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randy at cr autoglass
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Date Posted: 07:14:14 05/26/06 Fri
In reply to:
Sayar
's message, "Re: New system for me!" on 21:52:46 05/20/06 Sat
>first off, i notice sayar used me as a reference to talk crap about your escort. in no way am i bashing it jeremy, he asked me if i remembered anything about it. and all i recalled was the pictures i took of it with the youngster sitting in the port. other than the fact that it was pretty loud. so please dont take that as criticism just a recallection of memory. and sayar you have not tried the amplifier capacitor trick so dont play that way!!!!
i hope to see everybody in the lanes soon.. hey jeremy give me a call about hosting a show in dickinson this year. Meca is getting pretty slim with their shows and we may think of doing one (either meca or db junkies) later this summer.
>
>Well I never got a very good look at the Escort but
>from what I remember the enclosure is very thin. If I
>remember right the face looked like it was only 3/4"
>thick and made out of particle board (correct me if I
>am wrong). Well enclosure flex kills SPL. It is
>absolutely inperetive that the enclosure is extremely
>stiff. I would not go with anything less then 2"
>thick MDF on tour enclosure and 3" for the face.
>
>Also rounding the port sides can help big. Christifer
>from Cactus Sounds gained 1 dB. @ 163 dB. on the
>Term-Lab solely by rounding his port on the face of
>his enclosure. Also rounding the back side of the
>port is also useful.
>
>I am stretching my memory on this one, but if I
>remember right you were using 2x4's for internal
>braces. Angle iron is a much better option. The wood
>that 2x4's are made out of is not the strongest wood
>in the world. Angle iron seems to work out much
>better from what I have seen. Not only is a piece of
>1.5"X3/16" angle iron a lot stronger, it takes up like
>1/10th the air space the 2x4's do. I usually take a
>piece of angle iron and weld a 6"x6" flat plate on
>each end and drill 6 holes in each plate. This allows
>me to screw or bolt it to the inside of the enclosure
>and the plate further increases straight of the
>enclosure because it spreads over an wider area then
>the 2x4's do.
>
>Additionally because 2x4's displace a lot of airspace
>they cerate turbulence inside the enclosure especially
>if placed by the port. That further can reduce SPL.
>The angle iron is useful there too.
>
>At the absolute minimal I would at least use a 3/4" or
>1" threaded rod if you do not want the angle iron. It
>will still be a better option then the 2x4.
>
>I suggest two braces for top to bottom and two for
>side to side. Now you may not want to run a brace
>from te front to back. I have been told by many SPL
>masters that running one from the front to back messes
>with something and reduces SPL. Usually you only gain
>SPL from going front to back if your enclosure flexes
>a lot.
>
>A stiff enclosure is extremely important!!!! I cannot
>stress it enough. Your enclosure should be so strong
>that you should be able to knock on it and it feel
>like concrete. If it does not then you are loosing
>SPL due to flex. Never in my life have I ever heard
>of anyone loose SPL by strengthening an enclosure. In
>fact if you are really looking for some SPL I would
>reinforce the bottom of your enclosure with concrete.
>Many world champions do that and it works out very
>well.
>
>I was talking with Randy form C&R Auto glass the other
>day about your Escort. He told me from what he
>remembers your box is not all the way forward to the B
>pillar. If so sliding it forward may be advantageous
>unless it changes the 1/4th wave frequency to your
>disadvantage.
>
>Also I do not know how you sealed your wall off but
>using expanding foam and silicone is absolutely
>inparative. The wall must be completely sealed off
>from the back. Or else you can loose major SPL
>
>I do not know how you built your trim panels to go
>around the enclosure to seal the wall off, but I found
>it is usually better to not build trim panels and
>build the face so that it is flush against all sides
>of the vehicle. That way you do not need trim panels.
> Trim panels are not as strong because they are not
>physically part of the face. Thus making the face big
>enough to completely seal everything off is preferable
>in my opinion.
>
>I also found that it is a good idea to make the top of
>the baffle about 1/8" too big. This places pressure
>on the roof essentially bracing it which can increase
>SPL.
>
>Here is a tip that Mark Barfield told me (3rd loudest
>vehicle in the world): No sound off organization, to
>the best of my knowledge, considers the undercarriage
>to be part of the cabin or part of any rule that
>pertains to in front of the B pillar. Therefor you
>can fiberglass or reinforce the undercarriage of the
>vehicle which will make the floor stiffer. This can
>greatly increase SPL by over 2 dB. in many cases
>(unfortunately not mine).
>
>Then there is the fact of the enclosure itself. I do
>not know how big it is but if it was my vehicle the
>enclosure may be bigger. It appeared a bit small.
>But I do not know the exact volume of it so I am not
>100% sure. But the port seemed too small. Port area
>is also very important in SPL. I think if you went
>with more port area you would greatly increase your
>score, assuming you re-tuned everything.
>
>In my Jeep my port is 450 square inches. If I had the
>room it would be like 800. I know a guy that has the
>world record in his class that is running a single 18"
>RE MT in a bandpass enclosure and he has about 1,000
>square inches of port area.
>
>Did you actually tune your port with your SPL meter?
>Or did you just put in a port that you though would
>work and call it a day? I assumed you actually tuned
>the enclosure with your meter but if you didn’t then
>you may be loosing major SPL.
>
>Also I noticed that you place pieces of MDF on the
>floor by the enclosure to cover up the holes in the
>floor for the back seat area. Well those covers would
>be a lot more useful if they were air tight. I found
>that any modification to the front of the B pillar
>that is designed to take up air space, works
>signifently if it is completely air tight. You do not
>have to necessarily glue it to the floor. Some
>weather strips on the wood and duct tape can do the
>trick.
>
>I did notice you did slide your passenger seat forward
>and lean it forward. That is good. Many people don’t
>do that. But taking out your drivers side seat may
>help a lot too. It often helps because the seat
>blocks the natural movement of the rear wave coming
>out of the port. I gained about .6 dB. @ 155 dB.
>(Term-Lab) by removing mine.
>
>I recently found a neat trick when I was at a comp in
>FL. I found that placing objects on your passenger
>seat can help increase your SPL score a lot. Just
>anything solid to take up air space. I believe that
>it helps because not only does it take up airspace it
>helps capture the waveform in the passenger side of
>the vehicle there for creating more of a standing wave
>my the sensor. There is no rule in any sound off
>organization that says you cannot have a messy car and
>there for have "stuff" on your seat. They may not
>allow a wooden box, but a big case of CD's or
>something like that should be legal.
>
>And finally bracing of the body... I do not know if
>you gain or loose SPL my having people push on the
>vehicle. But it is definitely something to try. If
>you gain SPL by having people push on your vehicle
>then throw like 15 people on it. I have seen people
>gain 3 dB. by having a lot of people on their vehicle.
> Windshield, both doors, roof, side windows... all
>flex.
>
>Also I would play around with your door pins. Move
>them in, move them out. Play with them and meter the
>system. I gained a few tenths by moving my
>passenger’s side door pin all the way out.
>
>I would suggest you hook up your stock alternator to
>your 16 volt batteries. You could do this by taking
>two high current relays and wiring them in such way
>that when you flip a switch your vehicle runs of your
>battery up front and your alternator switches to power
>the back batteries for the run. And you can wire up a
>second switch that will bypass the alternator’s
>voltage regulator and full field the alternator. That
>will cause the alternator to put out maximum current
>as long as it is full fielded. You can run the wire
>to full field your alternator to a momentary push
>button switch. Then when you push the switch you will
>full field the alternator which will keep more voltage
>present at the terminals of your amplifiers and
>consequently make the amplifier produce more power.
>
>There is a amplifier modification that can be done
>that is useful and legal in all sound off
>organizations as far as I know. I read an article
>about this mod awhile back and tried it myself. It
>does work. What you do is you open up all your amps
>and find the positive and negative voltage rails after
>the power supply. Then you run capacitors to them to
>give them reserve capacitance. So when you burp your
>system the caps discharge and you additional reserve
>power for the burp that the power supply cannot
>supply. This leads to more power to your subs. Think
>of it this way. The definition of clipping an amp is
>“when the output of the amplifier exceeded the output
>of it’s power supply”. So if you reduce the voltage
>drop at the rails when you burp the system you can get
>more power out of the amp. The caps do that.
>
>If you want more info on how to do that I can hook you
>up. The guy that I learned how to do this from gained
>about 1 dB. @ 139 dB. with only a 100 watt amp! Plus
>he was only running a single 5.25” Bose woofer and he
>still did 139 dB. on the Term-Lab.
>
>I have done everything I have explained here and found
>that it all works in my vehicle (accept the
>fiberglassing the undercarriage). I believe most of
>these trick will work for you too. I suggest trying
>all of them and metering after each change.
>
>Please excuse any spelling errors. :P :)
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