Random thoughts on the basics of SQ

[gstokes]

I'm no rookie but pale in comparison to most of you when it comes to car audio knowledge but i do have some thoughts on SQ i want to share and the first being the importance of a H/U with generous preamp voltage (4V minimum) so you don't have to add a line driver and risk introducing noise into the signal before it reaches the amplifier, some of you will choose to use a electronic crossover and/or DSP with multiple amplifiers but i prefer the simplicity of a 5/6-channel unit and possibly the addition of a DSP if i struggle too much with time alignment but the KISS principle applies strongly, keep it simple stupid. Anything you place between the H/U and the amplifier increases the risk of introducing noise and unless the crossover has a built-in line driver you're reducing critical preamp voltage which requires increased gain and that's never a good thing especially for SQ.

Matching the sensitivity of all the speakers or getting close as possible, this ensures all the speakers are equal in intensity (SPL) at the same volume level all things being equal.

A larger engine working at a slower rpm is more efficient than a smaller engine working at a higher rpm, this logic holds true for amplifiers as well, drivers powered by a smaller amplifier that is working at or near capacity won't sound as good as those drivers powered by a larger amp that is just loafing, choose an amplifier that makes at least 20 - 25% more power per channel than your drivers are rated for. As an example, my MB Quart OA1100.5 outputs 75Wrms x 4 at 4ohm on the main channels and 500Wrms x 1 at 2 ohm to the subwoofer, my main speakers are rated for 45Wrms max and the subs are rated for 400Wrms max, 22.5% more power than i need on the mains and 25% more power than i need to the subs, the amplifier lays down the power without breaking a sweat and that is essential when your goal is SQ.

All amplifiers are not created equal, some are better for SQ and some are better for SPL but getting both in the same package can be challenging, pick one or the other and design your system based on the choice of SQ or SPL.

My system is being designed for SQ and the smart money goes with MB Quart as they have been around forever and like Infinity or Alpine they are recognized for making reference quality amplifiers and speakers but it's a buyers market for car audio gear, choose whatever brand you prefer.

Most of all, do your homework, read reviews and don't get fooled by snake oil and wives tales, one of the most important aspects of any system but especially one designed for SQ is the interconnects (RCA) and the speaker wires, here is very informative page with even more links that will teach you everything you need to know to make your system sound the best.

If i got anything wrong or backwards please don't hesitate to correct me as i am still learning and always will be.

Good Luck & Have Fun..

Myths and Snake OIL : Empirical Audio

Click to read more...

 

[winkychevelle 10+ year member]

You my friend have much to learn about sq

High voltage preouts only help block electromagnetic noise, keeping the gain knob down doesnt necessarily mean better sq as all the gain knob does is match voltage input to voltage output.

Matching speaker sensitivity is no really necessary thats what the gain knob is for to level match. Regardless of sensitivities the drivers side will always be louder do to driver placement relative to the listener

Thus the reason for time alignment. Crossover points and slopes can change the sound quite substantially.

Headroom on power is always good.

Driver placement and enclosure makes a huge difference as well.

But u either have to redesign you car interior or use a dsp to get true sq.

Mb quart makes ok amps but they have fallen from they position of being great since the maxxonics buyout.

U have alot more to learn in reference to sq installs.

My system ordered

Pack gm44 to rockford 360.3

Hertz mille components run active off a zed draconia

2 polk kappa perfect 10s infinite baffle off a zed minotaur

Lots of sound deadening and a healthy dose of knu wire.

 

[gstokes]

good insight and thank-you for the corrections..

 

[dbjunior 10+ year member]

Drivers side won't always be louder I have a 4ch running an active front stage and each channel has its own gain so I can add power to a tweet or mid on either side to balance it as well as use the t/a on hu to get it centered and high enough. Placement and install is most important in sq. I have seen cheap equipment sound amazing with a great install.

 

[winkychevelle 10+ year member]

Drivers side won't always be louder I have a 4ch running an active front stage and each channel has its own gain so I can add power to a tweet or mid on either side to balance it as well as use the t/a on hu to get it centered and high enough. Placement and install is most important in sq. I have seen cheap equipment sound amazing with a great install.

He was talking about not using a dsp and his amp doesnt have left/right gain knobs.

And I agree cheap equipment can sound great. Keephopealive used 30buck mid for the longest of time and his tweets werent super highend either

 

[gstokes]

I am gathering that rear fill is pointless when trying to image a stage in front of you and the closer all the speakers are together the less RTA you will have to make, 4 hours ago i was preparing to put the subs in the back of my E150 van but now i am removing the center console and putting the entire MTX sealed enclosure with the subs facing up in it's place, then (maybe) make a raised lid with front firing port that fits over the enclosure and acts as a waveguide directing the sound towards the doghouse/engine cover and dash, that just might give me some half decent imaging..

If this works out and sounds decent i will have a custom console/sealed enclosure made locally and mount the 12's inside it.

 

[gstokes]

duplicate reply: edited

 

[winkychevelle 10+ year member]

1. Rear fill can be used but is incredibly hard to tun in correctly

2. The closer the speakers are primarily the mid and tweet the easier it is to control beaming and distortion from wave interference.

3. Bass is omnidirectional and can be located anywhere inside the vehicle. Keeping the sub volume low and rattles nonexistent will help keep the subs invisible position wise. And a ported box or transmission line or 4th, 6th order are all good options for sq systems. Sealed has its place but is much more difficult to tune as the only variables is box volume and box shape.

4. A wave guide on subs is pointless. A flared port keeps air schuffing down and mostly in audible

 

[gstokes]

okay, with the subs upfront and personal i will be able to keep the level down but trying to direct then reflect the lower frequencies without actually changing the direction the speaker faces is fruitless, correct ?

An enclosure that angled the subs (let's say 45 degrees) towards the windshield would do better job at directing the sound than my goofy idea of a bass waveguide, i am brilliant but i over-think stuff sometimes, stick to the KISS principle //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[winkychevelle 10+ year member]

Changing the direction of the bass will not make difference at all unless it causes loading which could make the sub louder. A downfire box has always been my favorite box as it directs the sound into the chassis which helps u feel it better allowing u to turn the bass down more to easily blend with the front speakers. You shouldnt even know you have subs t8ll you turn them off