Hertz 240 Watt 4 Speakers 1 Subwoofer
Do It Yourself: Yes (Some parts may need professional help)
Difficulty: Average to Hard
Happy New Year!!!
Just one day after new year, I began to think of upgrading the interior of my Pug particularly on audio. By far, this is the most challenging DIY to date, but I managed to do it within the weekend.
I’m in love in car audio since I’ve own my first car. I’ve learn a lot, some from the professionals, others by trial & error basis.
Anyway, for my Pug. I’ve decided of “SQ” setup. This is the most challenging setup in car audio because it is more on Sound Quality, clarity, sound balance through out the entire sound frequency (we are talking a big range here from 20Hz to 20kHz). Another setup called “SPL” (Sound Pressure Level), this is more on raw power and the main objective is how loud you setup can produce before audio clipping, quality is second here.
The drawback on SQ are…
- Expensive components involve.
- Hard to tune but once you hit it, shortcut roads are not in your option anymore.
Before choosing Hertz, I went a lot of audition on other brands just to get the best value for money (and promotion, this is the jackpot), namely…. (all of the audition was based on my ears and what was available at the dealer at that time. I’m not auditioning their demo car as this is unfair)
- Macrom – Italy, good vocal but lack of mid bass. I own one of the M2 5″ series and still having it in my Kancil.
- Mohawk – Malaysia, good value for money but it is more on SPL, lately their products able to tune to SQ but I’m still skeptic on the performance.
- MB Quart – Germany, very harsh tweeter.
- Dynaudio – Germany, very well known to SQ community and too common.
- Rainbow – Germany, not very much option. A nice SQ.
- Sinfoni – Italy, hand crafted and not very much option. A nice SQ.
Why I chose Hertz….
- I’ve got promotion at that time.
- Not too common.
- Manufactured by the company who produce a well known Audison amplfier, Conection accessories etc.
- Very good mid bass and well balance soft sounded tweeter.
I still have plenty of upgrade plan, this is considered as part one because I only have Hertz front components. The system was matched with my…
- Two years old Clarion APX4240 amplifier (purchased it from Eneos 1U).
- Four years old al cheepo subwoofer (the box was given to me by my friend as he accidentally fried the voice coil and unable to get the replacement. Luckily for me, I’ve found 8″ bass speaker on sale).
- Peugeot RD3 head unit.
For this setup, I laid a one time installation using 8AWG grade cable for the power and ground and 18AWG grade cable for the speakers. The is no RCA output from the head unit, so I’ve to use the speaker level input. Furthermore, the stock head unit does not have remote lead to turn on the amplifier. Until I found a good way to solve this issue, I will use my cigarette lighter 12V feed as the remote lead signal temporarily.
For 12VDC feed for the amplifier, I tapped directly from the battery. Well it is not directly on the terminal, I’m using the relays and fuses box. With the cover, it is well hidden from the plain sight.
The cable was laid beside the battery all the way to the firewall. If you notice, there is an extra rubber gourmet which is just nice for the cable to pass through.
The speaker output from the head unit was directed to amplifier. Then, the output from the amplifier was connected back to the original wiring to drive the speakers. This is speaker level input method. All of the wiring connection was done using heat shrink tubing, much more reliable than the pvc tape or block connector. IMHO.
All the speaker cables are routed behind the instrument cluster, then downward at the A pillar to the door sill. The cables are laid along the door sill using all the factory supplied wiring harness.
Temporarily, the amplifier was not properly mounted in the boot. Plan to change it later.
I’m using two method of amplifier gain adjustments. Mathematical using multimeter and ears approach. Since I do not have oscilloscope to be able to tune perfectly. It will be done up to my satisfactory level.
- Get the optimal speaker output voltage in AC by getting the square root of RMS power of the amplifier x the speaker impedance in each channel. In may case, it was 15.5 volt. For example, my amplifier able to produce 55 watts x 4 channel. Thus, for front two speaker setup = 60 watts x 4 ohm = 15.49 volt. For bridged connection, get the rated bridged amp power instead.
- Connect the multimeter to the speaker output of the amplifier. Set it to 20VAC range.
- For front component, I’m using 1000Hz test tone recorded at 0dB, for sub is 50Hz test tone.
- Flat out the bass and treble; turned off the loudness.
- Crank up the head unit volume to 3/4 of the maximum volume (which is 22) and increase the amplifier gain to get 15.5 volt.
- Note: For my setup, I’ve to turn down the volume to 1/2 as 3/4 yield a 22VAC before gain which definitely a clipping.
- After done the above adjustment, I’m using a few audio CDs to fine tune the sound staging and subwoofer level.
- It is a mixed music from Celine Dion (A New Day Has Come), Ella (A Journey Beyond…), Search (Memori Hit Rock Otai), Awesome 80’s Disc 3 compilation, Metallica (Black); M. Nasir (Terbaik M. Nasir – the best album to test full frequency of sound production; rich of orchestral instruments) and a few track from IASCA Test Audio.
- Finally, the setup was done with 65Hz highpass for the front components and 65Hz lowpass for the subwoofer.
Although the tweeter looks small, it is actually same as the factory fitted tweeter. The original tweeter looks big because of the casing. The white connector is an aftermarket connector, you can have the casing from any electronic outlets.
Hertz supplied with a lot of tweeter mounting kit to cater all kind of installation. The one I’m using is direct replacement of OEM mounting. There are flush mounting, surface mounting and wedge mounting with 30 and 60 degrees angle.
The mid bass speaker was mounted on a spacer as there is not enough depth to fix the speaker. The passive crossover was taped to the door membrane. A few cuts was done at the door card styrofoam before fixing to accommodate the crossover.
That’s all from now. To be continued…
- Reuse the original sponge lining (which is glued together with the OEM speaker). No more excessive door card vibration.
- Changed the mid bass speaker cable to 18AWG, originally using supplied tweeter cable.
- Changed both tweeters polarity as it were out of phase.
- Changed the speaker spacer / adapter from MDF to plastic, more robust and fit nicely.
- Rerouted ground and power cable termination points to minimize cable tension.
- Downgrade the fuse rating from 40AMP to 20AMP, adequate for current amplifier requirement