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Post subject: Re: Build Thread! - 2 x 12 Closed Back Cab
Posted: Fri Jun 01, 2012 9:25 pm
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BMW2002Ti wrote:
" Have you ever tried a convertable or having a port/no port option? "Topp, that exactly how you properly build a ported enclosure. I put a two-piece movable 2-4 inch (depending on the speaker) cylinder in cylinder into the cab. Then, slide the cylinders to increase and decrease the volume of the port and listen to the response. When I hit upon the best response with the least amount of boominess--- measure the dimensions and cut a ported duct to those dimensions. The volume of the port depends on speaker, amp dampening factor, and use of insulation in the cab. So the empirical or experimental way to find the best volume for the duct is the best of each cab and speaker set.

You can close off the hole for the duct to see how the cab responds to no duct--- prior to permanent fixing. And the wood used and how the cab is assemble, plus the overall dimensions (tall or squat) also effects response.


I have seen advertised on ebay, "convertable" speaker cabinets with a back panel on or off.
I am thinking that with the air hole port, open or closed, that the sound behind the speaker
cabinet will be not be affected as if a whole backpanel was removed or installed.

So, BMW, I think I like your idea of having a strong "movable" port that can be closed
or be opened to allow for air possibilities is great. Thanks for sharing. I am planning
on having two or three tone-ring cabinets made. They will not need air ports.

I'm definitely having approximately five speaker cabinets made. Up until today, I was planning
on having open-backs similar to combo guitar cabinets. I've read that open-back-speaker cabinets
fill a room much more completely. I have read that closed-back speaker cabinets are
great if one is in front of them, but not off to the side of their projected angles.
I've a 1963 Tremolux 2x10 closed cabinet & a 1994 Tone Master 2x12 closed cabinet,
so I'll compare these to others, another time.

But, my goal before today, is to have open-back speaker cabinets built for most gigs. And,
if I like the tones/sounds, I can mic open-backs for outdoors or when against a dead wall.

But, funny thing is, most dedicated speaker cabinets are closed-back with some closed backs
providing air-ports. But, hardly any speaker cabinets have open-backs.
Why do you think that is?

Why not set an amp head on a 2x12 open back speaker cabinet
and get a "Twin Reverb like" setup?

Toppscore 8)

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Post subject: Re: Build Thread! - 2 x 12 Closed Back Cab
Posted: Fri Jun 01, 2012 10:23 pm
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Topp, you need to remember that 4 cubic internal feet is really a BIG cab (the Twin Reverb is prolly no more than one cubic feet--if that). You need to account for any insulating material and the thickness of the wood--- so the size of the cab is like 6 x 4 X 2 feet. But, these things really project well. The sealed cab reinforces the speaker cone. So, it doesn't need to move as much as when the back is open--- to make the same volume.

But if you make the thing with 3/4-inch MDF--- it'll make a TR seem lightweight. I have two subs in my house, for hi-fi use. And two tubed EICO HF81 prolly makes 100+dB at 1 watt @ 1 meter. I help make a couple of these things of guitar use (with JBL K130's). And a 15 watt 6V6GT push-pull head will blow you through the wall. But, the weight and size is so cumbersome, really only for home or studio use.


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Post subject: Re: Build Thread! - 2 x 12 Closed Back Cab
Posted: Fri Jun 01, 2012 10:47 pm
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BMW2002Ti wrote:
I have two subs in my house, for hi-fi use. And two tubed EICO HF81 prolly makes 100+dB at 1 watt @ 1 meter.


That oughta peel the sheetrock right off of the ceiling, Steve!

8)

I have a 15-inch Cerwin-Vega powered sub (100W per) wired up to my home theater, along with a pair of JBL 4312's connected to the A/V receiver (Pioneer VSX5000). When a Huey "flies overhead" on screen I can just about tell what the rotor RPM is and how high the EGT gauge on the aircraft's instrument panel is reading. Plenty loud for my old ears!

:mrgreen:

Arjay

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Post subject: Re: Build Thread! - 2 x 12 Closed Back Cab
Posted: Sat Jun 02, 2012 12:20 am
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Joined: Sun Nov 20, 2011 3:16 am
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BMW2002Ti wrote:
Topp, you need to remember that 4 cubic internal feet is really a BIG cab (the Twin Reverb is prolly no more than one cubic feet--if that). You need to account for any insulating material and the thickness of the wood--- so the size of the cab is like 6 x 4 X 2 feet. But, these things really project well. The sealed cab reinforces the speaker cone. So, it doesn't need to move as much as when the back is open--- to make the same volume.

But if you make the thing with 3/4-inch MDF--- it'll make a TR seem lightweight. I have two subs in my house, for hi-fi use. And two tubed EICO HF81 prolly makes 100+dB at 1 watt @ 1 meter. I help make a couple of these things of guitar use (with JBL K130's). And a 15 watt 6V6GT push-pull head will blow you through the wall. But, the weight and size is so cumbersome, really only for home or studio use.


I agree a good quality 2x10 tone ring cabinet will be heavy,
but could be a quality recording studio "tone monster".

I am not going to spoil the OP's thread intentions.
I will start another thread discussing open vs closed back cabinets.
Thanks for everyone's contributions. Toppscore 8)

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Post subject: Re: Build Thread! - 2 x 12 Closed Back Cab
Posted: Tue Jun 12, 2012 7:11 pm
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Retroverbial wrote:
BMW2002Ti wrote:
I have two subs in my house, for hi-fi use. And two tubed EICO HF81 prolly makes 100+dB at 1 watt @ 1 meter.


That oughta peel the sheetrock right off of the ceiling, Steve!

8)

I have a 15-inch Cerwin-Vega powered sub (100W per) wired up to my home theater, along with a pair of JBL 4312's connected to the A/V receiver (Pioneer VSX5000). When a Huey "flies overhead" on screen I can just about tell what the rotor RPM is and how high the EGT gauge on the aircraft's instrument panel is reading. Plenty loud for my old ears!

:mrgreen:

Arjay


JBL 4312's are great speakers, and the last bass reflex speakers on the market that still had solid ash wood cabinets! I have had my 4312's since the mid eighty's, paid $600 for the pair at the Ramstein BX. No finer made speakers available...well under $5K that is.

Hollis, hope the cabinet handles are coming along, the one you made is cool, never thought you were going to make em, thought you would buy em...those are some serious skills you got there. And that Egnater head looks great on top of that cab...I can just picture the egnater color scheme on that cab!

T2

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