Your Expert Opinion

[KoolinNSX]

It just don't have the sound quality which I'm satisfy with. It has a loud background hssing noise when the volume is low. There's no in between volume level. Level 7 is too soft and level 8 is too loud. When it is loud, it does not deliver a pleasant output compare to my other car stereo, it actually hurts.

Here's my setup. Alpine CDA-9855 head unit with factory door speakers. I have a sub with SOS enclosure and an amp. The center speaker doesn't work anymore. I was informed that there could be an incompatible issue with the door speaker amp and the head unit. At the same time, I was told that those door speakers are specially build for the NSX and after market will never sound as good because I'll be missing the mids. I'm so unsatisfied that I'm ready to switch out the speaker and the factory amp but i'm also afraid that after spending the money that there's no significant improvement. Any comments or suggestion are welcome. Thanks.

 

[TURBO2GO]

You wired an alpine head unit directly to the factory speaker system? I believe that the Bose system has amplifiers built in... and an EQ... you are sending it a very strong signal now, the voltage is way up and the system is interpreting this as a loud volume level. This would explain why you are getting so much hiss, as well as the huge shot in volume when you go up one notch.

I have never taken the NSX system apart but just from my audio experience, this sounds like the problem.

The bit about aftermarket speakers never giving you as good a sound as the factory is nonsense.

I would ditch the factory speaker system, get some of those door plates from D'Ecosse, and get something else in there. ALmost ANY aftermarket speaker will outdo what you have now.

 

[D'Ecosse]

Did you install this yourself or did a shop do it?

Actually it is quite possible to wire up an aftermarket head (like your Alpine 9855) to the OEM speakers and get a quite pleasing result, certainly better than the OEM head with the OEM speakers

The key is in how it was wired up - the OEM head has pre-amp outputs and the amplifiers are indeed in the speaker assemblies. You need to ensure you are using RCA pre-outs from the Alpine head with a suitable RCA adapter to the OEM harness. You cannot use the amplified speaker outs from the head - I strongly suspect this is what is wrong. (Also do not use a line conditioner with the speaker outs either - completely unnecessary & will just give you more problems in trying to get everythying set up adequately)

So first step would be to check on the wiring and see if you can make what you have work (if the amplified outputs were indded directly wired up to the OEM amps there might be some damage however);
but since you already have an amp, may be the best ultimate solution to upgrade it to a 4 channel and get some components for the doors to complement your sub.

I believe that the Bose system has amplifiers built in... and an EQ... .

No EQ - the amps receive a 'flat' audio response from the head (which is why you can use either OEM head for aftermarket amp or aftermarket head with OEM amp/speakers).
You may be thinking of the footwell speaker amp where it actially feeds the centre speaker as well as the one in the floor - however that is nothing more than a crude capacitor filter.

 

[KoolinNSX]

Did you install this yourself or did a shop do it?

Actually it is quite possible to wire up an aftermarket head (like your Alpine 9855) to the OEM speakers and get a quite pleasing result, certainly better than the OEM head with the OEM speakers

The key is in how it was wired up - the OEM head has pre-amp outputs and the amplifiers are indeed in the speaker assemblies. You need to ensure you are using RCA pre-outs from the Alpine head with a suitable RCA adapter to the OEM harness. You cannot use the amplified speaker outs from the head - I strongly suspect this is what is wrong. (Also do not use a line conditioner with the speaker outs either - completely unnecessary & will just give you more problems in trying to get everythying set up adequately)

So first step would be to check on the wiring and see if you can make what you have work (if the amplified outputs were indded directly wired up to the OEM amps there might be some damage however);
but since you already have an amp, may be the best ultimate solution to upgrade it to a 4 channel and get some components for the doors to complement your sub.


No EQ - the amps receive a 'flat' audio response from the head (which is why you can use either OEM head for aftermarket amp or aftermarket head with OEM amp/speakers).
You may be thinking of the footwell speaker amp where it actially feeds the centre speaker as well as the one in the floor - however that is nothing more than a crude capacitor filter.

Unfortunately, what it sounds like from you it was an incompetant shop who installed it for me.

This is great info!:smile: I'm not much of a handy man so I'm going to bring it to a reputable shop to have the wiring checked out. If the better route is to get some components, I will need the door plate from you. Do I just PM you for the purchase? I will keep you guys posted. Thanks again!

 

[D'Ecosse]

You may want to share this with your new installer.

What you want is a harness adapter something like this:

There will be a couple of changes for yours obviously:
The picture was for a Sony Head unit but the principle is the same - the actual wiring diagram is specific to your Alpine

1. You would just have the Alpine-supplied harness (instead of the black Sony one) on the right of the picture. The white connector plugs into your OEM harness and is a readily available install accessory your shop should be able to get.
2. This one is shown with two sets of RCA connectors as was constructed for the owner using the OEM Bose footwell speaker as well as the OEM doors - in your case, you only need the one pair of RCA jacks that will splice to the wires going to the doors (tell the shop that they will need the RCA jacks on the white & grey pairs for the doors)
3. Be sure to have them connect an auxiliary ground wire from the black wire junction to a true chassis ground - this will help to eliminate noise from your system. (that's the thick black wire with the ring lug at the top left of picture)
4. The remote power output actually needs to be spliced into the adapter harness as it needs to provide the power enable for OEM amps also
5. The 'power antenna out' actually needs to run out to the car & the line broken because the power enable for OEM amps & antenna is on the same common connection originally - See this post for where to break into the wire for antenna. This will allow your head unit to control the antenna as intended so it only operates when you select the tuner as the source.

Now all of this assume that they didn't butcher up your OEM wiring - this adapter will work if the OEM wiring at the head unit connector is restored to original.

If you go this route, even if you decide to go with after-market speakers later (or if it doesn't work out because your amps are damaged) then it will still be worthwhile - instead of connecting the RCA outs from the head into the new harness jacks on your adapter you'll just run with a an RCA extender to your amp, then run speaker wires to the doors.

 

[VADER33]

All of this searching makes my head spin. I have an Alpine HU and a Soundstream amp left over from my S2000. I also have a PG amp with an 12 inch ALphasonik Sub. I would like to get the head unit dropped in but I can not find a clear cut method of doing it. And yes, I searched. Only fella I saw that was helpful modded his stock center console. Not sure how or if you can get your aftermarket HU in the car. I wonder if it is worth pulling the stock console and taking a look at what is underneath. I will post pics.

 

[KoolinNSX]

You may want to share this with your new installer.

What you want is a harness adapter something like this:

There will be a couple of changes for yours obviously:
The picture was for a Sony Head unit but the principle is the same - the actual wiring diagram is specific to your Alpine

1. You would just have the Alpine-supplied harness (instead of the black Sony one) on the right of the picture. The white connector plugs into your OEM harness and is a readily available install accessory your shop should be able to get.
2. This one is shown with two sets of RCA connectors as was constructed for the owner using the OEM Bose footwell speaker as well as the OEM doors - in your case, you only need the one pair of RCA jacks that will splice to the wires going to the doors (tell the shop that they will need the RCA jacks on the white & grey pairs for the doors)
3. Be sure to have them connect an auxiliary ground wire from the black wire junction to a true chassis ground - this will help to eliminate noise from your system. (that's the thick black wire with the ring lug at the top left of picture)
4. The remote power output actually needs to be spliced into the adapter harness as it needs to provide the power enable for OEM amps also
5. The 'power antenna out' actually needs to run out to the car & the line broken because the power enable for OEM amps & antenna is on the same common connection originally - See this post for where to break into the wire for antenna. This will allow your head unit to control the antenna as intended so it only operates when you select the tuner as the source.

Now all of this assume that they didn't butcher up your OEM wiring - this adapter will work if the OEM wiring at the head unit connector is restored to original.

If you go this route, even if you decide to go with after-market speakers later (or if it doesn't work out because your amps are damaged) then it will still be worthwhile - instead of connecting the RCA outs from the head into the new harness jacks on your adapter you'll just run with a an RCA extender to your amp, then run speaker wires to the doors.

As usual, you are one of the greatest asset to this forum. Thanks!