Douglas yee

Bill Fitzmaurice, so as long as I dont run the amp near full power with my cab set up as you stated I won't have to worry about damage to the amp itself? 

So I received this spec sheet from Eminence. I may have to return the speaker for something else as it does not appear to handle to my amp power, (240W@8ohm 350W@4ohm)

    101109A

Re    4.10    Ohms    fs    46.7    Hz

Le    0.80    mH    Mms    35.3    grams

QM    11.95

QE    0.33        Cms    0.330    mm/N

QT    0.33        Rms    0.866    N*sec/m

Xmax    3.00    mm    Vas    62.0    liters

Pmax    150    Watts    SD    366.1    cm^2

Bl    11.27    Tm   

Coil Diameter    2    Inches    EBP    139.7   

Gap Height    0.313    Inches    Magnet Weight    38    ounces

Efficiency    1.82    %    Winding Width    0.550    inches

            SPL    94.6    dB 1W-1m

Thanks for all the help everyone. 

Stevie, you are correct in assuming I want to use what I have available. I'll ditch the smaller ports for the larger one you mentioned and see what up. I play bass for fun and had the cab that wasn't being used. 

Basically this cab is just for home play through so it will never be maxed out. I just needed it to sound good enough.

Sorry I am having a hard time finding data for the speaker.

The speaker is NOS, from SWR factory close out I bought from a local builder. The speaker its self is 10" 8 ohm, 250 watt Eminence Megoliath. That's all I could find out for now. I went to the Eminence website but no info is available. I emailed their tech for a spec sheet but they are closed for a holiday today here in the US.

Sorry I didnt mention I will be replacing with a 10 or 12 bass speaker as well. The box will be closed up. 

I'm repurposing a 1x12 open back guitar cab to bass cab and need help determining port tube size. Its a cab I built years ago and figured it would be an easy conversion.. The cab is all 3/4" Pine box, with 3/4" ply baffle and back. Interior volume and speaker displacement is

1.19 cu. Ft. or 33.2 l volume

.079 cu. Ft or 2.25 l displacement

I plan to use standard 2" port tubes for the conversion. Is there a formula to determine how many and what length the ports should be or does it matter that much at all?

Thanks for the assistance.