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4-way active setup in a Polo with 15 inch subwoofer

Kannan

Well-Known Member
Joined
Jan 13, 2008
Messages
1,476
Points
113
Location
Chennai
3-way front stage active with rear passive and 15 inch subwoofer in a Volkswagen Polo

35795

I was approached to help in building a setup that could be used for both SQ as well as a a decent SPL in a Volkswagon Polo.
The owner had quite a bit of equipment of which the most challenging was the 15 inch Digital Design subwoofer.
The car being a hatchback, it was tricky to design one to satisfy both the needs of listening which oscillated from pure sound quality to a bit of head banger as well.

Amplifiers - 3: Audison LRX (4-channel amp), Hertz HDP4 (4-channel amp) and a Hertz HDP1 (mono).
Speakers: Frontstage (Fully Active) - Audible Physics RG50 tweeters, Audible Physics NZ (3.5 inch) wideband and Audible Physics Brahma (6.5 inch) midbass

Rear Fills (Passive) - Hertx Mille components
Subwoofer: Digital Designs 15 inch (4 ohm single or as 2 ohm dual voice coil)
Head Unit: Pioneer 5000 series
Digital Source: Allo Digione
Processor: Helix DSP mkii pro
Cables: Belden coaxial, Connectix interconnects and Belden Speaker Cables

SUBWOOFER

The biggest challenge in this setup was to design the subwoofer due to limitation of space.
I did my Maths and decided on a 3.2 to 4 cubic feet 2nd order bandpass enclosure.
As it was the persons daily ride, and mostly within city, he was open to give away the wheel well for the fiberglass/wood fabrication.

I will let the pictures speak here.

35784

35785

35786

35787

35794

This way of designing the subwoofer had many advantageous with respect to this car.
1. i could get good depth in the enclosure and get both the bandpass accurate.
2. The 1st bandpass located at the bottom, trapped the back waves and directed it out via the 2nd bandpass which was facing up and at the farthest end from the sub.
3. As the base of the sub was completely locked into the wheel well (which was completed damped on all sides), there was no rolling or vibration even at the highest SLP levels.
4. It left enough space to mount all the three amplifiers in the boot along with the DSP and the digione. All I had to do was run one RCA cable from the Pio head unit to the DSP. I could keep rest of all the signal cables short, except ofcourse the speaker cables.

Front Tweeters and Wideband:
This was another big challenge due to the shape of the dashboard, limited depth, airbags, puny A Panel and external air vents close to the A Panel in the dashboard.
For the wideband to play its capable bandwidth from as low as 250hz, I needed minimum 1 to 1.3 liter enclosure.
I managed to fabricate this by cutting out a portion of the A Panel cover and utilizing the entire cavity of the A Panel. Then the wideband and tweeters were properly angled to keep them as away from the windscreen and side windows as possible and still minimize it from getting off axis to the driver's seat. The wideband compensated for stage height and the tweeters for width in the design.
The A Panel at he bottom had a little vent for routing cables etc, this I left deliberately open to reduce encosure resonance. The metal face of the A Panel was covered with a 8mm layer of rock wool pad to prevent reflection from the metal surface.

The pics:

35789

35790

Final finish:

35791

35792

Rear Tweeter fabrication:
As the rears were only fills to be used when there were rear passengers, I fabricated the tweeters as close to the midbass on the doors.

35793

The install was completed in 8 working days as the installers could not work continuously.
It took another 8 hours to troubleshoot the nitty grity and fully tune the setup.

The Helix DSP pro is a marvel, a super SQ beast with tons of active tuning features

I finally settled for
Wideband: High passed at 289 hz (at 12db). (No low pass
Tweeters: High passed at 12600 hz
Midbass: Bandpassed between 80 hz (18db) and 289 hz (12db)
Subwoofer: Low passed at 80 (18db).
Db levels set individually for complete blending of the all the drivers.
Time aligned for proper imaging and staging.

Totally phase aligned, time aligned and gain matched with ears using a collection of tuning tracks and later fined tuned with familiar songs.

The DSP comes with a remote which can/was mounted in the front under the Pioneer headunit. It can store up to 30/40 presets and the user can switch to a needed preset instantly with a flick of a button.
I provided three preset options:
One pure SQ setting with only frontsatge, one with the rear also paying and one full SPL setup.

Impressions:
The depth is almost a foot outside the windscreen, superb height and width as well. No digital grain or fatigue. Expecting further refinement in another 100 to 150 hours of break-in.
The output from digione has better fidelity than the output taken from Pioneer.

Chennai guys are welcome to audition. But need to seek permission of the owner for a mutually convenient time.
PM me if interested.

I have kept it brief, if there are any queries and sugesstions, please post here.
 
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rikhav

Well-Known Member
Joined
Mar 27, 2008
Messages
2,260
Points
113
First proper car audio build documented on our forum.
Maybe there is some old thread that I am not aware of
Excellent work and execution
 

Mahi

Member
Joined
Dec 24, 2017
Messages
71
Points
8
Location
Bangalore
3-way front stage active with rear passive and 15 inch subwoofer in a Volkswagen Polo

View attachment 35795

I was approached to help in building a setup that could be used for both SQ as well as a a decent SPL in a Volkswagon Polo.
The owner had quite a bit of equipment of which the most challenging was the 15 inch Digital Design subwoofer.
The car being a hatchback, it was tricky to design one to satisfy both the needs of listening which oscillated from pure sound quality to a bit of head banger as well.

Amplifiers - 3: Audison LRX (4-channel amp), Hertz HDP4 (4-channel amp) and a Hertz HDP1 (mono).
Speakers: Frontstage (Fully Active) - Audible Physics RG50 tweeters, Audible Physics NZ (3.5 inch) wideband and Audible Physics Brahma (6.5 inch) midbass

Rear Fills (Passive) - Hertx Mille components
Subwoofer: Digital Designs 15 inch (4 ohm single or as 2 ohm dual voice coil)
Head Unit: Pioneer 5000 series
Digital Source: Allo Digione
Processor: Helix DSP mkii pro
Cables: Belden coaxial, Connectix interconnects and Belden Speaker Cables

SUBWOOFER

The biggest challenge in this setup was to design the subwoofer due to limitation of space.
I did my Maths and decided on a 3.2 to 4 cubic feet 2nd order bandpass enclosure.
As it was the persons daily ride, and mostly within city, he was open to give away the wheel well for the fiberglass/wood fabrication.

I will let the pictures speak here.

View attachment 35784

View attachment 35785

View attachment 35786

View attachment 35787

View attachment 35794

This way of designing the subwoofer had many advantageous with respect to this car.
1. i could get good depth in the enclosure and get both the bandpass accurate.
2. The 1st bandpass located at the bottom, trapped the back waves and directed it out via the 2nd bandpass which was facing up and at the farthest end from the sub.
3. As the base of the sub was completely locked into the wheel well (which was completed damped on all sides), there was no rolling or vibration even at the highest SLP levels.
4. It left enough space to mount all the three amplifiers in the boot along with the DSP and the digione. All I had to do was run one RCA cable from the Pio head unit to the DSP. I could keep rest of all the signal cables short, except ofcourse the speaker cables.

Front Tweeters and Wideband:
This was another big challenge due to the shape of the dashboard, limited depth, airbags, puny A Panel and external air vents close to the A Panel in the dashboard.
For the wideband to play its capable bandwidth from as low as 250hz, I needed minimum 1 to 1.3 liter enclosure.
I managed to fabricate this by cutting out a portion of the A Panel cover and utilizing the entire cavity of the A Panel. Then the wideband and tweeters were properly angled to keep them as away from the windscreen and side windows as possible and still minimize it from getting off axis to the driver's seat. The wideband compensated for stage height and the tweeters for width in the design.
The A Panel at he bottom had a little vent for routing cables etc, this I left deliberately open to reduce encosure resonance. The metal face of the A Panel was covered with a 8mm layer of rock wool pad to prevent reflection from the metal surface.

The pics:

View attachment 35789

View attachment 35790

Final finish:

View attachment 35791

View attachment 35792

Rear Tweeter fabrication:
As the rears were only fills to be used when there were rear passengers, I fabricated the tweeters as close to the midbass on the doors.

View attachment 35793

The install was completed in 8 working days as the installers could not work continuously.
It took another 8 hours to troubleshoot the nitty grity and fully tune the setup.

The Helix DSP pro is a marvel, a super SQ beast with tons of active tuning features

I finally settled for
Wideband: High passed at 289 hz (at 12db). (No low pass
Tweeters: High passed at 12600 hz
Midbass: Bandpassed between 80 hz (18db) and 289 hz (12db)
Subwoofer: Low passed at 80 (18db).
Db levels set individually for complete blending of the all the drivers.
Time aligned for proper imaging and staging.

Totally phase aligned, time aligned and gain matched with ears using a collection of tuning tracks and later fined tuned with familiar songs.

The DSP comes with a remote which can/was mounted in the front under the Pioneer headunit. It can store up to 30/40 presets and the user can switch to a needed preset instantly with a flick of a button.
I provided three preset options:
One pure SQ setting with only frontsatge, one with the rear also paying and one full SPL setup.

Impressions:
The depth is almost a foot outside the windscreen, superb height and width as well. No digital grain or fatigue. Expecting further refinement in another 100 to 150 hours of break-in.
The output from digione has better fidelity than the output taken from Pioneer.

Chennai guys are welcome to audition. But need to seek permission of the owner for a mutually convenient time.
PM me if interested.

I have kept it brief, if there are any queries and sugesstions, please post here.
Very good working kannan sir, well equipped system
 

VSTEREO

Active Member
Joined
May 7, 2016
Messages
146
Points
28
Location
Chennai
Very good system, Kannan sir. Fabrication work is top notch.

Can you explain the integration of Allo Digione with rest of the gear ? I have seen few using Allo in Car but never had a chance to listen one.
 

MaSh

Well-Known Member
Joined
Oct 12, 2012
Messages
2,556
Points
113
Location
Bangalore
Oh my god, what a setup in a car.

What's the clearance of the front Tweeters from the Airbags? The left one in the pics seems a bit close, maybe the angle shows it as such.

MaSh
 

Kannan

Well-Known Member
Joined
Jan 13, 2008
Messages
1,476
Points
113
Location
Chennai
Well
Oh my god, what a setup in a car.

What's the clearance of the front Tweeters from the Airbags? The left one in the pics seems a bit close, maybe the angle shows it as such.

MaSh
Well clear of airbags.

Can you explain the integration of Allo Digione with rest of the gear ? I have seen few using Allo in Car but never had a chance to listen one.
You can do it in 2 ways. If you want to use only the local content attached to the raspi (pen drive or HDD), then you can simply use the inbuilt hotspot feature of Volumio and control it headless from you mobile or any tablet by connecting to the Volumio hotspot.

If you also want to stream content like spotify or tidal, then you will need an active internet connection. You can do that by using your mobile data or with a dedicated Jio type data card.
 

mpasanthosh

Member
Joined
Oct 23, 2015
Messages
46
Points
18
Location
Salem
Excellent work !.

I have auditioned the car it sounds very good, have to admit the subwoofers enclosure design was nicely done, and a very complicated design.
The fiberglassing on the a-pillars is top notch.

The AP drivers do perform very well in the properly tuned and time aligned setup.
 
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