amp added, bass nearly gone

danger boy

quick rundown on what i did last week.

I replaced my Pioneer HU with a new 2006 model Pioneer DEH-4800MP HU. Cool.

Added a 4ch Alpine MRP-F250 amp. (40wX4) tiny i know.

had them replace all the wires.... power and speaker/interconnects. 16 guage i think.

I am running older 5x7's in the rear... Polk EX357. and stock in the fronts till i can find someone locally who sells Polks around here. It's tough man.

So i calibrated the crossover in the amp and levels as best I could. I know the EX357's can't handle alot of bass.. but once i added the amp... now nearly all my bass is gone. Before when they were running off the old HU, the bass was better.. albiet, easily clipped.

So now i can't fingure out how to get some of the bass back other than to add a subwoofer. But truely, i know the EX357's can produce some bass.. they sound like only the tweeters are working now. I mean, the bass is only about 20% of what it used to be.

Very odd.

Ok next ?. Which subwoofer would you all recommend and amp too. I'm not looking for intense volume, just enough bass to add to the music I listen to.

If i add say a Polk MM2104 what amp would drive that? I have pre outs on my HU and Alpine amp for it.

Dennis Gardner

I would say that your high pass crossover setting on your new HU is set wrong. It has a two way crossover built in it since it has sub outputs.

You have settings for this HP crossover that limits bass to all 4 channels at 50/63/80/100/125Hz. Without a sub, you should have the sub setting turned off to run full range or at least set the crossover to the lower settings to give more bass.

exalted512

Check your high pass filters on your amplifier first. See where the frequency is set at. I'm not 100% familiar with that amp, but on some really small amps theres not a frequency cut off, just a high, low, or full pass(all pass). If thats the case, turn it to all pass and adjust the frequency from the head unit.
-Cody

danger boy

Yeah i tried the HU settings first... and basically got nowhere. so just today I tweaked the crossover and output settings on the amp itself. that made the difference right there.

Before the volume was to loud on the fronts. Now i backed them off some, and lowered the crossover in the rear EX357's. and that helped the bass response quite a bit. A subwoofer is needed for sure.. but till then, i can now live with this for a while for sure.

Thanks for the help guys. here are a few pics. not to impressive i know. but i love posting pics. ha ha.

Ok, just thought of a question about adding a subwoofer down the road. Would the subwoofer be hooked up from the two pre out on this ALpine amp.. or would a subwoofer amp have to be connected from the HU pre outs?

exalted512

The 4800 I believe has sub controls on the head unit(frequency and level) so it would be more beneficial to connect it the preouts on the back of the radio
-Cody

MacLeod

That is a great amp Al. I had one for well over a year. Yeah it aint the most powerful in the world but it was cheap, well made, small and made good clean power. What more could ya ask for?

disneyjoe7

Lack of bass could be a speaker phasing problem. Where a bass note one speaker moves out the other one move in, canceling the bass note. Recheck output connections to amp and speaker where Pos + is Pos+ / Neg - is Neg -.

danger boy

good idea Steve. I do notice now that i have an amp.. each speaker doesn't blend as well. The speakers are in their stock location. Two 5x7's on the rear deck and two 5x7's in the doors.

The balance seems off for some reason.. meaning when in the drivers seat.. i hear more of the left rear speaker than anything. Very odd.

danger boy

MacLeod wrote:

That is a great amp Al. I had one for well over a year. Yeah it aint the most powerful in the world but it was cheap, well made, small and made good clean power. What more could ya ask for?

Agreed.. it's small. But so far sounds pretty good. I'm thinking when i get the time to add a subwoofer.. i'd like to get another Apline mono amp that looks just like this one. The "twins" will rock the car.

MacLeod

They had one. Their V Power line got a complete makeover this year and dont look anything like the old ones.

Im sure you can find one of the old ones on Ebay.


In fact, here is one now!
http://cgi.ebay.com/Alpine-MRP-M350-V-Power-Mono-Amplifier-05-AMP-350-WATTS_W0QQitemZ250049787004QQihZ015QQcategoryZ18797QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

danger boy

MacLeod wrote:

They had one. Their V Power line got a complete makeover this year and dont look anything like the old ones.

Im sure you can find one of the old ones on Ebay.


In fact, here is one now!
http://cgi.ebay.com/Alpine-MRP-M350-V-Power-Mono-Amplifier-05-AMP-350-WATTS_W0QQitemZ250049787004QQihZ015QQcategoryZ18797QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

cool thanks. is that the same as the one i have in my car, except it's mono or is mine the newer model?

What's the dif between A, B and D class amp?

MacLeod

Its the same series as yours. In the V Power linup they had a 50x2, a 40x4 and then the 350x1 mono amp.

The one you have is a Class A/B. Theyre not as effecient as a Class D but are much cleaner.

The benefit to using a Class D is that they are much more effecient and so they can make a lot of power with not a lot of input voltage, heat or size. However as they tend to have high distortion and dont do well over 200 Hz (unless its a high dollar one like the Xtant 1.1) theyre much better suited for subs.

disneyjoe7

danger boy wrote:

What's the dif between A, B and D ?

Nerd, Geek, Jock.

1996blackmax

There are a few full range class D amps around now.

MacLeod

Yeah, and ironically, Alpine makes em now.

Alpine and Xtant are the only ones I know about.

Id love to have an Xtant 1.1 on each of my speakers but not at $450 a piece!

Ouch!

Their amps are getting stupid expensive!

A couple years ago the 4.4 went for $450. Now its $700!!!!

1996blackmax

Eclipse also makes full range class d's.