kkell3232

My car originally came with the HiFi speaker/amp option. The original Nokia amp was removed at some point and replaced with an amp and subwoofer somewhere in the car. Those were then removed at some point, and when I acquired the car a few years ago all that remained was this mess of cables and two crossover filters under the carpet in the front:


I replaced the head unit with the Continental TR7412UB-OR a couple of years ago and sound quality has been ok but not great, no distortion just a bit muddy. I'd like to get rid of this mess of cables in the front and have a cleaner solution under the passenger seat. I have no desire to replace the original HiFi speakers at this time but understand they may need to be refreshed. I sent some pictures to a local car audio guy who says I need to get an amp, but I'm confused as this setup seemed to be working more or less. Do I really need an amp or is my newer head unit sufficient (ie can I just put a couple of new passive crossover filters under the passenger seat and call it good)? Thanks and please pardon my ignorance, I am trying to learn as I go...

Overdraft

Similar situation for me and I asked almost the same question to the forum for my wife’s cab. The Nokia amp was still there and looked to be connected - but wasn’t - so caused me a couple of hours of tracing and thinking of options after removing the seat to trace everything. In the end, I pulled the Nokia amp out and ended up buying a Blaupunkt Breman SQR 46 from Gert at Carnewal which installs seamlessly and looks 100% period correct in the dash. It has adequate power to run the speakers and It is a little shallower than the OEM radio so there is room in there for wiring. My door component speakers were excellent so although I had bought a new pair , I ended up reusing the Nokia OEM ones….but the rears were the paper cone units and shot so I got an OEM replacement set from Suncoast which were plug and play and mounted in the existing holes and were a noticeable upgrade. I then ran an RCA cable from the radio head to the frunk and put an Alpine mini powered sub from Crutchfield wired with an RCA “y” cable adapter (again from Crutchfield) The sub was wired directly to the battery.

993s are not a great platform for audio installations but well,….this set up is good to very good AND very sensible cost and looks 100% factory. Bluetooth is excellent running off music off my IPhone and the mic unit for the phone and call quality is spot on. I even enjoyed doing the install. 🙂

pp000830

Hi Kkell,
Adding an amp to the Continental head to clean up the sound is problematic as the Continental unit has no line level outputs for a power amp and if an adapter is used with its speaker outputs it will introduce a considerable amount of distortion defeating the purpose of an upgrade. Here is a page that discusses getting good quality sound from a 993:
https://993servicerepair.blogspot.co...or-993-in.html
Andy

jwong1977

If you can somehow get the wiring back to stock form again, I found the Alpine PXE-850X to be an excellent option to replacing the original Nokia amplifier. It has more than enough channels to power all of the speakers, including having separate channels for the three way system in the front. It also has time alignment which moves the sweet spot to your driver's seat, and if you use the wiring harness I found, none of the stock wiring needs to be disturbed at all.

Here's a link to the thread I started, https://rennlist.com/forums/993-foru...ry-wiring.html

If has all of the steps I went through to replace the Nokia amplifier. The only catch for you would be how to get everything back to stock again. But even if you did your own custom wiring, this solution is neat because it fits exactly where the Nokia amplifier was under the passenger seat.

kkell3232

Thanks for the replies. @jwong1977 I like your setup, but if I am reading correctly, the Continental head unit can't be paired with an amp unless I get a line out converter? Andy, are you saying this sort of harness would introduce too much distortion?

I guess the saving grace is that the Continental head unit has at least as much power as the original (albeit underpowered) Nokia amp. @Overdraft if I had to do it again I would probably buy the Blaupunkt, but for now I'd like to see if I can make do with what I have, which I think means buying a couple of new passive crossover filters to put under the passenger seat. If anyone else has done this please chime in, would welcome any additional advice.

jwong1977

The PXE-850X has speaker level inputs. Just run the speaker output on the Continental straight to the amplifier. It’s a pretty adaptable unit.

71-3.0-911

^^This. Line outputs are not required. Here are a few to consider. You can simply use the speaker lines and place a compact amp where the Nokia was previously. This is the route I'll take this winter as my car is in the same position. Previous HiFi car that was all "upgraded then removed" prior to my ownership.

https://www.crutchfield.com/S-6vCIgw...mplifiers.html

pp000830

Hi Kkell,
To answer your question, yes.
The purpose of adding a power amp is not to increase volume but to reduce distortion that typically comes from driving the internal amp in the radio near or past its rated output.
When harmonic and other distortion starts to pass 1% it can be heard and will reduce the intelligibility of voices and sound.
Internal power amps in automotive radios have much higher distortion than a preamp even when driven within their rated output and so by using an adapter, the distortion is amplified along with the signal.

In your case, the speakers in the doors and rear deck may be dried out. Inspecting them and replacing them if found to be dried out would be my first step while retaining the continental unit.
Also getting rid of the speaker boxes and replacing them with a new set of coaxial speakers may improve the efficiency of the speaker system and so reduce the power demands on the Continental head improving intelligibility of the sound at levels where it can be heard over engine and cabin sounds.
If the sound can not be improved by this buying a new head is the way to go. A new radio head in a single DIN size that fits in our car can be had for as little as $100. Also, certain heads have power ratings in excess of 25 Watts RMS (different from peak power) and for some, this may eliminate the need for an external power amp. Power amps rated at > or = to 75 Watts RMS per channel are ideal for hi-fi quality sound in our cars but may be a bit of overkill if one is simply trying to incrementally improve the clarity of the sound. For reference, if only peak power is listed in the specification the RMS power is approximately 70% of that value.
Andy

kkell3232

I finally got around to removing the aftermarket component speakers, cleaning up lots of sloppily applied sealant and noticed white batting stuffed inside the sound box. Assuming it did not come this way, I'm trying to think of a reason why someone would want to do this? Trying to make it a closed chamber? I don't get it.

jwong1977

I did a bit of researching about the hifi enclosure, I believe it is a design called a transmission line enclosure. Someone correct me if I’m wrong, but the white stuffing material was there from the factory.

here’s a description of how it works.

pp000830

HI J,
Seems like a variation on a Bass Reflex enclosure. In any event, the system as powered by the Nokia amp, I feel, is so underpowered that it renders any attempt to make the speakers better by their enclosure moot.
Andy

jwong1977

Seems similar to that Bose Waveradio thing that came out about 20 odd years ago. I believe the op will replace the Nokia amp, hopefully a more powerful amplifier will make better use of that enclosure, but I honestly do not know if it will or will not. What I can say is the Alpine DSP/Amp I recommended is a nice sounding unit that fits nicely in the stock location of the Nokia amp, and doesn't require any cutting of the existing wires.

kkell3232

Agree- I think the Nokia Lautsprecherbox is just a weirdly shaped ported subwoofer box. Some audiophiles will choose to line (but not stuff full) ported enclosures with Poly-Fil or similar for what sounds like largely theoretical reasons, trying to damp the midrange and boost the low end. Since the door is already apart I'll experiment a little with the placement of the stuff that's in there to see if any discernible difference.

The Alpine amp sounds like a great solution. I am waiting on some new Infinity speakers and will see how they sound driven by the head unit only; if found wanting then either a new head unit or amp will follow. Lots of good suggestions from previous threads on this topic.

wesr

I overhauled the Hi-Fi system using the Continental CD7426UB-OR and a variety of components. Basically ditched the boxes and replaced all the speakers/tweeters, added an amp, DSP, and compact subwoofer.

It’s been pointed out many times that the 993 is not a great platform for car audio. That’s true but I am happy with the results. Major improvement.

jwong1977

@wesr which side is the Kenwood subwoofer located? Did you have to remove anything to get it to fit? I’d love to add a tiny subwoofer under my seats too.