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Speaker upgrade - tweeters report, rear question #1627736
09/12/2018 22:17
09/12/2018 22:17
Joined: Sep 2014
Posts: 37
Rijeka, Croatia
gturcic20vT Offline OP
Discoverer
gturcic20vT  Offline OP
Discoverer

Joined: Sep 2014
Posts: 37
Rijeka, Croatia
Hello,
Recently I've upgraded my Coupe speakers. Main theme is tweeter placement, don't know if it's been covered on forum but wanted to share my experience.
In the end, I have a question, regarding rear speakers.

This is a basic passive system - headunit and speakers in stock positions.
I wanted "decent" sound quality at low to moderate volume. I didn't want to get amplifiers, subwoofers, active crossovers for multiple reasons - mainly fear of never ending project, tinkering with the interior, and rising cost.
As a baseline, I know (or think I know) how a decent "neutral" sound quality system should sound. Years ago I had an interest in home Hi-Fi, listened to some amazing high-end gear, had a decent Marantz / Denon amp/player and floorstander speakers; now i have a Pioneer AV receiver (average sound, but love the other features) and Qacoustic 3020 speakers.

It took me a while to get the sound "right".

Short(er) version:
I've changed the head unit, and then all the speakers, then swapped the tweeters, finally changed the tweeter position. Phases:
1. old Alpine + factory speakers
2. Alpine HU + factory speakers
3. Alpine HU + Hertz speakers, tweeters in dash
4. Alpine HU + Hertz + ESX SQ6.2T tweeters in dash
5. Alpine HU + Hertz speakers, tweeters in pods

I'll write my (subjective) marks on different arbitrary categories and scale:
1=bad ... 3=good ... 5=excellent
Overall sound - how pleased am I with the overall sound
Clarity/Detail - how much of finer tones, voices or melodies can be heard
Stereo imaging - how balanced are left/right channels and how wide/deep is the imaginary soundstage
Smoothness - opposite to "harsh" = no sharp tones or vocals; does not cause fatigue on long and/or loud listening.

..... OVERALL SOUND ... Clarity/Detail ... Stereo imaging ... Bass ... Smoothness
1 .......... 3.0 .................... 3 ....................... 3 .......................... 4 .......... 3
2 .......... 3.5 .................... 4 ....................... 3 .......................... 2 .......... 4
3 .......... 3.5 .................... 5 ....................... 4 .......................... 3 .......... 2
4 .......... 3.5 .................... 4 ....................... 4 .......................... 3 .......... 3
5 .......... 4.5 .................... 5 ....................... 5 .......................... 4 .......... 4

My conclusion - aftermarket tweeters don't work well in stock "in dash" position. The couple (Hertz, ESX) I tried sounded very harsh, much worse than factory ones. Could be that factory tweeters have particular on axis/off axis sound dispersion patterns.
Experiment, try and test what sounds best. Massive differences lie in placement.

Long version:
Years back (2004), when I purchased the car (second hand) it had a basic Blaupunkt HU, and I swapped it for a mid-level Alpine. I was pleased with the sound on stock factory speakers - I didn't listen at high volume, and it had decent overall balance - enough bass, no harsh treble.
Since that Alpine didn't have USB (or Bluetooth) 2 years ago I swapped it for Alpine CDE-177BT. It's high-end model from the "classic" 1DIN line; it has many features for tuning the sound (parametric EQ, time delay , HPF, LPF filters etc.) I had vastly more detailed sound, but somehow, lost quite a lot of bass. However, I refused to go the "upgrade the chain" route.
Then, a year ago, I replaced stock speakers in my other car, and hearing the benefits, decided to do the same on Coupe.
Since I'd let the HU power the speakers directly, I looked for high sensitivity ones - bought Hertz ESK 165L.5 2-way components (Energy series, 120€) for the front and DCX 170.3 2-way coax (Dieci series, 60€) for the rear.
I've let the local audio shop install them, and sound-deaden the doors and rear panels, both body metal and trim panels. The tweeters went to stock position (behind mesh on the dash), other speakers also.
After the install, the sound was very different. There was much more detail, but even less bass, and treble was very "bright". The installer said Hertz speakers tend to have "bright" tweeters, but everything should "loosen up" a little with run-in.
With more listening nothing changed - there was very little kick-bass, and the tweeters sounded very harsh on some tones - piercing on high male or female vocals, sharp "s" consonants etc. I could EQ some of it with HU (with boost in 100-400Hz and dip in 2-8kHz), but then the back speakers sounded really muddy and unnatural. Displeased, I've even opened the dash side panels and checked all the wires and connections to the supplied speaker crossovers etc, but everything was wired ok.
After 2 months I got back to audio shop, and they talked me into changing the tweeters - they proposed ESX SQ6.2T (60€), and i had them put in the dash, replacing Hertz units. The sound became smoother, but after listening for a few days, I noteiced it lacked some detail and musicality compared to Hertz.
Displeased, I searched the web, and after reading various oppinions and advices on in-car reflections and speaker placement, decided to try and place the Hertz tweeters (that I liked better, regardless the harshness) in supplied pods, somewhere on A pillars. Since I didn't want to alter the interior, I mounted the cups at the base od A pillar, with a longer bolt that goes to the existing hole in the pillar trim panel. And that's it - the harshness is gone; the tweeter volume is lower, so the bass gets a little better; I can listen a lot louder without fatigue.

Now the question - has anybody put just 16cm woofers (without tweeters) in the back side panels, instead of 16cm coaxials?
As is, I'm very pleased with the overall sound. The rear speakers produce a lot of bass, and nicely fill-in the cabin, but I have to adjust fader to +5 (on a scale -15 to +15) to the front. If centered, the front sounstage gets dispersed. Would loosing the tweeters in the back focus the image back to front, and how would it sound for the (occasional) rear passengers?
I have a pair of 16cm Hifonics Titan woofers with full 18dB/octave crossover on idle.

SOME PICTURES

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HERTZ tweeters in dash
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HERTZ tweeters on A pillar pods
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Last edited by Gunzi; 13/12/2018 11:39. Reason: edit images for forum coding
Re: Speaker upgrade - tweeters report, rear question [Re: gturcic20vT] #1627737
09/12/2018 23:07
09/12/2018 23:07
Joined: Jan 2009
Posts: 599
Spain
avtokrator Offline
Enjoying the ride
avtokrator  Offline
Enjoying the ride

Joined: Jan 2009
Posts: 599
Spain
I strongly suspect the sound quality problems come from the factory supplied filters, these are majorly designed to work with power amp. Try to avoid them and see if there is positive difference.

Re: Speaker upgrade - tweeters report, rear question [Re: gturcic20vT] #1627875
13/12/2018 11:40
13/12/2018 11:40
Joined: Aug 2007
Posts: 7,063
Southsea
Gunzi Offline
Club Member 189
Gunzi  Offline
Club Member 189
Forum is my life

Joined: Aug 2007
Posts: 7,063
Southsea
Great write up and whilst I didn't go to the detail you have of swapping the tweeters around, I found a significant improvement in sound quailty by replacing the headunit and front speakers vs the OEM kit from the 1990's!

I installed 6x9's in the rear position to give extra bass to the overall music experience, so can't comment on fitting mids without the tweeters in the back.

Re: Speaker upgrade - tweeters report, rear question [Re: gturcic20vT] #1627878
13/12/2018 12:46
13/12/2018 12:46
Joined: Aug 2007
Posts: 802
Germany
neil_r Offline
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neil_r  Offline
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Joined: Aug 2007
Posts: 802
Germany
I was happy enough with new tweeters in the standard positions but a small active sub in the left boot wing cavity fills out the bass very well giving a richer rounded sound. The rear speakers choice or level is then not so important.


1997 20V
2000 V6 manual S-Type and 2011 5.0 XKR
2016 Tucson 1.6T AWD
2018 Mazda2 GT
Re: Speaker upgrade - tweeters report, rear question [Re: avtokrator] #1627988
16/12/2018 21:30
16/12/2018 21:30
Joined: Sep 2014
Posts: 37
Rijeka, Croatia
gturcic20vT Offline OP
Discoverer
gturcic20vT  Offline OP
Discoverer

Joined: Sep 2014
Posts: 37
Rijeka, Croatia
Originally Posted By avtokrator
I strongly suspect the sound quality problems come from the factory supplied filters, these are majorly designed to work with power amp. Try to avoid them and see if there is positive difference.


I don't know if I misunderstood You.
It's a passive system, without active crossovers before dedicated amps, and that's my decision.

In a passive system, You need to have a crossover. Without it, tweeters get damaged playing too low frequencies, and woofer coils can overheat trying to play too high frequencies.

Simplest crossover is 1st order (6dB/octave) = capacitor in series with tweeter, inductor in series with woofer.
Stock Fiat speakers don't have a dedicated crossover, tweeters have a small capacitor in series, on the back of the plastic housing. Don't know if stock woofers have anything.

More advanced crossover is 2nd order (12dB/octave) = many aftermarket component speaker kits have them, either "in line" box or a bigger box. My Hertz kit has one with tweeter level switch (+2, 0, -2dB).
Some higher end kits have 3rd (18dB/octave) or higher order...

Any crossover is a compromise, but it's necessary if You want to cover the audible range (20Hz - 20kHz) with "normal" speakers.

Crossover "should" work the same with integrated or dedicated amplifier, at least in low to moderate power range. It does affect amplifier damping factor, but I'm no expert on the subject. I think the speaker kit manufacturer made the crossovers as good as they can be, within the budget and driver (speaker) limitations, and I wouldn't consider bypassing them.

BTW, my alpine HU volume goes on a scale from 0 to 35. I usually listen to 10-15, maximum 18. I can just hear difference in volume for every step, so I assume it's around 1dB increment. With those assumptions, the volume control goes to +35dB, and I only listen to +15dB. It's a 20dB difference, or 100x the power. The internal amp is rated at 4x50W (even if real power is way lower), so I'm listenig to less than 1W of power. However false this math is, I wanted to show that I'm not pushing the internal amp.

Re: Speaker upgrade - tweeters report, rear question [Re: gturcic20vT] #1628010
18/12/2018 07:39
18/12/2018 07:39
Joined: Aug 2007
Posts: 802
Germany
neil_r Offline
Enjoying the ride
neil_r  Offline
Enjoying the ride

Joined: Aug 2007
Posts: 802
Germany
Originally Posted By gturcic20vT
In a passive system, You need to have a crossover. Without it, tweeters get damaged playing too low frequencies, and woofer coils can overheat trying to play too high frequencies.


You are right - the head unit outputs a full-frequency signal. The bass/midrange unit may have a smooth enough roll off of output as the frequencies rise not to need any filtering. High frequency signals contain little enough energy to not worry a bass/mid driver and they can't reproduce those frequencies so they don't have much effect on the basic sound. There might be resonances that one would like to avoid though so filtering may still be desirable if affordable.

Tweeters can't take the high amounts of power in the bass frequencies so overheat their voice coils and melt them. A high-pass filter is essential - the simplest of which is, as you say, a capacitor in series with the tweeter.

The order of the crossover governs its filtering slope and is not necessarily a guide to quality but more the degree of filtering required to correctly integrate two drive units being applied adjacently in the frequency range.

Yes, you don't actually need a lot of power to make noise. More power enables you to drive less efficient but better speakers similarly loudly. For example, a home hifi with 200w per channel does not go that much louder than a 20w amp driving the same speakers. The beefier amp can control and drive more complex, less efficient speakers and my have better transient response etc, but it is not really significantly louder.

These days, pick a good but sensibly priced head unit and good affordable speakers and you can get a perfectly acceptable sound in a car. Trying to get more sound quality, especially in the noisy environment of a car, costs dramatically more and probably only increases the quality by a small amount.


1997 20V
2000 V6 manual S-Type and 2011 5.0 XKR
2016 Tucson 1.6T AWD
2018 Mazda2 GT
Re: Speaker upgrade - tweeters report, rear question [Re: gturcic20vT] #1628037
19/12/2018 00:39
19/12/2018 00:39
Joined: Jan 2009
Posts: 599
Spain
avtokrator Offline
Enjoying the ride
avtokrator  Offline
Enjoying the ride

Joined: Jan 2009
Posts: 599
Spain
That’s exactly what I meant, try the simplest 1st order filter, a cap...also, knowing the driver characteristics definitely is primordial.
You are right, the Fiat factory system doesn’t have nothing but a cap for the tweeter, the mid/woofer driver is directly connected. And yes you all are right about filtering the drivers signals, and yes - the commonly supplied crossovers “should” work as intended, but in most cases they are not so great build and component quality, and/or properly calculated, and this strongly affects the sensitivity and the signal attenuation. In home system the high frequencies are the first to be “eaten” by the room and everything in it, but the car interior is different, you have the windscreen just above and acts as excellent reflector, so in my opinion at yet very moderate power levels the desired hi-freq sound should be obtainable without so much hassles, that’s what makes me think there is something wrong in the electric path. These 50 Watts/channel aren’t very real Watts of power...

Last edited by avtokrator; 19/12/2018 00:39.

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