THAM 15 vs Cubo 15 vs Cubo 18 ?

[chris661]

I think it's a big box which was IIRC designed for exceptionally high efficiency.

You need to understand that you're up against Hoffman's Irow Law - Small, Low, Efficient - pick any two.

For my subs, I picked 40Hz as my "low", and then played around with the other two to see what I can get.

We can't pick your compromises for you. Your first post says you want a punch in the chest in large venues and outdoors. I don't think two of any of those cabinets will do what you're after. For reference, my PA system will do that, but it's a total of 8x 15"s in ported boxes, loaded with some really good drivers.

Chris

 

[freddi]

out of my toys (I'm ~immobile and never done real PA work) this one had a little kick for a cheap 18" driver

 

[martinsson]

What do you think of this, is this a good compromise??? a slightly larger THAM 15 box. W22”/D24”/H30” with a B&C 18TBX100

You mean like the THAM18 although it may be slight larger (312dm3 external volume instead of 260dm3 as in your example).


Martinsson's Blog -

 

[Brian Steele]

Can you spare an inch?

20" x 25" x 30" dual-expansion THAM-style layout, using a B&C 15TBW100. This is without any semi-inductance or lossy Le modelling though. If I can get hold of a ZMA impedance file for the B&C 15TBW100, I'll be able to calculate the semi-inductance parameters and include those in the model.

I think the Dayton Audio PA380 might work in the same box. It has a much lower Xmax, but it's also a lot cheaper.

 

[bjorno]

Hi Brian,

FYI:

b

 

[Brian Steele]

Thanks Bjorno. With semi-inductance enabled, the response looks like the attached (in red).

 

[Lukey123]

Thanks brain Steele. Looks ok, definitely a possibility... the one that’s keeps coming up on top in my sims in the SS15 with a 18tbx100... just trying to find a slightly lighter Driver. And cheaper if I can.

Im only just scratching the the top layer with this program and I don’t really understand It fully, and I’m not going to pretend like I do. But I think I get the basics, But this is the best looking result I’ve had so far.

 

[Brian Steele]

From that graph, it looks like the semi-inductance option wasn't enabled for that sim.

If you are set on using an 18" driver in your build, going with a BVR or OSTL alignment might be better, given the restricted dimensions that you have to work with.

 

[Lukey123]

Well I had a pair of Yamaha 15” reflex sub years ago, and they were pretty pathetic, you hardly knew they were on.. so I’m slightly reluctant to go back to 15”s even though I know they will be very different. And I don’t want to build 15s and wish afterwards I’d build 18s. So my general thinking is to cut out the middle man and go straight to 18s if I can.

At the risk of sounding very dull, I don’t know what that means ?? What is a BVR or OSTL alignment? I’ve never come across that term before

 

[Brian Steele]

At the risk of sounding very dull, I don’t know what that means ?? What is a BVR or OSTL alignment? I’ve never come across that term before

BVR = Big Vent Reflex

OSTL = OffSet Transmission Line

The OSTL should have a wider usable frequency response than the BVR, at the expense of some efficiency.

 

[tonskulus]

hmm I need to make one tham15, just to see which one is better overall cubo15 or tham15.
I have one cubo15, just finished some measurements @ outdoors / ground plane.

Orange: cerwinvega 12", reflex (just for comparsion), 2.8V @ 1m
Red: cubo15, 2.8V @ 1m
Blue: cubo15, 20V @ 2m
Green: cubo15, 20V @ 1m

Calbrated mic, umik-1 was used.