I still don't know what your talking about -

Sorry I have moved past this - goodnight!

 

Good questions - I would love to answer them and I will use some graphs... but as you can see there are some questions in front of yours.

In the meantime, there is some useful insight which relates to your questions throughout this thread...

Derek is doing well, I'll let him know that you were asking about him...

Cheers.

PS The bitching is starting to settle down...

 

adding a second battery to a car audio system is only going to add stress to the, already taxed alternater.. the second battery will do nothing to aid in the vehicles performance while the system is being run in a linear fashion.. however while driving down hyway 7 from regina to saskatoon after a fantasitk rider victory over any nfl team. i am crankin on the airbourne... blonde bad beautiful at full volume.. my system has a current draw that far exceedes the alternater. now since music is not linear its safe to say that the electrical system is going to be drawing execessive current and acceptable current in a rapid non-linear fashion.... during peak demands the standard battery, should be able to handle the overload for the millisecond or two. then the alternater should be back on track... this is the only time that a second battery will make any difference for our music... now if we are talking spl. then thats a whole other ball game.. and i can clarify that topic if needed...

 

Thank you very much for your insight -

I will seriously consider what you have suggested.

Please don't take my pause as a ‘no’ or any form of disagreement with your argument.

PS It has become quite evident that for the most part, they aren't arguing with me, as much as they're miss-quoting me - to create an argument.

 

I will be opening another thread later on, in which I'll be discussing SPL systems - this thread is 99% about pure SQ - of corse they are related in many way's but not all, so I have decided not to talk directly about SPL at this time.

I have been sucked in to a couple of small debates though...

Thank you for your offer.

Cheers

 

well iam not an spl guy anymore but i did build a car that in iasca of 2008 was the loudest sq car in the world at 153db on 1000watts and scored in the 377 on the sq sheets. this yr my sq car places second in canada and its score was to date top 5 in the world.. so my knowlege on spl and sq is probable pretty clean and accurate..that being said, for sq adding a second battery is not.. i repeat not neccessary to acheive our goal of tonally acurate and clean clear and precise music... since we are sq guys and not the bass head variety type.. most of the time iam driving my car listning to music like sara k. or livinston taylor.. now does my system reach 115db.. yes.. and i have no subs... and use 2- 4 channel 50 watt amps... actually my system befor compression of any driver reaches 117db... nice to have measuring tools... now if i add another battery what have i accomplished.. except to tax the alternater even more... for those very few and quick times that there is a cresendo in the music that exceeds my alternater, my aftermarket battery can more than handle the load, on paper does it make sense 2 add more batteries... absolutley...... but when you factor in load vs draw vs time.. now the picture becomes a little more blurred or clear depending on your take..

 

Sounds like you have properly designed all aspects of your system - welcome to the thread...

 

Thanks for the reply!

If had lots of extra cash I'd go with there Supremo line, Which is there "High-End" line of car audio speakers.

I find these speakers to have there own Image is I might say, They are very warm and not overly bright, I find the midrange blends extremely well with the tweeter, Even though it is up higher.

They truly give you a studio/live experience, Exactly what it says on there website.

 

Linear SQ System Design:

Step 1 Determining Available Current & Wattage – PART B

Before we can move on to determining what components and overall topology to use, we must define the quantity of current that is likely to be continuously available. To do so we must understand a little bit about efficiency ratings and apply a little Watts/Ohms Law.

So let’s begin:

In SQ, it’s advisable to only use Class A or A/B amplifiers, and each of these have different net efficiencies, do to their respective design approaches.

As a rule of thumb, Class A is considered 25% eff. and Class A/B is considered 50% eff.; however, we need to expand on this general rule, in order to competently determine our current requirements.

These generalities are generally accepted for each class, which is to say that these are likely to be the maximum efficiencies that one would discover, from various manufacturers, using either of the Classes etc.

I have introduced the term maximum, which suggests that the efficiency of these amplifiers (and others) varies – and they do. So here’s where it becomes counter intuitive:

Amplifiers are less efficient during periods of lower power output, then during periods of high output. What this means, is that the efficiency is based on the amount of wattage output and that amplifiers are most efficient during full output.

In SQ design, we typically aim to utilize no more than 50% of an amplifier’s rated RMS power (more on this to come); which in turn means that the amplifier is running at less than its rated efficiency.

Simply put, for every amp we input, we get less than an amp out, at least in the form of current, with the balance being lost /converted to heat.

So what does this plainly mean to you and me?

It means that based on the 40 amps that we are likely to have available, that if you use a Class A/B amp that maximally 20 amps of current will be used for sound reproduction and the balance will be converted to heat.

Using Watts Law we can determine the power a circuit can output, by taking the known net operation current of a device, and multiplying it by the known net operation Voltage, to develop a score that we call Wattage!

Formula: I x E = P

Current = I
Voltage = E
Resistance = R
Wattage = P

So it has been determined that our power supply has 13.8 Volts and 20 amps of net goodness:

P = E XI
P= 13.8 X 20
P=276 net sustainable Watts – this figure does not include contributions from the battery(s) or any other interim source of current.

Now this may seem like a small amount of power – but if it’s pure, and dynamic – it’s plenty for 99 out 100 SQ systems!

Here’s some insight as to why:

Let’s just pretend that all of our drivers in our system have same efficiency and that it is a low one of say – 86dB, everyone will agree that it’s not only low, but that it’s lower than you are likely to average.

There are a few different types of efficiency measurements and scores. The one most commonly referred to and the one that we are looking at is derived at by injecting 1-Watt of Pink-noise in to a driver, while taking an SPL measurement at precisely one-meter away, with the microphones diaphragm place at/on 0-degrees Axis.

Distance is very important here, because a Law known as the Acoustic Inverse Square Law reveals to us that if we change the distance that the SPL drops or increases. So test measurements are highly standardized, in this regard.

Now, I highlighted the Acoustic Inverse Square Law, to lead to some other relevant points of education.

The ‘AISL’ tells us that every time we double or half our distance from a source of sound that the SPL decreases by 6dB or increase by 6dB respectively.

Other laws tell us that we may achieve similar gains (with all things / variables staying the same) by changing the wattage:

Example 1: doubling or halving the power injected into a speaker would produce a 3dB gain or 3dB reduction respectively (MECP-Bronze).

Example 2: Increasing the power by 10-times will increase the SPL by 10dB which is equal to twice the loudness. Inversely, decreasing the power by a factor of 10 will cut the perceived SPL by half (MECP-Bronze).

So armed with this knowledge, let’s get back to our central theme /point – proving that 276-Watts is adequate for SQ system design:

Starting with 1-Watt of Pink-noise injected into our 86dB system, we will achieve an SPL of 86dB @ 1-meter from a driver (not taking any acoustic gains from vehicles air space).
@ 2-watts = 89dB
@ 4-Watts = 92dB
@8-Watts = 95dB – Reference Listening Level for SQ
@16-Watts = 98dB – Almost 10x’s the power – almost a 10dB gain – almost twice as loud (Fletcher & Munson). If some of you are paying attention, you will note that 16- Watts of true full band power, is plenty for most quality front-end... 32-Watts put the gravy on it (headroom), if you will.
@32-Watts = 101dB
@64-Watts = 104dB – common limit for High-pass drivers – Mid/Tweet’s in SQ because of mechanical limitations.
@128-Watts = 107dB
@256-Watts = 110dB
@512-Watts = 113dB

Please note that each 3dB requires twice the amount of current over the previous level - 100% increase in current consumption yeilds a maximum acoustic increase of only 33%.

Also Note: that the more Voltage that we put in a speaker, the more we use up it's limited Xmax, which reduces the drivers sonic goodness and overal reliability (more on this later).

So let’s stop here.

It may appear that we have fallen short of the MECP guidelines, which state that we must be able to achieve a peak of 115dB, not average, but there’s more to take into consideration.

1. The dynamic power stored in the amplifiers capacitors (good amp +3dB)
2. The short term dynamic power of the alternator (+.5-1.5dB assuming it’s maxed out)
3. The reserve current that a battery provides for short term peaks (+3dB)
4. The fact that your average system efficiency isn’t as likely to be as low as 86dB (+2dB)
5. And the fact that all vehicles offer no less than a 6dB gain in average output do to acoustic coupling that takes place between our ears and the speakers in the vehicle (which doesn’t occur in large air spaces).

So when these considerations are brought into the fold, we easily reach and surpass MECP guidelines - peak guidelines, as well as, sustaining their continuous requirement of 95dB.

Linear SQ systems sound quite robust at levels averaging between 85-100dB, which many of you may find quite surprising.

Stay tuned, more to follow!

 

I think I might buy one of these for myself!