Andre The Giant

I found this amp Rockford Fosgate PBR300X4 which is 75 watts RMS @ 4ohms and was thinking of using this to replace the original booster in the car to drive all main speakers (which I think are original) with this head unit which I already have: JVC Kd-sx980. On top of this I would like to use my 12" subwoofer with it's own amplifier just for extra bass.

Questions:

1- Is this a good amp to use in the restricted space where the booster is ?
2- Since my radio has RCA jacks, should I be using this setup on the amp instead of the high level input of the speakers ( I assume yes )
3- Since I want to keep everything as stock as possible, I will have to use all new wiring, wiring. If I use the existing speakers by taping into the wires, does anyone know the power rating for these original speakers ? (I'm sure it's not too bad since there was an inline booster)
4- Last but not least since the speaker locations and type don't produce much bass response I was thinking of adding that subwoofer with a 150 watts RMS amp. How should this be connected since the head unit doesn't provide a subwoofer entry, would I just tap into the right or left side wires from one set of speakers, or any suggestions ?

It's either I use what I have plus the new amp BPR300x4 or another, or change everything, head unit, new amp for main speakers plus a new subwoofer amp combination which would better match with everything, please advise ?
For the subwoofer, I don't need booming bass, I just need to be able to hit the lower frequencies with a resonating bass and not a thumping bass if we understand each other.

I want to see what are my options. I have gotten used to having a subwoofer with my built in system in my 2011 Ford Edge and boy what a sound. It's not very powerfull all together, but plenty for enjoying some good Pink Floyd (Welcome to the machine) to some techno, yes you heard right techno... LOL

bureau13

In my personal opinion, the best thing you can do for sound with any stock car system is swap out the speakers. Especially given how old the stock speakers in any 928 are. To your subwoofer question, however, you may be able to run the line outs to your amp for your main speakers and then use the speaker-level outputs to your powered sub, if it has speaker-level inputs IF the JVC doesn't turn off the internal amp when the line outs are used. I have no idea if heads generally do that or not, I always get one with dedicated sub outs (which is another, better option, but will require you to get a new head unit).

joejoe

Floyd and techno.... love em both. Original amp in car is pretty low output. Most (if not all) aftermarket units have more power. Use rca jacks when possible as the output will match amp better. Speakers may be a problem as they are old and not positive of ohm. I have heard some say they are 2 ohm, others say 4, I do not know. Does the unit have pre-out for sub? Going to keep watch on this post and good luck.

Andre The Giant

Thank you bureau13 and joejoe. No sub pre-out on that old JVC and yes I think that when you use the pre-outs for main amp the internal head unit amp is bypassed.
The speakers that HANS has developed for this car, does anybody have a link to contact him or a post so I can find out what price I'm looking at ?

bureau13

I just bought a set from Hans...they're supposed to ship out today, I think, so I haven't seen them yet. They're not cheap, but supposed to be very nice. There may be cheaper alternatives, but given the mounting challenges, it's hard to say.

I've always simply contacted him through PMs. If you do a search on door speakers, or Sharkwoofer, or drop links, or several other things, his name will pop up. He seems busy :-)

Andre The Giant

Bureau13, once you get them installed I would love to hear your opinion on the sound and what type of amp/head unit configuration you have, so I can somewhat compare.
I have done some more research and have found a username hans14914 and have emailed him to see if that is the correct person.

bureau13

That is indeed the right person.

Right now, the car has some probably cheap Pioneer in it, that may or may not function. To be honest, my priority has been getting everything running and functioning correctly, but my insurance decided that with a ratty interior, surely this can't be worthy of collector car insurance So, I'm working on the interior. Yes, I just bought Hans' speakers to plug my speaker holes Well, not really...I always upgrade the stereo system in my vehicles, so this was going to happen eventually, and I wanted to make sure he still had speaker kits available. The point is, I may not be able to actually hear them when I initially install them, certainly not with the head and amp I will eventually use.

Amp-wise, that Rockford Fosgate is one of the ones I've looked at, if I stick to the stock location (I THINK it will fit, not 100% sure). The head unit I think i want is the Pioneer DEH-80PRS.

killav

I am using the same Fosgate PBR300X4 amp in my 87 S4. It does fit with no problems underneath the factory passenger cover by the seat.

The only thing I don't like about it, is that the floor level HISS is rather annoying. When the volume is all the way down, the hiss is noticeable. Even with the amp gains at a reasonable setting (not all the way up). But the amp is great other than that. Still no bass however without a subwoofer. But it plays loud and clean. Also, it does get VERY HOT when cranked up.

I would run RCA jacks to the new amp from your JVC, even though this amp will take high level inputs.

The factory wires to the speakers are fine in my opinion. Audiophiles will spend thousands on cables and wires, but absolutely not necessary in most applications.

For the sub amp input wiring, you could get a sub amp that will take high level inputs and do as you mentioned and run one of your rear speaker wires to the input. Just make sure the sub amp has a built in crossover to kill the high frequency's to the sub.

Or, you could get a LOC (Line Output Converter) from anywhere (sonic electronics for example) and run your speaker wires to this, and it converts the high watt signal to a low voltage RCA output for any amplifier.

HTH.

bureau13

If his head unit switches off the internal amp when line-outs are connected, he still won't be getting a signal to his sub amp. Personally I think I'd spring for a new head unit. You can get some decent, modern gear for not a lot of money these days.

rnixon

If you're going to fit a sub and amplifier, I'd get a larger amplifier in a non-stock position. It doesn't have to be huge - I use this one, which I find very good and is still quite compact. I have it in the passenger footwell - here's a thread discussing install locations.

The designs that were compact enough to fit the stock amplifier position didn't have specs that looked that good to me. I already have aftermarket speakers (6 DynAudio, with the two in each rear panel unused) and a sub inside the spare tyre's rim (this one). It has quite a small driver, but produces a reasonable amount of bass. If you ditch the spare, then something like a sharkwoofer provides a lot more bass and space for an amplifier or two.

I'd probably start by getting a better head unit, especially as they're not that expensive. Having the sub level controllable from the head unit is necessary IMO.

Bmw635

Great timing. Any rec'd on head unit to match this PBR-300X4 that I am getting ? Some of the rec'd on old threads are at least 3-4 yrs old . TIA.

rnixon

The amplifier that I linked above has a switch to drive the subwoofer channel from the average of the other 4 inputs - I expect that other amps can do this too. Alpine also sell a separate sub control, so that you can adjust the level when the headunit doesn't have a sub output. I'd rather put that money towards a better featured headunit though.

rnixon

No HU recommendations, but I would check that all your speaker sets are 4 Ohm for that amplifier:

Alan

You should not connect a sub-woofer input to existing speaker outputs - since those will likely already have some high-pass filtering by the crossovers or amps to eliminate low frequencies that they cannot reproduce.

You should feed the line-level/pre-amp RCAs to the new amp (for best quality) and also feed these to the subwoofer - most will accept at least 2 sources (e.g. to combine sub input across at least L/R on a single channel).

I do agree that the stock speakers are likely the biggest limiting factor here - due to both original quality and age and probably deserve the most attention.

Alan

bureau13

You can split the line outs? I was thinking that wouldn't work so well, but I could be wrong.