Small bass amp enclosure size

[JungleVip]

Hi,

I am building a small portable bass amp around a 2 x 25w tripath running two 8'' super 8 speakers. I would like some help if possible with the enclosure design please.

I think I am going with the closed box ideas so far.

Will I need to separate each speaker? What is the ideal volume of the enclosure? Does the horizontal/vertical alignment matter? Any other considerations?

All help greatly appreciated

[bjorno]

Originally Posted by JungleVip

Hi,

I am building a small portable bass amp around a 2 x 25w tripath running two 8'' super 8 speakers. I would like some help if possible with the enclosure design please.

I think I am going with the closed box ideas so far.

Will I need to separate each speaker? What is the ideal volume of the enclosure? Does the horizontal/vertical alignment matter? Any other considerations?

All help greatly appreciated

Hi,

I would separate the drivers in a closed box because you are using separate power amp's for each driver.

The volume needed for flat response is at max= 12.9L if Q=0.7opt box is used = net volume , i.e. less damping material and eventual bracings.

You can adjust the internal volume down a bit by slightly damping your box :

Sub Box Polyester Fiberfill

Even when it's not necessary I would stuff the volumes using a maximum density of 0.5 lb/ft³ ,thus decreasing the required closed box volume to ~1/1.15 = ~87% of calculated volume= ~11.2L/driver.

¼ “ wool felt covering the internal walls would be a good alternative if ~12.9 L(0.455 cu.ft) per driver volume is preferred.

SPL at maximum efficiency(=88%) and 2 drivers/ driven from separate tripath amplifiers is estimated to be ~ 103.9 dB/24(W) ref. 4Ohm at 1m (cone excursion= ~3 mm) occurs when ~27.3 (W) is consumed from the battery(power source).

Max SPL(efficiency=81%) is ~ 106 dB at 1m(cone excursion= ~3.9 mm) ; ~40 W available to the 2 driver sub at a battery dissipation of 50 W.

Note: 2 ApexJr super8 drivers are perfectly excursion safe at 1Hz when using a 2x 25W Tripath amp: No need for a HPF to restrict the lower FR end.

PS: If including the Tripath amp and if battery power is built in the enclosure: I would take on the 'Boominator' approach by designing a separate compartment in between two closed boxes.

b

[JungleVip]

Thank you very much for this

JV