Mad idea of the day - the 'mixed back' cab

SunDevil

I like a Clelestion Blue in an open backed cab, but the G12H I want to mix it with works best in a closed back, so if I want them both in a 212, how about I cut a new back board with an apature only behind the blue?

Would I need to box off / separate the two speakers to get 80% of the best of both worlds?

Anyone ever tried it?

Baz

octatonic

Mesa used to make a halfback cab.
Is this the sort of thing you mean?
I'm not a huge fan myself- it was a bit 'neither fish nor foul'.

SunDevil

Sounds like it could be - 1 Half open and one closed but without ending with two small, individual cabs?

"..used to make" - sounds like it was an inspired hit then?

octatonic

SunDevil said:

Sounds like it could be - 1 Half open and one closed but without ending with two small, individual cabs?

"..used to make" - sounds like it was an inspired hit then?

They weren't that popular.

stickyfiddle

Might be worth trying a back-board that's 70% closed, so you get some air behind the Blue but keep a fair chunk of the G12H side closed. 

I have a feeling it wouldn't be worth the effort. And if you wanted more of the effect you'd need to make an internal divider; very rigid and firmly fixed, at which point you risk making both sides of it sound quite boxy. 

I imagine @ICBM would have a good instinct for this, if he hasn't already seen/heard it done.

slacker

I've got a pacific woodworks cab that has a partition. The lower section has a theile port and the upper is semi open.I like it. 

guitarfishbay

octatonic said:

SunDevil said:

Sounds like it could be - 1 Half open and one closed but without ending with two small, individual cabs?

"..used to make" - sounds like it was an inspired hit then?

They weren't that popular.

The Road King cab? I thought they were still available just nobody ever stocks them.

http://www.mesaboogie.com/cabinets--simulators/guitar-cabinets--simulators/road-king-series/2x12-road-king-horizontal.html

martinw

I made one a few years back for @Pete24v ;
It was a 4x10, with 2 open and 2 closed.

ICBM

Yes, Mesa still make half-open/half-closed cabs as part of the Road King series as guitarfishbay said.

You do need the closed side fully closed for it to work properly, even if there isn't an opening behind the speaker.

Pete24v

martinw said:

I made one a few years back for @Pete24v 
It was a 4x10, with 2 open and 2 closed.

Yep, one of my favourite cabs with celestion G10 Vintage and Alnico Golds in an X pattern. The idea for it was basically an upgraded version of an old Laney cab I had in the 90's which from memory sounded great. I'll have another one built at some point, with hopefully lighter materials and or speakers ;-)

SunDevil

Cool - sounds like it's worth me messing around a bit and seeing what I can come up with

sweepy

That MJW 4x10 worked a treat, I used to own it and used it with my Bassman, so it's not a mad idea at all

ecc83

Compared to the enormous variation put into amp design, voicing, valve types, traffs, bias regimes..There seems to be little constructive experimentation with speaker cabls? Maybe because you need good skils/tools to make them and they are expensive things to get wrong?

Mind you, I doubt there is any "magic lost design" out there waiting to make someone a fortune? Playing around with loading, sizes and enclosure is only really going to affect the LF response and the polar plot to some degree and THAT will be subject to room effects.

Dave.

ToneControl

wouldn't you need to reduce the effective cab volume (space) for each driver  by splitting the cab?
Thus compromising what could have been achieved  with the unified cab volume?

Cirrus

ToneControl said:

wouldn't you need to reduce the effective cab volume (space) for each driver  by splitting the cab?
Thus compromising what could have been achieved  with the unified cab volume?

Yes.

I wouldn't bother - generally speaking a 2x12, be it closed back OR open back, is going to sound bigger (and better) than effectively two 1x12 sized cabs, one open and one closed, that just happen to be in the same box. Unless you *like* the sound of small cabs, then all bets are off. The mesa cab gets round it by being big, so the fully enclosed speaker has basically a 2x12's worth of volume to itself.

SunDevil

Yep - I was thinking the same

I can see a potential benefit with 4 speakers split open and closed, but less so with a 212 due to that closed back speaker effectively sat in a tiny box.

i might get more 'mileage' from messing around with apature size on an open back to find the sweet spot that keeps the Blue and G12H happy

ToneControl

I  would recommend having a removable panel on the back though, I have one on a  Zilla. I leave it off since I have 2 Celestion Golds in there

ChrisMusic

Open and closed back, like this ?

http://i.imgur.com/jsgTLBX.jpg

https://www.vinstrum.com/image/cache/data/vinstrum/IMG_9408-2000x2000.jpg

http://i906.photobucket.com/albums/ac266/mrrdillard/Mesa amp/photo1.jpg

octatonic

ICBM said:

Yes, Mesa still make half-open/half-closed cabs as part of the Road King series as guitarfishbay said.

You do need the closed side fully closed for it to work properly, even if there isn't an opening behind the speaker.

I didn't realise they were doing it in the Road King cab.

ecc83

Ooo! I would make up a plywood frame and cover it with a sturdy speaker fret to protect those drivers.

Dave.

SunDevil

Just coming back on this - does it matter where on the back of the cab the opening is in an open back - does it need to be in line with the speakers or would top / bottom / L/R side be ok?