I`ve been messing with car audio stuff for years and i know what sounds good but i`m lost when it comes to the math side of things. I`ve even studied electronics at college and know how to use ohms law etc..... but when it comes to audio it`s all different. I need assistance with my amp/sub setup.

The subs in question are made by Mutant. They are in a dual bandpass box, NW10DBP. The amp is from the Alpine V12 range, MRV-T407. What i would like is opinions on how to set it up. Also, a bit of help from you techie guys. Here`s the specs of the subs: (each(obviously))

10 inch
4 Ohm
150W RMS
600W MAX
40oz Magnet
32-800Hz Response
93dB Sensitivity

The specs of the amp are: (i`ve used the 14.4V values here)

RMS Power, 20Hz to 20kHz

Per channel into 4 Ohms 60W, 0.08%THD
Per channel into 2 Ohms 100W 0.3% THD
Bridged into 4 Ohms 200W 0.3%THD

MAX Power

Per channel into 4 Ohms 140W
Bridged into 4 Ohms 400W


Can anyone tell me why they have not stated "per channel into 2 ohms" on the MAX power ratings?

I first tried 1 sub per channel but it hardly made any noise at all. I then tried the subs in parallel and bridged but the amp does not agree with 2 ohm bridged, although it did sound good before it cut out. The setup i`ve settled with is the subs in series and bridged on the amp. But thats 8 ohm!! Surely the power at that impedance is very low!?!?!? But it sounds really good. Not as loud as i would like but the quality is still there.

Can anyone explain this for me?

I`m considering buying another NW10DBP and running 2 ohms per channel. Each pair of subs would share 100W. What do you peeps think of that setup???

bc i dont think there are too many 2 ohm speakers

too many subs,not enough power.
You could just bridge the amp on one speaker (4ohm load)and have the same sound or better than what you have tried so far...Or get a Real amp that is 1 ohm stable:D (that's what you need to parallel your 2 subs)
....you asked;)

run them in a series. this will drop the ohms.

bc i dont think there are too many 2 ohm speakers

I understand there arent many 2ohm subs. It just seems weird to me that they state 2 ohm stereo for RMS but not MAX. Surely if it has an RMS value, it must have a MAX value too?

run them in a series. this will drop the ohms.

I thought parallel reduces impedance and series increases impedance? (ie. two 4ohm subs in parallel=2ohms, and in series=8ohms) Or is it because running the amp bridged, reduces the impedance also? (ie. 8ohms becomes 4ohms, and 4ohms becomes 2ohms etc)

too many subs,not enough power.
You could just bridge the amp on one speaker (4ohm load)and have the same sound or better than what you have tried so far...Or get a Real amp that is 1 ohm stable (that's what you need to parallel your 2 subs)
....you asked

I did indeed ask. And you have given an answer. Thanx. Everyones opinion is greatly appreciated. Thanx for the comments so far guys. Keep em coming!

the best set up would be in parallel that would make the speakers 2ohms. but your problem is your amp is most likely not be stable at that ohm(not designed for subs). the best thing to do with your current system is what eggman said and bridge the one speaker for now. if you want more than that you will need to buy a drffrent amp that is stable at 2 ohms and wire them in parallel.
1/4+1/4=1/2 (2 ohm)

eh, sorry bout that i ment to say paralel. I have no clue what i was thinking.

Ok i shall start looking for a 2ohm stable amp. I`ll use the Alpine to run some 6x9`s. Cheers guys.

One thing that is still bugging me is how the subs sound so good in series. If the bridged rms power @4ohms is 200W, then @8ohms it cant be much. Especially with the subs sharing the power. I`m not sure if it is less or more than running 60W per channel @4ohms. I`ve tried using calculators and converters on many audio based websites, but the figures i come out with just dont look right.

Anyone like to guess what the power would be at 8ohms?

got a jl 500/1 and i love it

a little more tuning then i like but it gives me room to grow

Have decided to keep my Alpine amp and go back to my Rockford Fosgate 18". Not by choice though.

I tried running just one of the subs bridged on the amp. Thats 200W running a 150W sub @ 4ohms. I set the amp at 3/4 gain to make sure i didn`t overrun the sub. It sounded really crisp for about 5 seconds before it stopped working and smoke started drifting out from the port. Completely fried!!:( :( :(

Have decided to keep my Alpine amp and go back to my Rockford Fosgate 18". Not by choice though.

I tried running just one of the subs bridged on the amp. Thats 200W running a 150W sub @ 4ohms. I set the amp at 3/4 gain to make sure i didn`t overrun the sub. It sounded really crisp for about 5 seconds before it stopped working and smoke started drifting out from the port. Completely fried!!:( :( :(


The gain does not control the output(watts)....it matches levels of INPUT.(volts)
Therfore,you were still putting 200 watts on it....technically.Combine that with the fact that your speakers were overrated,and BOOM.:eek2:

Either that or you hooked up something wrong.;)

Someday there will be a universal amp rating system,until then you have to keep the brand the same(or at least quality level).That ensures that the ratings will work together.....i.e. 300w amp with 300 watt speaker.

Good luck with your future installs!
Jay

The gain does not control the output(watts)....it matches levels of INPUT.(volts)
Therfore,you were still putting 200 watts on it....technically.Combine that with the fact that your speakers were overrated,and BOOM.:eek2:

Either that or you hooked up something wrong.;)

Someday there will be a universal amp rating system,until then you have to keep the brand the same(or at least quality level).That ensures that the ratings will work together.....i.e. 300w amp with 300 watt speaker.

Good luck with your future installs!
Jay I have overpowered every speaker I have owned with no blown speakers, for example i run a pair of Dayton RS Mids in my doors rated @80watts and I send them 120. If you learn how to set your gains with a DMM then slightly overpowering will not hurt unless you beat on them for hours and hours. I wouldn't do this with generic speakers though.

The reason speakers normally blow is because of clipping. Automatically setting your gain to 3/4 is ignorant, that's a sure sign of clipping. I have never had my gains up that high on any amp. The gain on my sub amp was about 1/2 way, it was rated @600watts@2-4ohms. It was pushing 700@2ohm before clipping at just over 1/2 way up.

Buy a DMM and Google: Gain Setting Tutorial

Oh and there are lots and lots of 2ohms speakers.

The reason speakers normally blow is because of clipping. Automatically setting your gain to 3/4 is ignorant, that's a sure sign of clipping. I have never had my gains up that high on any amp.

I`ve been running my RF 18" (350W RMS) on the Alpine amp for years. It has followed me through several installs. I have always had the gain turned right up, which is under 0.5V input. Also, +12dB bass boost. If i turn the gain down to match the pre-out volts it just doesn`t kick hard enough. I`ve gone through a 3V, 5V and now 6V pre-out HU and this has been the case for all 3 of them. Although the 5V pre-out was on an Alpine HU which uses the "Bass Engine" circuitry. My amp is compatible with that and sounded better than the others.

The sub is a good 6 years old and it rumbles hour after hour, day after day without a hitch. The amp never gets too hot.

Just referred to the instructions for my amp. They say.....

Input Gain Adjustment Control

Set the input gain knobs to the minimum (4V) position.
Using a loud cassette or preferably a CD as a
source, turn up the head unit volume until it distorts.
Then, reduce the volume 1 step. You can then
increase amplifier gain until the sound from the
speakers becomes distorted.

I can turn my gain all the way up without the sub distorting. This is how i set it up.

I would switch too two 8 ohm subs and wire them paralell. This would result in a 4 ohm impedence and make your amp happy.

Secondly the amp. gain is NOT a volume switch. It is too adjust for varying input voltages from different sources. The higher the voltage the less gain is required for the amp to make rated power. The lower ou run the gain the better off you'll be for several reasons. Every setup I ever installed had the gain less than 1/8th of the way up from minimum. If you have decent voltage from your source, anything over 1/4 isjust myddying the water.

The reason speakers normally blow is because of clipping. Automatically setting your gain to 3/4 is ignorant, that's a sure sign of clipping. I have never had my gains up that high on any amp. The gain on my sub amp was about 1/2 way, it was rated @600watts@2-4ohms. It was pushing 700@2ohm before clipping at just over 1/2 way up.

Buy a DMM and Google: Gain Setting Tutorial


I just did the google thing and read up about gain adjustment. The 3 choices i have is by ear, a DVM, and a scope. I don`t have a scope and my DVM is cheap and therefore, not very accurate. I decided on the by ear method.

Playing a 1KHz signal, i cranked up my HU to 31 before it clipped so i dropped it down to 30. I used that volume to set the gain on the amp. The only issue i had here was that my HU will only allow under 80, 120 or 160Hz to the sub pre-out, so i used a 160Hz sine wave and set the HU`s x-over to 160.

I then turned up the gain until the signal started to clip. This was at about 4/5 of the way so i turned it down to 3/4. Thats it!!! I played through the whole range of frequencies to make sure the system could handle them all, and it did.

I might do the DVM method just to see if the results are anywhere near what they should be.

I just did the google thing and read up about gain adjustment. The 3 choices i have is by ear, a DVM, and a scope. I don`t have a scope and my DVM is cheap and therefore, not very accurate. I decided on the by ear method.

Playing a 1KHz signal, i cranked up my HU to 31 before it clipped so i dropped it down to 30. I used that volume to set the gain on the amp. The only issue i had here was that my HU will only allow under 80, 120 or 160Hz to the sub pre-out, so i used a 160Hz sine wave and set the HU`s x-over to 160.

I then turned up the gain until the signal started to clip. This was at about 4/5 of the way so i turned it down to 3/4. Thats it!!! I played through the whole range of frequencies to make sure the system could handle them all, and it did.

I might do the DVM method just to see if the results are anywhere near what they should be.Here is how you set the gains with a Digital Multimeter(DMM). You can buy one at wal-mart for under 20 bucks.
Disable all crossovers that affect the amp, set your head units settings how you normally listen to them. (bass, treble, eq, ect...) Unhook all speakers at the terminals.Turn the amp's gain to its lowest setting.Turn the H/U up as far as you ever do. Get a 0dbTestone CD. For subs use a 50hz tone, if you use bass boost(this should be set prior to gain adjustment)use a 45hz tone. If its a mid and high amp use a 1khz tone. Now take the desired wattage that your amp produces and multiply it by the final ohm load.(Example: Phoenix Gold Titanium 600.2 Rated 600wattsx1@2-4ohms. Take a single 2ohm DVC sub wired to 4 ohms so it would be would be 600 x 4 = 2400. Now take that number and get the square root of it. sqrt(600*4)=48.9xxxxxxx. Turn the DMM to ACV 200V. Hook the DMM up to the terminals that are going to be used(If its bridged use the bridged terminals). Slowly increase the gain till you reach the desired volts or very close to it, in this case 48.9. Turn the volume back down and reinstall the speakers.

This also applies to setting it by ear instaed of getting desired volts listen for distortion. Although a 1khz tone at full volume is very annoying and depending on your speakers can damage your hearing.. Use a 50hz testone for subs and a 1khz tone for mids and highs.