Sencheezy

Damn, hope all is well

Wow hell yeah!!

Nice

Amazing write up

Happy birthday bro!!!

Happy birthday

Las Vegas = fi lol

Whoa, is that from LV or is that a recone?

awesome!

Which way to aim a trunk mounted woofer box in a car has been quite a topic of speculation for years. Folks, through experimenting have found that oftentimes the woofer box sounds much better when aimed backwards, the explanations I hear for why this works are usually quite absurd. One absurd explanation is "the sound wave travels further when the box aims to the rear and by traveling further it sounds better. " Not true, sound actually looses volume as it travels, not becoming louder like his explanation seems to imply! Folks also say "the wave has more room to develop." Well I don't like this explanation either, sound can really reinforce itself amazingly well in a small enclosed space without the need for any wave developing space! And there used to be a story floating around called "bass trap" which inferred a magical property of some cars to eat up all the bass and not let it get to your ears. There still really exists, a problem of building a wonderful well thought out and superbly engineered woofer box which makes bass so perfect my eyes water, with only a few watts of input on my test bench, but then barely has any output when installed into the car, this has driven me nuts for years. Or, building a great box for 12's and installing it only to have less bass than the one I did the day before in a different car using only 8's. The big clue came when I noticed there was much more bass with the trunk open than with the trunk closed! How the hell can that happen??? Opening the trunk lets sound escape(!), letting sound go away cant possible be a good thing. Then why does opening the trunk make the bass inside the car much louder???? I dragged out the test equipment (audio Oscillators, RTAs, Pink noise generators, and built me a couple of test boxes to experiment with. After a few days of playing with all the fun toys I discovered the bass that goes away when opening the trunk was causing cancellation when kept in the car (trunk closed), and turning the box backward made less of a difference when opening the trunk, and moving the box all the way to the back of the trunk eliminated having an increase in SPL when opening the trunk totally. In summary I found: 1. box at front of trunk speakers aiming forward or up through the rear deck = poor in car bass response, much better with trunk open. 2. box at front of trunk speakers aiming backward = better in car bass response by far, slightly better with trunk open. 3. box at back of trunk with speakers aiming forward = better in car bass, no difference with trunk open. 4. box at back of trunk with speakers aiming backward = best in car bass response and gets less bass with trunk open. I used sine waves and mapped out the phase relationships between the incident (direct) sound wave entering the car and the reflected wave that hits the back of the trunk and reflects forward. Since the reflection is bounced into the listening area, you can treat them much the same as having two sources... I drew some pictures to illustrate what I found. In this picture, try to imagine the back of the trunk is the vertical black line at the left of the picture and the little square is the speaker box. This picture is an illustration of what happens when sound comes out of the right side (front side) of the little square speaker box. Sound actually goes forward into the car (incident wave (RED)) and also backwards to reflect off of the back of the trunk (reflected wave (YELLOW))... Both the incident wave and reflected wave get to the listener but they are way way out of phase causing mucho cancellation in the listening area. If you could open the trunk, the reflected wave would disappear and NOT reflect back into the car thus no cancellation... In this picture, the speaker box has been aimed at the trunk instead of in the car and it is plain to see the incident and reflected wave are not nearly so much out of phase as in picture 1! Resulting in much better bass! This picture it represents the speaker box being moved to the rear of the trunk with the speakers aiming forward. The waves are a little closer to being in phase with each other. (were gettin there!) Finally, in this picture we are aiming the rear mounted speaker box to the rear so the incident and reflected wave are very close to being in perfect phase, reinforcing each other quite well. These pictures are simulating a 60Hz bass note with the rear of the box mounted approximately 3 feet from the back of the trunk (reflector) ... Keep in mind we are only discussing the incident and rear reflected sound in an effort to try to simplify this, the reflecting sound waves in a car are much more complex than these drawings indicate but we must start simple before we work ourselves into the more complex, hopefully this will be a nice foundation for those of you who wish to study this phenomenon further. And for those that have the mindset that this can't be true because the interior of cars are small in relation to bass wavelengths, so what? The full wavelength does not have to completely develop to be OUT OF PHASE or IN PHASE with its own reflected sound. The pictures above are showing a 60Hz wavelength and the bounce distance to reflect back out of phase a complete 180 degrees is just over 4 ft. At higher frequencies the distance is less (120Hz is 2.3ft)

Yeah peavey. found on parts express

wow lmao, probably the worst thread / responses I've ever read on this forum. Heisenberg - You should probably stop responding OP - You should do a little bit more researching around here, and just in general. We are here to help you yes, to make informed decisions, but this can't be done if you think 12 + 12 = 24 when talking about sub woofers. What you are trying to compare is referred to as "sd". You want to compare the difference of the sd when comparing a 12 to a 15 etc. I would spend a month or two researching before making another purchase, of any kind. Bassink - Thank you for attempting to straighten this mess out. OP, to answer your question, in a basic response, I would chose the two 12" xcons vs the single 15 and tune it to 32hz with adequate port area. And pay someone to build the design.

http://lmgtfy.com/?q=groundpounder

I come up with 4.4 cubes net. I would do two dss ethos 12". Best option imo

Yeah, I like this one. Definitely has that "in your face" mentality I was describing previously.

I know tim (14k) is really good at PS

Love this quote! And thank you for your response.

any update on that burp box of the driver you have on hand?

I say, make it something bold, and emasculate, create the image of performance and build quality. I like the darker colors, that goes along the image these woofer portray. That in your face, no holds bar performance. Something that represent nothing was left to chance. The image is everything, so it needs to represent so. I like the open-air font, I do, but I don't think of an 70 pound woofer when I see it either. So just try to find that balance, and I'm sure it will draw much interest.

I like it! But it definitely reminds me of chip foose font.

Hey Honda, it's interesting you bring up Tubes, I was doing a little bit research yesterday, (not to thread jack), so feel free to move. source http://www.diymobileaudio.com/forum/technical-advanced-car-audio-discussion/38784-given-cabin-gain-reality-do-we-need-low-fs-2.html Anyway, I think we now understand that damping factor, which is a quality associated with an amplifier, isn't an indicator of anything. I'm going to stop using that term now. The output impedance of the amplifier, if it's great enough, can have an effect on the sound of the system, and that amplifier quality is often called "outut regulation" and is included in the CEA 2006 standard. Here's how that works: As we know from yesterday, the amplifier's output impedance is in series with the speaker. By Kirschoff's laws, the voltage in a series circuit divides proportionate to the resistance. Let's say our amplifier has an output impedance of 1 ohm and we're using a 4 ohm speaker. If the amplifier makes 20 volts (100 watts at 4 ohms by P = E^2/R), then 1/5 of the voltage is dropped across the output impedance and 4/5 of the voltage is dropped across the speaker. 1/5 of the voltage is 4 and 4/5 of the voltage is 16. Now, we can figure out how much power is dissipated by the amplifier's output Z by 4^2/1. Which is 16 watts. 16^2/4 = 64. So, our amplifier that made 100 watts at 4 ohms makes 80 watts at 5 ohms and only 64 of those watts make it to the speaker. OK, an amp with an ouptut impedance of 1 ohm would make a better door stop than an amplifier, but it makes a good example and the math is easy. In that example, we used the nominal impedance of the speaker (as if it was a simple resistor). A speaker isn't a resistor, so if we wanted to figure out how the frequency response of the speaker would be affected by the output impedance we would use the measured impedance at a bunch of frequencies, do the math and plot the curve. Since the voltage from the amp divides proportionate to the series resistances, it's easy to see that the output impedance has a greater effect at frequencies where the speakaer's impedance is lowest and a smaller effect at frequencies where the speaker's impedance is greatest. If the amplifier's output impedance is really high, if you put a resistor in series with the speaker, or if you use 1000 feet of 30 gauge cable, resonance will be nearly unaffected, but the frequencies above that will be more affected. Lovers of Tube amplifiers claim that the 2nd order distortion makes them sound warmer, but I don't think that's what causes that effect. Our brains find very low levels of constant distortion objectionable--zero crossing distortion at 1% is nasty. Distortion on transient peaks has to be about 20% before we say it's as nasty as 1% constant distortion and it's nearly inaudible at 10%. If it was second order distortion that made tubes sound good, there would have to be whole lot of distortion. However, many old tube amps had VERY high output impedance. that output impedance attenuates the midrange and leaves the bass unaffected. If you're driving a full range home speaker, the midrange would be attenuated a little, but the bandwidth of the attenuation would be large--we can hear .5dB of attenuation if the bandwidth is more than an octave wide--but the bass would be unaffected. There's the "warmth" that tube lovers love. Passive crossovers don't screw things up, they're just tools that we use to modify the impedance of the loudspeaker at some frequencies to cause less power to be applied to the speaker at those frequencies. The simplest explanation of how they work is that they raise the impedance at frequencies we want to get rid of so the amplifier makes less power at those frequencies. A capacitor on a midrange or a tweeter raises the impedance at low frequencies so less power makes it to the speaker. There are many different ways to design passive networks, but two are prevalent. The cheesy way is to calculate the value of the components using the nominal impedance of the speaker (as if it was a resistor) and then apply the crossover to the speaker (like the way we use active crossovers). Passive crossovers depend on the load impedance to determine the frequency, Q and slope of the filter, and applying a filter designed to provide particular values to a resistive load won't have the same response when applied to a speaker with an impedance CURVE. People who design these kinds of crossovers often use a Zobel network to flatten the impedance that the crossover "sees", so the response applied to the speaker is what they originally designed. The other way to design the crossover (now made pretty easy since we can use computers to model the response) is to use the actual speaker's impedance as the terminal load in the calculations and to choose the component values according to the impedance curve of the speaker. that's the best and most economical way, but without modeling software, it's very difficult. To Scott's point, all passive components have their own DC resistance, which we often refer to as parasitic. That resistance only screws things up if we don't consider it in the design of the network. --- I was wondering what would your take be on this response, regarding the sound of Tube amplifiers?

awesome, looks like things are on track.

Where are the pics?