sub problem

I have installed a 15"sub(SWR-1541D Alpine) and mono amp(MRD-M300 Alpine).I set up amplifier the way Alpine recomends(from Alpine's site PDF file"Maximize the output of your MRD-M300/MRD-M500") and now even at low volume it seems that it's playing with "distortion".I know that Alpine recomends MRD-M500 amp instead of MRD-M300 but i cant through many awayi have already bought MRD-M300.I don't know what's wrong.May be you guys know any different settings for this amp.or something else what could be a problem or may be ....i don't know what to think of.I checked all wires....they seem all right..i do not know what to think of.May be something wrong with a sub or amp????????They both new.Any ideas plz... Thank you

Do you have any X overs? Are you using a stock or aftermarket head? Also what kind of enclosure and what's the volume?

The head unit is a Sony CDX-M730 , no X overs( i am runing another amp for my components and 6 x 9 (MRV-F340 Alpine amp 4ch),enclosure is sealed volume is 1.4-1.45 cu.ft Are you using a stock or aftermarket head? i do not know how to answer this because i do not understand the difference betwen stock and aftermarket.......sory. i only can listen musik at low volume to get clear base but 15" sub must hold 500 RMS and 1500 peak my amp only 200 RMS   everything is new HU amps and sub and speakers is it enough info ....if not ask something else plz

Stock means that you have the original factory radio that came with the car. Aftermarket means that you have upgraded to a better head unit such as you have done. As far as the distortion goes hard to figure out with out seeing you car. But you might want to check your ground. Were did you ground your amp? Is it grounded to clean bare metal? Also on the MRD-M300 what size power and ground cables do you have? Also I know the bass is distorted but is it loud? Let me know all this so I can try to further assist you.

The graund is on a clean metal ,the wires on a MRD-M300 is 8gauge(Both the same ground and power and separate power wires to amps) ,the bass is loud but distorted but not loud "to become a deaf" but i am 99% sure that this amp and sub could play much better The car is a new 2002 A-Class 170 CDI mercedes and distortion is from a sub not from a car parts.Once again thank you very much bberman1 for your help i hope eventualy we find the course of this problem

try turning the gains down on the amp...the amp could be working too hard and throwing out distortion like mad, thus creating your problem... sometimes "optimum" isnt what is really optimum for your setup...there is no magical way to do one thing that makes it perfect in all situations...

Might want to change out the RCA cable and see what happens. It could also be the enclosure might want to try a 2.5 cu/ft enclosure the larger the enclosure the cleaner it will sound.

correct bberman, and the less power it takes as well...when you make an enclosure larger, you decrease the subs power handling capabilities...

Roman I have plenty of experience in this and have had cars with the same problem as you because of bad grounds. So when you say "distortion is from a sub not from a car parts." That’s not true If have a crappy ground connection. Then your amp will not be getting the clean power it should thus creating distortion. So yes car parts do have to do with distortion.

I forget to mention that i had enclosure 1.8 before..and believe me it was absolutely no changes but 2.5 it's too big fo my little mercthe gain switch is on 12 ( it has 18,12,6 and 0 db adjustments..... so how you can see the amp is not working too hard) Low pass filter is on 80 Hz, Subsonic filter is on 25 Hz, Parametric Eq is on 50 Hz, Width is 1, Level is 10 db, Bass compensation is on "on" maybe this settings no good ? Any suggestions on a different setup? Does someone know where i can learn about frequency because i do not understand them for example in the set up file it says:"Warning: Since it is possible to overlap the subsonic and low-pass filters, you may create a condition where amp will produce little or no output. Make sure that the subsonic filter frequency is significantly lower than the low-pass filter frequency, unless you have a very specific performance goal in mind".I understand what they meen but i am not very clear about it or another example:"Set the width (Q) to affect the desired frequency range around the center frequency. For example, if you would like to boost frequencies between 45-75Hz, the bandwidth is 30Hz, which corresponds to Q=2 if the center frequency is 60Hz. Just keep in mind that higher Q is more narrow, and lower Q is wider. If an overall subwoofer level increase is required, it is advised to set the P.EQ to its widest setting (Q=1 for M300, Q = 0.5 for M500). 4-4 Adjust the level as needed for either boost or cut. Please note that it may be necessary to go back and re-adjust other settings such as input level at this point, depending on your tuning goal."I want to learn about overlaping,boost or cut e.t.c......and sory for my bad english RCA's goldplated and quite thick..... maybe this Alpine's sub not good enough?I did not hear it anywhere to compare .At low volume it's quite good Does someone know how can this sub play? Thank you again.