Amp: too much power?

[snocross1985]

I have 2 woofers that run at 50W rms, 75 peak. I want to hook these up to an inexpensive amp. Will a 200W amp w/2 channels be too much power or will it run it if it is pushing 100W to each channel? Should i look for something with less power? I need some major advice on this topic.

 

[Redrig]

check the rms power of the amp for the ohm of the woofer and the way you wire them. (stereo or mono). do you those specs?

 

[snocross1985]

rms power of amp: Not sure, guessing that the 100W per channel is peak?

Woofer ohm: 4

Stereo or mono: how to do both? Which is better?

Its only a cheap wal-mart amp, here's the link: http://www.walmart.com/catalog/prod...oduct_id=2168514&path=0:3944:3947:96481:39008

Like i said, i only want something cheap and not expensive, preferably less than $50.

 

[Redrig]

ok if its 100w peak then if you wire the woofers in a bridged sequence then your amp will push 200w rms. so if i were you id wire the woofers in stereo which is positive from amp to positive to woofer and neg from amp to neg of woofer. same way to each woofer. then your amp should push (not 100% sure) about 25 watts rms to each woofer. and that should work fine.

 

[snocross1985]

would that be too little for my woofers? I don't want them to sound bad cause they are underpowered. Sorry, don't know much about this stuff.

 

[onelasttry]

don't worry about that amp. you'll be lucky to get 25 rms out of each channel. not dissing... just a fact.

 

[Redrig]

if your amp is 1 ohm stable you can wire them for 100 watts rms each. if not you can wire them to 2 ohms whicjh would be 5o watts rms.

http://paudio.tripod.com/subwooferwiring.html

heres a wiring diagram. hope this helps if not feel free to ask more questions. theres alot of people here with alot more knowledge than me on this so keep posting if you confused.

 

[onelasttry]

I did the numbers on the amp. it's maximum potential draw is 22.5 amps @ 13.8 volts. take a very leanient estimate of 42 percent power used by the power supply and the remaining amperage draw is about 12.5 amps. 12.5 amps will get you about 63 watts rms. that is the total output from both channels. so it is around 31.5 watts per channel rms.

that is peak amperage draw. no matter how you wire it, thats the MOST it can do. if it did any more it would blow the fuse (then the amp soon after) since that is the recommended fusing of the amp before meltdown.

 

[Redrig]

don't worry about that amp. you'll be lucky to get 25 rms out of each channel. not dissing... just a fact.

can you explain this im not saying your wrong. its just i always thought if he bridged his woofers he could get 200 watts rms outta his amp.

 

[onelasttry]

Look up.

 

[Redrig]

lol sorry. if i give you my amp and tell you how its wired can you tell me how many watts its giving my subs.

 

[onelasttry]

tell me the brand, size and fuse rating of the amp and i'll give you the variables on how you can drive power out of it and how much.

 

[expo5.0]

almost every low end amplifier is hamstrung in just that same way. the peak power claimed is far, far above the amount of voltage that can be allowed through its fuse. however, that doesn't mean it won't hit those high peaks as was stated above (it just wont' do it consistently)- a fuse doesn't necessarily blow as soon as more draw is put on it than it is rated for. for a short period of time most fuses used in an audio system can pass as much as 3-4 times their rated amperage. this is not to say that the rms of the amp is going to be higher than 31 (it probably won't even be that high) but it is possible for that amp with the recommended fuse to push much more power than the fuse would allow you to believe.

 

[Redrig]

ok thanks, its a targa amp. model tlx-0252. and fuse requirment is 25 amp. my 2 12 in woofers are rockfords rated 200 watts rms. thats why i asked to see if thats what they are actually getting... there are bridged also... thanks again.

 

[onelasttry]

expo, your absolutely correct about fuse delay, however keep in mind that pushing more than 5 amps over rated amperage for .8 seconds will terminate a fuse. (buss fuse thermal ratings)

Since the fuse rating of the amp is directly proportional to the maximun current loads acceptable to the board design (which has TRACERS that act like fuses) if you don't lose the fuse, you'll lose the amp.

i'd rather lose the fuse. Thermal heat @ 5 amps overdraw cannot exceed .8 seconds within the fuse. the board is usually built to hold out for 1.1 seconds so the fuse just barely saves the amp.

So.... do you get peaks? Yes. Are they substancial enough in duty cycle to be effective? not likely. they would really need to hold the peak for about 1.5 seconds to effect the output of the amp since it is it MOSFET inside and operates MUCH slower than TTL amps. IF this were a high end amplifier, The amp would use AS-MOSFET logic and would then be extremely fast and durable. Unfortunately the cheaper amps use 4000 series mosfets and the rules of peak just don't apply as much because the substandard technology is designed to cut off before it dies (which is a very conservative number on 4000 series mosfets. )

Overall, i agree with Expo. There are just a few variables of cost effective equiptment that don't follow the rules of the "good stuff". The good stuf runs AS -Mosfets and can handle peaking so they are designed to do it more often.

 

[Redrig]

snocross, did you already buy this amp? and hopefully some of this info helped.

 

[expo5.0]

thank you-

i know absolutely nothing about electronics that doesn't directly apply to car audio and high end car audio in particular

 

[onelasttry]

redrig, i'll answer you if you can't figure it out but i'd rather teach you something if your game.

take your fuse rating... 25 amps.
take your voltage.... 13.5 volts
take your resistance..... 4 ohms.

then go here: http://www.ohmslaw.com/

and try and figure out what your amp is putting out.
these are the factors to take into consideration..... Your amp is a class AB amp so the efficiency is not very good. this means your power supply in your amp will consume a lot of the power the amp is drawing. The more the power supply consumes, the less your subs get.

So let's take the percentage of 40 and call it your efficiency. take 40 percent away from your fuse rating. that leaves what roughly? 15.5 amps or so? that's the amount of power being consumed by the audio section of the amp. that's the power your doing in amps.

Now ... you want to know the power your doing in watts.. so take 15.5 amps, 13.5 volts, and 4 ohms resistance and go to that website and find the equation for it. see what you come up with.

Side note: For class "D" amps the efficiency rating is much better. 68 percent efficient or better.

 

[onelasttry]

Expo, you were absolutely correct in speaking of high end equiptment. EE's and Et's look at the amp from the inside, so i just give a different perspective on things

High cost amps break all the rules. they run KILLER $22.00 a piece mosfet n-channel outputs and are built so well they bend rules easily. the cheap stuff runs that tokyo 4000 series mosfet stuff and when it says 25 amps max... it means it....lol.

 

[snocross1985]

I have not bought it, just looking around, any other recomendations for my situation and preferably not too expensive.