Port area per cube question??

[Kyblack76]

My issue, is adding more and more power, and seeing nil on the meter.... like nothing, Brian.

ALso, a lil issue of subs getting hot... that sort of deal.

My understanding NOW, is that my enclosure is to large....

ill work to SHRINK.

And when you shrink it, you loose efficiency and alter your frequency response.

I personally never alter enclosure designs just to allow more mechanical power handling. You can control mechanical with the SSF.

You select the sub based on your goals, design the enclosure based on the sub you selected and the desired frequency frequency response, and then power it accordingly.

Still running the SP4's? How much power?

Yes sir...

same ones.. same leads even

DC 10k at .7

now, 2 6500s at .35. I ONLY gained .3

a 54.5 to a 54.8 at 36hz.

Also, everything got hot as fuck. Amps would thermal 2 songs in.

I ran a Sig Gen, and saw i was hardly over 1ohm reactive (i know how you are with that, fact is that was a big issue) 85 % of the time.

I wired up, to 1.4.

All stays golden, i only lost .9 db on the meter. I have to say, the subs SOUND better. I dont care what anyone says.

Wired down they sounded like shit.

Anyway, i was shocked to see min gain, with all i did.

Only thing not touched? was the enclosure.

PLEASE advise.

Im told to shrink volume, lay off the port, and numbers will increase, playing LOW LOW will also.

(i can play 23hz at full)

[Kyblack76]

I still would like to bust 31hz..

but, im shocked i didnt gain with the added work.

lot of money and time went in that.

[fecupe2001]

IMO you didn´t gain cause everything was more efficient before , i´ll never wire below .5 ohms , did it a couple of times and didn´t like it at all, i prefer to keep everything cooler!

Brian, you are by far a better builder than myself, but may i ask, why do you say if power doesn´t affect port area? i´ve gotten tons of times the same result, bigger port area works better with more power for spl applications, also on my explorer, even keith miller and pipo sanchez had the same results with their walls, once they add power they need to retest port area!

Maybe it´s because once the box sees more power the subs start to pressurize the ported chamber and load the port harder? just throwing ideas out there, talking about our 4th order bps for example, if that´s the case, maybe more power on a common ported box on the back tends to act the same with that extra power? once again, just trying to get more knowledge about this, cause i always get results like this and that´s why i think port area does depend on power , at least a little bit, cheer man!

[CleanSierra]

I'm glad Brian showed up, both Brian's. And always happy to see Fecupe. I like the reading.

[Krakin]

It's the amount of excursion (with everything else staying constant) between the two powers that creates a higher velocity. So the easy thing to do is to just design a port that will work properly at the x-max of the driver so that you don't have to worry about the velocities going too high when adding power.

[bkolfo4]

.35 and .7 is DCR, so don't confuse that with impedance.

Did you measure the actual difference in power between those 2 amp setups?

Let's say you doubled the power, you would be doing good to gain 2-2.5 dB at those levels. And I seriously doubt you doubled the power. . .

People don't understand what it takes to go from 155 to 157 dB. I would laugh when people would say they could not believe my suburban only did a 157.X with 4 15's. For a C-Pilar wall in a suburban tuned to 34 Hz peaking at 37 Hz, I thought it was pretty darn good. . .

[bkolfo4]

Port area vs. Power -

Power definitely matters, but what I stated is that you really need to model up the system to see how it affects the excursion in the given alignment before you factor it into a design (meaning reducing the amount of port area because you are not using the available excursion).

If you can't determine that you will be excursion limited due to the amount of power you have, then it is best to just design for maximum excursion, regardless of the amount of power.

You see more port area helping SPL, because 99% of enclosures in cars do not have the required port area for the port to operate at 100%.

Edit - I will also add that many SPL vehicles take advantage of operating the driver at a frequency in the alignment where excursion is limited by the port tuning. Since they do this, they can drive the sub with a lot more power for short periods of time (mechanical power handling is increased, but thermal is suffering from less cone movement/cooling). Driving it past the "normal" limits will see gains with additional port area. I hope that make sense.

[Cj Kumz]

Port area vs. Power -

Power definitely matters, but what I stated is that you really need to model up the system to see how it affects the excursion in the given alignment before you factor it into a design (meaning reducing the amount of port area because you are not using the available excursion).

If you can't determine that you will be excursion limited due to the amount of power you have, then it is best to just design for maximum excursion, regardless of the amount of power.

You see more port area helping SPL, because 99% of enclosures in cars do not have the required port area for the port to operate at 100%.

Edit - I will also add that many SPL vehicles take advantage of operating the driver at a frequency in the alignment where excursion is limited by the port tuning. Since they do this, they can drive the sub with a lot more power for short periods of time (mechanical power handling is increased, but thermal is suffering from less cone movement/cooling). Driving it past the "normal" limits will see gains with additional port area. I hope that make sense.

Great Info. So that is why most people will lean more towards having a higher port area per cube right? What is the most sq inches per cube that you have used, ever gone over 16?

[Krakin]

IIRC CleanSierra had one well up in the 20's one time, possibly the box for SlaminSuburban

Turned out great.

[Ritch40]

Krakin,

just out of curiosity, what kind of number do you prefer to try to maintain for rear port velocity?

I, with any modeling Ive recently been doing, shoot to stay below 110ft/sec. I was just curious if by chance stumbled across a given number that seems to consistently yield good results? That question asked, I know there probably is no ideal number simply because there is no end to the list of variables.