Shribe

iTrader: (1)

I purchased a Camaro with the sealed box pictured. It has two old Rockford Fosgate subs, one says classic on it and has a bigger magnet. I hooked up a little Alpine amp that is:

Alpine MRH-T305 2 Channel Power Amplifier.
Rated 100W bridged, 50W 2 channel.
Low total Harmonic distortion (THD) at .3%.

I wired it positive from amp on one channel to postive on one sub, then neg from that sub to the other positive on the sub, then neg to the other channel neg on the amp which is in series/bridged? I could barely hear it after wiring it up. I put my bazooka back in and hooked it to one channel and it was much louder.

Is the amp too small, do I need a port, or do I need to wire one channel for each sub at 50W? The subs are dual coil, and I had the gain turned all the way up with low pass on. The box is 28 by 14 by 12 with cutouts to fit. Thanks for any ideas.

Gummie

I’ve got a few comments but would like some more information in general.

Here are the specs the internet turned up on your amp:

* 30 Watts X 2 Channel RMS @ 4 ohms 0.08% THD
* 50 Watts X 2 Channel RMS @ 2 ohms 0.3% THD
* 100 Watts Mono (Bridged 1 Channel) RMS @ 4 ohms 0.3% THD

(this is all that really matters for our purposes)

link 1, link 2. Try as I might I couldn't find an actual users manual. Alpine's site only had the 300 and 306.

Your subs are wired correctly in the standard bridging procedure; that is running your subs in series with the amp bridged. The only problem is that depending on the subs’ impedances your amp might not be able to handle the load. I’m guessing that you probably have two 4 ohm woofers, which means that you’re running at a 2 ohm load. This isn’t within amp spec and is thus bad for the amp. Take a multimeter to the box and see what the load being presented to the amp is.

Those subs are pretty old (circa 1992 for the classic series). It's possible that their coils might have corrosion on them that's resisting cone excursion. I know this is the case with a few of the older woofers I have. Push the cones in by hand. You should feel the resistance of the suspension but it shouldn’t feel scratchy or grainy. Here's info on the subs in case you're curious. The classic sub is most likely a PCH-410 (assuming it's a 10"). I’m guessing that the other sub is just your standard series 1 punch. There's also the possiblity that one of the subs might be blown but is still allowing for some current to flow through its coil. Since you already have a multimeter out check each sub to make sure that everything's ok.

It’s generally not recommended to mix two or more different subs. It throws off response and especially isn’t a good idea if the box is a common chamber design.

Are those holes where the wires go into your box sealed? That's not your problem but it's not helping either.

Also, the subs are not dual coil. The classic at least (since I was able to ID it) was made well before the option was available.

For kicks and giggles try hooking up just the classic series sub to both channels bridged and see what it sounds like.

Shribe

iTrader: (1)

Gummie, thanks for you response, it is very helpful. The subs seem to be in good shape as far as the cones, they do not scratch. The holes are not sealed, I thought that could be a problem. I will try this weekend to check the ohm and also try to hook up the one sub.

Shribe

iTrader: (1)

Gummie, thanks for you response, it is very helpful. The subs seem to be in good shape as far as the cones, they do not scratch. The holes are not sealed, I thought that could be a problem. I will try this weekend to check the ohm and also try to hook up the one sub.

Gummie

Not a problem. Be sure to keep us updated on your progress

RookieCamaro

I had a problem like this with my amp/sub combo when swithing to better subs. Aparently, my amp has a high output plug section and low output section, and when both of my plugs are into both sections , i get a crappy bass. when i only have one plug in either one of the sections ,i get a good base

ApexAnalog

It is generally not a good idea to wire two separate woofers in series, especially if they are different types. Wiring two subs in series sums their impedences and introduces intermodulation distortion. Dual Voice Coil is an exception because the two coils share a cone, but it is still good to send both coils an identical signal to get the best quality.

Two Subwoofers, 4 ohms each

In Series --> 8 ohms
In Parallel --> 2 ohms

As long as your amp can handle the low impedence, your subs will sound better run in parallel.