Stereo amplifier question..

[NW-ZJ-SCOTT]

first of all, Im not sure this is the right section to post this.


Alright, i have two 10" cvr subwoofers in one of the jeeps, and powering them is a cheap cheap Dual 300w 2ch amp.

The problem i am having is the bass fades, the amp seems to have a mind of its own. in one song, it can go from sounding "alright" to all of a sudden its trying to hard and the subs sound maxed out. and then it will fade and the subs are hardly there. very faint bass

I suspect the amp is too small for these 10" DVC subs. I was just looking for opinions.:confused1

 

[GrimmJeeper]

2 questions, and a guess at whats happening for each.

1.) is it during the same song? if so you may need a capacitor because the amp is starving for power. either that or the wiring is too small to get enough power to the amp. those CVR subs pull alot of juice that's why they sound so good, especially if they are the DVC models. I've had em in 10s, 12s, and 15s and they are my favorite speakers by far.

2.) is it from song to song? like one song hits hard, and the next doesnt? if so are these downloaded MP3's? how compressed they are and what the bitrate is greatly effects the bass and highs. if you think of an audio waveform as something like this:

v^v^v^v^v^v^

the mp3 compression chops the top of the highs and the bottom of the lows to make the file smaller. the more compressed it is the more audio quality you lose.. its usually most noticeable on deep bass because there is nothing there anymore for the amp to boost up.

hope this helps.

 

[NW-ZJ-SCOTT]

1: Yes same song. every song. bass fade's in and out.

amp wire is 4ga from batteyr back to a block. where my 4ch amp and the 2ch amp each get 8ga. with 8ga Ground.

my 4channel is a very light duty amp.. I think its 400watt max.. so 50x4 RMS iirc

the speaker wire going from the amp to the subs is 16gauge. Not huge but should handle the subs IMO..

I have the subs wired in parallel down to 4ohms according to the wiring schematic on kickers website. Im going to try to re-wire them in series.

 

[GrimmJeeper]

are they dual voice coil subs? your amp just might not be able to handle two subs, try disconnecting one of them and see if it still happens. 4g should be more than enough so i doubt you're having power draw problems, unless your ground is faulty. Sorry I can't be of more help.

 

[r33pwrd]

what ohm rating is the amp and subs?

 

[NW-ZJ-SCOTT]

They are 8ohm DVC. I have them wired identical to this

 

[GrimmJeeper]

That should work, but wiring them in series is going to pull twice the load from your amplifier. what is the model number of your amp? putting too much of a load on it could damage it.

 

[kastein]

Wiring them in series will make for more resistance/impedance, which could either increase the load on the amp or decrease it depending on what impedance load it was designed for. What does the back panel + spec sheet for your amp say it was intended to drive?

 

[djblade311]

are you able to test this amp using mid range speakers? if the midrange since they use less power, if they fade as well, then something is happening between the line out and your amp. If they dont fade, then its likely a power draw issue.

What gauge power wire and ground are you using?

I'd recommend a different amp honestly

 

[r33pwrd]

so your only running the amp at 4ohms? Do you know what the raiting on the amp is? it should say 300 watts @ X ohms...

 

[FlexdXJ]

How long is your ground? Keep it under 18". Thats doesn't sound like your problem though. Are your lights dimming when the bass hits?

 

[camarors8992]

Are your lights dimming when the bass hits?

Dual 300w 2ch amp.

Doubt it.

 

[NW-ZJ-SCOTT]

No power draw issues, the power and ground wires are 8GA and the ground wires are about 12" long

After reading the specs on the amp i think its got to go, this amp would be better for some cheap 6.9''s rather then two DVC subs.
General:

• <LI id=rrli15 type=circle>PWM MOSFET power supply <LI id=rrli16 type=circle>2 Ohm stable stereo operation <LI id=rrli17 type=circle>Class A/B output design <LI id=rrli18 type=circle>Stereo/bridged simultaneous operation <LI id=rrli19 type=circle>Bridgeable operation <LI id=rrli20 type=circle>Extruded aluminum heatsink <LI id=rrli21 type=circle>Barrier strip connection terminals <LI id=rrli22 type=circle>Side mounted controls <LI id=rrli23 type=circle>Auto-reset speaker short circuit protection <LI id=rrli24 type=circle>Speaker short circuit protection <LI id=rrli25 type=circle>Reverse polarity protection <LI id=rrli26 type=circle>Bi-color LED status indicator
  Power Output: <LI id=rrli35 type=circle>4 ohms at < 1% THD+N: 50w x 2 RMS <LI id=rrli36 type=circle>2 ohms at < 1% THD+N: 75w x 2 RMS <LI id=rrli37 type=circle>4 ohms bridged at < 1% THD+N: 150w x 1 RMS
• Dynamic power: 300w

 

[GrimmJeeper]

No power draw issues, the power and ground wires are 8GA and the ground wires are about 12" long

After reading the specs on the amp i think its got to go, this amp would be better for some cheap 6.9''s rather then two DVC subs.
General:
PWM MOSFET power supply
2 Ohm stable stereo operation
Class A/B output design
Stereo/bridged simultaneous operation
Bridgeable operation
Extruded aluminum heatsink
Barrier strip connection terminals
Side mounted controls
Auto-reset speaker short circuit protection
Speaker short circuit protection
Reverse polarity protection
Bi-color LED status indicator
Power Output:
4 ohms at < 1% THD+N: 50w x 2 RMS
2 ohms at < 1% THD+N: 75w x 2 RMS
4 ohms bridged at < 1% THD+N: 150w x 1 RMS
[*]Dynamic power: 300w

Fixed for readability.

The amp is your problem. if you are running it as a 2 channel (one output powering each speaker) you are only pushing 50 watts to the subs, they are starving for power that the amp cannot give. if you are running them bridged the amp is still not really pushing them at all, those subs need at least 300 RMS to get em moving good. like i said in an earlier post the bass is fading because the speakers are pulling more juice than the amp has to give.

I would pick up a mid grade hifonics amp, something around 500w should push those 10s nicely. remember its all about the RMS, the max power that they try to show off is BS you will never see that wattage.

 

[NW-ZJ-SCOTT]

the max power that they try to show off is BS you will never see that wattage.

Completely agree. I have always known to check the RMS at the same OHM you plan to run. for some reason i seen 300w on the box and remembered they sounded great with my MTX amp that was rated at 270w. didnt cross my mind that the MTX was a better quality amp and was actually Under rated, alot of people said it was closer to 350rms bridged at 4ohm.

Ordered a new amp, another cheapy off Ebay but this one is rated at alot better power.

NEW amp
2 x 200W Rms @ 4 ohm Stereo
2 x 300W Rms @ 2 ohm Stereo
1 x 600W RMS @ 4 ohm bridged
1 x 800W Max @ 4 OHM Bridged

Rather have just a hair "too much" and be able to turn it down, rather then not enough and have it all turned to max.. (witch sounded like crap and the dual would power-trip)

 

[GrimmJeeper]

those speakers will take a lot of abuse, part of why i liked em so much. i had my 15s get so hot a few times that the car smelled like burning electronics for a day or so haha. they still sounded great though. i love the bigger subs because they hit loud but still punch hard like the 10s do. I had a hifonics 1000w amp running each of 2 15s and it was crazy loud.

sounds like you've got it worked out, should be good to go now. what brand of amp? you have to be careful about cheap stuff... not only because they may over state the ratings, but because the circuits in the amp may just be whatever they pulled off the overstock shelf. they could be more than what they are rated at as well.