SPL Questions

I would like to start a topic about questions we all might have and I think together we can be smart. So feel free to ask or chime in.
To go big or to go small that is the question. (Big box or small)
Next question, How do you measure ohm rise and how can you help reduce it?

with price of wood id say small just playing man

ohm rise s a simple calculation that is thought in physics if your running in series you simple add together your resistors and if your running in parallel you divide one by the resistance and add the total resistance you find and then divide one by that

I.E. series. 4+4=8 dual 4 ohm voice coil sub

I.E. parallel 1/4=.25 .25+.25=.50 1/.50=2 same sub as before

now series connection is positive on one side of sub is connected to amp and the negative on the same side is connected to the positive on the other side of the sub and the negative on the other side of the sub is connected to the amp.

Parallel is positive on one side of amp to positive on the other side and the connected to the amp. and same with the negative.

big box or small box would depend on power i would say now mike correct me if im wrong i know you know this but the smaller the box the more power the sub with withstand and the bigger the box the less.

my question i have for whom so ever wants to find out. is there a way to apporximate the wattage that is coming out of the amp without guessing.

im saying the answer lies somewhere in the equation watts= volts * amps(current flow)

Enclosure size depends on space available, power, vehicle resonance, speaker specs and also the goal of the frequency bandwidth. Just to name a few things

James Reed wrote:

Depends on space available, power, vehicle resonance, speaker specs and also the goal of the frequency bandwidth.

explain vehicle resonance for me please.

i think smaller is better for a strictly spl box. it will help out in cone control.
and bigger usually reduces rise.

the last box for the 18 was 5 cubes tuned to 31 peaked at 41 with a 152.3
this new box is 5.6 cubes tuned to 55 peaked at 51 at the comp with a 153( i think it should be higher for that tuning)

my rise with the big box is from .5 to 1.2
rise with the smaller box was from .5 to about 3.5
both of those were at the peak spl freq

to measure it you need a multimeter and a clamp meter
measure the ac voltage and the current going to the speaker
divide the voltage by the current and you get the resistance

devious wrote:

ohm rise s a simple calculation that is thought in physics if your running in series you simple add together your resistors and if your running in parallel you divide one by the resistance and add the total resistance you find and then divide one by that

I.E. series. 4+4=8 dual 4 ohm voice coil sub

I.E. parallel 1/4=.25 .25+.25=.50 1/.50=2 same sub as before

now series connection is positive on one side of sub is connected to amp and the negative on the same side is connected to the positive on the other side of the sub and the negative on the other side of the sub is connected to the amp.

Parallel is positive on one side of amp to positive on the other side and the connected to the amp. and same with the negative.

big box or small box would depend on power i would say now mike correct me if im wrong i know you know this but the smaller the box the more power the sub with withstand and the bigger the box the less.

my question i have for whom so ever wants to find out. is there a way to apporximate the wattage that is coming out of the amp without guessing.

im saying the answer lies somewhere in the equation watts= volts * amps(current flow)

fritosaregood wrote:

i think smaller is better for a strictly spl box. it will help out in cone control.
and bigger usually reduces rise.

the last box for the 18 was 5 cubes tuned to 31 peaked at 41 with a 152.3
this new box is 5.6 cubes tuned to 55 peaked at 51 at the comp with a 153( i think it should be higher for that tuning)

my rise with the big box is from .5 to 1.2
rise with the smaller box was from .5 to about 3.5
both of those were at the peak spl freq

to measure it you need a multimeter and a clamp meter
measure the ac voltage and the current going to the speaker
divide the voltage by the current and you get the resistance

Have you actually measured for the vehicle tunning(the sound wave path and length for tune) or are you just guessing higher is better?

goggle links you to sites that answers your questions you never copy of goggle you copy of the links goggle finds you but no that came from school and thousands of dollars that i should of not spent on education. lol

devious wrote:

James Reed wrote:

Depends on space available, power, vehicle resonance, speaker specs and also the goal of the frequency bandwidth.

explain vehicle resonance for me please.

Every vehicle has certain sweet spot for tune and cabin gain. The resonance frequency is this sweet spot, which is what is being refereed to as resonant.

the natural cars peak is 45.
found from using a sealed box and having almost every ported box tuned low or higher peaking a 45.

higher is usually better, if i could take away the cars natural resonance and make it higher with stiffing things it would do better. which it did today. i got the peak to change to 54hz and raise the score. with stiffening the roof some

can you explain the way your saying to get the cars tuning freq

im out of here to much for me ill be in the pic section

jonatan wrote:

im out of here to much for me ill be in the pic section

i thought you wanted to up your game since some of us are catching up, haha

ok let me clear up my question is there an equation to finding the sweet spot instead of constant guess and test

jonatan wrote:

im out of here to much for me ill be in the pic section

LOL. good section to be in too i might say. You guys did a nice job of getting some great shots.

awww low blow i will reveal soon

ok im losing you guys here focus lol i want answers

You measure the wave path from the sub to the mic position. Using that measurement you can then figure the 1/4 wavelength. Im sure you know 1/4 wave well from your t-lines you have done frito.

we are topic changers, u dont know cuz u dont post often hahaha

ok help me im going to have 4 feet as from my sub to position of mic how would i go about finding the res freq

James Reed wrote:

You measure from wave path from the sub to the mic position. Using that measurement you can then figure the 1/4 wavelength. Im sure you know 1/4 wave well from your t-lines you have done frito.

and you tune to that freq?

I think kyle told me something about someone doing that before.

devious wrote:

ok help me im going to have 4 feet as from my sub to position of mic how would i go about finding the res freq

that would be 70~71hz using james's method

explain tline for us that dont know please and if we do we might call it something else or nothing at all

hell i dont know what 1/4 wavelength is and im a physics major or at least trying lol. cause the 1/4 wavelength of a 70 hz note would actually be somewhere around 100000 meters. so nothing adds up here.

devious wrote:

ok help me im going to have 4 feet as from my sub to position of mic how would i go about finding the res freq

http://en.wikipedia.org/wiki/File:Standing_wave_2.gif

This is the goal. You want the waves to over lap just perfect at the mic. So both the wave coming in and being reflected at are there highest peaks minimizing loss.

But to answer you question 4 foot is would put you at about 69Hz