Opinions on the Fosgate P3 series subwoofers
12-19-2007, 06:31 AM
#62
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Originally Posted by phreaktor
Elaborate.
With a more powerful amp, you can leave the gains turned down and provide a very solid clean signal without clipping.
To quote one of my favorite websites:
"Damaging Woofers:
When a woofer is driven with a high powered amplifier to high levels, there will be a significant amount of current flowing through the voice coil. Since the voice coil has resistance, there is a voltage drop across the speaker's voice coil (which the amplifier appreciates greatly :-). This means that there may be a great amount of power being dissipated (in the form of heat) in the voice coil. When a speaker is driven with lots of clean power, the cone moves a great deal (in proportion to the output voltage from the amplifier). For speakers with vented pole pieces (or other types of venting), this movement forces a lot of air to flow in the magnetic gap (area where the voice coil rides). When the woofer moves out of the basket, the chamber that's under the dust cap and around the voice coil expands (increases in volume) which pulls cool air into the magnetic gap. When the woofer moves the other direction, the chamber size is reduced and the hot air is forced out of the vent in the pole piece. This air flow cools the voice coil. If a relatively low powered amplifier is driven into clipping (to a full square wave for a lot of people), a relatively large portion of the time, the voltage delivered to the voice coil no longer resembles a sine wave as it would with an unclipped signal. While the amplifier's output is clipped, the voice coil is not being motivated to move as far as it should for the power that's being delivered to it and therefore is likely not being cooled sufficiently (since the speaker is driven by a linear motor, the voltage applied to the voice coil determines how far the voice coil moves from its point of rest). At points a, b, d, e, f and h the voltage is changing causing the voice coil to move in the gap and therefore pull in fresh cool air. At points c and g, the voice coil may still be moving a little due to momentum but may not be moving enough to cool properly. Remember that during the clipped portion of the waveform current is still flowing through the voice coil. Since the displacement of the voice coil (and therefore the airflow around the voice coil) is no longer proportional to the heat being generated, the voice coil can overheat. This excess heat may cause the voice coil former to be physically distorted and/or melt the insulation off of the voice coil wire and/or cause the adhesives to fail (especially if the speaker is rated to handle no more than the power that the amp can produce cleanly). If your speakers are rated (honestly) to handle the maximum 'clean' power that your amplifier can produce, slight clipping isn't generally a problem. Severe clipping is more likely to cause a problem."
Extracted from: http://www.bcae1.com/2ltlpwr.htm
Last edited by StreetOC192; 12-19-2007 at 06:47 AM.
12-19-2007, 06:35 AM
#63
Originally Posted by StreetOC192
With a less powerful amp you will have a tendency to turn the gains up to get the desired output from the sub, turning up gains introduces clipping. clipping is detrimental to a voice coil.
With a more powerful amp, you can leave the gains turned down and provide a very solid clean signal without clipping.
With a more powerful amp, you can leave the gains turned down and provide a very solid clean signal without clipping.
12-19-2007, 06:48 AM
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Originally Posted by phreaktor
I thought clipping was when the amp reaches distortion level? What does the cleanliness of the waveform have to do with the current levels in the coil? Does clipping cause current spikes? The speaker is the load correct?
12-19-2007, 07:04 AM
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Originally Posted by phreaktor
Makes more sense now. Thanks for the learning experience.
It's sort of like running a car on a dyno.
It's sort of like running a car on a dyno.
12-19-2007, 07:19 AM
#67
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Originally Posted by phreaktor
you suck.
12-19-2007, 07:23 AM
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Originally Posted by vo7848
I looked at the FI website. The BTL's were a bit much, but the 3 subs below were quite appealing. I really like the BL series 12, but it doesn't have cu ft specs for sealed application. I'm assuming it can't be used in a sealed enclosure. 
https://ssl.perfora.net/www.ficaraud...iew.shopscript
Any opinions?
Since they come in D2 coils, I could crank the RF amp I have up to it's max setting. Supposidley the RF amp box stated the amp was bench tested at a 951watts output level. I'm not really too sure how accurate that is though.
https://ssl.perfora.net/www.ficaraud...iew.shopscript
Any opinions?
Since they come in D2 coils, I could crank the RF amp I have up to it's max setting. Supposidley the RF amp box stated the amp was bench tested at a 951watts output level. I'm not really too sure how accurate that is though.
12-19-2007, 07:23 AM
#69
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Originally Posted by StreetOC192
With a less powerful amp you will have a tendency to turn the gains up to get the desired output from the sub, turning up gains introduces clipping. clipping is detrimental to a voice coil.........................................]
12-19-2007, 07:28 AM
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Originally Posted by StreetOC192
The Fi subs are really nice. I don't think you can go wrong as long as it fits the box size, doesn't hit the hatch, and can be driven with the amp you will be running it with.
Example:
1. Flatwind Coil
2. Copper Coil
3. BP power
https://ssl.perfora.net/www.ficaraud...iew.shopscript
12-19-2007, 07:29 AM
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Originally Posted by vo7848
Now that you mentioned this. I remember the rule of thumb, an amp's output power is usually good up to 75% of the gain. Anything beyond that is distortion.....
12-19-2007, 07:31 AM
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Originally Posted by vo7848
Now that you mentioned this. I remember the rule of thumb, an amp's output power is usually good up to 75% of the gain. Anything beyond that is distortion.....
My HU max volume is 80 so I set my gains for what I'd want it 60.
My amp has a remote Gain control which I think is awesome. Its nice to be able to adjust the gain on the fly instead of messing with bass boost.
12-19-2007, 07:32 AM
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Originally Posted by StreetOC192
The gain control is 100% driven by the output voltages of the headunit. In theory, you are supposed to set the gain to the rated output voltage of the headunit so that when the headunit is outputting it's max signal the amp will be putting out it's rated rms power. In the real world however different sources put out different levels (a FM radio station may not put out the same level as a cd), so when tuning you would normally compensate by using your strongest signal (usually a cd) and set the headunits volume at around 75%. Then adjust the gain up a little at a time until you hear clipping (some amps are even equipped with a handy clipping light), and then back off just a hair until the clipping is gone. on a sub it's hard to hear minor clipping so you can also use a multimeter to adjust the gains until the rated rms power is being output.
My amp is overkill for my sub anyway
12-19-2007, 07:37 AM
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Originally Posted by blasian
I couldn't get my damn multimeter to get a valid voltage
My amp is overkill for my sub anyway
My amp is overkill for my sub anyway
http://www.subwoofertools.com/forum/setgain.asp
12-19-2007, 07:43 AM
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Originally Posted by vo7848
I'm really leaning towards the SSD12 model in the attachment below. How you feel about the options it comes with in the drop down menus?
Example:
1. Flatwind Coil
2. Copper Coil
3. BP power
https://ssl.perfora.net/www.ficaraud...iew.shopscript
Example:
1. Flatwind Coil
2. Copper Coil
3. BP power
https://ssl.perfora.net/www.ficaraud...iew.shopscript
The copper coil option as you could imagine will dissipate heat more so than the standard coil because it's made of copper, but I would think the copper being a softer metal would not be as wise of a choice.
The bp power option, I am really not sure what that is......I have no advice to give you here.
For your application and given the bench tested output of your amp, I would just stick with the standard voice coil. I would think the upgrade options are more for the hardcore SPL competitors.
12-19-2007, 08:16 AM
#76
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Originally Posted by StreetOC192
The flatwire coil option simply helps the power handling of the sub. The coil has more surface area to dissipate heat and will take more power then the regular round wire coil that comes in the ‘stock’ version of the sub. This option will also make the sub tend to be more prone to ‘peaking’ for a budget daily driving sub where you don’t have to use a ton of power to get maximum output and sacrifice sound quality a little bit.
The copper coil option as you could imagine will dissipate heat more so than the standard coil because it's made of copper, but I would think the copper being a softer metal would not be as wise of a choice.
The bp power option, I am really not sure what that is......I have no advice to give you here.
For your application and given the bench tested output of your amp, I would just stick with the standard voice coil. I would think the upgrade options are more for the hardcore SPL competitors.
The copper coil option as you could imagine will dissipate heat more so than the standard coil because it's made of copper, but I would think the copper being a softer metal would not be as wise of a choice.
The bp power option, I am really not sure what that is......I have no advice to give you here.
For your application and given the bench tested output of your amp, I would just stick with the standard voice coil. I would think the upgrade options are more for the hardcore SPL competitors.
12-19-2007, 08:20 AM
#77
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Originally Posted by StreetOC192
The gain control is 100% driven by the output voltages of the headunit. In theory, you are supposed to set the gain to the rated output voltage of the headunit so that when the headunit is outputting it's max signal the amp will be putting out it's rated rms power. In the real world however different sources put out different levels (a FM radio station may not put out the same level as a cd), so when tuning you would normally compensate by using your strongest signal (usually a cd) and set the headunits volume at around 75%. Then adjust the gain up a little at a time until you hear clipping (some amps are even equipped with a handy clipping light), and then back off just a hair until the clipping is gone. on a sub it's hard to hear minor clipping so you can also use a multimeter to adjust the gains until the rated rms power is being output.
12-19-2007, 08:21 AM
#78
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Originally Posted by StreetOC192
This option will also make the sub tend to be more prone to ‘peaking’ for a budget daily driving sub where you don’t have to use a ton of power to get maximum output and sacrifice sound quality a little bit.
12-19-2007, 08:48 AM
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Originally Posted by vo7848
I can't say that I quite understand this statement. Could you reword it?
12-19-2007, 08:57 AM
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Originally Posted by StreetOC192
Basically (and this is all theory), a flat wound vc should/could allow the cone to travel farther with a given amount of power. The reason i said for a budget daily driven sub was not necessarily aimed at YOUR application, but rather someone looking for the most "bang for the buck".
I've taken apart a few subs and seen tightly woven coils. The cheaper coil version is not as tightly and flatly spun around the interior cone, which would degrade the dynamics of it, which in turn would decrease airflow. Did I get that correct?By purchasing this flat coil option, I'd have a sub that would run more efficient over a longer amount of time, before reaching it's failure point. Hence, making it a better sub for the extra $20 spent rather than purchasing an actual better sub built for SPL. This is of course all meant for a person that just wants a better sub, but doesn't wish to go all out like the hardcore SPL guys. Did I get this correct too? I'm just re-explaining it in my own words to see if I really got the message correct.
I'd probably purchase that option then. At outdoor events, it's pretty common for me to play the radio at a high volume for an hour straight.