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SQ on a budget

 

New member
Username: Ab0tj

Post Number: 2
Registered: 02-2004
What would be a good amp to buy (on a budget) that will do about 120Wx4 RMS into 4-ohms to run some Audiobahn mids and tweeters? I'm looking for good SQ here. I saw a (GASP!) Boss amp on eBay that actually looked good. It's an IQ400.4, anybody heard of these? 210x4 RMS and 0.01% THD, 105 dB s/n. Only $140. Now I know Boss has not always had a good reputation, but this one actually looks good. What are your opinions? Is there something else I should get instead?

Thanks
Alex
 

Gold Member
Username: Glasswolf

Post Number: 1197
Registered: 12-2003
you won't find a good amplifier that large for that cheap.
The closest I can suggest is the Kicker KX800.4
~$270 US
100W x 4 @ 4 Ohms
Class-AB

Do you really think you need that much power?
Honestly, audiobahn isn't that good, and probably won't survive that much power in the real world.
CDT would have been a good alternative for less expensive, well-made components.
www.thezeb.com has good prices on CDT, and www.etronics.com has Kicker
 

New member
Username: Ab0tj

Post Number: 5
Registered: 02-2004
Actually these are rated higher than 120, I just figured I probably won't be able to stand it when it's running that much power anyway.
 

Anonymous
 
Hey, glasswolf, i understand a little about what damping is, but could you explain it a little more? I know that 500/1 and 1000/1 has 500 damping. thanks
 

Anonymous
 
another thing, what is the best setting to have th 500/1 LP filter set on for the 10w7? I want to blend the sub with the midbass from my VR525 comps, as best as i can. I have the w7 sitting in the backseat of my mustang with the cone in the middle of the front to seats, so the imaging is outstanding. Also i have the advanced bass control on the amp turned off.
 

Gold Member
Username: Glasswolf

Post Number: 1205
Registered: 12-2003
Boss amps are over-rated, and cheaply made. Those ratings are probably 2 Ohm ratings, or severely inflated, especially if it's a class-AB amp. If it's a MOSFET of Class-T amp, you'll be sacrificing sound quality for power.

Damping Factor:
It's somewhat more technically complex than this but the "damping factor" of an amplifier is usually thought of as an indicator of how "tight" an amplifier will sound when powering large bass speakers.

Here's why:

A speaker is essentially a coil of wire mounted within a magnet. As it moves within the magnet's field of energy, a signal is induced back into the voice coil. This signal is called "Back EMF". It's essentially a voltage that has been generated by the loudspeaker itself. The larger the loudspeaker, the larger the voltage produced.

If this Back EMF is not compensated for properly in the amplifier circuitry the result is an over accentuated or boomy bass sound as the Back EMF signal tries to oppose the signal you actually want (the one from the amplifer).

Good amplifier design allows the amplifier to negate this unwanted signal and thus control the loudspeaker properly resulting in a much "tighter", controlled sound from the loudspeaker.

From a technical stand point, damping factor is a reciprocal of the amplifiers output impedance and output impedance is a derivative of the amount and implementation of negative feedback within the amplifier. Beware datasheets that state damping factor values with qualifying the frequency range. A high damping factor number is only of real use at lower frequencies as high frequency devices produce very little Back EMF.

Properly designed negative feedback not only corrects for Back EMF but also produces other benefits:

Low distortion, low noise and flat frequency response.

you may want to place that 10W7 in the trunk, with the box against the back seats, firing toward the rear of the car. much better resonation that way. having the sub right near you the way you do is actually not good for SQ.
Imaging relates to your components, not really to a sub.
cross the sub over @ about 80Hz.
 

Tim L.
Unregistered guest
you really can't get GOOD sq for THAT cheap.. if it was THAT EASY, then the secret would have been out on that amp and a lot of people would have it..

i agree with the recommendation for the kicker kx800.4..
 

Anonymous
 
you know glasswolf, i had thought that the SQ would not be good having the sub in the backseat like that, but actually it is really great. I had put my ear right near the sub before when it was playing ( at low volumes of course) and it sounded like a$$, but i actually think it sounds better where its at now. granted, there isnt as much resonace in the car, but i had to put it there for now because the ported box its in wont fit in the trunk. eventually i want a sealed box that will fit in the trunk, because im more into SQ. thanks for the help man!
 

New member
Username: Ab0tj

Post Number: 6
Registered: 02-2004
Allrightie, sounds like I'll just run them off the deck for now until I can save some $$$ for a good amp. Thanks, guys. And BTW that was at 4 ohms, not 2, and my friend has a Boss amp that is said to run 4000 watts RMS, and we measured it as 3870 RMS before it started clipping, so not too bad, but that's of course all bass. What I mean to say is I don't think they overrate them I just didn't know about the quality.

Thanks
Alex
 

Tim L.
Unregistered guest
well, you know what? maybe you should just get yourself that boss amp.. we're here to give OPINIONS, and that's all you should take them as.. the BEAUTY and FUN of SYSTEMS is that YOU BUILD THEM!! DARE to BE DIFFERENT!!

if everyone listens to us, EVERYONE is just going to have JL AUDIO this n that, this n that of that, and we'll all just have the SAME freakin systems.. =4

everyone shouldn't wear nike, or drink Coca cola..
 

New member
Username: Ab0tj

Post Number: 9
Registered: 02-2004
jeez, I wasn't trying to offend anyone. Like I said I was asking about SQ not power and I got a good answer from you all.

-Alex-
 

Gold Member
Username: Glasswolf

Post Number: 1209
Registered: 12-2003
you're welcome to try that boss amp out if ya want to of course. I just don't trust tehir reliability. I've seen too many of them fail.

There's a reason teh amps are so cheap, just like there's a reason JL is more expensive, and a reason JL has the good reputation it has.
These reputations are earned over time.

A lot of people seem to be very happy with Boss, and even Legacy, Pyramid, and Sony. If they're happy, then for them, that's all that matters.
I'm just offering my personal views based on experience. As noted above, take it for what it's worth.
If you bought every product I hate, hey, no harm done. It's your car, your system, adn your ears that matter to you in the end.
 

Tim L.
Unregistered guest
^ exactly..

no offenses or ill will alex.. i was just saying that i don't think everyone who asks for advice should just follow any of our opinions as ORDERS.. someTIMes it seems that way.. it's good if people ask because they're curious, but make a decision on their own.. what they like.. look of an amp, this that, whatever.. RESEARCHING products helps..
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