How much bass is too much bass?

[michael hurd]

I also am using the stock head unit, with a line output converter- this goes to a pro audio active crossover that drives the amplifiers in my system. Anyone who says the stock head unit sucks has never experienced a properly implemented and integrated system.

Yes, the stock head unit is short on features, I would love a unit with bluetooth myself, however finding a solution that is OE in terms of integration is hard.

You can add in an aux input to the stock unit and use the headphone jack out on your phone for playback of music, it is not quick and easy like swapping out the head unit though.

If you were real handy with a soldering pencil, you could transform the stock cassette function into another input, just have to make it think that there was a cassette in the deck in order to use it.

There are many OE type solutions in terms of adding USB charging and 1/8" AUX jacks to the dash or wherever you desire, just cruise eBay.

 

[michael hurd]

As it has been mentioned a few times, the devil is in the details. Most people approach a project without the right amount of patience, skill, time and money necessary.

Define a budget, but figure you will spend more than that, however base your choices on the budget and performance first.

In terms of what I would approach first would to be to improve on the amount of sound deadening, adding foam tape and other materials to reduce buzzing, rattles and generally make the cab quieter, this will also keep it warm in winter and cool in summer when the AC is on. The most important areas are going to be the doors , and the rear interior panels.

This requires the seats, seat belts and most of the interior to be removed to do a proper job. While the carpet is out, it's a great time to power wash it at the local car wash and hang it up to dry, while running all your wiring. Vacuum all you can out to start with before washing it, once any sticky residue is out from power washing, vacuum it again, you will get more out.

After that, if you have to buy speakers, forget buying rear speakers, this is a waste of time and money. Spend a few bucks and buy a decent set of 6 1/2" component speakers for the front doors. These can be driven off the deck power.

Next up is to figure out how much room you plan on using for a sub enclosure. If you toss the factory tool box under the back seat, you can get more volume for an enclosure.

Most amps will not fit properly behind the rear seat on the back cab wall, also drilling holes to mount it is asking for troubles. There is room under the front seats to mount smaller amps, however you have to fabricate brackets to mount them off the seat base, and out of the danger of water / salt ( if you live in the rust belt ) and spills.

As for picking subwoofer drivers, you need to know how much volume you have to work with, you can use many different ways of calculating this.

Always use the largest radiating elements that fit, this will ensure that the amount of excursion is low for a given volume level, and intermodulation distortion is low.

For most systems, a single run of 4 gauge copper or 1/0 copper clad aluminum wiring is quite sufficient to avoid voltage drop to your amplifier(s).

 

[michael hurd]

What is 'power handling'?

Power handling without context is meaningless. I can burn the coil on a 500 watt RMS rated subwoofer driver with 100 watts RMS if I give it an ac signal in a region where the coil is not moving, say 400 hz. If the coil is not moving, there is no air movement, and it will try to transfer heat through the gap to the magnetic assembly, once that heatsink gets hot enough, the coil will start to overheat.

Think I am lying? Ever grab a hot 100 watt incandescent bulb?

I can also apply several times more power to a speaker in a dynamic signal.

What is Xmax? There is no hard and fast industry standard, some companies use a simple calculation of the coil length and coil gap height to 'calculate' it. This is rather meaningless, since you can have a speaker with more usable stroke when the coil is past the 'calculated' point.

This is generally a point where the motor force has dropped 30% of it's rest center position. The best method to determine this point is through analysis with a Klippel system that uses a laser to measure the cone displacement, and drives the speaker under test signals with an amplifier.

What is Xmech? This is the point where the coil crashes into the backplate, or the suspension stretches tight, and driven to this point, the speaker can suffer damage beyond repair.

I can also damage a 500 watt rated driver with a 50 watt or less signal in a ported enclosure, by driving it below it's tuning point with no high pass filter in place, where cone motion is not controlled.

To recap: power handling is almost a meaningless spec without context.

Thermal power handling vs. mechanical power handling. This depends largely on the type of enclosure the speaker is loaded into. Generally, a driver in a sealed enclosure will run into excursion and thermal issues before any other types of enclosures.

Ever watch someone plug a speaker into a wall and marvel at the length of time it takes that 'abuse'? I could design an enclosure / driver combination that would take that for days on end, simply design it so that there is a large impedance peak at 60hz, and voila~ there is very little power that the driver is consuming.

 

[michael hurd]

Impedance: I mentioned I can design a driver / box combination that will take all sorts of abuse from plugging it into a wall socket, 120V AC, 60 hz, on a standard 15 amp circuit.

Well since we know Ohm's law does not lie, say the driver / box combination has a nice large impedance peak of say 80 ohms at 60 hz. Let us calculate how much power the driver consumes at this frequency: (120v^2) = (14,400 / 80) = 180 watts. There will be adequate cone motion, and therefore the coil will stay nice and cool.

Moving on, we can calculate the amperage through the coil: 180 watts / 80 ohms = 1.5 amps

Now, if I was a 'marketing' type guy, I could post a video of said device and proclaim that my '4 ohm' subwoofer can handle 3600 watts being plugged into the wall. Wouldn't really be lying would I?

 

[great white]

the other negative thing I forgot to mention about OEM head units is that some have active equalization in them.

Known as "bass rolloff" in laymans terms.

What it does is start to remove bass as the volume increases. This is a survival strategy built in to protect the lower end speakers that tend to be in OEM setups.

Some have other equalization schemes built in that can be annoying when chasing SQ.

Personally, I've never noticed it in my 98's Delco.

There are LOCs out there that claim to compensate for bass rolloff, although I remain skeptical about it.

JL Cleansweep, Audiocontrol, etc are some of the bigger players. Of course, more cost is going into the setup now. There comes a point where it's worth your while to just go aftermarket from a cost per feature point of view.

I have read some anecdotal info that some have sent Delco radios back to the original manufacturer and they can program the eq response to just be flat. Which is what you want for a HU if chasing SQ. You don't want the HU processing the sound at all, just producing it a pre-amp signal as clean as possible..

How important that is depends on what you want out of your system....

 

[boy&hisdogs]

What do I think about that chart? It is not really helpful in deciding what is good.

I was worried that you might say that. Is there really any way to say which one is better, or more likely to be better, given specs available online? Is there even going to be much of a difference between name brand, similarly size/spec/price subs after all other variables (like install and fine tuning) are taken into consideration? I'm still stuck wondering WHY that kicker sub has 2x-3x the RMS rating as the others, while everything else is similar.

I have similar questions about the door speakers too. How do I go about narrowing it down to the best few choices so that when it comes time to listen to them in person, I'm not stuck listening for a needle in a haystack?

So here's where my plan is so far:
Stock head unit
LOC (most likely the one mentioned above)
AUX input (don't have the steering wheel controls though, so I'll probably use a different one)
New 6.5" door speakers (not sure which yet)
Down firing DIY box
Sound deadening

The jury is still out on the sub.

 

[great white]

Steering wheel controls have nothing to do with your choice of "aux in" method...

 

[boy&hisdogs]

Steering wheel controls have nothing to do with your choice of "aux in" method...

But isn't the reason you went with that one because you can control the ipod from the factory truck controls? I know that I still could hook it up, but the extra features (and extra $$) would go to waste because i can't make use of it anyway. If I have to reach for the buttons on the radio I might as well reach for the ipod. Something like the PAC AAI-GM9 would work just fine and cost half as much.

 

[michael hurd]

Unfortunately, if the company included all the information needed to choose a product based on specs, you would have a hundred plus pages of information to compare say 10 different products.

A full Klippel report ( without any destructive testing ) on a subwoofer driver is 7 pages of data.

Since I know a few people in the business that constantly develop and evaluate their own products against other competitors, I have a bit more insight than some.

Every company has their value lines, mid line and top line products. Believe it or not, there is more focus in engineering their value and mid lines to be pretty much bulletproof.

I am not sure how many companies in total make a 6 1/2" component set today, but there are loads.

These are some of the companies I would recommend based on experience with their products, and knowing what goes into their development.

Alpine
JBL ( part of the Harmon group )
JL Audio
Infinity ( another part of the Harmon Group )
Energy ( owned by Klipsch now, who were a private entity and bought out by Audiovox in the last few years )
Kicker

 

[michael hurd]

"Is there even going to be much of a difference between name brand, similarly size/spec/price subs after all other variables (like install and fine tuning) are taken into consideration? I'm still stuck wondering WHY that kicker sub has 2x-3x the RMS rating as the others, while everything else is similar. "

Yes, there is going to be a difference, most average people couldn't tell good from bad though, being that the accepted norm is to listen to relatively low fidelity devices.

If bad sound were fatal, audio would be the leading cause of death. ( Quote from Don Davis of Synaudcon )

If you truly want to find your threshold of speaker induced distortions, follow this link to Klippel:

http://www.klippel.de/listeningtest/lt/

Of the many different types of distortions, harmonic distortions are the most benign, since the distortion is 'harmonically' related to the original signal. 2nd order harmonic distortion is not as noticeable as higher orders of distortion.

IMD is by far the most irritating forms of distortion, it is caused by a bass driver that is undergoing large excursions while also producing a higher frequency. It 'modulates' the upper frequency up and down.

Ever talk into a fan and sound like Darth Vader? The airflow from the fan ( albeit DC flow ) is modulating your voice.