BicuspiD

I removed the Bose from my 93 Touring and have the BA Pro 6.5 comps in the doors, and a single 10" Rf HE 4ohm sub in a box. I have recently decide to run the front channels off of my existing amp, which will give them ~160w ea. (amp is 210x2 @ 2ohm, speakers are 3ohm). I want to buy an amp to run the sub, but not be over powering the rest of the system - should I stay around the same power as each door channel, or go a little less/more? I figured a 200wx1 would be a good complement, but I dont want too much bass. Maybe 100 watts to the sub?

If you are only driving 1 10" sub, Does it make a dramatic difference between running a Monoblock 'D' class amplifier and a regular 2-channel amplifier bridged?
I could get a 2 channel and bridge it to get the same power, its loads cheaper, but its not a "Monoblock D-Class subwoofer amp". Will this really make that big a difference with the realatively low wattage/non competition use my car will be for? IS one amp cleaner than the other? (tube amp aside) Will a 100w monoblock hit harder than a 100w "normal" amp?

The D class are much more expensive, and, because of Ohm's law, (Thanks Ohm), I will need double the amp watts to run a 4ohm sub. I really dont want to spend $350+ for an amp right now, but I want to buy the right one

I notice most amps are rated at 2ohm ie 200w x1 @ 2ohm. This equals ~100w@4ohm correct? So in effect I would need a 400wx1 @ 2ohm to give me the 200 I'm looking for(at 4 ohm)?

I am a little confused as u can see.. I would like to use my existing speaker, I just want to make sure I buy the right amp for the sub, , like Goldilocks, not too big, not too small, juuuuust right.


Thanks for any advice/insight you guys can offer..

ZenFox

This is from my limited knowledge, and may be overruled by someone with much more experience than I.

Bridged amps up the power, but also increase the total harmonic distortion, if I recall correctly. Take This amp for example...

360W@ .5% THD x1 bridged
90W@ .05% THD x2 @ 4Ohms

For comparison, The monoblock amp:

300W@.05%THD x 1

So, the monoblocks are cleaner, but I'd need a person with a wee bit more experience than I to tell you if it's going to make a noticable difference. Personally, I'm having the same issues... which sub? which amp? etc..

-ZenFox

RX-7-Tobi

Hi friend,

first of all, it is not bad to have a lots of power. You can destroy a sub more easyly witha bad and underpowered amp because it can't control the sub properly. And it makes less dist. at same level cos it does not run at the limit all the time.
Class D only is good for subs. Has better efficiency and so less amps at same watts output. But most of the standard amps will contol the sub a touch better because the damping factor (res. of the amp compared to the load of woofer/s) is less.

Tobias

BicuspiD

OK.

I figure a 300w sub amp will keep up with the door speakers fairly well..


Lets say I have an amp that is 2 ohm stable, and outputs 300 w x1 @ 2 ohms -


If I feed that into a 4 ohm load - How much power will the speaker actually be seeing? Is this bad for the amplifier?


FYI My system is:
Panasonic CQ-VA707W 7" Monitor/Tuner
Emerson DVX2100 CD/DVD/MP3/SVCD Player
BA Pro 6.5 Comps (3 ohm)
RF Punch HE 10” SVC (4 ohm)
Eclipse 36401

Icemark

Only the cheaper amps rate by 2 ohm. It is a marketing gimic to trick you into thinking you are getting more power than you really are.

Typically an amp rated at 300 watts at 2 ohms will only be about 150 watts at a normal load of 4 ohms.

But as mentioned above, the distortion also radically increases with a 2 ohm vs 4 ohm load.

And what kills speaker??? you guessed it... distortion!

So if you are running a 300 watt load into a speaker with a 1% THD you are 100 times more likely to blow that speaker up than if you were running a .1% THD amp.

Too toss even more into the mix, if you are running a 150 watt amp into its limits, and it starts clipping (the amp is unable to reproduce the sound correctly at the top and bottom of the wave form because of limits in the output section of the amp) then you will blow the speaker even faster.

So, for proper bass spend a little and get proper equipment. Don't cheap out. Even if you have to use head unit power for your dash speakers, just so you can afford a decent amp for the woofer, do so.

West TX RX-7

Run a mono on the sub. More power for your money. 250 rms is plenty for 1 or 2 10's. I run a Fosgate 250 2 chanell in my truck bridged on 2 10's in parallel (2 ohms) and it rocks. A mono is mo betta though, i just ran the 2 channel cause i picked it up for 110 bucks off ubid.

In my rex i run 2 Fosgate BD500.1 mono's on 2 12" subs. a 250 2 channel on my center channels, a 250 2 channel on my rears and a power 360 Fosgate 2 channel on my components. To give you an idea of sub power vs other speakers power. I never turn my amps up passed half way on the subs.

spyfish007

Use a ClassD mono amp with 250 to 500 W RMS. The reason for mono amps and class A,A/B,D, etc are only to provide options for your system. Most bass frequencies are hard to locate the speaker placement so mono is acceptable, even though the CD might have those frequencies recorded in stereo, you the listen can't tell. For this reason, people use mono amps for bass. There is also things like dampening factor of an amp to consider .... higher the number the additional control over the speaker. For this reason, people use one speaker on one amplifier channel--better speaker control. Sub amps will usually have more distortion in them because it is more difficult for most people to hear the difference. Hence the reason that class D amps are popular. You sacrifice that distortion (which is hard to hear) for a big increase in effiency. Your amp is small and puts out more than the equivelant class A or A/B. In case you are wondering the classes are just a reflection of the design of the output stage transistors.