T48 stack

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Bruce Weldy
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Re: T48 stack

#31 Post by Bruce Weldy »

Keryn O'Shea wrote: Mon May 15, 2023 5:21 am
Bruce Weldy wrote: Sun May 14, 2023 7:18 pm chance of a screwdriver slipping and poking a hole in the cone.
Great tip.. are you speaking from experience Bruce?
No, but I had a scare or two......one thing I do now if I'm screwing from the front of the driver is to put one of the baffle cutouts on top of the cone when screwing in the driver. I've got a bunch of those BB discs hanging around from all the speaker builds.

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

Bruce Weldy
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Re: T48 stack

#32 Post by Bruce Weldy »

Bill Fitzmaurice wrote: Sun May 14, 2023 8:36 pm 1/4" lags is overkill. What works very well is metal roofing screws, which come in many lengths and have a 1/4" hex head.
I'm not even sure I know what those look like....do they have a washer head?

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

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Bill Fitzmaurice
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Re: T48 stack

#33 Post by Bill Fitzmaurice »

They do. I always have some on hand for any job where I want to use a screw that doesn't countersink.

Keryn O'Shea
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Re: T48 stack

#34 Post by Keryn O'Shea »

Bruce Weldy wrote: Mon May 15, 2023 7:02 am .. if I'm screwing from the front of the driver is to put one of the baffle cutouts on top of the cone when screwing in the driver.
Another great tip.. that one should stop me poking the screwdriver into my finger instead when I'm fitting drivers!
Bill Fitzmaurice wrote: Sun May 14, 2023 8:36 pm What works very well is metal roofing screws, which come in many lengths and have a 1/4" hex head.
Do yours have a fine thread Bill? Nearly used them in an 8" AT for the driver once, as it was late and l wanted to test it. Also liked the washer head for that purpose.
AT8 14", AT10 19", T30 28" LAB12, T48 36" 3015LF, THT 20" LAB15, SLA 4x3"/4x4", CArray 6x4", TLAH, TLAP, J10 FLat, J12 Flat, OT12 Flat, OT15 CD, SLAP 2x6"/4x6", WH8, DR280 Mld'd, XF210. Next J10L

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Bill Fitzmaurice
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Re: T48 stack

#35 Post by Bill Fitzmaurice »

Coarse thread. They're expressly designed for going into plywood, making them ideal for driver mounting.

jakkle21
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Re: T48 stack

#36 Post by jakkle21 »

A lot of progress was made this week.
They are both as far as I can get them without buying more plywood.
Compress_20230525_184654_4288.jpg
I checked my local fancy wood store, and blthe 1/2" BB sheets are currently $65 here in Northern Arizona, and very available.
Compress_20230525_184654_4667.jpg

howiez
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Re: T48 stack

#37 Post by howiez »

jakkle21 wrote: Thu May 25, 2023 8:53 pm I checked my local fancy wood store, and blthe 1/2" BB sheets are currently $65 here in Northern Arizona, and very available.
Wow, maybe prices and supply are coming back around!

jakkle21
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Re: T48 stack

#38 Post by jakkle21 »

We can only hope. They are now $5 less than they were in January

jakkle21
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Re: T48 stack

#39 Post by jakkle21 »

Yesterday I was cutting panels 5 & 6, a long with bracing, and I had a question. In the plans it says they should be spaced 6" to 9", does that mean I should use however many I need to hit at least 6 and most 9 inches between each other and the sidewalls?
In other words, 4 sets of braces since my cabs are 35" on the inside?

Bruce Weldy
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Re: T48 stack

#40 Post by Bruce Weldy »

jakkle21 wrote: Wed Jun 14, 2023 6:24 pm Yesterday I was cutting panels 5 & 6, a long with bracing, and I had a question. In the plans it says they should be spaced 6" to 9", does that mean I should use however many I need to hit at least 6 and most 9 inches between each other and the sidewalls?
In other words, 4 sets of braces since my cabs are 35" on the inside?
Sounds right to me....

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

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Seth
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Re: T48 stack

#41 Post by Seth »

You could do 3 spaced 8¾", 4 spaced 7", or 5 spaced 5 13/16"
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Bill Fitzmaurice
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Re: T48 stack

#42 Post by Bill Fitzmaurice »

Don't worry about exact spacing. If anything it should be randomized, to prevent resonance.

jakkle21
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Re: T48 stack

#43 Post by jakkle21 »

Thank you for all the responses.
One more question while on the subject, what are the pros and cons of more or less braces?
My thoughts are, more braces gives you slightly more riged and sturdy cabs in exchange for a more weight. Possible slightly reduced performance from lost space, but possibly slightly better from being more rigid.

Grant Bunter
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Re: T48 stack

#44 Post by Grant Bunter »

jakkle21 wrote: Thu Jun 15, 2023 1:44 pm Thank you for all the responses.
One more question while on the subject, what are the pros and cons of more or less braces?
My thoughts are, more braces gives you slightly more riged and sturdy cabs in exchange for a more weight. Possible slightly reduced performance from lost space, but possibly slightly better from being more rigid.
The importance of bracing is often misunderstood.
A tiny reduction in response from lots of bracing is a very small price to pay compared to a -3dB loss from panel flex due to inadequate bracing.
Don't forget if you require lots of mouth braces, you need to add extra braces in the horn path too...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Seth
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Re: T48 stack

#45 Post by Seth »

jakkle21 wrote: Thu Jun 15, 2023 1:44 pm Thank you for all the responses.
One more question while on the subject, what are the pros and cons of more or less braces?
My thoughts are, more braces gives you slightly more riged and sturdy cabs in exchange for a more weight. Possible slightly reduced performance from lost space, but possibly slightly better from being more rigid.
If I were building 36" T48's (jealous that you are :thumbsup:), I'd probably do 3 in the mouth, 4 up the back between panels 5 & 8, 3 braces between panels 3 & 5, 4 braces between panels 4 & 6.

Like Grant said, you want the cab RIGID, otherwise output can be compromised. The less panel flex the better. Bill's got it all sorted out. You'll be fine if you follow the plans.

Braces can be made of any quality ply if there's not enough scrap in your BB pile. Can even be done in ¼".
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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