95Honda

Optimum port area has NO RELATIONSHIP to the box volume. This is kind of a bad rule of thumb... The only way to know if your vent has enough area is to model for Vent Velocity. "Less ports are more efficent" = Basketballs make good salad dressing Honestly though, both vent options should not introduce much compression with any 15" drivers, I would go with whatever option fits your build better...

The video should be deleted. Horribly misleading. The guy doesn't really have a clue on what he is doing, either...

Your not to blame, it is just understanding what you are measuring. This is why there is a lot of confusion on what is going on when test equipment is involved. Even something as simple as a DMM can get you started down the wrong path if you don't know what you are doing. The terminals could also very well be faulty, but the fluctuations you were reading (especially the ones without the terminals) was being caused by the woofer.

Don't worry, the fluctuations you see the amp never does. Also, what you are seeing can very well be lower than the driver DCR due to the current flow from the driver. Again, the amp will never see this though, only your multimeter...

And don't forget, you CANNOT measure impedance with a mutimeter the way you have it hooked up. You are in no way measuring what your amplifier sees...

Re-read what I posted about the current levels causing your meter fluctuations. They are anywhere from 1/1,000 to 1/1,000,000 of an amp. You amplifier has what is called an output impedance. It is very low, like well under 1/100 of an ohm. It completely dampens out ANY current fluctuations caused by your woofers turning spurious acoustic energy into electrical energy... Want to see how output impedance works? Tap on your woofers with the amplifier off and then on. You will see how it dampens out the woofer... It literally acts like a brake on the cone...

That means 1 millionth of an amp... Yes, .000001.... Also, take a 25 pound weight and lay it on the cone (find a way to do this without damaging the driver) and you will see the fluctuations drop because of the increased mechanical dampening...

Believe me, it doesn't take much. It could be as simple as the mass of the probes or the way the leads are angled from the terminal. You are talking micro and milliamps... The bottom line is, you don't have to worry about anything you are measuring being presented to the amplifier.

Oh, and the fresh recone has more mechanical dampening since the spiders are new, so that is why you get less flucuation...

You kind of need to go back to basics to understand what is going on here. The terminals aren't the reason for your erratic readings. A loudspeaker is a transducer. It takes one form of energy (electrical current) and coverts it to another form (acoustic energy). It also can also do the opposite, change acoustic energy into electrical current. Your multi-meter measure DC resistance (in no way does it measure impedance). It does this by applying a very, very minute amount of DC current to whatever circuit is placed in series with it and it measures how much current flows through the circuit and calculates the DC resistance from this. Any, and I mean ANY small (talking micro to low milliamp) current introduced into the circuit under measurement will throw off the meter, substantially. The subwoofer will produce milliamps of current with you talking in the same room at a low level and it being 10' away... That is how easily it effects the meter readings. So why are my direct leads making a difference? Simple, due to tension on the leads you have changed the mechanical dampening on part of the suspension and reduced the woofers ability to act as transducer. You have changed it just enough to dampen out some of the cone movement and therefore some of the current being introduced to the meters DC resistance measuring circuit. It is also easy to see how this works if you have a recone by itself out of the motor. You can hook up the leads any way you like and you won't get any more fluctuation than the meter leads by themselves as the recone cannot act like a transducer without the motor attached. Additionally, if you were to place a tight shim in the gap that locked the cone in place you would not see the fluctuations. And lastly, these measurements do not in any way AT ALL represent anything your amplifier sees. You are talking milliamps of current, once connected to your amplifier the output impedance dampens any of this, completely, and it will never effect the overall load your amplifier sees in the slightest. I hope this clears up what is going on.

Jeeze... Nobody is saying thinking is a crime. What people are saying is think about what you are doing logically and make informed decsions. When we see bandpass ratios, port area rules of thumbs, RMS questions, etc. it makes the people who want to help think you aren't serious because you aren't doing all your homework. The comments are meant to keep you from wasting time. I remember when nodoby would get butt-hurt on audio forums, it has been a long time... Lol... (And no, this comment is NOT directed at anyone in particular)

99.99999% of the people who are going to give you and answer have no idea what the impedance they are presenting thier amplifiers actually is. So honestly, you aren't going to get any objective answers to this unless someone has a swept impedance curve of thier subwoofer system and the amplifer you are talking about. This is kind of the problem and where so many different opinions come from, they are not based on any sort of facts, just gut feeling. You can get in trouble because guy X runs the same subs as you and the same amp and is fine, but your box may have a completely different impednace curve and you might cook your amp where guy X was fine the whole time...

I don't really do it for buisness anymore, this was a personal favor for a friend. I really have no idea who in my area builds decent boxes...

Also, don't forget that anything can be shipped to an APO if it less than 75 pounds. You can have it mailed to a family member and then have them forward it to your APO address or use a place like "Ship It APO". I had everything from gun optics to paints sent to me in Germany that the vendors wouldn't send directly...

I was dissapointed with a few of the instal points. I had pre-assembled everything in Colorado and ensured every fastener was aligned and fit perfectly, lubricated all threads to prevent galling and oxidation and then carefully dissasembled everything. I next printed out detailed instructions on assembly order, torque specs, etc. The installer managed to cross-thread one of the 1/4-20 button head hex screws that held the grill in place (because he managed to install the grill upside down and the holes don't line up perfectly that way). I picked up a tap and chased all the threads. They also did not understand how to instal the quick dissconnect the right way, they actually ruined the first one. I guess the moral of the story is, no matter how thorough you are, if you don't do it right yourself, it doesn't always get done correctly. I do admit I am picky about this, this is easily my 200+ loudspeaker I have built, I have doing this since the late 80s. But I am still dissapointed when a decent shop can't see a project through to the end without issues... My buddy Tony was super patient with them and ended up getting what he wanted in the end, so that is really all that matters...

It took a long time to get it done, too... I am finally finishing my H/T, too. The last parts should be waiting for me when we get back from vacation next week...

Thx. Was good to see it come together...

So I finally got back to Seattle to hear the system last week... It has been almost 2 years since I built the box... Well, it is loud, real loud. Loudest single 15" I have ever heard. The response was also smoother than I had thought it would be. Not real peaky, but I attribute that to the vehicle more than anything... I designed for a flat response, and the cabin gain (at least from the passenger seat) isn't horribly ragged. It would keep up with some decent rock tracks and sounded pretty good with overall. Little John was obnoxiously loud, as expected, and my buddy listens to alot of Dub-Step, which also shined. The HO alt held solid voltage with the Cresendo 3500 well into clipping everywhere but idle and there were no heating/shut-off isses... All in all that Mayhem is one hell of a driver. Thanks Brian Owens for the idea... He is easily knocking at the door of 150db in that 4-runner...

If you go ported, you will probably have a lot of ripple in response and it probably won't sound too good...

Your 12s are already in a 4th order enclosure. Are you wanting to build a bandpass? They are more complicated and only potential gains in output over a small range of frequencies. If you aren't really good at designing and building enclosures now, I would suggest building your knowlege base or hiring out the work.

I would purchase a copy of the Loudspeaker Design Cookbook.

Even if you can't find a LOC a simple voltage divider will work perfect. All you will need is a pair of 20 cent resisters to knock the input voltage to the amp in half which will probably be perfect. You already know the input impedance of the amp so it is pretty easy to design and build, I will walk you through it through email if you would like, no problem.

He is. It is a fixed low level output, he explained it earlier. It isn't enough to get what he wants.

There is another way to use your current equipment, and do it cheap. This may sound bad, don't judge until you try it, but you could use a very cheap LOC (Line Output Converter) from the powered Zone 2 output and run that into the balanced input of the Crown. To be honest, depending on the Zone-2 output rating, you could run the Zone 2 speaker output directly into the balanced input of the Crown. This would give you volume control from the Onkyo. Tell me what the rated power output (including impedance specified) and I can tell you if you could run it directly. That crown will take well over 10VRMS on the input, and a low powered speaker output would only take mild attenuation. Worst comes to worst, you don't like the way it sounds and you are only out $10 for a LOC...

He is using this for music, the sub out won't really help much.