Experienced installers please.I have a question about ohm/resistance on a older model amp.RF Punch 200x2?

Question

First let me start by telling you what Im running.Initially I was running a rockford punch 200x2(dsm) transana with 2 OLD school punch 12's.The 12's are the older series aound early 90's.They are only 100 watts nominal/Rms and 4 ohms each.I was running a 12 to each channel.Being that these particular subs are NOT very loud,I decided to add a 3rd 12 that I had lying around.This sub is a polk audio around 300 watts rms(i think) and also 4 ohms.

Ok,I am running all 3 subs in what I call "tri-mode".Which is 1 12" on each channel at 4 ohms and 1 12"(The polk) Bridged at 4 ohms at the same time.It actually sounded really nice.

However,for reasons unknown (because it happened when My girlfriend was driving/listening)one sub was overheated and on the verge of blowing.My girlfriend said she was jamming out real loud and began to smell something burning.Every since then,it sounds weak.

My guess is she was clipping the amp at an extreme level and was unable to hear it due 2 the polks bass

Answer 1

im not completely familiar with "tri mode" but you do realize that

the channel with the 2 ohm load will draw more power than the channel at the 4 ohm load....... possibly causing cancellation issues as well as the amp getting extra hot extra fast...ive experimented in ways like this myself and found that the best way to improve the performance of your audio system if youre not satisfied with it is to sell the old one and spend more money on what you need......and even though thats a rockford amp i just dont see a 400 watts amp(if its bridged) taking on 3 12s effeciently...im not saying im right im just saying thats what my experience tells me...im not a pro installer but ive learned a lot from painful hours of trial and error

Answer 2

I may have read it wrong but the Polk was the one that overheated and you have the two Rockfords right?  Or was it that one of the Rockfords that overheated?

I would run one punch on each channel.  Then I would take the JBL and wire it to a 8 ohm load then bridge it.  However, you would want to be a little careful on the gain still because the JBL may be overpowered a little bit.

If one of the Punchs overheated and you have the Polk left then I would try wiring the Punch on one channel.  Then take the JBL and run a single voice coil on another channel.  Then both channels are at 4 ohms.  Finally take the Polk and bridge it.  

Edit:  I read below and saw that you did say that you have the Polk still so it was one of the Punchs that overheated.  So, like I said above, would just run a single voice coil on that JBL.  Since the power handling is 180w you won't need to worry about it overheating.  

Both channels would have to be the same impedance for the tri-mode to work effectively.  

Good luck with your setup.  I'm sure your going to have one wierd box in your car with three different subs, lol.

Answer 3

Old school Fosgate ... got to like those "cheater" amps of its time, particularly @ competitions.

Tri-mode, Ch1 & Ch2 have to be ran at the same impedance.  As you already pointed out, that's not an issue if you run the amp in stereo mode as each of the channels have independent gain adjustments.  There isn't an issue if you run two 4-ohm subs on Ch 1/2 and run the JBL bridged at 2 ohm.  As you know, the DSM amps are plenty capable of it.

Edit: I misread it too ... One of the Fosgate subs blew and so now there's a Polk, JBL & the old school Fosgate sub in the equation.  I definitely now see your dilemna because your highest power handling sub's impedance (Polk) is 4 ohm (which you will use in bridged mode) and the two subs (JBL/Punch) you want to run off Ch 1/2 have mismatched impedances.

Answer 4

Wow.. Umm. That smell is a burning amp. Now. This is probably the first time I've heard of this, but hey.. It happens. You can't run one sub per channel AND bridge another sub into 2-channel amp. The amp will see the ohm loads and say "Wtf?!" So. I don't think you mentioned the coil configuration so I'll quickly explain it.

One 4-Ohm Single Voice Coil sub = 4-Ohms

Two 4-Ohm Single Voice Coil subs = 2- or 8-Ohms

One 4-Ohm Dual Voice Coil sub = 2- or 8-Ohms

Two 4-Ohm Dual Voice Coil subs = 1- or 4-Ohms

Three 4-Ohm Single Voice Coil subs = 1.34- or 12-Ohms

Three 4-Ohm Dual Voice Coil subs = 2.67- or 6-Ohms

Don't try to tangle a bunch of different model/size woofers together. I recommend finding your amps Watt @ Ohm load rating and use the small chart I wrote above to wire them correctly. Remember, adding more speakers don't give you more bass. The amp can only divide the power equally to each speaker that's connected to it. Hope that saves a few coils and amps for you.