Upgrading OEM audio with subwoofer: Where to place hi/lo adapter (instead of speakers or parallel)?

[snowdog]

Hi,

Like title, I am upgrading my 2021 Cupra Leon with a subwoofer (I still have a few old amps and subs from older cars) as the default audio is rubbish (low tone wise as well as max volume).
I am well aware how to install in analog audio systems, however my OEM HU does not have pre-outs.

Therefore, I need a Hi/Lo adapter.

Do I place this instead of my rear speakers or won't it mind if I hook it up parallel to the speakers?


I have bought a Car2Iso2Car cable:

I have also bought a :

https://www.audiotec-fischer.de/en/helix/accessories/aac.3#technicaldata

This hi/lo adapter shouldn't trigger a fault in the cars headunit. Question is, will it still not if I keep the original circuit to my back door speakers and just hook up the hi/lo adapter parallel to them? Or must I use it instead of my rear speakers to not trigger a fault in the computer?


I have some work laid out still, have to learn where the Quadlock is placed but I think it's behind the touchscreen:

 

[Rilot]

It depends on what kind of load it puts on the speakers. Impedance for parallel devices is halved so if the stock amp is expecting a 4 Ohm load and this also presents as 4 Ohms, then the actual load will be 2 Ohms which can make some headunits go spaz.

 

[snowdog]

13 Ohm it says, so (13*4)/(13+4)= 3,05 ohm ?
Hmmm, that might be a problem.

 

[Rilot]

3.06 isn't that much lower than 4. I'd expect that to be within tolerance for the amp.

 

[jpaul]

if you read on link - the helix circuitry is meant to deal with this https://www.audiotec-fischer.de/en/knowledge-base/tech-talk/adep/

they're a reputable brand ! - but you usually don't run them in parallel - if you are driving speakers too amp can be introducing distortion which will go to helix too.

(like for similar upgrade on BMW systems) I would try and determine if the existing equalizer can be defeated so that the low frequency signals are delivered to the helix,
any surround sound/Logic7 type of electronic best off too.

If you have multiple amps they could drive the rear speakers instead ?

e: I think some people do use mobile phone microhones to help in eq'ing systems, in conjunction with an appropriate test sound track.

 

[snowdog]

If you have multiple amps they could drive the rear speakers instead ?

I'd need a lot more cable work (speakers cables back to front) and multiple amps would probably mean beefier cables as well.

I have 4 ch amps too, but the problem is in my last car, it sounded worse with rear speakers amped as opposed to just the subwoofer on 2 of the 4 channels. I presume because the amp or power supply (read: car power system, all the lights dimmed a lot on the music at high volumes, it was 35mm² cable so unless I messed up some connections the wire was thick enough) was at its limit? I had a feeling that just using the fronts with sub and no rear speakers sounded much better at high volume.
However... Especially in the back of the car the sound stage was a bit odd as you'd have exaggerated lows and little highs. Hence I'd prefer the original audio to ''supplement'' the rear without hooking em up to my amp.

I've had contact with an audio company now and they said parallel is fine, but I might need the AAC.3 HP (high power) as my car might have an extra OEM amplifier. Although if I paralleled them at the headunit my assumption is it's not yet amped at that stage.

I'm leaning towards trying to parallel wire them, and if it gives faults (e.g. fader control gone) then use the Helix and just unplug the rears for now.

My idea was just having the fader to front slightly while just boosting the gain on the SUB (sub does have LPF on the amp obv.), which means 50/50 front/back it'd be bass heavy, but I can adjust fader if I want more bass or less bass whatever mood I'm in and depending on the music). It'd still mean in the rear the audio would be possibly unbalanced a bit (bass heavy) but Treble at least filled in from the doors a bit. And ofc the car itself has a 5 step EQ (as in 5 bars corresponding to a frequency range and from -9 to +9 db)in which I can play with the lows or boost the highs.

Boosting the low end is no problem with a seperate amp as you can just increase the gain for the sub.

 

[snowdog]

So I've done it, main annoyance is the HU is behind the glovebox and needs a lot trim removed to get to.
Helix parallel to the rear speakers is absolutely no problem, no errors on the computer or so, everything works like it should.
Surprise was the HU being in behind the glovebox instead of the screen and the battery being in the boot instead of the engine bay.

 

[Deleted User 298457]

Surprise was the HU being in behind the glovebox instead of the screen and the battery being in the boot instead of the engine bay.

It's like they have secretly solved all of the issues that you'd come up against when doing jobs like this a decade or so ago would introduce.

 

[jpaul]

Having the HU and screen separate ? it wasn't just a separate Amp with a digital feed from the screen, that nonetheless hides most of the electronics - like the BMW HK system.

it's pretty complex to have a bus for speaking remotely to a touch screen for sending display data and sending touch data the other way.

 

[mjt]

Long time no see! That's quite the upgrade from the Galant

 

[snowdog]

Having the HU and screen separate ? it wasn't just a separate Amp with a digital feed from the screen, that nonetheless hides most of the electronics - like the BMW HK system.

it's pretty complex to have a bus for speaking remotely to a touch screen for sending display data and sending touch data the other way.

Aye, WIP:

Long time no see! That's quite the upgrade from the Galant

Aye, I've had a Seat Leon before this for 5 years, before that I've had a Renault Megane 3 for a few months, Here's them side by side:

Other pics:

Yep it's a Hybrid (company car), but still quick enough, and more special than a Golf GTE. ESP can be completely disabled, and a nice DCC, where I can set the dampening from very soft to bouncy rock hard. The rear end is quite playful actually, lift off oversteer is very easy.

Interior:

Nothing special but comfy enough, Seats keep you well centered !

Has all the bits 'n bobs, heated seats, heated steering wheel, can pre-heat and pre-cool the car in advance automatically via scheduling or the mobile app... I absolutely love the pre-heating and the heated wheel, definitely never want a car without heated steering now .

Fuel economy is rubbish, if I don't charge daily (we have chargers pretty much every 4-5 streets here but I'm lazy so I usually only charge it once every 3 days or so) it drinks 10l/100km but my boss pays for the petrol so meh.


In NL Cupra doesn't sell the 2.0 TSI at all. All models ( Leon, Formentor, Born) are full EV or plugin Hybrid only. Ateca was the last model with just an ICE. Has to do with the car tax here which heavily penalizes ICE's.
Example, a Golf GTE is ~€45k same as the Cupra Leon, for a full options model, but the Golf GTI which is still being sold is From 54k without any extra options. Golf R is completely ludicrous, 69K I believe.

 

[mjt]

Nice! Surprised they don't do full fat Cupras in NL, but understandable given the BPM. Looks good though and with a decent spec. Not bad for a company car

 

[jpaul]

yes nice car .. on street charging , sounds leaps ahead of uk.
Interesting, in a good way, to see Samsung branding on the HU, had thought they kept oem manufacturers identities more discrete;
seeing drill discrete mods in a company car are ok ?

 

[Leon245ps]

Hello everyone!
I own a Cupra Leon eHybrid, but I am fully disappointed by its sound. I already changed its speakers and now I want to add an amplifier. I bought a focal 4.320 and now it is time to place it.
As I have seen in this thread you have dismantled all the "panels of my interest" . Can you advise me which panel should I open, in order to find the speaker's ISO connector?
Starting from the speakers, where are the wires headed to? To the MIB control unit in the glove box or to the infotainment screen?
Also, I don't want to cut the original (manufacturer's) speakers' cables and put my amp in the middle. So, do you recommend an aftermarket ISO plug just for the speakers? This way I won't have to cut anything.
Thank you in advance,
Paschalis

 

[Datblue1]

Can you advise if the multimedia unit in the glovebox is behind the blank plastic trim