Speaker placement in a rectangular 1x12 cabinet?

[Dave Locher]

I have a closed 2x12 cabinet that I am converting to 1x12. I have been told by a tech guy at a speaker company that the speaker should not be perfectly centered. My question is, how far off center can it be? The easiest thing in the world would be for me to just install the speaker in one of the two speaker holes and seal off the other hole, but my original plan was to make a new wood face with just the one hole.
It is a small cabinet for a 2x12 - the speakers are almost touching each other and maybe 1 or 2 inches from the sides. I can see how having one speaker that far skewed from center might create some odd dynamics.

Thoughts? Advice? Expert knowledge to share?

[Lake Placid Blues]

Re: Speaker placement in a rectangular 1x12 cabinet?

By slightly off setting it from dead center is prevents what are called standing waves inside the cab. It doesn't need be very far from dead center, perhaps 5/8 of the way over instead of 1/2 way.

[Dave Locher]

Re: Speaker placement in a rectangular 1x12 cabinet?

So I assume too far off center [i.e. shoved over to one side] would cause some other set of problems? At the very least I could imagine uneven pressure on the cone?

[Drano Max]

Re: Speaker placement in a rectangular 1x12 cabinet?

Just make center mark, then move it left or right about 3/4" - 1". That's all there is to it. Probably don't even need to go that far.

[Dave Locher]

Re: Speaker placement in a rectangular 1x12 cabinet?

Ok, I get that part. Now I'm asking if having it WAY off-center would cause problems?

[Darg1911]

Re: Speaker placement in a rectangular 1x12 cabinet?

Ok, I get that part. Now I'm asking if having it WAY off-center would cause problems?

I would guess probably not seeing how full range cabinets with a woofer and tweeter ( or woof, mid, tweet) will generally have the woofer placed at the bottom of the cabinet. But, a heavy driver placed far off center is going to unbalance the cabinet and probably make it a little less steady to move around. Probably not a big deal. I assume you are considering just blocking the one hole in the 2X12 instead of building a new baffle. I would suggest just trying it for yourself. Cut a board and drill holes that line up with the existing speaker hole pattern so you can bolt it right up to the T-nuts that held the speaker. That makes it easily reversible so you can turn it back into a 2X12 with no hassle. If it doesn't work out off center, for whatever reason, then built a new baffle. Or if you have time and are up for experimenting, try both. See if one way sounds any different/better.

[Dave Locher]

Re: Speaker placement in a rectangular 1x12 cabinet?

I would guess probably not seeing how full range cabinets with a woofer and tweeter ( or woof, mid, tweet) will generally have the woofer placed at the bottom of the cabinet. But, a heavy driver placed far off center is going to unbalance the cabinet and probably make it a little less steady to move around. Probably not a big deal. I assume you are considering just blocking the one hole in the 2X12 instead of building a new baffle. I would suggest just trying it for yourself. Cut a board and drill holes that line up with the existing speaker hole pattern so you can bolt it right up to the T-nuts that held the speaker. That makes it easily reversible so you can turn it back into a 2X12 with no hassle. If it doesn't work out off center, for whatever reason, then built a new baffle. Or if you have time and are up for experimenting, try both. See if one way sounds any different/better.

Good advice, Darg1911! Thanks. I'll give it a shot and see what I get.

[devastone]

Re: Speaker placement in a rectangular 1x12 cabinet?

I have a ported Freda 1-12 cab that has the speaker offset quite a bit because of the porting, it sounds great but he did a lot of research on building these cabs so I'm not sure how it will translate to the dims of your cab. I'll send a pick and dimensions tonight if you want, I'm at work now.

[Dave Locher]

Re: Speaker placement in a rectangular 1x12 cabinet?

I have a ported Freda 1-12 cab that has the speaker offset quite a bit because of the porting, it sounds great but he did a lot of research on building these cabs so I'm not sure how it will translate to the dims of your cab. I'll send a pick and dimensions tonight if you want, I'm at work now.

I just found an image online. That looks to be very close to the same dimensions as my cabinet, but in my case it's sealed tight and the speaker is even more off-center. But apparently it's still worth a try. The worst that can happen is it sounds odd and I make a new face for the cabinet.

Any idea what the purpose of the rectangular port is? My cabinet was actually ported at the bottom when I bought it and I sealed it shut because I was trying to get close to the sealed 4x12 sound I already had. Best I could tell, it was a bit tighter on the low end after I sealed it up but it wasn't a huge difference and I didn't notice any other changes.

[devastone]

Re: Speaker placement in a rectangular 1x12 cabinet?

The rectangular port is the port, no porting on the back, it's all sealed. He also designed them to be built from 1/2" Birch instead of the normal 3/4" so it is quite a bit lighter. I can send you dimensions tonight if you want, porting can make a small cabinet sound bigger if it is done right, maybe you can make a removable port?

Oh yeah, FWIW, my cab is one of his prototypes, so can't guarantee it is exactly the same size as his production models (unfortunately he is OOB), but is should be close.

[Demanic]

Re: Speaker placement in a rectangular 1x12 cabinet?

You could always make a cover for the empty speaker hole with a port in it. Just make sure it's the right size. You could also cover the empty speaker hole with something like a 12" drum head and use it as a passive radiator. Just make sure it's anchored down so that the rim doesn't vibrate.

Sent from my MotoE2(4G-LTE) using Tapatalk

[devastone]

Re: Speaker placement in a rectangular 1x12 cabinet?

Hmm, maybe try just one speaker loaded in the current cab, from the controversial Kevin O' Connor London Power books (I say controversial because some people swear by him, other people swear at him).

What's the best cabinet design? Something between a large sealed cabinet and a slightly smaller but still large bass reflex design: a "detuned" cabinet with a single driver. This is essentially a cabinet built for two identical drivers with one driver left out and it's mounting hole left open. The port is not tuned to any specific frequency but instead allows a broad range of frequencies to be reversed through the shallow duct. Instead of having a brick-wall bass roll-off, the low end rolls off gradually but slightly slower than the raw driver. The large cabinet does not sound boxey so mids and highs sound three dimensional, unlike a sealed cabinet which sounds comparatively sterile. We sometimes call this an "open-front" design since it is like having an open-back cabinet where you bring along your own wall. The closed back gives consistent sound regardless of room placement; therefore the port cannot be on the back. The only caveat is one that applies to every other design: that elevating the cabinet seriously reduces low frequency output, so -always leave it on the floor.

From the book 'LONDON POWER DIY Speaker Cabinets for Musical Instrument Applications' by Kevin O'Connor

[Dave Locher]

Re: Speaker placement in a rectangular 1x12 cabinet?

Well if I'm just sealing off one speaker hole then I can certainly experiment with the other hole open, closed, and covered with a "port" cut into the blockoff plate. Plywood's not that expensive!

1/2" would be nice. Mine is all 3/4", plus there is a piece almost the size of the bottom inside of it so it's like two bottoms in terms of weight. That's the main reason I'm going to one speaker: less weight! Hauling that thing up and down stairs was never fun but I'm starting to care more as I get older. I'm also making a new enclosure to hold my head, a bit smaller and 1/2" rather than 3/4" wood, just to make it lighter, a bit smaller, and therefore easier to move and carry to shows. Too bad I don't have roadies, I'd still be playing a 4x12!

[devastone]

Re: Speaker placement in a rectangular 1x12 cabinet?

Referring to the quote from the O' Connor book, he is saying to leave the 2nd mounting hole open. Seems like that would be really quick and easy to try, just remove one speaker and see what it sounds like, and it should be similar to the Freda design based on what I found, of course, YMMV, etc... but seems like an easy place to start.

[Dave Locher]

Re: Speaker placement in a rectangular 1x12 cabinet?

Referring to the quote from the O' Connor book, he is saying to leave the 2nd mounting hole open. Seems like that would be really quick and easy to try, just remove one speaker and see what it sounds like, and it should be similar to the Freda design based on what I found, of course, YMMV, etc... but seems like an easy place to start.

That is my plan: when I get my speaker I'll just install it, plug in, and play. Then I'll block the open hole with wood to see what changes. I then might try it with a smaller port cut into the blockoff piece. Whichever of the three my ears like best, that's what I'll do. I'm hoping the open hole sounds best or as good as the others because it is the easiest and it would be the lightest!

By the way, I really appreciate all the responses I'm getting. You're making my life easier. Thanks.