2 ohm - 4 channel amp - driving one DVC sub

 

cold in MN
Unregistered guest
i have an OLD 150x4 amp that says its 2 ohm stable and has some sort of built in crossover for some of the channels. I would like to hook this amp up to my new 8" sub. The sub is 200W RMS/ 400W peak. dual voic channel. http://www.cardomain.com/item/POLMM2084DVC

the problem is is that i don't know exactly how to hook up all four channels to this sub. or even if i should. i've looked for this confiuration online everywhere and can't find an exact match.

i know channels 1 and 2 on the amp can be bridged for one voice channel on the sub, but can i run channels 3 and 4 bridged into the other Voice Channel on the amp?

any help is appreciated!


 

Gold Member
Username: Carguy

Post Number: 1445
Registered: Nov-04
Yes you can. Bridge channels 3 and 4 for your 2nd voice coil.
Make very certain that you do not send "stereo" signal to the amp. Mono out the rca input terminals. If the voice coils receive 2 different signals from the amp, it will cause damage to the coils. The speaker has to move in same direction always. This is why it's never a good idea to power each voice coils separately.
 

cold in MN
Unregistered guest
that makes sense.... but how do i mono out the rca's? (bare with me, it's been years since i've done any of this car stereo stuff)

FYI, the amp has two low inputsbut they both have a switch that says "bridged - MO / ST" is that what you are talking about?

here's a pic of the amp.
http://www.pbase.com/levidickie/image/39596897
and
http://www.pbase.com/levidickie/image/39596898


BTW, i am pulling the signal from the line-out off my other amp running the front and rear speakers.
 

Gold Member
Username: Carguy

Post Number: 1464
Registered: Nov-04
Okay, it looks like the switch is there for mono and stereo mode. Set it to mono on both channels (1&2, 3&4). Then using a Y splitter, connect to both channels. You are trying to supply the same signal to both 1&2 and 3&4 rca plugs so that voice coils will move in same direction.
So you're basically going from one rca to 2 rca ends for your 4 channel amp.
 

cold in MN
Unregistered guest
sweet.
thanks, i'll give that a shot.

oh! one more question... it appears that only channels 3&4 have a built in crossover. what can I or should i do with that?
channels 1&2 only have a level dial, but i'd like to utilize the built-in crossover if possible.

i have an active crossover i could put inline BEFORE this amp, but i'd rather not if i can help it.

thanks again.
 

Gold Member
Username: Carguy

Post Number: 1466
Registered: Nov-04
Your best bet is to test and see if it controls channels 1&2 also. Set the crossover on 3&4 and then connect the sub to 1&2. Next, try the other channel 3&4. See if the bass is same on both bridged channels. If it is, then the crossover is controlling both. If not, set it to flat. Last thing you want to do is supply uneven signal strength to the voice coils.
On 4 channel amp, it's given that most people would be using 3&4 for rears or subs. That is why it comes with crossover.
 

cold in MN
Unregistered guest
Thanks a lot for your help.

by the way, for future reference, how would I 'mono-out' the RCA's?
 

Gold Member
Username: Carguy

Post Number: 1468
Registered: Nov-04
By using the Y splitter cable. It takes one rca and gives 2. So you connect the one side to HU, and the 2 side to left and right channels of the amp. Or if your amp has a mono/stereo switch, use that.
 

haupty
Unregistered guest
i have a 600w jensen amp x4 channel and i have one kenwood 12" sub. i have the positive on the first channel and the negative on the fourth channel. it hits pretty good for what it is. the sub is only one voice coil though. i have my rca's running of of my pioneer supertuner 3 into y jacks onto the amp so it powers the whole amp. i have the levels all the way up. the bass boost on both bridgable channels (1&2,3&4) and the lpfs all the way down. is there anyway to get anymore pound out of this setup? without turning the deck up . the sub seems to has its most power as hooked up though i may be wrong. i also have the amp set on 2 channel instead of 3 or 4.
 

Gold Member
Username: Carguy

Post Number: 1508
Registered: Nov-04
Your setup doesn't seem right. When you say "Levels", what do you mean? Are you talking about the gain/level control? That one should be set to match your HU's preout voltage.
A 4 channel amp cannot be turned into 1 channel sub amp. According to your post, you mentioned Pos from the first and neg from the forth. That is not correct. You have to bridge in pairs to get 2 channels. So for example, channels 1 & 2 together and 3 & 4 together. Then hookup the subs to them. If you only have 1, then you will have to leave the other pair alone. Do not try and bridge those 2 pairs into one channel.
This might be the reason why you're sub is not pounding that hard.
With proper setup, you should be able to turn up the bass boost and lpf to the frequency you desire.
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