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best rockford fosgate amp for oem sub

6K views 34 replies 10 participants last post by  EdwardChen 
#1 · (Edited)
I'm installing the oem ex sub in my 03 dx. I want the amp to fit where the stock amp goes. What is the best rf amp for this? What is the stock sub rated? Peak and rms. What are the measurements of the stock amp? Thanks!
 
#3 ·
#4 ·
I dont believe a 5 channel amp exists that will fit in the stock location of the OEM amp but I could be wrong. To up the wattage on the OEM sub will end in a blown sub. Ditch the OEM sub and dont even try and mess with the amp, go aftermarket. What seems expensive, around $200, right now will be well worth the cost in the long run. How much time do you spend in the E listening to the stereo? Its possibly the best investment one can make to a vehicle is a decent sound system.
 
#5 ·
Hey Rob,

The Rockford is actually just a single-channel amp for subs alone - the wattage is definitely high for the stock sub, and I know the OEM sub is pretty wimpy so I'll have to dial it down to keep from blowing the thing! My biggest issue was cost in combination with space, though - I really didn't want anything taking up cargo space in the back (considered an Infinity Basslink, but that's as far as I went) and a Stealthbox was $500+. As it stands the Rockford cost me around $125 on Amazon, the OEM sub $65 on Ebay, and it'll just be the cost of the install on top of that. I'm spending that money with full knowledge it's not gonna be a killer system, though. For what it's worth, I've already upgraded the head unit and put Polks in the doors that I'm really happy with.

I really just wanted a little bit more bass up front without having to sacrifice any space in the rear and without dropping several hundred bucks. I couldn't really come up with any other solutions that fit those criteria. Is there anything else you might suggest for the OP or others who are going this route, though? From seeing your posts I know you know your stuff as far as audio goes - so any suggestions you have appreciated!

Thanks...
 
#6 ·
The Fosgate amp is very close in size to the OEM, and could very well fit in its location; however the Fosgate PBRs run very hot and I would not put it in such a cramped location.
It will easily fit under a front seat and have plenty of air to keep its temps under control, and will be invisible if put under the front of the seats (where slide adjuster is).

The 300.1 isn't a bad match for the oem sub, it's a sizable jump from 45w but with the gain level kept conservative it should perform a decent bit better than on the OEM amp.

I do think that amplifying the fronts with a 4ch would provide better bass considering you are amplifying 4 more capable 6.5's instead of just the one stocker in an enclosure. The PBR300.4 is the same size as the 300.1, and at 75w rms x 4 it's a nice little powerhouse.
 
#7 ·
The 300.1 isn't a bad match for the oem sub, it's a sizable jump from 45w but with the gain level kept conservative it should perform a decent bit better than on the OEM amp.

I do think that amplifying the fronts with a 4ch would provide better bass considering you are amplifying 4 more capable 6.5's instead of just the one stocker in an enclosure. The PBR300.4 is the same size as the 300.1, and at 75w rms x 4 it's a nice little powerhouse.
Hey Audiophyle,

I had considered that, but the guys at my local shop seemed to think the OEM sub might be overwhelmed/drowned out by powering the Polks I've got in the front as well which is why I picked up the PBR300x1. I don't have it installed yet, though, and I trust your opinion - are you thinking that wouldn't be the case, and I might be better off with a PBR300x4?

In that case, would it be two channels running to the sub and one each to the R/L front speakers? Also - you'd said "amplifying 4 more capable 6.5's" - did you mean 2 more, i.e. the 2 front speakers?

Thanks...
 
#11 ·
Lorez,

I think Audiophyle is referring to 4 more capable speakers as the 4 6.5" Polk drivers in the doors, each amplified by the amp.

I definitely agree that amplifying your door speakers are a better use of wattage than the sub, although I personally would probably do what you're saying, amplifying the fronts and using the last two channels for the sub.

Either way, the 4 channel amp gives you a lot more flexibility than a mono.
 
#14 ·
I think Audiophyle is referring to 4 more capable speakers as the 4 6.5" Polk drivers in the doors, each amplified by the amp.
Bingo. Got it - my bad, misunderstood his post!

Man, I wish there weren't eight million different ways to set up a system! :twisted:

I've got a decent head unit and door speakers I'm happy with, just wanted a little boost in sound (bass in particular) without dropping a ton of cash or giving up cargo space. I was thinking putting in that RF PBR300x1 and the OEM sub would be the best way to accomplish that, but now you all have me second-guessing things. It seems like the general consensus is that the best bang for my buck would be:

1) Not installing the OEM sub at all and using an RF PBR300x4 to drive all four Polks in the doors
2) Installing the OEM sub and using an RF PBR300x4 with one channel to drive each of the front Polks and two channels to drive the OEM sub

Either way, I wish I could just hear all the options and know what I'll end up with but that's not possible! I appreciate you guys chipping in your input, now just gotta decide which way to go with this thing :?
 
#12 ·
Lol, yes what I mean is amplify the 4 new speakers in lieu of amplifying the sub.
Yes they will very easily overshadow the oem sub, which is the point ;-)
You would have 4 6.5" speakers vs 1 6.5" speaker playing much louder bass, because the Polks will play louder & lower than the OEM sub when amplified at 75w rms.

I think the big hangup is the fact its designated as a "subwoofer" and have a ported box people tend to forget its still only a 6.5". It will not play super low bass, and if you compare the oem sub to a polk 6.5" the sub will win because it has an enclosure (which makes a big difference) BUT if you compare that oem sub to FOUR Polk 6.5's, it has no chance in hell of competing. So you could replace the OEM sub by amplifying the other speakers and get more bass from the Polks than you can from the oem sub with more power.

You could also run the 4ch to the fronts & the rears to the sub like you mentioned, and isnt a terrible idea either. The 4ch amp cannot be bridged, but neither than the OEM amp. You would hook each rear channel to each of the sub's voice coils just like the OEM setup was done, and then run a summed (mono) signal into the amp's rear inputs.
That would actually get you the same power to the sub as the 300.1 (75w x2 vs 150w x1) but would also get more bass & volume out of the fronts by amping them with the other 2 75w channels. The rears wont be very loud, but they dont do anything anyway. (who cares about rear passengers, they can hear the fronts just fine too)
 
#13 ·
What he said, the 6.5" sub is the same size as the door speakers, Mikes mod or not, there is no getting around that. Decent proper powered aftermarket door speakers will deem the wimpy OEM sub useless. Think of it as in old days terms where thin paper speakers were replaced with a good pair of 6x9's and it blew the doors off.

With the work on my own system and keeping the factory sub enclosure with an upgraded 6.5" sub receiving proper power, its still washed out by the proper door speakers even with the pair of 10" woofers stealth mounted in the spare tire cavity turned off. After all that work to get the 6.5" upgraded and running, I now know for fact it was a waste of time and money.

If your not looking for serious bass, invest in capable door speakers and an amp to power them and a head unit that will get the signal to the speakers that pleases your ear. In the end, for many thats the end goal. Some sealing of the cabin, dampening of the panels and such is a great way to improve the sound as well.

I hate seeing people invest time and money in a system then doing it again and again. A good friend did this for decades until realizing he was being stubborn. We set him up with a proper system, he was ecstatic, then he sold the car to lease an Audi, with a factory system. He gave up at that moment with upgrades, lol.
 
#15 ·
Being that this thread got way off topic, let get it back on topic.
I'm installing the oem ex sub in my 03 dx. I want the amp to fit where the stock amp goes. What is the best rf amp for this? What is the stock sub rated? Peak and rms. What are the measurements of the stock amp? Thanks!
 
#17 ·
The Fosgate amp is very close in size to the OEM, and could very well fit in its location; however the Fosgate PBRs run very hot and I would not put it in such a cramped location.
Way off topic? Your question had been answered and the thread progressed onward. The PBR300.1 is their smallest option, it is VERY close in size to the OEM, but use in OEM location at your own risk. (again, they run hot)

The OEM sub doesnt really have a published power rating, nor does a power rating even really mean anything anyway. The OEM amp pushes around 22w rms to each voice coil, so roughly a 45w rms sub? You will be hard pressed to find a replacment amp that pushes less than that, so just get the smallest amp you can & call it a day.



Now to get back to the "off topic"
LoRezSkyline get the 300.4 & you will have the most options for testing.
Run it as is with 2ch from the 300.4 on the oem sub & the others off the deck (2ch unused on amp). That will be the same as if you had the 300.1 hooked up to it.
Then hook the fronts to the 300.4 so fronts & sub are amp'd.
Then unhook sub & just run all four speakers off the 300.4 and note all changes in the sound. Pick the best result you saw & report back to everyone on here.
 
#20 ·
As I am in the process of doing an audio system upgrade, I can attest to the futility of trying to add power to the stock sub.

I recently installed a RF R600-5 amp, and I had to disconnect the wires to my four aftermarket door speakers to detect the output from the sub. As stated above, four powered aftermarket door speakers simply overpower the output of the stock sub.

At this point I am looking at other options for some extra bass. I really like the idea and placement of the stealthbox but a 500W woofer under the dash seems like a recipe for vibrations, oh, and it's $500 :shock:

At this point I'll entertain any suggestions.
 
#23 ·
It did seem like an unusually low output from the factory subwoofer (after I added power). I initially wired it at 8 ohms to keep the power down, but I tried a 4 ohm load (breifly running 1 voice coil) and tried it a 2 ohms. It didn't seem to make much difference.

Honestly I think the factory sub was more noticable (louder) running off the factory amp, but its really hard to say after all of the door speakers came to life, and not knowing the frequency response of the factory sub perhaps I had the LPF too low.

I am admittedly green at all of this, and the E is my "practice" vehicle so that one day I can do it all right the first time on my TL. I was trying to keep the price down so I grabbed that "entry level" amp instead of the one I really wanted (the RF 1000W 5 ch), but now I've done gone an ordered a single enclosed 10" sub. :roll:

At this point I'll hope that the sub I got will liven up the low end.

Thanks to both of you for your many great posts on the forum that have gotten me to where I am. :food004:
 
#25 ·
Where'd u put the P300 at? I contacted RF and they said I could install it in the stock location, if it fits and if the sub is not lower then 2 ohm, it will work just fine. I don't want to have to do any cutting or rerunning any wires. Stock location would be ideal for me. You have any pics of the install?
 
#27 ·
The PBR300x4 and the PBR300x1 are the exact same size.

If you run the rear left to one sub voice coil & the rear right to the other voice coil, you will get the same amount of power to the sub as the mono amp would, you would be pushing the channels at only 4 ohm each, AND you would have 2 extra channels for powering the fronts.

The 300x1 does not have better cooling.

The 300x1, 300x2, and 300x4 are all the exact same size. The 500x1 is the same width & height, but a couple inches longer.
 
#29 ·
Gotcha, FYI they both have DTM.

Not to mention its really not even a big deal. The point where the transistors contact the amp chassis is always going to be a "hot spot", all RF has done is slip a large pad under the transistors so their foot print is slightly larger (larger diameter hot spot). Between the PBR300x1 & the P300.1 the P300.1 will have much better cooling because its larger (more chassis = more surface area = greater potential for thermal transfer) and is a much more efficient design (class D, and not being over driven by digitally boosted power supply).

PBR300x1 will run very hot to the touch, and this is the sacrifice for its tiny size.
 
#33 · (Edited)
rs pbr300 sub connection question

I am going to resurrect this thread with a question about the dual coil sub and the rf pbr300. I recently upgraded the stock stereo in my EX with an aftermarket and did the bypass kit. I am going to purchase a pbr 300 for under the seat and hook up the stock sub. I have never hooked up a dual coil before, and this is prob a stupid question so be gentle. Others on the forum have installed the rf pbr300x1 1 channel amp which is rated 75w at 4 Ohm. The rf pbr 300x2 2 channel amp is about the same price and is rated 2x100w at 4Ohm. Wouldn't connecting one of the channels of the 2 channel amp to the sub in parallel be a better option than the 1 channel amp for the same price? It also says it can be bridged at 300w. only thing it doesn't have is a low pass crossover.
 
#34 · (Edited)
I am going to resurrect this thread with a question about the dual coil sub and the rf pbr300. I recently upgraded the stock stereo in my EX with an aftermarket and did the bypass kit. I am going to purchase a pbr 300 for under the seat and hook up the stock sub. I have never hooked up a dual coil before, and this is prob a stupid question so be gentle. Others on the forum have installed the rf pbr300x1 1 channel amp which is rated 75w at 4 Ohm. The rf pbr 300x2 2 channel amp is about the same price and is rated 2x100w at 4Ohm. Wouldn't connecting one of the channels of the 2 channel amp to the sub in parallel be a better option than the 1 channel amp for the same price? It also says it can be bridged at 300w. only thing it doesn't have is a low pass crossover.
What is the resistance of each coil of the sub?
You don't want to send a stereo signal to a single dual voice coil speaker.
 
#35 ·
In general, assuming your two voice coils together (however you wire it up) ends up at the same 4 ohms, you'd be fine to use the 2 channel amp and just use one of the channels vs. a single channel amp.

We can help you more with the wiring of the sub if you tell us what it is and what the impedance the coils are.
 
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