SPL Questions

yeah, dropping net means you can use less port area. I think that where your gain really came from was the port area and added net. If you could use both and get your tune down with that thing i suspect it would be rockin good. One of the problems of a setup like you have. Space is hard to come by.

I may add to get your actual amp power, you have to also consider your I^2*R losses, i.e. heat soak. Since we are dealing with an AC system. But other then that, you are right on the money Tony!!!!

I am a certified electrical engineer if anyone has any electrical questions they need answered.

WOW i missed a good conversation.
OK matt yes there is a way to find out how much power your amp is putting out. Your amp will only put out what your fuse on the amp will let it so if you have a 100 amp fuse and your voltage is 14 volts.
100*14=1400 watts
Amps*Voltage=Power
Ok now on to the wavelength, to help increase your spl you want your waves to meet, not 180 off. Picture two waves in water if one is getting bigger and it meets one getting smaller they will crash and make each other smaller, but if it meets a big wave they will get bigger. To get you freq you take the speed of sound (1130 feet per second) and divide that by how many feet there are between the sub and the front glass.
1130/10=113hz
113/2=56.5Hz
113/4=28.25Hz
So the three peaks are at 113 hz, 56.5 hz, and 28.25 hz. This formula is usually accurate to within 1-2 Hz when appiled in a car.

rob t wrote:

WOW i missed a good conversation.
OK matt yes there is a way to find out how much power your amp is putting out. Your amp will only put out what your fuse on the amp will let it so if you have a 100 amp fuse and your voltage is 14 volts.
100*14=1400 watts
Amps*Voltage=Power
Ok now on to the wavelength, to help increase your spl you want your waves to meet, not 180 off. Picture two waves in water if one is getting bigger and it meets one getting smaller they will crash and make each other smaller, but if it meets a big wave they will get bigger. To get you freq you take the speed of sound (1130 feet per second) and divide that by how many feet there are between the sub and the front glass.
1130/10=113hz
113/2=56.5Hz
113/4=28.25Hz
So the three peaks are at 113 hz, 56.5 hz, and 28.25 hz. This formula is usually accurate to within 1-2 Hz when appiled in a car.

If that is true, the fuse part then why are JL slash amps not fused at all, no on board fuse, how would u apply that formula then? That would only work as a "rough" estimate to get you in the ball park, but not exact.

if they have no fuse then i bet jl recommends an external one to protect the amp

mine is like that too external fusing 250 amp

rob t wrote:

if they have no fuse then i bet jl recommends an external one to protect the amp

They do, so if I use a 200 amp fuse, does that mean my JL amp puts out 2800 watts? No..... That is my point, that is all.

The problem is you are figuring at 100 percent efficiency. Which is not the case. Not to mention you will only see that "Fuse rating" met or exceeded when you have done something wrong.

well if you put a 200 amp fuse on your amps and something goes wrong then you will blow the amp instead of the fuse. The fuse is designed to protect the amp for things like james has just stated. If you put more power than the fuse can handle it will blow, which means an amp cannot make more than the fuse can handle.

rob t wrote:

well if you put a 200 amp fuse on your amps and something goes wrong then you will blow the amp instead of the fuse. The fuse is designed to protect the amp for things like james has just stated. If you put more power than the fuse can handle it will blow, which means an amp cannot make more than the fuse can handle.

but then you have those guys in MECA i think it is. They go buy fuse ratings and some how they are burping really big amps off of only like 25 amps of fuses, or so ive heard

yea alot of those guys are miracle workers, like the 177 something with 1 15. its crazy

#s I will break down for you. One thing to take into account is these tests the cabin was a little bit to cold and resulted in lower scores then the previous tests when we did the 177 with the 15" version.

DC 18 modded XL SPL motor:

157.2 dB on 27.3 watts

172.4 dB on 1355 watts

175.1 dB on 3051 watts

177.3 dB on 6976 watts this is the closest matched power to testing the DD9918z which did 177.2 on 7777 watts.

178.3 dB on 34,586 watts (paper cone limited at a 178 before it folds, score does not represent peak score on given power)

this guy did a 157.2 on 27.3 watts! I guess thats how they are doing it

im lost

i wanna see the box inside it but they said no pics, If you see it at a show you can look inside though. Its also just a 4th order bandpass.

sweet

anybody know how to design bandpasses?

is its not half cubic ft of sealed and half cubic ft ported put together?

rob t wrote:

anybody know how to design bandpasses?

Yeah, but im not going too lol. Pain in tha ace.

kylevh21 wrote:

is its not half cubic ft of sealed and half cubic ft ported put together?

Not quite that simple.

that was a guess im no expert

kylevh21 wrote:

that was a guess im no expert

I wish it were that simple They can get LOUD

Generally, I typically call for building a bandpass to be for reaching accross a broad range of frequencies (SQ), rather than just a few (SPL), that's just my approach though. If built and designed appropriately, the enclosure style can provide a huge spike in a very limited range of frequencies, which, in turn, makes an SPL enclosure (just as any other style of alignment could). The key idea is to find an alignment that optimizes thermal and mechanical handling with maximal output in the desired passband... Some woofers can work better in bandpasses, as compared to other types of alignment (Like the Lvl4 XL).

that was the next thing i was going to say^^^^^^^^^^^^^

MikeWilson wrote:

Generally, I typically call for building a bandpass to be for reaching accross a broad range of frequencies (SQ), rather than just a few (SPL), that's just my approach though. If built and designed appropriately, the enclosure style can provide a huge spike in a very limited range of frequencies, which, in turn, makes an SPL enclosure (just as any other style of alignment could). The key idea is to find an alignment that optimizes thermal and mechanical handling with maximal output in the desired passband... Some woofers can work better in bandpasses, as compared to other types of alignment (Like the Lvl4 XL).

I would much rather a tapered and stuffed T-line for SQ if you've got the space to even consider bandpass or a T-line.

A properly tuned downfire box can "act" just like a bandpass box. I have seen it in the extended cab s10's, the downfire box that PROBOX made was pretty awesome for the concept.