|
one loud vett Unregistered guest | I have a 1995 rockford fosgate punch 200ix amp,itsa 500 watt amp.I was running 2 10" kenwoods in a ported box until I ddecided to replace them with 2 10" rockford punch he subs,200rms 400peak.The amp was too much for the kenwoods and is too much for the rockrords.I dont know why my local stereo shop sold me 8 ohm subs.Whats the difference 2 4 8 ohm?Should I be useing 4 ohm? |
|
Silver Member Username: TjmutlowPost Number: 248 Registered: Sep-05 | Is the amp bridged, if so the single 8 subs bridge down to 4ohm and that is what that amp is stable at bridged. |
|
Silver Member Username: MixneffectOrangevale, Ca. USA Post Number: 627 Registered: Apr-05 | Ohms are just a measuring unit of resistance. In car audio applications a 4 ohm load is nominal. There are also other loads as well i.e. 12, 8, 6, 4, 3, 2, 1.5, 1, .75, .5, .25 Ohm Take your scenario for instance; You have an amp that can push 500 watts, but into what load? 2, 4, 8 ohm? What? An amp that is rated 100 watts RMS at 4 ohms may only push out like 75 watts at 8 ohms, sometimes even 50 watts depending. Look at other amps specifications and see. Some amps will drop wattage by about 75% when the resistance doubles, while others will drop to 50%. I think it has to be based on how robust the amp is built. Taking the 50% rule to be on the safe side; the following projections would be true; 50 watts X 1 @ 8 ohms 100 watts X 1 @ 4 ohms 200 watts X 1 @ 2 ohms 400 watts X 1 @ 1 ohm 800 watts X 1 @ .5 ohm Furthermore; The resistance plays other roles as well. A 1 ohm load will not "dampen" the signal as much as an 8 ohm load. This affects the amp as well as the sound. The amp will be able to push out more power (watts) with a lower load (ohms), but it may take a beating from the signal coming back. That's why amps are said to be unstable at a given load. As the signal leaves the amp it runs through the load and then comes back. If the signal that comes back into the amp is too strong, the amp will distort, malfunction, clip or go into protection mode. The sound will also suffer when a lower resistance load causes the amp feedback problems. The signal must be clean going out of the amp as well as coming back in. Getting back to your situation, I would not say that an 8 ohm load will be the problem. IMHO I believe it has to do with the "gain" setting on your amp as well as other bass boost, HU bass levels, and or any other sources that may alter the signal. The gain level should be set at optimum level without overloading the speakers/sub. If your gain level has been set with the bass levels at "0" then any time that the levels are boosted above that level, the speakers/sub will distort. There have been arguments to how a "gain" should be set. Some believe that it should be set with a volt meter to match the HU RCA output voltage levels. They base this on the fact that some manufacturers design the "gain" knob as an "input sensitivity" knob. Well, it has not been established which manufacturers do it one way or another. I personally tune my "gain" setting by ear. Another variable may be that your speakers/subs may not handle the RMS ratings that they are advertised at. Yes, many manufacturers inflate their specs. When you look at a frequency response graph, you will notice that the graph will be more flat in the middle, and it will taper off dramatically on both extreme ends. Most manufacturers will take the highest dB levels from in the middle of the graph and average them out. This they say is the output. I am here to tell you that it is not entirely true. Middle frequencies are easier to reproduce (mechanically) than lower frequencies. The lower a frequency is, the more a speakers motor will have to work to reproduce the same dB levels. So, when a graph is given for a speaker, it would be wise not to average the middle of the graph, but average the entire graph. This would give you a better projection on how loud your speaker will be (dB) per giver watt. Another variable to take in consideration is the voltage level that it has been tested at. I don't have the formula at hand, but www.bcae1.com has an excellent educational tutorial. If I may, I would have to say that the speakers you have are not capable of handling your amps power. It is not because your speakers are 8 ohm. I would check the gain setting, and bass levels. If you like your speaker's sound quality or volume, then I would get an amp that would be better for your application. Your amp is a terrific amp, but it is too powerful for your speakers. |
|
Unregistered guest | No the amp is not bridged,I think it has way to much power for the subs as it is,but thanks for the advice. WOW mixneffect thanks for all the info I emailed you with a few other questions,hopefuly it doesnt get stuck in spam.You sound like a audio encyclopedia.THANK YOU |
|
Unregistered guest | No the amp is not bridged,I think it has way to much power for the subs as it is,but thanks for the advice. WOW mixneffect thanks for all the info I emailed you with a few other questions,hopefuly it doesnt get stuck in spam.You sound like a audio encyclopedia.THANK YOU |
|
frustrated Unregistered guest | why are my posts not showing up on yhis |
|
Silver Member Username: MixneffectOrangevale, Ca. USA Post Number: 632 Registered: Apr-05 | Jesse, I hope you will stick arround. There are a lot of knowlegeable people here. In no time you at all, you will be up to speed. Just read, read, read. Welcome aboard. |
|
Silver Member Username: PhuktupbassheadScottsdale, Arizona United State... Post Number: 333 Registered: May-05 | Straight up! mixneffect is right. I've been all over the web looking for my own answers... it's tough. come to this site, though, and all the answers to the questions you didn't know to ask come to light. Thanks ECOUSTICS!!! |
|
Silver Member Username: PhuktupbassheadScottsdale, Arizona United State... Post Number: 334 Registered: May-05 | hey, Mix tell us more about these amp scams and how to determine on our own what is true or false. same scenario with subs. I feel this is a good question almost everyone would like to be clearer on. |
|
Silver Member Username: MixneffectOrangevale, Ca. USA Post Number: 641 Registered: Apr-05 | I believe chauncey posted a link that has "The Good, Bad, and The Ugly" list of audio brands. "tell us more about these amp scams" I cant think of any off the top of my head, but maybe a question may come up in the near future involving some bogus info, and if I see I will definetly give my $.02 worth. |
|
Gold Member Username: Chaunb3400Huntsville, Alabama U.S. Post Number: 2857 Registered: Jul-05 | http://pub14.ezboard.com/fcaraudiotalkfrm27.showMessage?topicID=27.topic This |