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My Poor 3000gt Vr4-help Me Change Speakers-long!!!

Discussion in 'General Car Audio Discussions' started by peter_euro, Dec 26, 2003.

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  1. peter_euro

    peter_euro Full Member

    peter_euro, Jan 5, 2004
    #61
  2. peter_euro

    peter_euro Full Member

    peter_euro, Jan 5, 2004
    #62
  3. geolemon

    geolemon Full Member

    That Ebay auction for the big sheet, yes, that's the same stuff, you definitely could use that. You'd probably have some left over too.

    The damping spray is really more to prevent vibrations, not what you want.
     
    geolemon, Jan 6, 2004
    #63
  4. peter_euro

    peter_euro Full Member

    Lefovers, LOL... quite a bit of left overs, according to my calcs... it is roughly 146x10in along the perimeter plus about 45X24 for the bottom piece... can you calculate the rough surface area? According to my calcs, it is about 17.7 sq feet to cover... LOL, I gotta look around for a better deal... I have to hit the electronics store tomorrow for the potentiometer... BTW, with the fiberglass inside, this box is heaaaavy... :(
     
    peter_euro, Jan 6, 2004
    #64
  5. peter_euro

    peter_euro Full Member

    Lefovers, LOL... quite a bit of left overs, according to my calcs... it is roughly 146x10in along the perimeter plus about 45X24 for the bottom piece... can you calculate the rough surface area? According to my calcs, it is about 17.7 sq feet to cover... LOL, I gotta look around for a better deal... I have to hit the electronics store tomorrow for the potentiometer... BTW, with the fiberglass inside, this box is heaaaavy... :( [/b][/quote]
    K Geo, I give up on the dual potentiometers... Impossible to find in double gang with this low Ohm rating and adequate power rating... :( I am just gonna go with two (I found 250 Ohm 25Watt just in case, LOL)... I will just make myself a little control panel and count on both being close enough... My questions: is it ok to run the powered voice coils on the subs together to get the 1 Ohm and then the other 2 voice coils separate to hook them up to the potentiometers? I do not think the potentiometers are rated from exactly 0 to the max (250Ohm) and there is most likely a residual resistance in the unit, is this going to affect the sound quality at all or will it be neglible? :rolleyes:
     
    peter_euro, Jan 6, 2004
    #65
  6. geolemon

    geolemon Full Member

    I thought I gave you a link to a site that sold those dual-gang ones??
    It was like $7 or something... Mouser electronics maybe? :unsure:
     
    geolemon, Jan 6, 2004
    #66
  7. geolemon

    geolemon Full Member

    ..but if you want to do the separate pots, that won't hurt anything. In fact, to answer your question more directly, it's good to keep the potentiometers separate, electrically.

    The dual-gang pots are two physical pots, after all. Essentially the same thing as having two pots, but inherently coordinated. ;)
     
    geolemon, Jan 6, 2004
    #67
  8. peter_euro

    peter_euro Full Member

    The power handling was like 0.5 watt on those... I do not think it would work... I checked right away... ;) I hi and lo and came up with nothing... And digikey charges a minimum of 25 bucks per transaction... (or $10 surcharge under 25)...

    Here is what I found:

    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...egory=4664&rd=1

    I can get 2 of them and matching knobs for $12.00 shipped... Does this sound ok?
    BTW, my local electronics store sucks, they do not carry any potentiometers below 10k Ohm... And Radio Shack sucks too... :(
     
    peter_euro, Jan 6, 2004
    #68
  9. peter_euro

    peter_euro Full Member

    The shipping on this item is $11.25 so like 40 bucks for the whole thing... or I can have 20 sq ft of this stuff
    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...gory=15199&rd=1

    for $29.50... I have no clue which one is better or is foam just a foam? I cannot believe there are actually frequency ratings on these things, LOL... :rolleyes:
     
    peter_euro, Jan 6, 2004
    #69
  10. geolemon

    geolemon Full Member

    That foam is 1.5" thick, the parts express stuff I linked you was 2.5" thick...
    I couldn't comment on how much you'd need, but this is likely cheaper mostly because it's thinner. The thinner stuff probably will work fine for you.. but the thicker stuff would likely also be a bit better. Notice a difference? Probably not.
     
    geolemon, Jan 6, 2004
    #70
  11. geolemon

    geolemon Full Member

    The power handling was like 0.5 watt on those... I do not think it would work... I checked right away... ;) I hi and lo and came up with nothing... And digikey charges a minimum of 25 bucks per transaction... (or $10 surcharge under 25)...

    Here is what I found:

    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...egory=4664&rd=1

    I can get 2 of them and matching knobs for $12.00 shipped... Does this sound ok?
    BTW, my local electronics store sucks, they do not carry any potentiometers below 10k Ohm... And Radio Shack sucks too... :( [/b][/quote]
    Well, think this through...

    These large subwoofers are usually only about 0.5% efficient.

    That means, if you are feeding 1200 watts into them, that only 6 watts of energy is actually working to the end of moving the voice coil. So you have 6 watts worth of motion, or "horsepower", or thrust, if you will.

    Now, I'm pretty certain that a subwoofer is not efficient when operated as a generator, as well.

    It's inefficiency means that energy out will be less than energy in, by definition.
    Particularly since it's changing state from electrical, to kinetic motion, that's causing electrical energy again. Just not efficient.

    Let's optimistically say that it's 10% efficient in translating that 6 watts into motion and then back into power.
    So 6 watts in (effectively, in terms of what's translating into motion) would end up producing at most 0.6 watts out, across that resistor, if that 10% efficiency were true. I don't honestly know how efficient this particular voice coil motor would be when operated as a generator, but I feel pretty confident that that 10% number is optimistic. B)
    And that's not considering what actually would be produced, considering the resistance the potentiometer was set to, etc.

    AND that's only if you are running it at full-bore maximum-excursion, right? Realistically, the sub won't be pumping away at maximum excursion, it'll be somewhere between maximum excursion and no excursion, and changing all the time, with the music. ;)

    I don't think the 0.5 watt one is really that big of a risk. B)

    Hey, if I'm wrong, and it dies... just remove the spent potentiometer, twist the wires leading to each potentiometer together (so the sub operates just like as if no potentiometer was there at all), and then buy some more expensive, higher wattage ones. :bye:
     
    geolemon, Jan 6, 2004
    #71
  12. peter_euro

    peter_euro Full Member

    Well, think this through...

    These large subwoofers are usually only about 0.5% efficient.

    That means, if you are feeding 1200 watts into them, that only 6 watts of energy is actually working to the end of moving the voice coil. So you have 6 watts worth of motion, or "horsepower", or thrust, if you will.

    Now, I'm pretty certain that a subwoofer is not efficient when operated as a generator, as well.

    It's inefficiency means that energy out will be less than energy in, by definition.
    Particularly since it's changing state from electrical, to kinetic motion, that's causing electrical energy again. Just not efficient.

    Let's optimistically say that it's 10% efficient in translating that 6 watts into motion and then back into power.
    So 6 watts in (effectively, in terms of what's translating into motion) would end up producing at most 0.6 watts out, across that resistor, if that 10% efficiency were true. I don't honestly know how efficient this particular voice coil motor would be when operated as a generator, but I feel pretty confident that that 10% number is optimistic. B)
    And that's not considering what actually would be produced, considering the resistance the potentiometer was set to, etc.

    AND that's only if you are running it at full-bore maximum-excursion, right? Realistically, the sub won't be pumping away at maximum excursion, it'll be somewhere between maximum excursion and no excursion, and changing all the time, with the music. ;)

    I don't think the 0.5 watt one is really that big of a risk. B)

    Hey, if I'm wrong, and it dies... just remove the spent potentiometer, twist the wires leading to each potentiometer together (so the sub operates just like as if no potentiometer was there at all), and then buy some more expensive, higher wattage ones. :bye: [/b][/quote]
    LOL Geo, you could probably sell snow to an Eskimo... The only reason I was concerned was because the Adire tutorial recommends this value... I emailed Dan W. to confirm but have not heard anything back :( I think I am going to call them tomorrow and try to extract some answers...

    I think I am just gonnal go for those 2 single ones because they seem to be of higher quality plus the resistance is lower thus leading me to think that the minimum setting on these should be closer to 0 than on the double one that is rated 500 Ohms...

    I actually talked to the guys from the body shop and I do not have to worry about picking up the car until next month, so I should have plenty of time to take care of everything... (including that second set of Illusions, LOL) and I still have to wait for the Brahmas and Max Fidelity neo tweets to arrive... BTW, what year is your pathfinder? I am gonna use the Hex drivers I have in the Mitsu to replace one of the Hex mids that I burnt out and I am waiting for a set of Hex500 to do the kicks and go 3 way up front....

    And I cannot believe you are considering 22 in spinners, LMAO...
     
    peter_euro, Jan 6, 2004
    #72
  13. geolemon

    geolemon Full Member

    Good thinking. B)
     It's a '95.
    I just picked it up this year, last year of the "good" body style/chassis type.
    I loved my old '90 Nissan pickup, thing was fantastic.
    It was a sonofabitch trying to find a Pathfinder that was both 2wd (so I can lower it, of course :D ) and a 5 speed.
    Seems more soccer-moms purchased these cars, and they apparently want 4wd and automatics. :rolleyes:

    And I'm not pondering spinners, believe me. :lol: I'm not a "spinner" sort of guy.;)
    I asked him how much for the rims without the spinners, and/or just the tires.
    Spinners are essentially bolt-ons, replace the center cap.

    Once winter is over though, it is go-time. Got to get some wheels...
    I put snow tires on the stock rims. B)

    ...got to do the suspension too, I'm not going to want to drive around all ghetto-fabulous stock-high up in the air, on a set of 20's and low profile tires... :rolleyes:
    Ick. I tease people for that, I don't want to DO that! :p
     
    geolemon, Jan 7, 2004
    #73
  14. peter_euro

    peter_euro Full Member

    LOL, I guess we took completely opposite directions... Mine is a 1990 (I bought it in 1995) but it is not only a SE 5sp but also a 2door and 4x4... This is probably the rarest of them all since as you said, housewives decided to make it a vehicle of choice and kinda castrated it, LOL... You lower yours, I bumped up mine a bit (over 3 inches) to fit those 265/70/17 tires and rims... Mine is actually a fully capable off road rig because it has a heavy duty aftermarket suspension components and shocks plus Doug Thorley headers and 3inch custom exhaust... Notice the tip at the rear instead of driver side... :p

    I did everything on the Pathfinder myself including alarm and the stereo, believe me it is plenty loud and the huge 7th order banpass box really delivers with those 2 JBL 1200GTi subs... The amps are Planet Audio 4channel 4300 plus Concept 1200 for the subs... The only thing I will be doing shortly is to change my front stage by leaving Hex600 mids in the doors and doing Hex500 in the kickpanels... There is 160sq feet of sound deadener in the truck too... This is actually my daily driver... :rolleyes:

    http://us.f1f.yahoofs.com/bc/5d2095/bc/Pat...fK76._AfY9TYCxt

    http://us.f1f.yahoofs.com/bc/5d2095/bc/Pat...fK76._ANwkVrtDE

    http://us.f1f.yahoofs.com/bc/5d2095/bc/Pat...fK76._A_kuDxtq0

    http://us.f1f.yahoofs.com/bc/5d2095/bc/Pat...fK76._A1q6SmFK4

    http://us.f1f.yahoofs.com/bc/5d2095/bc/Pat...f6N7._AIcQbu1mF


    I think it is still pretty good for a 14y.o. daily driver... :rolleyes:
     
    peter_euro, Jan 7, 2004
    #74
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