MkIV Octavia VRS Audio upgrade - disappointing

[SkOmk4]

My question is not really about the "VRS Audio upgrade", but I hate opening new topics for very similar issues...
I have a Style trim with stock audio (not Canton) and I noticed a HUGE discrepancy in the sound quality between different levels of volume. At low volume the sound is extremely crappy - sounds like a cheap empty tin-can; the higher the volume, the better the sound quality... Is this the general perception? Or is-there something wrong with my ears?
Comparing to my previous cars, I can say without any doubt that the standard audio of my 2008 Megane sounds much, much better than the Octavia, only at low volume; they become comparable at higher volume and at some point the Octavia sound quality goes above the Megane one. There's no comparison between the 2018 Megane GT that had a factory fitted Bose system and the Octavia...

[MP1983]

On 29/10/2022 at 22:26, Filternz said:

...

Below is the xover of the flax fronts you have. Electrically, its a 3rd order on the tw (or 2nd order with a contour network for the woofer, not sure what the second 4.7uF cap is doing as no schematic neither I can measure it) and 2nd order on the woofer. A few tips to try:

 

* check with a multimeter if there is a connection between the two 4.7uF caps by measuring on the side of the coil. If there is, then its a 3rd order electrical which may well be a 4th order acoustic slope (24db/oct). You can then try the following: remove the last 4.7uF cap (before the tweeter) and replace with wire. Remove the 18uF cap on the woofer - the value for a 4ohm driver (I haven`t measured it so a shot in the semi-dark) is large indicating this is likely also a 24db/oct slope. Try replacing it with a small cap - you can use the 4.7uF - this will give you a lighter roll-off and more midrange coming from the midwoofer Those are mounted very low in the Octavia so you`re (to the left side) at least 60 degrees off-axis - at such angle driver roll-off for a typical 6.5" with a phase plug would start at 2.3-2.5Khz (hence some not adding a crossover at all). Note, leaving the coil only (so using wire instead of the cap) would roll-off the driver with a shallower slope but will start earlier so don`t do it (you could, but with a smaller coil instead of this one). Its an easy modification - you need to resolder a few components on the PCB.

*if there is no connection between the two caps then this may be a contour network for the woofer (it may have a narrower cone resonance). Then one of these 4.7uF caps shall be connected to the large coil and one of the resistors should be across it (shorting it, effectively). If that is the case, try adding a piece of iron (a nut) inside the small tweeter coil and see if it brightens sound. If it does you can use hotmelt glue to leave it there or just replace the coil with a bigger value. You can also try replacing the tweeter cap (its one of the 4.7uF ones) with a bigger value as well, this will move the crossover point to a lower frequency hence clearer sound. Woofer advice from above also holds.

 

A piece of caution - doing the above will brighten the sound and may improve your midrange but will reduce power handling and may introduce another problem - at higher power to get more distortion our of the tweeter as its Fs is likely 1.2-1.3Khz and these rarely have ferrofluid in the gap so resonance shall be more pronounced. Still, doing it will give you more means of affecting sound from the car equalizer later on.

[Felix2021]

18 hours ago, SkOmk4 said:

Is this the general perception?

I wouldn't call it "extremely crappy", but yes, it is general perception. It 's a mix of how our ears work, car accoustics and components used.

It might seem as a paradox, but it's much easier to build a system that sounds good at high level, than one that sounds good at low levels.

In theory in VAG cars there's EQ, that should be managing this to some extent, but bumping the highs and lows at low levels, but it's not very effective. Probably they didn't want to overdo it. It works more or less the same, as "loudness" function that was hated by many.

Sound deadening of the doors should help, as well as replacing at least the tweeters, which are really crappy.

 

2 hours ago, MP1983 said:

Electrically, its a 3rd order on the tw (or 2nd order with a contour network for the woofer, not sure what the second 4.7uF cap is doing as no schematic neither I can measure it) and 2nd order on the woofer.

According to specs both are 2nd order filters. Second cap might be part of a notch filter, which is commonly used with Focal speakers, due to having rigid cone of the tweeter. It's there to remove possible cone resonance frequency, hence limiting distortion.

I have actually built active speaker set using Focal TC90TD5 as part of my thesis.

[MP1983]

9 hours ago, Felix2021 said:

According to specs both are 2nd order filters. Second cap might be part of a notch filter, which is commonly used with Focal speakers, due to having rigid cone of the tweeter. It's there to remove possible cone resonance frequency, hence limiting distortion.

I have actually built active speaker set using Focal TC90TD5 as part of my thesis.

Manufacturer specs give the combined (acoustic) slope, not the electrical as its the important one. How you achieve it is your biz. I seriously doubt they put a notch on a tweeter, can you share an example? A typical hard dome has a resonance at 23-27Khz, the values for such notch are tiny and totally unneeded as even 3rd harmonic would be at 8-9Khz and it would be scarcely amplified by the tweeter motor as its weak.

 

[Felix2021]

16 hours ago, MP1983 said:

Manufacturer specs give the combined (acoustic) slope, not the electrical as its the important one. How you achieve it is your biz.

Depends on the manufacturer.

Looking at this XO pics you attached, to me it seems to be 12dB electrical filter. Then again, it's hard to be sure without schematics.

 

16 hours ago, MP1983 said:

I seriously doubt they put a notch on a tweeter, can you share an example?

Maybe not in this case, i don't know. But it's quite common to have a notch filter on a tweeter. This allows for "cutting" it fair bit lower.

 

16 hours ago, MP1983 said:

A typical hard dome has a resonance at 23-27Khz, the values for such notch are tiny and totally unneeded as even 3rd harmonic would be at 8-9Khz and it would be scarcely amplified by the tweeter motor as its weak.

Maybe we're talking about different things, but notch filter is calculated based on Fs of the speaker.

http://www.mh-audio.nl/Calculators/NFC.html

""Most drivers benefits from using notch filters, specially tweeters and midranges where the component values can be kept small. Using this filter on bass drivers calls for very large (and expensive) components."

 

I have ordered Focal's to my car. Let's see how they sound when i get them and have some time to install. I still have to install mats in the rear doors, and planning to do it while installing speakers.

If i have some time, i'll try to take some measurements before and after with my UMIK1.

Edited 9 November, 2022 by Felix2021

[MP1983]

Look Felix, typically a notch (LCR or CR in rarer cases) is used to suppress a cone resonance. While there are tons of online calculators that offer crossovers, lcr and l-pad calculation, they`re mostly useless and everyone that has designed at least a few speakers knows it. Actual approach is by measuring and then designing using software, such as LSP Cad or similar. Then you`d find our how misleading and useless are those online calcs such as the one posted, especially on crossovers. A strong resonance of a tweeter at Fs can be suppressed easily enough by a simple resistor across its terminal (usually using an l-pad). Complex LCR networks are rarely needed and usually employed by people believing they`d solve an issue that indeed they created by using the tweeter improperly. And again - a crossover type and its behaviour is determined by the acoustics (combined) slopes, not by its electrical order. There are very complex 1st order networks that while offering a simple 6db/oct decay indeed involve 10-12 elements such as coils, caps and etc.

 

Anyways, topic went elsewhere. Before you close measurements, I`d also run impedance sweeps so actual crossover adjustments can be done.

Edited 9 November, 2022 by MP1983

[Felix2021]

I'll pass on replying this time...

[Filternz]

Thanks for the awesome replies. A little over my head - but I do have a simple question. Getting a second amp and going active setup and removing the cross-overs, then getting it tuned should yield the best result, yes?

[Felix2021]

I think you would gain much more by replacing the Focal amp to something with DSP, like Match M-5DSP and tuning using sound processor.

I still don't get why you are getting sound, that is "almost worse than stock". Maybe your garage messed something up during installation?

Have they set the gain correctly? Crossover setting? Have you checked all of that?

Maybe would be worth to try Focal's speaker simulator/dummy load, to lower built in amp's distortion?

[MP1983]

14 hours ago, Felix2021 said:

I think you would gain much more by replacing the Focal amp to something with DSP, like Match M-5DSP and tuning using sound processor.

 

This. The Match series have inbuilt de-equalization so signal is flattened from whatever factory equalization applies. Then you can manipulate it as you wish and you will get much better sound. The Match DSP8 is a better choice than than the 5 as you can set separate delay for each speaker upfront (total of four), individual crossovers left-right and run the back with two separate channels (passive xovers should be employed) but in general terms you don`t want to run backs even if for filling and then you`d have two channels to bridge and drive a sub or two small subs. The 8-channel one came a few months ago so pretty new. Then at some later point you can even do a 3-way upfront, use one channel +/- for the backs and one channel for sub. Its a great unit.

[Felix2021]

Have completed IS VW 165 installation in the front.

Difference is quite big. Bit better bass extension, better mid range and highs, much better decays/reverbs (like guitar strings) and details and better sound stage (git some depth to it). I like it.

That again makes me think, that @Filternz should review amp settings, as there has to be something wrong. Flax + amp should be MUCH better than stock, unless something is messed up.

[Felix2021]

Small update after a bit longer drive today.

Actually bass extension and quality is much better than with stock speakers. But biggest difference is in case of "dense" music. Before Roots by Sepultura sounded flat and everything turned into one piece of "noise". Now it's much better. Sound is selective, you can hear separate instruments and bass line sounds much better.

Wonder how it develops when speakers are fully "burned-in", as well as when i replace (and deaden) the rear...

[MP1983]

Front doors on my car had a tiny bitumen sheet but overall feel quite solid. The rear doors, however, feel as if made from chocolate foil so damping them should give you a big diff I think. Also the trunk, I have a feeling lots of noise comes from there (as well as some annoying thump when releasing clutch from standstill).

[Felix2021]

I agree front doors felt solid, but that was before using butyl mats and foam. By comparison before there were not solid at all

Done rear yesterday. Installed Focal IS VW 155 set, used butyl mats inside of the doors, but this time only below reinforcement, behind the speaker. Somehow didn't feel like removing the glass and mechanism this time. Also 10mm foam on the door card.

Noise is bit lower again. To be honest it slowly starts to feel almost "premium-like"

Sound is a bit better again, but it's not as dramatic difference, as when i replaced the fronts.

Anyway highly recommend both deadening of the doors and replacing the speakers. Those Focals are great for the money.

[zorglub]

where do you buy your deadening material ?

[Felix2021]

I'm getting it from local distributor in Poland.

I guess you can find plenty of them in France, you could also use Amazon. There's a big choice.

[Felix2021]

Bumping old(ish) thread.

 

@Filternz do you have any progress with your audio? Were you able to fix it/get good sounds?

I have found interesting amp - Axton A592DSP. It's 4 channel class D amp with built-in DSP,up to 4x76W RMS. Just ordered it, and will see how it works.

Just thought it might work in your case. It's plug and play, costs roughly same as Focal amp, and has DSP including 31 band EQ.

[twonks]

Hi all. It's been many years since I was here but, having just ordered a new Octavia I will be back

 

Car audio has been a passion of mine for many years and I have a lot of experience with Helix and VW based systems, having had a P-Six amp for 5 years before upgrading to a newer unit to get the better DSP.

 

Using a factory VW based head unit into the P Six at high level will always sound rubbish I'm afraid, irrespective of any de-equalisation.

I too have the same Flax component kit and ran them actively off the P Six, with a 750W mono block for many sub options in the boot.

 

The main problem with a DSP that offers de-equalisation is in general they will only do it at a set head unit volume control. To then hear the flat sound, you need an external volume control from the amp.

Because of this, you might as well simply use an external source with a clean digital out into the Helix (or any other such amp) and then use the same external volume control to adjust your levels. If it is an all Helix / Match system, the remote will also have programmable buttons to go between sources so you can still leave the factory connected at high level should you choose.

 

I ran an iPod touch through a camera kit to give me USB digital out, then through a Topping D10s to get optical from the USB and into the P-Six. All controlled from a Helix URC.2 remote discreetly in the dash. Also gave me sub level control as well as the source selection, and was immeasurably better than the factory signal in every way.

 

In my last VW, I was that impressed with simply amplifying the factory fronts using there own passive x/o and high passed at 90Hz in the Helix that I never bothered even considered putting the Focals back in. Combined with a 12" sub getting around 450W, it went plenty loud enough and sounded very sweet.

 

This was only with the external source though.

[Felix2021]

I'm actually pretty happy with sound of head unit with Focals. Haven't measured them yet, but i'm tempted to say they haven't overdone it with EQ. Currently, with head unit amp it sounds very good. I don't think it will be worse with Axton, but let's see...

I've seen numerous reports of people being really happy and getting a good sound with high-level inputs of the amps, so i suppose it's not that bad.

I don't want to mess with external source. Using Tidal via wireless AA, and quality is sufficient for me. Not building audiophile system here

Edited 10 December, 2022 by Felix2021

[MP1983]

I also find the factory HU decent - with no measurements at all just increased the inline cap from 2.2uF to 6.8uF and a bit of fiddling with the factory eq made it sound acceptable to me. At the end, cars are not for musical enjoyment - if its semi-decent and can get loud it should be sufficient.

 

What keeps me puzzled is the brilliantly idiotic idea to make an actively shifting active crossover. Yes, it is brilliant as a plan but quite an epic fail in terms of real results. At the end we`re buying a family car, not a farm truck where I`d listen to the news inbetween hay transports.

Edited 15 December, 2022 by MP1983

[GregB11x]

Hey, if I may borrow the topic for one question - does octavia (without Canton) have a speaker in the center of the dashboard? I have started listening to jazz music and even on medium volume I hear sort of buzzing/distortion on high tones coming from center console - al least it sound like is coming from there. The sound is like the speaker is broken and cannot play certain tones...

[MP1983]

Price list for the one sold in Bulgaria says 8 speakers for Style and I can confirm it has tweeters at the back so I guess if the same spec - no.

Edited 16 December, 2022 by MP1983

[Felix2021]

23 hours ago, MP1983 said:

I also find the factory HU decent - with no measurements at all just increased the inline cap from 2.2uF to 6.8uF and a bit of fiddling with the factory eq made it sound acceptable to me. At the end, cars are not for musical enjoyment - if its semi-decent and can get loud it should be sufficient.

I have installed Axton. Although i'm not 100% if i will use it or return it, i have to say i haven't experienced any issues described by some, concerning adaptive EQ. Axton sounds very good, it's improvement over built in amp, especially at low volumes.

However i'm wondering if i should keep it, as most probably i will not use it's DSP, so maybe it's better to get "pure" amp for the same money? Chances are, that it will sound better than Axton.

 

12 hours ago, GregB11x said:

Hey, if I may borrow the topic for one question - does octavia (without Canton) have a speaker in the center of the dashboard? I have started listening to jazz music and even on medium volume I hear sort of buzzing/distortion on high tones coming from center console - al least it sound like is coming from there. The sound is like the speaker is broken and cannot play certain tones...

Yes, center speaker plays music. Found that out when connecting external amp. It doesn't do very good job, but fortunately it's so low volume, that in my case it doesn't mess up the overall sound.

[Filternz]

11 hours ago, Felix2021 said:

I have installed Axton. Although i'm not 100% if i will use it or return it, i have to say i haven't experienced any issues described by some, concerning adaptive EQ. Axton sounds very good, it's improvement over built in amp, especially at low volumes.

However i'm wondering if i should keep it, as most probably i will not use it's DSP, so maybe it's better to get "pure" amp for the same money? Chances are, that it will sound better than Axton.

 

Yes, center speaker plays music. Found that out when connecting external amp. It doesn't do very good job, but fortunately it's so low volume, that in my case it doesn't mess up the overall sound.

You lost me there. What speakers did you install, and do you have the basic (non-canton) system? And you're running an Axton DSP amp and sounds decent?

 

Biggest issue with my setup is the factory HU doesn't seem to push any deep lows, and the mids from the front are so hollow and harsh sounding have the EQ at -9!!! House, pop, rap, all sound okay, anything with with a lot of clean vocals or rock music is bad.
I wonder if the Focal 4.320 AMP is just crap, and I need a better DSP amp. Also, I'm curious how the audio shop wired it up. The sub is active, and the ample is only 4 channels, so who knows where they took a feed for the amp form.

Might see if the AMP has any settings I can play with, or running the new speaks of the HU only (expect the sub which has it's own amp). For now I've just been putting up with it.

 

• AMP: Focal 4.320 AMP
• FRONTS: Focal PS165 Flax Evo components (inc passive crossover)
• REARS: FOCAL IS165 co-ax
• SUB: Cerwin Vega UPAS12ST 12" Active sub

[MP1983]

13 hours ago, Felix2021 said:

However i'm wondering if i should keep it, as most probably i will not use it's DSP, so maybe it's better to get "pure" amp for the same money? Chances are, that it will sound better than Axton.

Why not remove the factory crossover (I`d leave a big cap there, 6.8-10uF should do fine for a 4 ohm tweeter) and instead use the DSP one in the amp? That should provide superior results (for one listening position)