Polo GTI 9N Stealth Audio Upgrade Guide / Stealth Amp

[flat6]

Haha allegiance, read through all that, most are talking about the original HSK 165s which were fake, the new series are the real deal, you'll notice most users who purchased them couldn't tell the difference apart from different components in the crossover, yet are still the same components ect.. you see this a lot in all electronics.

They are genuine hertz one way or another, either factory seconds ect... but for $130 you really cant go wrong and they sound better than most of the crap you pickup for that price at jb

[flat6]

A few months passed and I learned a hell of a lot

Had an Eonon head unit that was driving me mad, It had all the features, gps, usb, Bluetooth, ect.. only problem was I didn't realize how crap the sound quality actually was until I replaced it with a Kenwood DPX-U6120, what a difference, this thing single headedly improved the whole setup and it looks great, keeps the interior more focussed


Picked up the Din Ring from JB Hifi for $30, simple universal mount, the unit actually mounts and screws into it

Replaced The Hertz Fronts to Morel Virtus 602's, these things are insanely good, the mid bass and soft clarity is their strong point where the hertz tend to be a lot more sensitive to highs.



The hertz didn't like running lower than 80htz on the high pass but the morels will happily run at full pass and sound amazing no matter what music you listen to, hell for $430 compared to $130 thats what you expect, left the hertz in the rear running on band pass for rear fill which worked out great.



Installed a Rear Reflex Plate, guy tried charging me $50 for a pair then ended up just throwing them in, are they worth it, couldn't really say, They may improve mid bass a fraction and everyone raves about them, all i can say is the system sounds great...



The Tweeters on the Virtus are the smoothest ive ever seen, even with the crappy head unit the highs were not ear piercing as experienced with the hertz HT25's



Over the course of a few weekends I decided to custom build a sub box into the cervature of the rear seats to maximize boot space, decided against down firing as it just wasnt optimal for the space I had

Have to say building your own if you don't have the tools is way more expensive but a great way to figure out what tools you aint got, yet Aldi have some great value on cheapie tools, they do the job well and haven't let me down yet.

Cut, measured and sealed the box, total inside box size is 28.9 litres sealed, about 4L larger than the manufacturer recommends, bigger box = deeper bass

YouTube'd a few videos about box carpeting, the half moon trick is where the moneys at, this video is a life saver
Carpet a speaker box - YouTube

The final product is amazing, perfectly seamed box, looks better than a bought one with thick quality carpet



Filled the Interior with some thick Dacron, you can pick this stuff up at any linnen store.

Chose the Polk Audio MM1240dvc for 2 reasons
At 425w RMS its perfectly matched to the Alpine PDX-V9 and its one of the smallest 12"s available that doesn't fall into the compact sub category, its still a full sized sub with a mounting depth of about 14cm
I have it wired to 2 ohms, on the PDX-V9 it makes no difference so wire it as low as you can.



Final Product, strapped it to the back seats with a short strap from autobarn, doesn't move an inch

Even with this thing in the back I can still load a trolley full of shopping into the back, box total was 28.9 litres


Conclusion

Over all this system cost me about $1400, and probably $600 in tools, I needed a tool shed anyway haha

How does it sound?

After a few weeks of getting it tuned right it is very satisfying, haven't touched it in over a month and am very happy with the end result

Midbass is insane, the Morels perform delightfully and the hertz play rear fill nicely

All up its a complete sound and with this guide can be had for under $1200

[noone]

Nice work. WI hope you're not inspiring me to spend more money on my toy...

[flat6]

Yeh it can get quite expensive if you let it, even though it was quite a tiresome job, its quite satisfying in the end, once you've done it once, the same principal applies to any car..

The car builders sound deadened worked out quite well, it stops a lot of the resonance you get from the sub, you don't realize how much **** rattles until you hit the cabin with bass!

Ended up using the rest on the boot, the 12 sheet box was plenty for the polo

One thing you'll notice is a rattle in the rear bumper, there's a cabin pressure vent that rattles like mad, I used a bit of deadener to keep the vent open a few mm which sorted it out.

[flat6]

Quick update this

When it comes to setting the gains on the amp, use test tones, you'll get a more accurate result every time
Realm of Excursion

Using 40htz, 70htz, and 100htz, start at 100, with the volume on the loudest you'd listen to it, turn the gain up until the humm turns into a buzz, then back it off a bit, actually found having the gain too low was the cause of the sharpness in the tweeters, strange huh.