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Old 04-11-2007, 04:12 PM   #1
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Definitive Guide to Tutorials

I decided to put all of the turorials I can find on the internet all together here for anyone interested. PLEASE feel free to post any ones that I have not listed, or report any links that are no longer working so we can keep this list as current as possible.

Box Building Tutorials
Fiberglass Tutorials
Sound Damping
Unsorted



Here are great INFO sites

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Old 04-11-2007, 04:12 PM   #2
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Explanation Of Audio Terms
As written by bassfreak in this thread

  • FS - is the free air resonance of the driver. this in its simplest form means the driver moves easiest and impedance is at its highest. so you get the most output with the least work.

  • VAS - its the volume of air that has the same compliance as the suspension. compliance is the measure of the elasticity of the air equal to the suspension. so a VAS of 3.5 cubes means that the suspension has the same stiffness as 3.5 cubic feet of air(imagine compression of that air as for stiffness).

  • CMS - is how "stiff" the suspension is. this is the measure of the stiffness of the suspension in n/m usually at or close to rest, where the VAS is the measure of the elasticity of the suspension in cubic feet related to the air that is equal to its CMS. think about this in a tire. you have the same amount of space to fill, but you put 25PSI in the left tire and 40 PSI in the right tire(off the car) the left tire has about the same air space but the amount of air inside is lower so CMS is higher. while the 40 PSI tire very similar amount of space but the amount of compressed air inside is greater, so CMS is lower the result is the tire with the lower CMS and same VAS(amount of space) is a stiffer tire!.

  • QES - is the electrical dampening. so in other words you pass a signal through the voice coil, and the QES is how well the energy in converted to usable electromotive force in the magnetic field....

  • QMS - is the damping of the mechanical aspects of the driver. so the QMS is how it controls the cone movement when the woofer resonates. the higher the QMS the more it opposes resonance because of lack of control. the lower the QMS the more it opposes resonance because of being over controlling.. so ther for the lower the QMS the "stiffer" the suspension or the faster it will try to stop movement..

  • QTS - is the total Q before you has electrical and mechanical dampening losses so to say. its the raw driver dampening.

  • RMS - is the losses of the suspension meaning that the stiffer the suspension with the same vas the higher the "losses".this can contribute to how much a drive is able to move in a certain box with a given power... softer suspensions will move easier...

  • KMS - is the measure of how linear the suspensions stiffness remains through its excursion. the result of the suspension stiffness exceed 4X its CMS is defined as Xsus.

  • Xmax - this spec is often over looked and very hyped. It is the measure of excursion of the motor in linear terms similar to KMS but for the electrical side of the driver. its defined as when the B/L drops to 71% of total B/L you have a QES that has doubled and its consider non linear.

  • Xmag - is the measure of how far the motor can move the coil. this is limited to coil height and the gap's fringe field also power handling. some woofers may have a Xmag well beyond its coil height because of the flux fields outside the gap and extreme power handling(DD9515 for example) this is a good indicator of how strong the motors actual strength is beyond linear excursion. both the magnetic field and electromagnetic field from the coil.

  • B - is the measure of the flux density in the gap. the less space between the gaps the more density you have. this is often complemented with a lower QTS.

  • L - is equal to the length of the voice coil in the gap. so the longer the voice
    the higher your L. so if you use a smaller gauge wire you can get more L, but you add more MMS. its a trade off adn there really is no better option only the one for the application...

  • B/L - is both the B and the L combined.

  • RE - is the at rest DC resistance. so when no voltage is applied and when the amp first turns on this the resistance the amp sees.

  • Impedance - is the measure of the resistance of the voice coil when a AC signal is passed through. this varies as frequency varies and boxes/aligmetns vary.

  • Pe - is the power handling of the woofer. its not thermal or mechanical but both. i think there should be both a thermal and mechanical spec but oh well.

  • FB - is the tuning frequency of the alignment.

  • F3 - is the -3 DB down point of the woofer, meaning that you are now relying on the mechanical dampening of the woofer instead of the dampening of the box and the woofer along with the port. in ported alignments you can hear anything under about -3 DB point, while the sealed boxes compliance stays much more linear so below this you can often hear it when you have the proper cabin gain.

  • SD - is the measure of the woofers cone area. a lot of people use 1/3 of the surround but i don't like to use this for a few reasons. as it doesn't relate to the actual cones displacement as its not constant.

  • BL^2/RE - this is to see how much B/L you have despite the RE rating. the lower the Re the less B/L you have so you can't compare a woofer rated with a B/L of 29@8 ohm and a woofer with a Re of 3.6 with a B/L of 22.


    quick example. 9515 with dual 4ohm coils 29tm so.. 29^2/7.2-116
    the 9515 with an RE of 1.8 per or series RE of 3.6 the BL is 21tm or 122.5
    its important to look at this instead of B/L when comparing woofers with different RE's
    also B/L is potential motor strength meaning its not actual, but it part of the actual strength. power handling and QES also indicate motor strength!
    The voltage x amperage(power in watts) that is applied to the voice coil is important and equally important is how much is used(wasted as heat vs turned into electromotive force).

  • MMS - referred to as the Moving mass of the speakers moving parts. its really simple but something that every good designer HAS to find a "balance" with among other parameters.
    sometimes people ask when is too much? or how do you "balance" it. if anyone shows interest in this maybe we can have a discussion on this.

  • KMS curves - its a simple graph of the suspension stiffness VS excursion! the flatter the better? not always! don't be fooled buy marketing and "ideal designs" because many designs aren't ideal for every application! another subject that can be dug into. questions!?

  • BL curve - and what in the hell does this mean!? simply it is a estimate(small signal parameter) of how well the motor maintains QES, along with B/L which is potential motor strength. is flatter better? generally yes, but there are sacrifices that MUST be made!! something else i would like to discuss and is a very hot topic between many people.

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Old 04-11-2007, 04:14 PM   #3
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Laymens Explination Of Audio Terms
As written by Geolemon in this thread



If you are looking to "get your feet wet", with understanding what the heck all these specs, figures, and numbers mean - my best advice is to NOT worry about the textbook definition of "what they mean" literally - there's really not much practical value in that for most enthusiasts.

Let's take a look instead at "what can I use these specs for, to understand this subwoofer better?"
...and you may be surprised that with many of these specs, comparing them from one manufacturer to another is like compariing apples to oranges.
So it pays to understand what questions to ask when you are looking at them, also.

Qms -
A mechanical / pneumatic "quality" number that truthfully doesn't lend a great deal of insight to helping you choose a subwoofer for most applications.
It is affected by physical properties that you can look at more accurately (IMO) through other specs, such as moving mass (look at Mms), suspension compliance (look at Vas, or a Cms curve), etc.

Qes -
An electrical "quality" number... think of it instead as a good indicator of motor strength. Do you need a subwoofer with a strong motor? You might be surprised to learn that high strength isn't always a good thing. (hint: Look at EBP... or check out Qts. )
The smaller the number, the stronger the motor.
(also, the smaller the number, the smaller the enclosure, quite often - but it is just one factor in that equation )

Qts -
A calculated number, using Qes and Qms - for a "total quality" number. I sort of downplayed Qms's importance earlier... and even in this calculation, Qes so far outweighs Qms in this calculation, that Qts actually ends up quite close in value to Qes - and small adjustments to Qes affect Qts much more than even large adjustments to Qms would have.
Anyway - this is an important one. One of the "main 3" you need to calculate enclosure size/type/performance. (along with Fs and Vas).
Qts mainly can tell you what sort of application your subwoofer is compatible in:
High Qts value? Very compatible in a sealed enclosure.
Low Qts value? Very compatible in a vented enclosure.
Qts around 0.45 (middle of the road)? Design compromise to work OK in either, rather than outstanding in one and bad in the other.
It's very helpful that way.

Fs -
Resonant frequency. This is the frequency the subwoofer most easily resonates at - and in free air, has the highest impedence (actual resistance with a subwoofer varies both with frequency and enclosure - it's not just "4 ohms" or whatever - it may rise up over 40 ohms, in fact, at points!) at that frequency.
What it's useful for looking at is in judging how low a subwoofer can play.
A low Fs means the subwoofer will be able to play lower...
...but means it won't be as efficient in the higher frequencies either.
So maybe not always a good thing - or rather, something you need to compromise with realistically, to target your own personal tastes... loud? Or low? Or a little of both?

EBP -
EBP stands for "efficiency bandwidth product", and it's just a helpful calculation, to expand on what Qts tells you with regard to the "what box is it good with?" question.
EBP = Fs / Qes. Simple calculation.
It includes Fs in the equation, because in a sealed box, the subwoofer needs a low Fs in order to play low frequencies.
In a vented box however, you can design the enclosure so that it helps extend the low frequencies farther than a sealed box, so Fs isn't as important for that.
Qes is important because in a vented enclosure, you have higher pressure forces at work - so you need a stronger motor to contend with them. In a sealed box, that stronger motor will drive up the system resonance (a box/sub combination version of Fs), making for bad sealed performance.
The actual EBP number tells you whether it's good in sealed or vented...
EBP at 50 or below, sub is best suited to sealed.
EBP higher than about 80, sub is best suited to vented boxes.
EBP in between, sub is OK in either sealed or vented.

Vas -
Suspension compliance. This number represents the "volume of air" that provides the same "spring" force as the suspension system on the subwoofer.
What it means to you, is that a smaller Vas makes for smaller enclosures.
What it also means, is that a smaller Vas makes for lower efficiency, and a higher system resonance as well.

Mms -
Moving mass. The cone and coil, and surround and spider even have a mass associated with them. The higher the moving mass, the lower the efficiency of the speaker - but the lower the Fs as well. A designer adjusts these when deciding how thick of a cone (of course a thick cone may be rigid too, which is a good thing), or what cone material to use.
This is one reason why "high output" SPL subs are actually much less efficient than cheapo subs. Cheapo subs can be louder than SPL subs? Yes, unless you have the wattage to make that SPL sub scream, and that cheapo sub melt.

Xmax -
Here's a good one... represents the linear excursion of the subwoofer, from the "at rest" position, moving in one direction, until the measurement limit is met.
AT least that's how SOME manufacturers list Xmax.
Others list it as "peak to peak" - which obviously doubles the value.
Others list Xmax when they really mean Xmech (like Polk, for example).
Some perform a calculation of voice coil winding length compared to the thickness of the top plate - that's the traditional method, and it's not horrible, it's just also not "apples to apples".
So you have to know what you are looking at, when comparing.

(and by "linear" - that means that the motor strength spec doesn't change, and suspension compliance spec doesn't change, as excursion changes. When it does begin to change, that marks the end of "linear" excursion)

Xmech -
This is essentially excursion without regard to how "linear" excursion is. This is how far the cone assembly can physically move, before it crashes into something and something breaks - coil smacks the back plate, cone crashes on the spider mount ring, tinsel leads rip out of the cone - needless to say, it's a limit you don't want to find the hard way!

Xsus -
This is the suspension component of "Xmax". Subwoofers may be "suspension limited", having a suspension that has a smaller range of linear excursion capability than the motor has. Xmax is always the smaller of the two values.

Xmag -
This is the motor strength component of "Xmax". Subwoofers may be "motor limited", having a motor that has a smaller range of linear excursion capability than the suspension has. Xmax is always the smaller of the two values.

BL curve -
This is an actual plot of motor strength with respect to excursion - simple plot really - motor strength on the Y-axis, excursion shown on the X-axis (and generally shows both positive and negative excursion - so traditional subwoofers with traditional architectures can look quite a bit like parabolas on these plots).
Very helpful for understanding visually exactly HOW LINEAR a motor can be - and even how gradually it rolls off after that limit.

Cms curve -
The same thing as the BL curve, but shows suspension compliance with respect to excursion... so you can see exactly how linear the suspension is, and what it's limits are, where they are reached, and even how graduallly it rolls off after that limit.

Re -
This is just the DC resistance measurement of the coil. It's always a bit less than the "nominal impedence", and really doesn't tell you too much, other than "this is the lowest the impedence will ever dip to, on the impedence curve". (at some frequencies, impedence may rise up very high - a 4 ohm speaker might hit 50 ohms at Fs!)

Le -
Inductance is potentially an important thing to look at.
a voice coil is a coil of wire - and so resembles an inductor.
What does an inductor do? It resists changes in current direction and flow.
What does a speaker do? It changes direction and frequency as quickly as the music throws those changes at it.
So - basically you want your inductance to be as low as possible.
Also... an inductor is a 6dB/octave low pass crossover - so at some point, inductance could be high enough that it prevents the speaker from playing frequencies higher than a certain point - the speaker itself prevents it - the lower the inductance, the higher the speaker is capable of playing.
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Old 04-11-2007, 04:16 PM   #4
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Please only post in this thread if you have a suggestion of a tutorial not listed, or if you have found a broken link.

Thank you

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Old 04-11-2007, 04:18 PM   #5
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Ignore this post... it will be used for future expansion in this thread
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Old 04-11-2007, 06:36 PM   #6
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Quote:
Originally Posted by The_spacemonkey
Ignore this post... it will be used for future expansion in this thread
You must spread some Reputation around before giving it to The_spacemonkey again.

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Old 04-12-2007, 02:00 AM   #7
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This is a great site for people who are so new to car audio that they don't even know what an amplifier is used for. It's broken down into logical sections that explains the "what's" and "why's" of basic car audio equipment without using a lot of technical jargon. Something even our parents can understand.

http://www.carstereos101.com/ (use the nagition bar on the left side of the page)
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Old 04-18-2007, 12:32 PM   #8
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your big 3 link is outdated since they changed their forum structure. here's the new link for it: http://www.sounddomain.com/ubbthread...e/1#Post312025
and another one from the12volt: http://www.the12volt.com/installbay/...TID=73496&PN=1
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Old 02-27-2008, 12:12 PM   #9
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another good site for beginners to learn the basics of a system is

www.caraudiohelp.com
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Old 06-28-2008, 07:28 AM   #10
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The following checklist can be used for the basic troubleshooting of noise in mobile audio installations. The key to success is to relax and systematically go through the vehicle. The problem WILL be found. Murphy’s Law states, however, it will be in the last place you look.


1. TO BEGIN: Be sure that system is correctly designed and matched for compatibility.

2. INSPECT VEHICLE: Verify ground from negative battery terminal connections to the fender and/or chassis. Upgrade as needed. This connection must be capable of handling all the current flow requirements of the system. ASSUME NOTHING, oversize as needed.

3. CHECK VEHICLE ELECTRICAL SYSTEM: Battery, alternator, etc. Make sure your alternator can adequately supply the sound system as well as other vehicle systems (alarm, lighting, etc.) AMPS/VOLTAGE NOT OK: See service technician to have system repaired or upgraded.

4. PROPERLY MOUNT COMPONENTS:
4.1 Electrically isolate them from the chassis.
4.2 Mount away from vehicle harnesses, computers, etc.
4.3 Do not hesitate to use a factory wiring diagram if needed. DO NOT GUESS!

5. PROPERLY RUN ALL CABLES:
5.1 USE CORRECT GAUGE WIRE. If in doubt, go larger.
5.2 Ground all components to a central point and/or use a "ground sniffer" to locate a quiet area.
5.3 Run power and signal cables down opposite sides of vehicle.
5.4 Properly terminate all connections (double check!).
5.5 Use a relay to provide clean power to accessories if needed.
5.6 Use the same gauge wire for power and ground.
5.7 Check signal cables for continuity and repair any open shields or cold solder points.
5.8 Ensure that the shield of signal cables, especially RCA ends are not touching the chassis.

6. HOOK EVERYTHING UP: Follow the instructions provided with the component and be sure of polarity. Make sure everything is working and set all line levels. If noise exists, please continue...

7. IGNITION NOISE: Check for noise in each of the following switch positions:
7.1 IGNITION ON, CAR NOT RUNNING: It is possibly related to an Electronic control module, digital dash, or possibly fuel pump. Do not attempt to filter an E.C.M.! Re-route cables away from control unit or fabricate a shield.
7.2 ACCESSORY POSITION, CAR NOT RUNNING (All accessories off): Substitute an isolated signal source (such as a walk-man CD, tape player, or home CD player), if the system plays fine, the head unit needs to be checked.
7.3 ENGINE RUNNING: Make certain no ground loops exist between components (if they do, see next section.).

NOTE: Pulse Width Modulated headlight switches (like some Honds cars use) can cause a whining type of noise when on, verify this type of problem by turning lights on and off while listening for noise. If this is the problem, the headlight switch may need to be replaced with an alternate type.

8. GROUND LOOPS AND/OR RADIATED NOISE EXIST: Check resistance of all ground cables; consider using central point grounding. Resistance needs to be as low as possible (around .2 ohms) on your meters lowest scale. If not, re-do or upgrade cables. If it is not possible to get the resistance’s this low, try to get them all at an equal value (all the same resistance.)

TIP: Use the combination of a DVM and a ground sniffer to find the best ground point. Remove the positive cable from the vehicles’ battery and check resistance’s from:
A. Ground point of all units with connection point on chassis.
B. Connection point on chassis with the negative terminal of the systems battery.
C. Battery negative terminal with the chassis connection point.

8.1 RADIATED NOISE: Place head unit next to amplifier and plug directly in (or use an isolated source such as a Discman or Walkman) and turn system on. Listen for noise. If noise is gone, please continue...

Muting plugs can be used to systematically troubleshoot the point at which the noise is entering the system. Muting plugs consist of a male RCA end with the positive and negative (tip and shield) connected together (a dead short). Open RCA ends can become an antenna radiating noises into a sound system. By inserting muting plugs into the inputs of each component in your system one at a time the source of the noise can be found.

This is a process of elimination starting with your amplifiers. Insert the muting plugs into the inputs of the amps. Turn on each amp (with the muting plugs inserted) one at a time and with the car running listen for noise. If none is heard, the amps are OK. If all amps are OK, connect the next piece in the signal path upstream of the amps (typically the crossover) by connecting its outputs to the amp inputs using normal RCA cords. Now insert the muting plugs into the inputs of that product and turn on the system. If noise is heard now, power the component with an external power supply. If the system is now quiet, the noise is probably entering through the components’ power supply. If no noise is heard, insert the plugs into the next component upstream in the signal path and check it the same way. Keep working your way upstream all the way to the head unit. Once the problem is found, you can stop.

9. ANTENNA NOISE I: Unplug antenna from the back of the head unit and listen for noise. If noise is eliminated, see section 13. ANTENNA NOISE II. However, if noise remains:
9.1 With head unit powered up and all speakers connected, slowly pull head unit from dash cavity and check for noise:
A. Noise Remains: Noise is entering on one of the power lines; ignition or memory. Install filter onto appropriate wire.
B. No Noise: The dash harness is radiating noise. Locate and re-route harness and shield entire harness next to the head unit. Isolate head unit chassis from metal dashboard.
9.2 If noise still remains, determine which of the following noises is present and suppress the noise at the source using the following sections:
10. IGNITION NOISE II
11. ACCESSORY NOISE
12. ALTERNATOR WHINE

CONTINUED
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Old 06-28-2008, 07:29 AM   #11
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NOTE: The following checks will not be necessary in most cases, but if the previous checks are not effective, continue.



10. IGNITION NOISE II: Determine the source of the ignition noise.
10.1 ONE OR TWO CYLINDERS: Try the following fixes in order:

A. Check for loose or defective spark plug wire.
B. Check for cracked rubber boots at the distributor or ignition coil(s).
C. Re-route plug wires away from car wiring or sensor leads traveling into passenger compartment.
D. Check for bad plugs (excessive gap).
E. Replace cap and rotor.
Note: you can often mist the ignition system with water to help sparks from failed equipment show up. Do this at your own risk of course.

10.2 ALL CYLINDERS: Try the following fixes in order:
A. Check ground from engine to firewall. Upgrade if needed.
B. Install a ground strap from the engine block to the chassis, as well as the hood.
C. Check heater core ground.
D. Check A.C. accumulator ground.
E. Move all wiring away from high energy ignition (H.E.I.) and plug wires.
F. Inspect H.E.I. ignitions, modules, and coils for the following and replace if needed:
1. Distributor cap; cracked, loose, or carbon build-up.
2. A rotor with burned black spot on wiper or pits in the surface.
3. Defective coil.
4. Oily film on lead terminals or inside of cap.
5. Defective ignition module (can cause ignition noise on FM only).

11. ACCESSORY NOISE: May be identified as a turn-on "pop", relay "pop", or other motor type noise.
A. Turn-on "pop" is usually due to components turning on before transients have a chance to settle. Delay the turn-on signal to suspect unit.
B. Relay "pop" is due to a component ground being at the same connection point as, say, the brake lights. Move the ground location. This can also be caused by excessively high gain settings.
C. Filter the power line to noisy motors (blower, etc) (check motor current draw for correct filter.)


12. ALTERNATOR WHINE:
12.1 CHECK ALL GROUND CONNECTIONS. If an audio component has some type of internal ground switches or jumpers, try changing settings.
12.2 CHECK ALL GAIN SETTINGS. Some components have gain built into their circuitry (either fixed or variable) and will increase signal levels. Gain controls are for matching signal voltage levels. They are not volume controls.
12.3 Check continuity of all RCA shield connections. Look for open or cold soldered connections.
12.4 On products with Balanced Differential Inputs, make sure no metal barreled RCA plugs are touching each other. This will defeat the differential circuit and create noise.
12.5 Eliminate all ground loops. (Refer to section 8: GROUND LOOPS.)
12.6 Install a cable from alternator ground to battery negative terminal along side the alternator charge wire using same gauge wire as main system power wire.
12.7 Install a filter on alternator output lead.
12.8 Have mechanic check alternator – repair or replace if necessary.

13. ANTENNA NOISE II: Fixed mast or power antennas go to section 13.2...
13.1 Windshield antennas: plug antenna back into radio and place aluminum foil over entire dash top and ground it with clip leads to door jamb switch.
A. NO NOISE: Use noise sniffer to locate which part of the dash the noise is generating from. After locating problem area, the following fixes are possible:
1. Line underside of dash with aluminum tape and run a ground lead to it.
2. If a noisy cable can be found, move it or shield it and ground the shield.
3. As a last resort, install a conventional antenna.
B. NOISE REMAINS: Measure resistance from antenna cable shield where it plugs into the head unit to a good ground using the lowest scale on DVM. Repair if necessary. Measure shield again. If ground is still bad, replace the antenna lead.
13.2 Fixed mast or power antennas: Measure antenna ground from shield at plug end to ground on back of head unit using the lowest scale on DVM.
A. POOR GROUND: Disconnect and clean all RF connections. Check for a good ground at the antenna trim ring and mounting bracket. If the ground is poor, run a braided strap from the base of the antenna to a good ground. If noise remains, please continue...
B. GOOD GROUND: Try using a test antenna. The base must be grounded. Hold the base, not the mast.
1. POWER ANTENNA TEST: Disconnect antenna connector. Measure the resistance from the mast to the center conductor pin of the lead-in.
a. If resistance is less than 2 Ohms using the lowest scale on the DVM, measure from the mast to ground. If open (infinite resistance), suppress at the source.
b. If resistance is more than 2 Ohms, replace the antenna.
2. FIXED MAST ANTENNA TEST: Replace antenna.

14. You’re Done!
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Old 02-09-2009, 04:08 PM   #12
sandt38

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I figured I would add this here as well:

Quote:
Originally Posted by sandt38 View Post
What a beautiful job Nasty.

I played with it for a bit tonight, and it is very well done. I'm gonna go through it more over the next couple of days. I have to say, I'm quite impressed. I never knew the Theme From The Pink Panther had such awesome SQ traits.

I'm very pleased. Thank you for taking the time to put that together, complete with an instruction manual!!!

You know, I expected you to sound more like the Tazmanian Devil than the mild mannered guy I heard on the disk...

Tons and tons of sushi for totoro!!!

I think, no matter how you feel about Totoro, you will be ahead of the game to download this!!!


***Edit***

New Download links: I am hosting these on Rapidshare, in zip100 files so even free users can download them.

You will need to have Winrar to unpack the files. It can be had for free.

Please place both downloads in the same folder. They don't need to be in their own folder, just the same one. When you begin to unpack one, both will be extracted and joined automatically. Please use the Gainsetting 1 folder first, and follow the directions from there.

http://rapidshare.com/files/19318814...ting.part1.rar

http://rapidshare.com/files/19317821...ting.part2.rar
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Old 02-09-2009, 05:25 PM   #13
Doodaddy

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Some of the links may need to be combed. I noticed a few weeks ago that Geolemon has let the Better Audio site slip. His links are down.
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Old 02-15-2009, 08:59 PM   #14
sandt38

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http://www.caraudiotalk.com/audio-fo...ead.php?t=1546

George. The single greatest tech discussion on a forum about speakers ever... and of course, I started it.
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Old 06-15-2009, 12:50 AM   #15
sandt38

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Focal Tools Disc

http://caraudioforum.com/showthread.php?t=318790
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