'filler'.

GM

GM,

Thank you.

I am moving on with connecting other boards now. While building this, one other question on the front baffle mounting,

Front Baffle (FB) will be mounted on 2x2 frame inside however, the horn cut out on FB starts ?” from the top and the horn box (inside) starts exactly from the top. So, mounting the top of the front baffle to this inside frame is questionable now.

(1) I can move the horn cut-out down by another inch and have a 1” frame inside for mounting the top of FB
(2) I can attach the top of FB to cabinet’s top board (can this be done drilling from top side of the cabinet into the front baffle) having neoprene in between.

Any other options? Appreciate your help.

Thank you,
Sri

[westend9]

Sri,
On the inside joints, pl400 or similar makes for a good seal. If you then wish to seal the wood on the inside with a shellac or varnish, you can seal across the pl400 adhesive with no consequence.

[srivenkat]

Sri,
On the inside joints, pl400 or similar makes for a good seal. If you then wish to seal the wood on the inside with a shellac or varnish, you can seal across the pl400 adhesive with no consequence.

Lance,

Thank you.

-Sri

[GM]

I know GM has mentioned it to me and others that the top panel has a lot of the MLTL sonic loading and a double panel on the top would inherently help with that loading.

Right, either make it out of something really heavy and/or perch something heavy on it [a large potted plant on top proved a great choice for any potential WAF/SO issues + a leafy plant makes a good diffusor of rear/side wall reflections] and no hardware is required as long as a good quality neoprene gasket is used.

GM

- - - Updated - - -

Hey all, sorry I've been absent for awhile, I've been very busy lately with all of the packing and moving to Canada after the election and all that... at least it's only a 50 mile trek.

Here are the latest plans, I love designing, but hate the labeling and page setup stuff. I will eventually create a PDF of the 3 or so drawing sheet, but Photobucket won't accept a PDF format, so I will have to send them via Private Email.

I figure that we currently have a net Vb for a single 416-8B/811B/802xx of 26.1407CF and with twin 416-8B/511B/802xx of 23.7068CF. Each 1/2" increase of box depth equals about .65CF. GM, just how accurate to 24CF do you want the Vb to be?

For the driver rear support, I am leaving a 1/4" gap, thinking that some surplus rubber conveyer belt (Rex's Hardware) can be used to create a snug fit around the magnet structures.

Making good on leaving the country if Trump was elected?

Regardless, hope all's well and 'mom' is recovering at a good pace.

Agreed, I started my professional career as a jack o' trades pencil, pen & ink draftsman with LeRoy text for the most part just because I had a knack for it all, but I questioned/'corrected' so many design errors that I quickly became a jack o' trades designer, allowing me to just scribble the critical bits n' pieces of a design with notes on whatever was available, then once a 'library' of finished drawings was available, just marking up a print, hence my lack of hardly any documentation of all my builds way back when beyond the occasional scribbling of critical dims on scraps of various leftover materials.

Well, based on T/S design theory the cab is technically too large for a single woofer unless some form of EQ is used and could be just right to way too small for dual woofers, so in the scheme of things a ft^3 here or there isn't going to be obviously audible assuming a Fs tuning unless it happens to interact with the room's acoustics in very specific ways, so strictly up to Sri as to where the cab size point of diminishing returns lies.

Hmm, with really heavy woofers like these and especially in 1/4 WL loaded cabs where even pinhole leaks can ruin its tuning, best IME to limit the gap to where a thin layer of craft felt makes a 'tap on' snug enough fit to create a slight compression [clamped in place] to ensure the driver is properly mass loaded and with a proper seal.

For basic reflex/ducted port speakers, there's typically more damping material plus an air mass 'plug' of ~uniform particle density, so this extra bit of driver damping, sealing isn't required except to handle high excursion/power.

GM

[srivenkat]

GM,

Like to share the cabinets progress....attaching couple cabinet pictures. I would say they are about 60% complete still lot to work on inside top/bottom, left/right stiffeners, baffle frames, driver support etc. Hope to see James around here, his drawings help tremendously.

I am trying to figure out how to support the back of drivers. I would appreciate if you can help me choosing the right (and simple ) way.

Can I use a straight board at the back of the driver, instead of cutting the shape of the 802/416 using router (bit hard for me)? So, this straight board will push the back of 802/416. Would it be ok?

I am going to use 2" thick Owens Corning 703 for left, top, and back - should I consider anything different given the shape?

Also, for the dual woofer configuration, I initially thought of going with a pair of 8Ohm (in series so 16 Ohms) 416 but now, I am thinking of going with pair of 16Ohms (in parallel so 8 Ohms) 416. For me, keeping it in 8 Ohms make things easier to try different amps.

I have bunch of pictures and I am planning to load them all in the Photobucket and post the link in the forum once I have the speakers ready, hopefully in a few weeks from here.

Appreciate all your help.

Thank you,
Sri

[RonSSS]

Now that's a project!

Ron

[mah]

Design, plans and build. Great work, guys.

[GM]

I would say they are about 60% complete still lot to work on inside top/bottom, left/right stiffeners, baffle frames, driver support etc. Hope to see James around here, his drawings help tremendously.

I am trying to figure out how to support the back of drivers. I would appreciate if you can help me choosing the right (and simple ) way.

I am going to use 2" thick Owens Corning 703 for left, top, and back - should I consider anything different given the shape?

Yeah, this went way beyond the initial design and I got to the point where I couldn't keep up plus there seems to be areas of the drawings that don't seem to jive with some of my thoughts on how to make this cab a triple conversion, especially when you wanted to start shifting things in the vertical plane where I made sure the two horn setups would fit and now supposedly don't if I understand some earlier Qs, so something's amiss and why I need proper drawings of each before commenting further.


The HF driver support can be a 90 deg 'V' slot cradle in a 1x4 hardwood board where the 'V' depth is the driver radius and the woofer can be two of these clamping the woofer [one above, one below] with a scrap piece of plywood or hardwood to make a rear plate to be able to preload the woofer[s] against the baffle as well as provide a bit of extra brace support across the 'V' notch on the bottom board.


I've never used 2" on large cabs, just 1" and never felt the need to add more except to the top plate on occasion, so using it elsewhere may be overkill, especially across the curved back.


GM