goalie 35

i will be man enough to appoligize for the als poor showing in the grey cup on sunday... as far as trash talkin anyone thats not what my comments are to 4 nor to build up my ego or accomplishments.. and my hockey league has players from all leavels of hockey from pro... kevin estrada, carolina hurricanes, dave gourlie, vancouver canucks draft pick, peter hay, weyburn redwings sjhl, brian gourlie, lethbridge hurricanes, dave archibald, ottawa senaters, newyork rangers, dave maklay, philedelphia flyers.. ect...... this league is stellar... and at 42 i have been playing at this level since jr... but its getting harder.. trust me.... and i see the writting on the wall, but for now i can still compete... and with dog baker.. iam really interested in learning from him and i dont want him to bail on this website because he keeps getting bashed.. iam only trying to help. i know so little and can use all the help i can for sq so at this point iam shutting my mouth and trying to get some more tips.... the top gun in the world is john meyer at 490 sq pro.. iam 460 so i need to learn to beat him... and so far dogbaker is the only one offering solid advice....here are some pics of my sqpl car and my sq car is in the oct. issues of car audio and electronics

jonesbrooklyn

iTrader: (5)

I'm still waiting for him to accept my invitation

dogbaker

Hey Guy`s

Busy weekend for me, so I `don`t think that I`ll much time to hang out in here.

I see that there have been some new comments, I will respond later, but no worries, everything is cool at my end.

I did have to explain to my woman though that trash talk is part the fun for us boy`s (and a few girls) that hang out in here and that while jonesbrooklyn can close to crossing the line that he truly wasn`t attacking her, just trying to òne-up` me.

In the end she asked to be left out of it - so let`s honour her request and she will let me stay and play.

Thanks

Lord Huggington

iTrader: (1)

Holy that looks like it's LOUD! What's in the window, it looks like a plasma screen? Are those 9512's? Got vids?

goalie 35

they are mtx 7512s box is two inch thick birch plywood.. each back window had a 15 inch lcd t.v in it.. dash had a panasonic 7005 dvd deck, ads 6is was the centre channel,running off an alpine 3511 amp, audio contol 4.1, with a coustic rta31. in the glove box was a ppi deq 231. doors had mtx axe 6.5 drivers two in each door.. plus 7 cases of dynamat and extremeliner.loudest i hit was 154 but averaged 152.7.

dogbaker

Hi Jones:

I didn`t realize that you were being serious - please tell me more about your sessions, such as, when and where they are, how long they are and what exactly will you be measuring and how.

Thanks

dogbaker

Hi Kevin

I have responded to your questions in context below...

Dogbaker,

I have a question about the sound quality benefits in using a transmission line or horn enclosure.


If I remember correctly, you had built a 6" woofer transmission line in a chevette that hit very loud? How was the sound quality?

I wasn`t the one that designed or built that box - sorry can`t comment on it.

For example, in home audio I have seen B&W use a 6" woofer in a tower transmission line style port and they sounded very very good, using a Classé amp.

Would using a 12" woofer in a box such as these give me as good sound quality(tight realistic bass). Would the enclosure not have to be so large that might as well use a sealed box?

With regards to TL boxes the size of the driver and it`s Qts score is most paramount. The size of the driver (SD) is directly proportional to the volume and throat requirements in that the bigger the driver, the larger the volume and throat etc. The Qts requirements fall in the range of .5 or greater, which is counter intuitive to new builders because such Qts` scores at this level are typically found in drivers which were intentional designed for sealed enclosures. The reason for the higher Qts requirement, is rooted in the fact that TL boxes can have weak acoustic suspension qualities and higher Qts driver inherently are more self supporting, in this regard.

The best way to go about developing quality outcomes is to initially use software aids to build your first prototype but then to use an O-scope to assist you in tuning it, as you stuff it the port line with Dacron fibre.

Don`t be surprised if you can`t achieve the quarter wave tuning that you had hoped for. TL`s are hard to nail but not impossible. If your first box after tuning is too far off the mark, you will have to modify the box or build another one. The process is called prototyping. As a point of reference most manufacturers build dozens of prototypes before they get to take a product to market.

If I was you - I`d budget to build at least two boxes, it usually takes me three prototypes before I am satisfied. But if you build at least two - I promise that your second one is likely to be better than your first, unless you nail the targeted tuning the first time around. Being out 1-3Hz is no big deal - more is...
With regards to ‘tightness’ in sound that has mostly to do the driver and the tuning that you pick. If you strive to build a linear SQ box the driver will become the number one determinate to the ‘tightness’ that you refer to – small tip – higher Qts score will most likely sound tighter...

As a final note do a lot of research before you start...
What type of box did you use in the mobile dynamics astro (with the amps in the rear head liner if i remember)?

They were sealed.

Thanks for your time
Kevin. (Mobile Dynamics 98 Grad)

taz23340

HI Dogbaker,
I appreciate your reply, I may be mistaken on whom you are, as I was at MD in FEB 98 (Sent you a PM about that). I thought you might be one of my teachers, (he had taken us go-karting and always won).

I do not mind to do some hard work and will re read the louspeaker handbook that i read many moons ago and as you said above, will try to do my homework before building (theres a cheezy line that says measure twice cut once, well i feel that applies to system design.) I learned in school that for one system we could have a notebook full of ideas that could take months to get throught and tweak, even if the system only took a week to build in the end.

as a side note;
I am not an engineer, will never be one, just enjoy good sound, it's why I got into the audio industry in the first place. I have however, realized that i do not have the memory or understanding to pursue an engineering degree, even if i do enjoy the theory and "math" behind many teachings that i have been lucky to have been given.

Having said that, I am sad to see that SQ is not as popular as it was 12 years ago. I still have some ideas that I drew out for SPL, but with three kids and not a fortune for income, street sq is all that is within my acceptable realm. That and I am no longer into saying "my dick is bigger than yours", I just want good sound and hope that others can appreciate the work that musicians put into their work, its only fair for us to try and listen to them in as ideal an environment as possible.

Whomever you are Dog, I appreciate you taking time to guide less educated or less experienced people with their questions just wish some who think they know it all would be willing to be told they dont without getting in a war.

thanks again.
kevin

dogbaker

Hello all...

As we're are about to progress deeper into SQ system design, we need to also develop a sidebar education about various contributing factors, one of which being amplifiers...

To save myself time - I have decided to cut and paste some data from own publications. In doing so, it's likely that they will refer to images and measurements that aren't present. It may also seem to jump around a bit, as I have removed some text/education and have left some thoughts incomplete.

The actual publications are dozens of pages in length and as such much to large to post...

But for those of you looking to learn all that you can - there is many good insights within the text that has been provided.

Please also understand that what you're about to read is an introduction to an actual college level progam, that I once offered. In other words, text from day one!

Dispelling Some Amplifier Myths

It is important for one to understand, and completely believe, that it is impossible, from objective means (through scientific measurement) to determine the absolute sound quality of any electrical, or electromechanical device. However, it is possible for experienced engineers, technologists, and some general technicians to determine many ‘goodness’s’ and ‘shortcomings’ from which, they may then categorize, and rate potentials of a given device. Even with such experience and skill-sets, one must also subjectively (listen to it) measure the device in its target environment (difficult to do in car audio), while operating at a target or likely level.

Objective device measurement is much like IQ measurement, in that if a device scores well, there is a high likelihood that it possesses superior performance potentials. If a device scores low however, it doesn’t mean that it won’t perform adequately or perhaps even excel, within a given application; there are simply no guaranties of a sonic outcome that can be derived from just reading specifications. In the same way, it does not mean that an individual isn’t smart, if they scored low on an IQ test – it merely suggests that we haven’t developed an accurate objective means to measure and correlate all their potentials. In short: you shouldn’t become just a ‘spec’ shopper; A more balance approach is recommended and as you will discover - is requisite!

Signal Measurement

In terms of objective signal measurement within an amplifier, the signal is predominately AC in nature while being measured at the outputs, but signals that are DC and digital in nature can also be found in virtually all amplifiers.

The power supply and its management circuits, are the regions or stages where these additional signal types reside. There should be no DC measured at the outputs of an amplifier! Our measurements and disclosures in this session will be based on samples taken at the outputs and as such, will be the AC type (or we at least hope that they are).

DMM

At this point, many of you have become familiar with DMM’s and may be realizing that such meters measure AC Voltages. However, while useful for general determinations, such as Voltage levels, they fail to provide any indication as to the quality or general usability of the signal sampled (we will demonstrate).

Oscilloscope

Some of you, many even have familiarity with entry-level oscilloscopes, which certainly provide more information, such as waveform geometry and visual depictions of attached parasitic noise levels, but even these devices aren’t equipped to measure much else at the outputs (again, this will be demonstrated).

Audio Test Suite

What’s required, is a sophisticated audio measurement suite(s) that perform several (in the hundreds of measurements) measurements with in a second or less, then correlates the data, reporting it as we request. This data can often take us beyond the 2-D landscape of a Voltmeter or the signal frequency measurement of an Oscilloscope (even though some phase measurements can be attained with one), into the 3-D landscape, providing incredible insight to a devices performance, at many different frequencies, phases, geometries and noise distortion levels - all at once!

Common Denominator

The common denominator amongst all of them is indeed Voltage measurement, facilitated by frequency insertion and the measurement and recording of all factors of influence. However, as we’ll be witness, there are literally tens-of-thousands of measurements that can be made. Furthermore, Voltage, the signal that we are after, changes several times a second, at the presence of ever changing frequencies of sound (music), and its subsequent harmonics and phase shifts, at a minimum.

Commentary on Manufacturer Specs

Before we progress to making measurments, we need and desire to make clear to you that the performance of a product, as documented by a manufacturer, is controlled by the method(s) of measurements, and the reporting of the values. Today there are several standards: CEA, EIA, ANSI, IEC, ISO, FTC, IHF, etc and many levels with each of them; however, it is important to understand that they all have different agendas or purposes. The truth(s) surrounding ultra-high quality devices is however, generally agreed amongst them, which is to say they all agree that a device which passes a more difficult or stringent series of tests, will in all likely hood posses greater performance potentials. Each of the aforementioned strives to provide a reference of different performance levels, in some cases minimum ‘goodness’ scores (CEA & EIA).

In terms of how manufacturers report their product performance, a wide canyon exists. To complicate matters further, what is reported is often incomplete and therefore invalidate or of no useful value in determining a complete picture of performance!

In this session, we will measure an amplifier from the perspective of determining its usable wattage by auditing its THD, IMD, Linearity, Noise content, Dynamic Range, Load stability and Headroom and if time afford Power Supply adequacy. Once these minimum samples are in our care, we will cross correlate them, to make our final determination. We many also measure the amplifiers efficiency at various output levels, as well as, audit the internals of the power supply with regards to layout, component quality, component adequacy and noise contamination

Amplifier Basics 101

It is our belief that you will completely enjoy the lab measurement segment of this education. Visual depictions will be provided, with excellent commentary on their meanings, and their common manipulation, for marketing proposes. However, to ensure your maximum understanding of the demonstrations, you must first become familiar with the most basic stages of an amplifier, there general purposes, classifications and the units used to quantify their measurement, as commonly reported specifications.

Amplifier Stages

Amplifiers can have several or just a few stages in their design; however, at least three primary sections must be defined/exist: an input stage, power supply and output stage.

The primary goal of every amplifier is to increase the amplitude (Voltage) of an inputted signal; in other words make a small signal - large. While this sounds straight forward, there are many potential pitfalls.

Most shortcomings today reside in the power supply, as it represents the largest area of investment and real estate. While many believe the ‘output stages’ are of paramount importance, in reality, they take a back seat to the power supply sections.

In terms of the outputs sections - It is true that the outputs are of vital importance; however, the costs of their components are low, and the technologies or topologies implemented today, are well documented, as well as, tried and true. It is factually, the power supply that supports the output qualities, most predominately.

Wattage or Power is based on two factors of current (I) and one factor of resistance (R), evidence by the Ohms Law formula I2xR=P.

Current is the essence of energy and without it, no work can be performed. Power supplies come in two varieties: current and Voltage biased types and both are present in every amplifier; however, the dynamics and stability of each of these sections work together to form the majority of an amplifiers usable power. In other words, the power supply sections control or contribute to the fidelity of a device many times more than any other section. The fundamental purpose of an amplifier is to produce linear power while interconnect to reactive loads (Loudspeakers). To do so, it must produce a constant Voltage into all loads while doubling or as much quadrupling the current availability, simultaneously; meaning in `Phase` (additional commentary will be provided during the `Determining Power Supply Adequacy section of this manual).

Getting back to the input section, while it is every bit as important to fidelity as every other stage, it requires the least amount of real estate, component cost, and technical complexity. They come in either balance or unbalanced configurations (balanced being more desirable), both of which are well document and understood.

In most cases the quality of the power supply dictates the quality of all other sections. In other words, an econo power supplies, often lead to econo output stages, which will in turn lead to econo input stages, with the least impactful typically being the input stages.

In the end, these stages sum together, adding and subtracting energy (coloration) as the signal flows through them - forming the sonic attributes of the device as a whole. In the broadest terms, an amplifier is supposed to increase an inputted signal, by a required gain, without adding any distortions, of any kind. Some amplifiers are classed as linear and others (still purposed for audio) are not. The overall goodness of an audio amplifier is determined by its faith amplification of the input signal. To this end, dozens if not hundreds of measurements schemes have been developed to objectively determine such goodness by taking samples or readings at the outputs.

Commentary on Topologies

While we have only provided a general overview of the requisite stages of signal management within an amplifier, you shouldn’t be caught up in the desire to understand more. The actual electronic workings are well beyond a general consumer and 12-Volt accessory technicians required plane of understanding. What is important is that you are aware that not all amplifiers are designed and manufactured equally. Being caught-up in the intricacies of varying design topologies and their subsequent pros and cons will not likely prove to be profitable, nor manageable.

Ultimately, all amplifiers destined for quality audio reproduction, must output the identical signal(s) to which are/were inputted, only altering the amplitude (Voltage).

Regardless of class or topologies, all amplifiers have one thing in common – speaker outputs, and from this interface, we can determine with great objectivity and subjectivity, the qualities of them.

Central theme – all quality audio amplifiers are required to possess a bandwidth from 20Hz-20KHz +/-3dB into all loads (1-8-Ohms), without adding distortions of any kind to the inputted signal; there subsequent application is determined by their gain & usable Wattage!

Amplifier Classes

Things are Changing: This is a complicated subject as there is literally, tens of amplifier ‘Classes’: A, B, A/B, C, D, BD, E, F, G, H, I, J etc… However, don’t panic, the most prevalent in home and car audio are: A, A/B, D, H, and T. Amongst these variants, efficiency, and faithfulness to the input signals is what makes them different.

Class A and A/B are pure analog types that are the least efficient (20-50% respectively at max output) but are the most faithful to the input signal and are available from just a few to thousands of Watts.

Classes BD, D and T are for the most part consider switching types that are far more efficient (75-90% respectively at max output) then pure analog types (A, A/B) but at the expense of fidelity. Such types often suffer from poor linearity, IMD, S/N Ratios, and Bandwidth scores. However, they have become popular implementations in high-output car audio systems, as current is at a premium in all automobiles. Wattage levels range from mild to truly wild!

Classes G, H and N are hybrid types that for lack of a better term, mix the best attributes of pure analog and switching types; Producing amplifiers with high efficiencies and good to excellent fidelity, with N being the most current of the sect. Wattage ranges are similar to that of pure analog types.

Power Supply Regulation

Regardless of type or class, amplifiers can be designed with loosely regulated or tightly regulated power supplies. Each has their own pros and cons, however, loosely regulated variants tend to provide superior results across the board, provided that the vehicles power supply is adequate; if not, all other things being equal, tightly regulated variants often produce superior outcomes in auto-sound applications.

One final note: It’s important to remember that specifications are only one part of the equation, one that is often over weighted in a consumers buying decision, it is equally important to audition a potential products performance at a local dealership, before making your final buying or application decision.

Signal Types 101

There are two types of base signals, AC or DC and within them various amounts of Voltage and Amperage (current). These variations are divided into - two sub categories: large & small signal types. Small signal types are mostly considered source or preamp signals (001-mV – 8-Volts with less than 1-Amp of current). Large signals types are considered power based, such as the AC entering your homes or the energy entering your loudspeakers (1-Volt – 120-Volts with more than 1-amp). Either type also possesses factors of capacitance and inductance (more on these to come). Regardless of the signal type, all possess each of the aforementioned elements; as such, you must strive to learn the following basic units of measurement and various expressions.

Please note that I have removed this most of this education... sorry

Impedance

Impedance is a composite resistance, which only applies to AC (Alternating Current) signal types. Contributing factors being a circuits total capacitance, inductance and resistance at a ‘one frequency’; in other words, the unit of measurement for AC Resistance is ‘Impedance’ and it changes or reacts with changes in frequency / phase; making it very complex.

DC resistance

DC (Direct Current) resistance is the factor of resistance measured at 0Hz, not complex.

Determining Usable Power

Okay, so now we’re set to start bring into focus the answer to the question: How do we determine the usable power of an amplifier?

Usable power is the product of a ratio between an amplifiers input vs. output signal and weighted against subsequent distortions that develop, as the input signal makes its way to the output terminals.

Input Sensitivity is a critical measurement as it determines the scale of amplifiers sensitivity to input Voltages. The more sensitive it is - the smaller the Voltages it can amplify - the more dynamic the amplifier will be. Good input stages will sense Voltages as low as .001 Volts.

Once a signal is sensed, it makes its way towards the output terminals. On route, it passes through several stages of filtering and manipulation. As the signal is processed, errors known as sonic colorations are added to it. These colorations can be reduced to two categories:

Waveform and Noise type distortions

Waveform types typically manifest themselves as changes in waveform Height, Length and Propagation time (Phase).

Noise types are comprised of signals that have no relationship to the primary signal. Such signals (noise) enter the scene through many paths, such as, invisible electromagnetic forces and patristic leaks throughout the circuit board, poor component quality, termination, and general layout, all of which, relate back to poor design or intentional compromise.

In the end stage, they combine and produce the distortion products of the device.

These distortion products are present in all amplifiers to varying degrees and from them, the limit of useable power is determined. However, as mentioned, application also plays apart. This truth leads to the fact that when much is taken or missing, much remains, in this light, most amplifiers released for production, output power that is useable to someone. The question is -is it useable to you or your client.

What is interesting about this progression is that it also applies to preamp, speaker systems and the cables that interconnect them, in other words, many of the measurements (metrics) for determining signal ‘goodness’ in amplifiers, can be used for determining the same in the aforementioned devices.

Audio Distortion

Distortion is the name given to alterations made to the input signal, in terms of waveform geometry or noise content. The acceptable threshold of which varies by application, or targeted fidelity. Such distortions are determined through various measurement techniques and protocols and then reported with the conditions disclosed.

While there are many, we will look at but only a few – arguably, the most important in determining the basic usability of outputted power, such as:

In General Terms:
THD THD + N
IMD – SMPTE
Linearity
Dynamic Range
Device Gain
Signal vs. Noise S/N
Frequency Response & Phase
Power Supply Adequacy
Efficiency at 1/3rd and Max Power

Remember, the condition of the measurement must be disclosed, in order for the measurement to be valid; more on this to follow –

Now armed with some base knowledge, let s make it real, let s measure an amplifier in real-time – live!

goalie 35

as you can see by the replys on your last post, not one word of what you said will improve the sq of my car..almost everyone on this board will agree that amps dont make enough of a sonic difference to put that much effort into which amp will make my car sound better.. class of amps, color, power features... really are not whats going to make or break your sq system... nor is deck design or wire choice so please dont elaborate on those issues either.. if you run good quality amps.. a decent head unit, and top notch speakers working in there normal operating range, you will have a good sounding system... now this thread is about sq so lets get some tips on getting better sq..
first things first.. after you have made the decision to go into the sq world, its time to pick a vehicle... now this really is a matter of taste as everything can sound awsome, just depends on how much work, time, money and whats the car for, just car shows or daily driver, will all make your decision for you.
... so lets say a daily driver, need back seats but can sacrifice trunk, have all winter to build and a shop, and want to drop good money.. have no problems rebuilding dash, dont want to use doors for speakers, will dynamat and do the big three....
some good cars are dodge,sx 2.0 , honda civic, honda fit, mazda 3, . all get good gas mileage, reliable, well built, and easy to disassemble and reassemble..