2 Jack 112s

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TwoTone
Posts: 13
Joined: Fri Jul 01, 2011 7:07 am
Location: Australia

2 Jack 112s

#1 Post by TwoTone »

Hi everyone,
I've got the plans, the speakers and all the timber cut to the right sizes bar a few of the smaller items like the bracing and backplate flanges.

I've never built boxes before, although I built some drawers a couple of months ago. So I'm a little nervous about cracking the lid off the glue and getting into it. But the time's come! I'm building them both at the same time rather than one then the other... I feel like I've got a pretty good feel for the plans.

Here's all the mouth/baffle panels cut out and ready to go.
bits ready for glueing
bits ready for glueing
baffles and grills
baffles and grills
Mouth panels, guide boards on and ready to go
Mouth panels, guide boards on and ready to go
The guide boards above I've protected with some wax paper so they don't glue to the job. I'm using a brad nail gun rather than screws.

Anyone have any experience with or words about the wisdom of finishing with a dark stain and varnish or shellac? I'm curious about the idea and how it would wear and the like...

more pics and stories to come soon :)

TwoTone
Posts: 13
Joined: Fri Jul 01, 2011 7:07 am
Location: Australia

Re: 2 Jack 112s

#2 Post by TwoTone »

Ok, so a couple of other threads here seem to indicate that high quality finishes will just prove a source of frustration once you throw them in the back of the car a few times.

Anyway the build continues apace, more photos below. So much glue, so little wood...

I'm a bit concerned about the next step, getting the top on to cut off the excess mouth panel. Not sure whether to nail and glue it before doing this, or just to hold it in place with clamps.

I'm also wondering about the low pass filter (i'm building this as a bass rig so no piezos). While I'm ok about the idea of the lp filter dropping the impedance and increasing the response in the hi mids, I am a bit concerned about the 2 kHz cut off, since the drivers themselves respond up to about 4 kHz. Aren't I then giving up the extra 2 kHz in response that I'd otherwise get for free? Should I consider changing some of the component values to raise the rolloff point? Or am I being concerned about things I won't hear? I guess it's also a pretty harsh part of the spectrum in that 2-4 kHz range, I'm open to suggestions here.

more to come...
Attachments
Glue everywhere
Glue everywhere
Driver spacer and phase plug extensions are next...
Driver spacer and phase plug extensions are next...

Bones
Posts: 361
Joined: Wed Dec 24, 2008 4:22 pm

Re: 2 Jack 112s

#3 Post by Bones »

I love the way these sound.. Nice looking build

The Big M
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Location: Syracuse, NY

Re: 2 Jack 112s

#4 Post by The Big M »

looking good! Keep going.

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LelandCrooks
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Re: 2 Jack 112s

#5 Post by LelandCrooks »

TwoTone wrote:Aren't I then giving up the extra 2 kHz in response that I'd otherwise get for free?
Nope.
TwoTone wrote:Should I consider changing some of the component values to raise the rolloff point?
Nope.
TwoTone wrote:Or am I being concerned about things I won't hear?
Yes.

It tames the rising response of the woofer smoothing response, not costing response.
If it's too loud, you're even older than me! Like me.
http://www.speakerhardware.com

TwoTone
Posts: 13
Joined: Fri Jul 01, 2011 7:07 am
Location: Australia

Re: 2 Jack 112s

#6 Post by TwoTone »

Ahh, of course. That pesky peak between 2 and 4 kHz on the Eminence 2512. This makes sense to me now.

Thanks

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Bill Fitzmaurice
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Re: 2 Jack 112s

#7 Post by Bill Fitzmaurice »

TwoTone wrote:the drivers themselves respond up to about 4 kHz.
Not off-axis. Axial response alone is moot. If you want more high end add an array.

TwoTone
Posts: 13
Joined: Fri Jul 01, 2011 7:07 am
Location: Australia

Re: 2 Jack 112s

#8 Post by TwoTone »

So I was trial fitting the drivers today and wondering about a couple of things.

How tight should I compress the gasket? I guess it just needs to be airtight.

Should I be removing the rear gasket so that I can screw down directly onto the speaker frame or just be leaving it there and compressing it?

I'm really happy with how the tops went on, the sides seem to be totally square so it should just be a matter of clamps and glue now... then the hardware.
Attachments
Trial fitting the drivers.
Trial fitting the drivers.

Gregory East
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Re: 2 Jack 112s

#9 Post by Gregory East »

Be sure to give up glue in favour of PL when you get to building subs. Hopefully you won't have any whistles in your jacks.
BAT10, Bad Auto Tuba. Reverse folded TAT to fit JBL 1014D, 350W driver, voltage limit unknown.

TwoTone
Posts: 13
Joined: Fri Jul 01, 2011 7:07 am
Location: Australia

Re: 2 Jack 112s

#10 Post by TwoTone »

The glue I've used is a polyurethane expanding glue as specified. Bubbles up and expands as per all the information I've seen here.

But yes, hopefully I've used enough of it and all the joins are perfectly sealed. I think that I read in one thread about using a straw to listen for leaks, so I will give that a try. I'm mostly concerned about where the baffle is joined to the mouth panels with the grill in between but I've used plenty of glue there and it's expanded out both sides, so I'm hopeful !

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LelandCrooks
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Re: 2 Jack 112s

#11 Post by LelandCrooks »

TwoTone wrote:The glue I've used is a polyurethane expanding glue as specified. Bubbles up and expands as per all the information I've seen here.
Not quite the same. You're probably okay with tops. PL does not bubble like the Gorilla stuff. Don't risk it with subs. Personally I can't stand any of the bubbly poly's, I'd rather use old fashioned yellow glue than them.
If it's too loud, you're even older than me! Like me.
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Bill Fitzmaurice
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Re: 2 Jack 112s

#12 Post by Bill Fitzmaurice »

TwoTone wrote:The glue I've used is a polyurethane expanding glue as specified.
The specified PL Premium does not bubble. Don't screw up a sub build for the lack of a three dollar tube of adhesive.

TwoTone
Posts: 13
Joined: Fri Jul 01, 2011 7:07 am
Location: Australia

Re: 2 Jack 112s

#13 Post by TwoTone »

Too late, I glued the sides on last night. Here's some pics of the glue, one from where it's still in the join, the other from a piece that I took off with a scraper.

Here's a link to some info on the glue.

http://www.titebond.com/ProductLineTB.a ... prodline=6

and the pics... if anyone has any opinion I'd be grateful to hear it, although at this stage I'm thinking that I might as well get the drivers in and test for leaks regardless.
Attachments
This is what it looks like once it's been scraped off. Note the honeycomb bubble effect that it gets on the inside.
This is what it looks like once it's been scraped off. Note the honeycomb bubble effect that it gets on the inside.
Here you can see how it has expanded out of the joint.
Here you can see how it has expanded out of the joint.

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LelandCrooks
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Re: 2 Jack 112s

#14 Post by LelandCrooks »

Don't use it on subs.
If it's too loud, you're even older than me! Like me.
http://www.speakerhardware.com

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Trey Fisher
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Re: 2 Jack 112s

#15 Post by Trey Fisher »

LelandCrooks wrote:Don't use it on subs.
+1

Splurge for the $3 stuff.
Yes, I'm an Authorized Builder

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