Author Topic: Gluing up speaker cabinet - 1/16” inch gap to fix - need help please.  (Read 6413 times)

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Offline sebr023

  • Posts: 45
Hi all!

Don’t know if I’m in the right section of the forum.

But I’m building some cabinet for some home theater speaker. I’ve already glued up the left and right speaker. Yesterday I glued the Center speaker.

Ive had my share of mistake on building the left and right speaker as I’m a beginner woodworker. But nothing I wasn’t able to solve or I couldnt live with.

I made a “bigger” mistake on the glue up for this cabinet. There’s a 1/16 gap on one of the edge of the cabinet.

The 100$ question: how could I save this?

A friends of mine told me that wood glue doesn’t stick to cured wood glue. 1/16 is a bit thight to go and sand/scrap cured wood glue.

If I clamp this, I am able to bring the cap tighter, but obviously I would need some glue to hold it.

The cabinet is birch plywood and I wanted them to stay that way, meaning I don’t plan on veneering them.

This is the orientation of the speaker, layed on its side.


The 1/16 gap is the middle :


2ft level to show the “bulge” (sorry lack of a better word) it causes.


If I don’t clamp and reduce the gap, the bulge will stay, and I will need to find a way to sand away the bulge, probably going through the birch veneer on the top of the plywood.
But I could pmace this face down, so it wouldn’t be a big deal I guess?!

Anyway, thank for your time and answer. Looking forward to read more advanced woodworker on this problem!

Thanks!


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Online Crazyraceguy

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Is that outer "skin" glued to the core, or it just trapped in there?
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Offline sebr023

  • Posts: 45
Is that outer "skin" glued to the core, or it just trapped in there?
Not sure what you’re referring too.
Everything you see in there is glued.
The bracing inside is glued in dado I did.


Hope this answer your question.


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Offline ChuckS

  • Posts: 4013
That looks to be an easy fix to me since the glue-up has been pretty recent.

1) Put a clamp on either side to keep the top in position (shown in red on the sides)
2) Use a heat gun to soften glue in the gap (about 2 mins a time)
3) Remove as much glue as possible from the mating surfaces (spray water if needed & repeat 2)
4) Let dry
5) Apply fresh glue, and clamp everything home.
« Last Edit: October 27, 2022, 06:26 PM by ChuckS »

Offline sebr023

  • Posts: 45
That looks to be an easy fix to me since the glue-up has been pretty recent.

1) Put a clamp on either side to keep the top in position (shown in red on the sides)
2) Use a heat gun to soften glue in the gap (about 2 mins a time)
3) Remove as much as glue from the mating surface (spray water if needed & repeat 2)
4) Let dry
5) Apply fresh glue, and clamp everything home.
Thank you!
How / what would you use to removing glue in there?  Small ruler? Feeler gauge? Trying to think of something thin but relatively sturdy


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Offline ChuckS

  • Posts: 4013
My tool of choice would be a palette knife or a putty knife. Anything stiff and thin such as card scrapers can do.

Something like this (price in CDN) - https://www.leevalley.com/en-ca/shop/tools/hand-tools/knives/60274-palette-knives-for-woodworkers
« Last Edit: October 27, 2022, 07:29 PM by ChuckS »

Offline sebr023

  • Posts: 45
Gluing up speaker cabinet - 1/16” inch gap to fix - need help please.
« Reply #6 on: October 27, 2022, 08:00 PM »
My tool of choice would be a palette knife or a putty knife. Anything stiff and thin such as card scrapers can do.

Something like this (price in CDN) - https://www.leevalley.com/en-ca/shop/tools/hand-tools/knives/60274-palette-knives-for-woodworkers
Oh yeah! Makes sens! I have a small putty knife and have 2-3 pallet knife laying around!

Edit: spelling


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« Last Edit: October 27, 2022, 09:09 PM by sebr023 »

Offline sebr023

  • Posts: 45
My tool of choice would be a palette knife or a putty knife. Anything stiff and thin such as card scrapers can do.

Something like this (price in CDN) - https://www.leevalley.com/en-ca/shop/tools/hand-tools/knives/60274-palette-knives-for-woodworkers
So just tried your suggestion, I will let dry over night and try to glue back up tomorrow.

When I was applying water with a spray bottle, I saw watered down glue coming out of the joint, so I guess that’s good news!


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Offline ChuckS

  • Posts: 4013
Sounds good. Make sure the clamps stay long long enough after the regluing, and good luck!

Offline sebr023

  • Posts: 45
Sounds good. Make sure the clamps stay long long enough after the regluing, and good luck!
How long are you thinking? 12hr? 24?
I’m using basic Lepage yellow wood glue, the « pro » version I believe it’s called.


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Offline ChuckS

  • Posts: 4013
8 hours should be enough since it isn't something subject to stress.
« Last Edit: October 28, 2022, 07:02 AM by ChuckS »

Offline sebr023

  • Posts: 45
8 hours should be enough since it isn't something subject to stress.
Thank you!


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Offline sebr023

  • Posts: 45
8 hours should be enough since it isn't something subject to stress.
Update:

Used 2: 2x3 steel piece to help spread the clamp force. Got a good squeeze out.


Even on the inside I got a squeeze out:


Which make me hopeful that the glue was everywhere it needed to be so the joint can hold!


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Offline Packard

  • Posts: 1694
Just to throw a wrench in the works:  Most speaker builders use MDF as it resonates less than other sheet goods and improves the sound quality.

Offline sebr023

  • Posts: 45
Just to throw a wrench in the works:  Most speaker builders use MDF as it resonates less than other sheet goods and improves the sound quality.
It’s debatable. I’m not an expert, far from it, but there’s test out there that proved it not necessarily true.

Also, I bought the kit from CSS audio. They recommend both. Also, some other higher end speaker manufacturer uses birch ply.

I bought the 1TD for left and right and the 2TD for the Center channel. They’re very well brace for the type of speaker.

I would still be curious to see the measurement of both  speaker in MDF and birch plywood.


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Offline Vtshopdog

  • Posts: 179
Yes, MDF and Birch ply are both used. Designer usually specs the cabinet material.
Material used will change the sound characteristics, but who is to say what sounds best?

This fellow is a DIY speaker building icon of sorts and generally builds everything with BB ply
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm

Even if you are just a wood nerd and not an audio nerd his site has tons of beautiful build threads and is worth a look.  He does a lot of cool variations on building what in essence are boxes.
(fair warning, if you fall in love with something on his site and want to build, a kit will set you back minimum $1k and more likely $2-4k)

LOL - Speaker building was my gateway drug to buying Festool....

Offline JimH2

  • Posts: 1182
Just to throw a wrench in the works:  Most speaker builders use MDF as it resonates less than other sheet goods and improves the sound quality.

Can we get some type of data to back up your "most" statement? Sounds anecdotal at best.

Offline Cheese

  • Posts: 10184
Just to throw a wrench in the works:  Most speaker builders use MDF as it resonates less than other sheet goods and improves the sound quality.

Can we get some type of data to back up your "most" statement? Sounds anecdotal at best.

Packard is correct in that JBL has always recommended MDF because it resonates less than ply. I purchased a JBL Speaker Kit back in the early 70's. It was a 20 page assemblage of written/technical material about proper speaker construction including materials and joint construction. JBL at that time recommended MDF boxes along with lock miter joints for every corner.

I still have a pair of the original JBL L100 speakers from the 70's & the L100's are manufactured from MDF with lock miter corners.  [smile]

And then there's the Altec Voice of the Theatre speakers. They were huge but constructed from all plywood. An interesting note is that I never liked the VOT sound because I thought its treble was too strident. Did the all-plywood construction generate some of the stridency?  [popcorn]

« Last Edit: October 28, 2022, 11:15 PM by Cheese »

Offline Michael Kellough

  • Posts: 5730
@Cheese , re the JBL manual, was Baltic birch generally available as an option back then?

Offline Cheese

  • Posts: 10184
@Cheese , re the JBL manual, was Baltic birch generally available as an option back then?

Not that I remember Michael, Baltic birch is a more recent thing. I just remember the MDF recommendation because that really surprised me. But then again after a little thought, it made sense because at the time the larger Wharfedale speakers were being filled with sand to dampen the resonances.

Offline sebr023

  • Posts: 45
We could speak of speaker design for a long while! There’s so many variables. Even with the filling in the speaker: egg crate foam, rock wool, jeans wool, etc. Each has their properties.


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Offline sebr023

  • Posts: 45
Gluing up speaker cabinet - 1/16” inch gap to fix - need help please.
« Reply #21 on: October 28, 2022, 04:49 PM »
Yes, MDF and Birch ply are both used. Designer usually specs the cabinet material.
Material used will change the sound characteristics, but who is to say what sounds best?

This fellow is a DIY speaker building icon of sorts and generally builds everything with BB ply
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm

Even if you are just a wood nerd and not an audio nerd his site has tons of beautiful build threads and is worth a look.  He does a lot of cool variations on building what in essence are boxes.
(fair warning, if you fall in love with something on his site and want to build, a kit will set you back minimum $1k and more likely $2-4k)

LOL - Speaker building was my gateway drug to buying Festool....
If you have time look up the criton kit, didn’t hear them yet as their being build, but from the reviews I saw, their pretty good.

It already set me back 1.5k cad. And I don’t even have the 5 bed layer speaker. And I’m aware that nothing in the world of speaker/speaker building.

I will take a look at your link!


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« Last Edit: October 28, 2022, 04:59 PM by sebr023 »

Offline Vtshopdog

  • Posts: 179

And then there's the EV Voice of the Theatre speakers. They were huge but constructed from all plywood. An interesting note is that I never liked the VOT sound because I thought its treble was too strident. Did the all-plywood construction generate some of the stridency?  [popcorn]

Cheese, tweeters are usually not real dependent on the cabinet, most all of them are little self sealed enclosures and the driver cone (or ribbon) generally does not interact with the speaker box very much.  Tweeter on most designs has a resistor somewhere in the crossover to attenuate the raw signal, a higher value resistor might have produced sound more to your liking.

For ply vs MDF my understanding is BB does have a higher frequency natural resonance than MDF but probably will manifest more in the upper bass and mid ranges than treble.  Think of the clatter a dropped piece of ply makes vs thunk of dropped MDF.  Realistically the crossover and cabinet designs plus construction will dominate the sound characteristics and material will be secondary as long as box is rigid and well braced.

Disclaimer:
All my above spew should be taken with a grain of salt as this is one of those topics where the more you learn the less you know.

EDIT:
Were the VOT's horn type speakers in the vein of Klipsch?  If that's the case then material might be very primary in sound.
« Last Edit: October 28, 2022, 07:10 PM by Vtshopdog »

Offline sebr023

  • Posts: 45
Gluing up speaker cabinet - 1/16” inch gap to fix - need help please.
« Reply #23 on: October 28, 2022, 09:58 PM »


EDIT:
Were the VOT's horn type speakers in the vein of Klipsch?  If that's the case then material might be very primary in sound.
[/quote]


I don’t know about the VOT, but the klipsch are often called having a “cold” sound because of their tweeter or very toward sounding in the upper frequency range!


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Offline Cheese

  • Posts: 10184
Were the VOT's horn type speakers in the vein of Klipsch?  If that's the case then material might be very primary in sound.

Yes, a large 2-way horn & woofer system.

I said the treble was strident but probably more correctly it was the upper mid-range frequencies that bothered me.

A typical 60's/70's VOT speaker.






Online Bohdan

  • Posts: 1023
Altec Lansing A7 "Voice of the Theatre" a good choice to get the music volume above the noise of a wood working shop.

Offline Cheese

  • Posts: 10184
Altec Lansing A7 "Voice of the Theatre" a good choice to get the music volume above the noise of a wood working shop.

Lol Lol Lol...now that's funny.  [big grin]

And with all the machine tools operating at the same time. [smile]

So @sebr023 did you solve your problem and do you have any additional photo's to share?
« Last Edit: October 29, 2022, 09:44 AM by Cheese »

Offline Vtshopdog

  • Posts: 179
LOL - the VOT's achieve a trifecta:
Take a ton of space
Sound bad (per Cheese)
Really ugly (I.M.O.)

Did a quick internet read and they have reputation of harsh treble but conversely are also a cult favorite.  Apparently they do not match well with high powered solid state amps that took over the market in 70's and 80's.  Best used with low wattage single end triode type tube amps circa late 50's.

Offline sebr023

  • Posts: 45
Gluing up speaker cabinet - 1/16” inch gap to fix - need help please.
« Reply #28 on: October 29, 2022, 01:11 PM »
@Cheese (did it work? How do I tag someone?)

Thanks for asking.
Yup. It pretty much did it!
I was left with a bump on the longer panel, but I don’t think I would be able to fix that anyway.



The opening was on the left side of that picture.

I’m happy with the result


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« Last Edit: October 29, 2022, 04:35 PM by sebr023 »

Offline Cheese

  • Posts: 10184
LOL - the VOT's achieve a trifecta:
Take a ton of space
Sound bad (per Cheese)
Really ugly (I.M.O.)

Did a quick internet read and they have reputation of harsh treble but conversely are also a cult favorite.  Apparently they do not match well with high powered solid state amps that took over the market in 70's and 80's.  Best used with low wattage single end triode type tube amps circa late 50's.

Ya, these were originally designed to be used as...wait for it...sound reinforcement speakers, as in auditoriums, outdoor music events and theaters. But somehow people decided in the 70's that they'd be great music speakers, so they became extremely popular because back then bigger was better and these things were relatively cheap considering their size and the quality of the components inside. [big grin] Just the horn driver alone, minus the horn, weighed 10-15#


Back to your tube amp statement, my friend drove these things bi-amped with a pair of Audio Research D51 and D79 tube amps to clean up the sound a bit.

« Last Edit: October 29, 2022, 01:39 PM by Cheese »