New Car, New Subs

[mikegett]

If you are looking for a decent amp, then pay attention to two primary factors for a subwoofer. The damping factor is how well the amp can control the movement of your subs cone. The higher the value, the more control the amp has. If you are running a sub, then avoid any amp with a value under 200. A/B amps that are meant for highs and lows can easily be under this value since mids don't require the extra control. A decent quality amp will average 200 to 400 for subwoofer use. Keep in mind the quality of your sub, and the box it will be going in. The higher the quality of the sub and the stronger the box will equate to lower resonance. This means that they will require less damping from the amp. A good sub and sturdy box can sound great with damping as low as 60. But as power is increased, the damping must be increased to reduce the resonance. Many subs can handle over 1000 watts producing quite alot of decibles. This is why I suggest staying at or over 200 on the amps damping factor. The second thing to look at is the signal to noise ratio. This refers to the dynamic range of the amplifier. In other words, how clean the sound is. In most cases a 98 db or above is acceptable. Many people will even argue that a sub amp has no bearing on sound quality from low dynamic range. This is not always true. The higher the dynamic range of your amp, the easier it is to reproduce the signal. Most subs amplifiers are pressed to the max of there RMS rating or beyond. A low dynamic range will mean the amplifier has a smaller window of reproduction and must be worked harder to achieve the same frequency reproduction. This means more distortion, smaller life spans on the amplifier, and less efficiency of a higher quality amp. I suggest staying with a signal to noise ratio of 100 or better. A high quality amp will be at least 105db.
I know you mentioned a price range of 300 for the amp. My personal recomendation would be the eclipse DA7122 monoblock. List price is over 700 dollars, but you may be able to get it off ebay for 400. At 2 ohms it has a RMS of 1000 watts and maxes out at 2000. It is by far the best sub amp I have ever seen. The dynamic range is over 1000 ( the closest I have ever seen is 800) and the signal to noise is 125. It is a class D, so the amperage used will be far less than a A/B amp. It also has balanced line adaptors built into the amp to eliminate any ground loops. My other suggestion would be the JL 500/1 monoblock. Once again, you can get it for around 400 off ebay. The damping factor is over 500 and the signal to noise is 95. The real benefit of the JL is that it will put out its rated power at 1.5, 2, and 4 ohm. This means you have a much greater flexibility when pairing the amp to subs. It is also rated at 11-14.5 volts from your cars electrical. Most companies rate the power at 14 volts meaning you will not achieve the full rated power.
I stand behind the IDQ's. They are a very decent sub and sound perfect for what you want. Sorry about the long post, good luck and just shop around. I don't know every company and neither do any others. You may find better subs or amps than what we have offered. Later, Mike G.

Wow... I REALLY Appreciat that info... That is extremely helpful! I really wanted to do this car right by starting fresh with a REALLY good system.. Now i have a question on the sub box... What makes an enclosure good??? And for my application... Whichwould be better for me Sealed or ported???

J

[mikegett]

Sealed or ported is more a personal preferance. Sealed boxes will tend to give a broader range of frequencies and sound cleaner. However, they are more inefficient and require more wattage. I have heard many ported enclosures that sounded great, but my skills at box calculating are limited. Consequently, I have always ran sealed.
The quality of your box is due to how rigid you make it. 3/4 is a minimum. I always use 1 inch. Stay away from the walmart 1/2 pre made boxes. They sound horrible. A subwoofer is not only producing sound waves on the outside of your box, but also on the inside. Try to avoid a perfect cube and angle the back if possible. This helps to disipate the resonance. Measure out where your subs magnet is located. Put your center brace in the middle of the magnet. This serves as a brace to reduce the sides from flexing and hold your sub snug in place. These babies are quite heavy and will flex the front of your enclosure if not properly held. All corners should have a angle brace if possible. My last suggestion is to round all square edges inside of the box. For example. Your corner braces and side brace anchoring the sub should have all edges rounded with a half round bit. If you use 3/4 material, you may wish to place a sheet of sound deadening material behind the magnet. I found that if you use 1 inch it is not needed. Your choice of material is primarily mdf and particle board. The denser the material the better. If you can make it out of solid hard wood such as cherry or walnut, even better. With solid wood you can safely go to 3/4 or even 5/8 thick stock and have no resonance and reduce weight. The draw back is the cost of the material.
You will want to be carefull sealing your box. Avoid silicone to seal the inside. The gases can deteriorate some sub surrounds. I use a helthy amount of wood glue around all corners inside. Hardware stores have very thin strips of rubber seal with adhesive on one side. It is pretty nice for sealing your sub to the box. Once your sub is installed, press on the cone. If it is stiff and springy then your seal is good. If it is spongy, then take it out and look for any leaks. Good luck, Mike Gettinger.

I will add a pic Monday of what I mean by bracing your sub.

SWEET!!! Cant wait to see those pics! Also on another note... Fiberglass boxes... how are they compared to a conventional wooden box???

hello???????

[violentrapture]

If done right, fiberglass won't flex...

[mikegett]

Sorry, I forgot about those pics. Here is a very poor sketch of what I mean. The main thing I want to convey is the center brace. I like to double it as a brace for the sub magnet as well. I can't realy comment on fibarglass. I have yet to hear any boxes made of it. I believe that it could make a very nice box, but I have doubts on the clarity of it over very dense wood. Density is the primary objective. Fiberglass is strong and resists flexing (with alot of expensive coats) but is not dense. Sound can't flow through objects of higher density. Lower density material tend to permiate sound giving the sense of hollowness. But, once again, I have yet to hear a fiberglass box. Maybe in the near future that will change when I start stalking violent for his setup.

No sketch........

[violentrapture]

Speaking of density, I've actually been toying with the idea of using the backing structure from one of our new products at work as enclosure material. It's a aluminum composite panel sandwiched honeycomb stuff, bonded with aviation epoxy and we get it in by the truckload for this product: http://www.stoneply.com (really cool stuff btw, in the architectural field).

My current enclosure is 18mm HDF coated with PVC underbody treatment.

*hides setup from Mike*

~vR

Hmmmm.... Sounds interesting.. Are you going to attempt it???

[violentrapture]

I have some sheets of it in my closet - it comes in sizes from 1/4" to 3/4", so I'm not sure which would be the best to use. My idea is to snag one of those eD Eu-700 drivers, have MDF, HDF, 1/4" and 3/4" ACM/Honeycomb and fiberglass enclosures made for it and do A/B testing to see if there's any sonic differences between them - it's not exactly high on the priority list right now though. :P
~vR

HEHE SWEET MAN That would be awesome to find out.... How much do these sheets run??

[violentrapture]

My cost? The trouble to drive out to the plant and snag the sheets. :P
With stone applied we sell for about $40/sq.ft.
Not sure what just the backing would run - I can find out tomorrow if you're interested though.

Heck yea man if its a good option i am interested! I am always open for options!

[nickgonzo]

Originally posted by jwth2005@May 15 2006, 04:28 PM
SWEET!!! Cant wait to see those pics! Also on another note... Fiberglass boxes... how are they compared to a conventional wooden box???

Quoted post

Fiberglass boxes are good for a few reasons. If you are looking for an alternative to the weight of a wooden box. If you are want to save trunk space (i.e. make fiberglass a box in spaces where a conventional MDF box couldn't go). If you want a flashy install that you can mold to whatever shape and paint whatever color you desire.

Remember, fiberglass gets its its strength from curves. I've seen people stand on little FG kickpanels that were made for a 4" speaker... FG is very strong.

If you had two boxes of the same airspace, one FG and one MDF.. I bet you couldn't tell the difference.

I have no doubt that a FG box is just as strong as a wooden box.. but the arguement is density... whether or not it sounds as good as a denser material

[violentrapture]

Talked to our GM today - going to provide our PM with box plans once I get the specs I need and plans drawn up and have them make boxes out of a variety of materials:

Fiberglass (what our company *does*) http://www.strombergarchitectural.com

MDF and HDF

Granite (odd choice, but when I brought up what I was doing regarding density, he suggested having one done out of pure granite panels, so there it is)

ACM/Honeycomb panels (backing from the StonePly material)

Anybody else have any other materials they'd like to see used in this project?

~vR

** Lyndon asked me too "there much of a market for these?
You just might see: "Stromberg - subwoofer enclosures" one of these days

I think a box made out of cherry wood would be sweet! IF anything cool lookin if stained!

[violentrapture]

Hm, I'll add it to the list - maybe if I can sell these after I'm done with the test it'll be a kick in his rear to open up a new division.

~vR

Haha you betcha... Id be intereste in buying one of em prolly... just all depends on which one sounds best....