Is it a real bass reflex cab ?

[vinceom]

Hello there
I have found an old behringer bass combo, the BX600. I want to use the cab, I have removed the amp. For behringer, the cab is bass reflex. But there are only 2 rectangular holes at the bottom of front panel. According to me, these holes are not ports. Ports must have a depth …
The internal volume is about 35 liters. Is it enough for a Beyma SM-212 driver ? The head amp will be a TC BH250.

What do you think it ?
Thanks a lot
Bob

 

[Hoochie Coochie Man]

Could be a "shelf port", (like the one in the old EV TL606 design). Or it is merely a "slot port" which would be a design choice of the engineer.

 

[Wasnex]

According to me, these holes are not ports. Ports must have a depth …

FYI, sometimes the port depth is the thickness of the panel. So yes it's a port. Whether it's actually engineered well is a different matter.

 

[Redbrangus]

The port for a bass reflex enclosure doesn't necessarily need to have any more depth than the thickness of the baffle board. Your Behringer box IS a bass reflex cab -- that doesn't necessarily mean it's tuned appropriately for the replacement driver you've chosen.

 

[vinceom]

Thanks for your answers. Thickness is about 2 cm … is it enough for a port.
Vituixcad says that with a beyma SM-212, internal volume 35 liters and ports with about 66 cm2, the tuning fréquence is bout 49Hz. Sounds good to me

 

[Redbrangus]

Does 66 cm^2 correspond to the total area of your existing ports?

 

[vinceom]

Does 66 cm^2 correspond to the total area of your existing ports?

Yes, 2 holes (L&R at bottom of front panel) . Each hole is 15cmx2.2 cm

 

[agedhorse]

Thanks for your answers. Thickness is about 2 cm … is it enough for a port.
Vituixcad says that with a beyma SM-212, internal volume 35 liters and ports with about 66 cm2, the tuning fréquence is bout 49Hz. Sounds good to me

The depth/thickness depends on the volume of the box, the TS parameters of the driver and the tuning of the system. Sometimes, the thickness of the material is just right.

Beware of the results of software, it's common for data to be incorrectly entered or incorrect assumptions to be made relative to how the software calculates the various results.

 

[eniac]

What does the frequency response curve look like?

Will that software let you apply different power levels to the driver and show you driver excursion? If so, at what power level does the driver finally reach its Xmax, and at what frequency?

 

[JamesGrant]

I'd refer to these as 'vented' enclosures but a quick Google suggests that ported/reflex/vented are used interchangeably (at least these days!)

So yes, it's a choice and can be part of a well considered system of enclosure and speaker. It may also be part of a poorly designed system of course!

If it sounds good, it is good!

 

[agedhorse]

I'd refer to these as 'vented' enclosures but a quick Google suggests that ported/reflex/vented are used interchangeably (at least these days!)

So yes, it's a choice and can be part of a well considered system of enclosure and speaker. It may also be part of a poorly designed system of course!

If it sounds good, it is good!

Vented and ported are the same thing.

 

[JamesGrant]

Vented and ported are the same thing.

Educated in England - not sure if that makes a difference. I'd learned (perhaps incorrectly) - but happy to be wrong of course! Three terms to describe a nuance regarding the 'type' of opening.

Reflex - like a folded design
Vented - like this post
Ported - like a tube (cylinder or other shape, generally no folds.

 

[agedhorse]

Educated in England - not sure if that makes a difference. I'd learned (perhaps incorrectly) - but happy to be wrong of course! Three terms to describe a nuance regarding the 'type' of opening.

Reflex - like a folded design
Vented - like this post
Ported - like a tube (cylinder or other shape, generally no folds.

All three descriptions are used to describe the same thing, I haven't found the above to be true in any of the circles I have worked in.

bass reflex = ported = vented

 

[ardgedee]

Ported - like a tube

I thought y'all called them "valves" over there.

 

[agedhorse]

I thought y'all called them "valves" over there.

Confusing isn't it?

 

[vinceom]

can we come back to my subject please ? How can I calculate the tuning frequency of this cab if the 2 ports have no depth ? Just 2 holes and depth is thickness of Wood (2cm) ?
Thanks

 

[ardgedee]

can we come back to my subject please ? How can I calculate the tuning frequency of this cab if the 2 ports have no depth ? Just 2 holes and depth is thickness of Wood (2cm) ?
Thanks

In seriousness -- that was answered in posts numbered 3 and 4: It's possible for the thickness of the baffle to be an appropriate port depth. It depends on the speaker's requirements and the cabinet's design.

 

[agedhorse]

can we come back to my subject please ? How can I calculate the tuning frequency of this cab if the 2 ports have no depth ? Just 2 holes and depth is thickness of Wood (2cm) ?
Thanks

You just answered your own question... see your own words highlighted in red.

 

[MIMike]

Can you contact Beyma to see what they recommend for a port size and depth for that speaker with your given box volume?
I did that once with Eminence when I was reworking a Bassman 4x12 cab into a 2x12 with a pair of their speakers. They were very helpful and the cab turned out great.

 

[eniac]

This thread's
Making me see red
Well, it's getting late
Think I'll go to bed