I decided to upgrade the audio system in my 1990 C4, as the one that was fitted (top of the range Blaupunkt from the 90s and an aftermarket 5" 2-way in the front doors) sounded like a kitchen radio. A broken one at that.



The front system will consist of

• Helix M Four DSP amp
• Scan-Speak 6.5" mids (16W/4434G00)
• Scan-Speaker 1" tweeters (D3004/602000)

I'm still on the fence if I should focus on a high end 2-way or add a cheap (as there are no other) underseat sub, as a fellow forum member did in his 964:



Scan-Speak drivers are pretty hi-end stuff so the question is, if the cheap under seat sub will be a benefit or ... will ruin the sound with lots of boomy bass? Maybe I will be better off with a hi-end 2-way system?

• the car is small
• I do not listen loud
• I do not listen to bass-heavy music

I have 6 extra channels available in the Helix DSP, so I can EQ / time align the sub.

I was considering DLS ACW10, but I'm open for sugestions. Price is not an issue - only space is.




PS. Singer is putting Kenwood KSC-SW11 subwoofer in their restomodded 911s, as a part of their $9950 premium sound system, but that is hardly a benchmark.

 

Doors already done:







I have closed all factory openings in doors with aluminum panels and run a layer od deadening material both inside the door and outside.

 

The pancake under seat sub is a great idea for adding bass without the weight of a huge speaker. Lovely looking car!

 

Helix M Four DSP amp - I'm gonna run the front 2-way system active + the amp still has 6 extra channels of DSP (pre-outs) that will allow me to EQ and time align the sub.

I was also considering running a Focal ISUB, which is a passive sub:




Peter from PSsound seems to like those as kick-subs. They could go to 50-60Hz, which would be more than enought for me. Beeing an audiophile, the idea of closed enclosures made of aluminum really appeals to me (I have a Magico M3 speakers at home, which are just such a design).

HOWEVER, the problem for me is their thickness. To fit the sub under the seat in 964, you have to rise the seat by ~15-20mm. I can do that under the passanger seat as my wife is much shorter than me (I'm 9'4 or 194cm in human speak), but I'm unable to give up a single mm under the driver's seat. Which means I could use only a SINGLE Focal ISUB out of the pair.

So the option would be a Helix M SIX DSP (instead of M FOUR) + single Focal ISUB under passanger's seat or Helix M FOUR DSP + an active underseat sub like DLS (or similar boom-box from Kenwood).

Having only one ISUB would mean pushing them even harder (they are rated 100 W RMS, but their sensitivity is abysmal - 83 dB). On the othe hand - the volume of the 964 interior is tiny, probably 50% of an avg. full size sedan, so MAYBE just a single ISUB would be enough.

 

The Helix M FOUR DSP should fit under the driver's seat one way or the other:





I bought this latest retro-look Blaupunkt Frankfurt 82 DAB as a headunit:

 

Nice small footprint. Modern tech sure makes it easier and less weighty to have a great sound system. I might need to look at a decent amp to drive my Focals.

 

How did you find the Frankfurt? On paper it looks better than the Bremen.

 

Nice, I’m looking forward to seeing the full build and your thoughts on how it sounds after completing it. Insulation makes a big difference when chasing SQ although at the expense of added weight.

Regarding the Frankfurt, what performance aspects make it better than the Bremen?

I’m waiting for a high quality 4 channel amp with built in sub to come out so I can stuff it under the passenger seat and replace the stock Blaupunkt. Ideally that in combination with a harness that will connect to stock without having to cut wires under the seat would make it a perfect aftermarket solution for our cars.

 

I have the Bremen SQR 46 DAB in my Testarossa. I'm about to replace it with Frankfurt. The later offers better sound quality, more features (DSP with x-overs and parametric EQ - 14 bands vs 3), more advanced BT (5.0 LE vs 2.1 EDR) and better mike/ more effective noise reduction for calls. It is all around a more polished headunit. It is available in Europe.

Blaupunkt RCM 82 DAB is based on a legendary Blaupunkt RCM 82 from 1992, so it is period correct for our cars.

It seems other ppl on Rennlist are already using it:

https://rennlist.com/forums/993-foru...frankfurt.html

 

Would it be possible to fit the ISUB Twin in the rear footwells? I assume that no one is riding behind you at 6'4.

 

That is another idea I want to expolre: one ISUB under the passanger's seat and another one in the rear footwell behing driver's seat OR replacing the glovebox (the idea is to put the sub behind the glovebox door, basicly replacing the glovebox inner structure and firing backwards).

 

Definitely wanting to follow this build. I have early 2000 blaupunkt replacement speakers and I want to upgrade.

Currently have the Porsche PCCM radio installed and it only has speaker line outputs. So I may be limited on my amp selections. I am wanting to do the sub in the passenger seat area, so space is of importance for amp and sub. I have been sold on the focals for the doors, but not yet purchased.

Questions: 1) Should I use a power sub or a sub powered by the amp?
2) Can I use the 6 channel amp to power the sub, door speakers, and the rear deck speakers?
3) Do I need install a converter to change the speaker line out to pre-amp output?

 

1) the only non-powerd sub in this micro-class is the Focal ISUB Twin (which may still be too big to fit). Which basicly leaves you with powered subs option only.

2) I'm not gonna use rear speakers. I will still have spare channels from the amp built in the headunit, but I feel there is no point. They are so small, that whatever you put in there, they will always sound like a kitchen radio. If I had spare ch in my Helix amp (which I do not have) I would use them as differential rear fill. Basicly all sound quality oriented installs only use front speakers + sub. All you gonna need is a 4-ch amp to power the front speakers (without their passive x-overs), that will also have DSP (for EQ + time alignment) AND at least one spare output channel for an active sub. The Helix M FOUR DSP I'm using has 4x100W for the front speakers, and 6 extra channels availble as RCA pre-outs (with DSP) of which I'm gonna use one for an active sub. This will allow me to EQ and time align not only the front speakers, but also the sub.

3) I'm not a fan of high level inputs. You basicly end up amplifying your headunit amp distortion, by another amp connected in series. Only makes sense in modern cars with factory infotainment systems, which have no pre-outs. The proper way to do it is to run a pair of RCA cables from your headunit. All modern aftermarket headunits have at least one set of RCA outputs (so called pre-outs). The Blaupunkt I'm using has 3 sets of pre-outs - one for the front speakers, one for the rears and one for the pair of subs.

A perfect installation on a budget, would be ($500) Blaupunkt RCM 82 + active sub, like this active ($250) Focal IBUS 2.0 (pictured in the original post). You can connect your speakers to the amp in the headunit and the active sub to the headunit sub pre-outs. Then you can use in-build x-overs to set high pass filter on the main speakers and low pass filter on the sub. And if the shop that will do the install has a mic, they can even use in-build 31-band EQ for basic system equalisation.

That will make your system sound A LOT better than stock. Later, you can upgrade your front speakers for some 6.5" component 2-way system (still using the amp from the headunit).

 

Thanks for the reply on my questions. Just to clarify, I will be keeping the PCCM as it has some great features I like and I am already invested in it. So, you would recommend the converter for speaker outputs to pre-amp? I was recommended this one: https://www.crutchfield.com/p_541LPA...-Advanced.html

and the amplifier I was looking at: https://www.crutchfield.com/p_091FDS...FDS-4-350.html
note: it can be converted to a 3 channel which would allow me to run the front speakers on 2 channels and the sub on the 3rd channel.

 

No need to use high level (speaker) outputs from the PCCM. You can use PCCM with an adapter like this to get RCA outs:




Link to Amazon:



C1 LineOut Connector (Yellow typically)
Pin 1 = Line Out Left Rear
Pin 2 = Line Out Right Rear
Pin 3 = Line Out Ground (for all)
Pin 4 = Line out Left Front
Pin 5 = Line out Right Front
Pin 6 = 12V switched 'remote' for amplifier (blue cable) (to your power supply remote)

Connecting to your amp via RCA line level inputs is a much better idea.

Prosonally, I wouldn't buy an amp without DSP. Time aligning the speakers + equalisation really makes a difference and helps the speakers to disappear (lets them work as a whole). This is just another level compared to simple x-over built into amps.