Subwoofer Fade Issue

[Marbzy]

Hi all,

I've recently purchased a new T6.1 and installed an underseat subwoofer. I carried it across from my previous T6.1 and had no issues with it before.

Installed same as the previous van but this time I've used speaker cable mounted into the quadlock connectors instead of RCA cables as i damaged these during the strip out of the old and had decent speaker cable to hand at the time.

No issues with the wiring or anything install related, but i've noticed that the sub is now much less 'punchy' than before. I'm always happy to have a fiddle and I've discovered the following:

The bass from the sub is far better than before if i balance all the way to the left or right, but obviously then I'm missing sound on one side of the van. If I balance to center then the sub is still working, but with no real punch. I've played with the gain and frequency adjustment at center balance and nothing seems to help.

Does anyone else have experience with this type of issue? or have i done something stupid like cross my +ve and -ve between left and right causing them to cancel each other out at center balance? I'm 99% sure this isn't the case but i cant seem to see any other obvious issues as to why the sound is so poor when at center balance.

Clearly the sub is receiving both left and right rear signal since it works great when balanced one way, so its leaving me stumped!

Its currently run without the fader active too, but this was also the case in the previous T6.1 and it worked more than fine without the fader, albeit using RCAs that time. Is it possible getting the fader active and the proper coding for a 4 speaker setup is the next step?

Side Note:- I have Carista and used it to enable the rear output pins but it doesnt seem to work; i also did this on the previous T6.1 and it didnt enable the fader on that one either. No difference to the output either with it on or off so i guess that Carista havent fully managed to work out that coding change as of yet. In the meantime ill try and get a hold of someone with VCDS to see if that could be the answer to my problems.

Any help and insight from any of the audio gurus of the forum would be very much appreciated until then!

Thanks,

Mark

 

[CJW]

Would help us answer if you told us which amped sub you’re using please.

 

[Deaky]

Sounds like the wrong polarity on one of the speaker inputs. Try reversing one side, even if the wire colours are correct.

 

[Dav-Tec]

Has the amp got a phase button or knob. Sub could be out of phase with the doors

 

[Howzat]

1. Carista. Rears wont program unless it see's resistance with proper speakers. Been there.
2. The fade issue is wierd because fade doesnt increase volume L<>R but reduces volume of the opposite side. What happens if you disconnect one side input (L then R for complete testing) from the sub?

 

[Dav-Tec]

1. Carista. Rears wont program unless it see's resistance with proper speakers. Been there.
2. The fade issue is wierd because fade doesnt increase volume L<>R but reduces volume of the opposite side. What happens if you disconnect one side input (L then R for complete testing) from the sub?

Regarding fader balance would effect the signal reducing 3dB half the power output from that channel. It's not a linear thing where by increasing the opposite side by 3db would counteract it as the amp is still recieving less overall signal.

I would check polarity of the input as reversing polarity on one channel would cause cancellations.

The sub could be out of phase with the door woofers also causing cancellations.

Another thing to take into account is the fact your using hi level instead of RCA. Some highlevel to RCA adapters have chips inside that remove the factory bass roll off. If it's one of the cheap plug n play adapters you see alot of the audio companies on face book flogging these will be cheap chinesium jobs that won't have this but I'm unsure what adapter he has.

Also does the 2 vans have the same headunit. VW have audio profiles built into the headunit. When you slow down it rolls the mid and top off slightly and increases bass, when you speed up the reverse happens to make the music more coherent. That's partly what the speed dependant volume setting is for as that tells the headunit how aggressive the profile needs to be for the user. We've seen different profiles used depending on the headunit. We have to offset this when we do a DSP install. Also the headunit uses all pass filters which is another nightmare in itself.

I'd start with polity and report back

 

[Marbzy]

Hi guys,

Thanks all for your input so far, answers to questions asked below:

@CJW - The sub is an inphase USW10

@Dav-Tec - Sub does have a phase button, but this doesnt seem to affect the output either way, also the Hi level to RCA adapter came from Absolut5 many years ago so id be confident in saying that it was a good'un. Also both vans had the same HU - The composition colour, software versions were different between the two (newer van, newer software version) but assuming that would make little difference. Have also turned right down / off the speed dependent volume adjust as thats just annoying, but for whats its worth should i be playing with that to help troubleshoot?




I have had a chance to play around with wiring and i have got it to the point where the sub is working better than it was. But if anyone knows the USW10, the speaker inputs on it are not labelled, so im assuming that the pin out i found was incorrect, as a result I've left the connections in their new config for the time being since it is semi working. Sadly i dont have the manual for the sub anymore but after looking at an online PDF it doesnt actually show the pin outs anyway as they supply a premade block to connect into hi level and the cables they supply have stickers on them denoting which cable is to go where. Again with the old van using RCAs, this is long gone, so only reference i had for pin outs is from another forum where somebody asked and i followed their information. Seems this was wrong.

Where im at now; at center balance, the sub seems to be working. But when i fade one way (cant remember if its L or R) then there is zero output from the sub at all. But after playing with what feels like every connection variation possible i dont think i can get it so it works so both L and R output if balanced totally that way, which isnt too much of an issue if it works at center of course.

I do get output from both L and R from the HU if i disconnect one side entirely and wire it in, so i know it isnt the pins in the HU that are the problem, but for whatever reason, when i wire in both L and R to the sub, it will only seem to give me one side, albeit with decent sound at center balance, so i guess thats something

I have emailed Inphase to see if they will give me a definitive answer as to what the correct pin out on the sub side is, so when they get back to me with that i will connect it correctly and see what that turns up.

With regards to the sub, i dont suppose anyone would have experience with the pin out layout, as getting this 100% correct would be the next step in getting things working properly

Im assuming since im not getting sound on the L or R from the sub that even if i managed to get the fader active, it would not show since im technically missing a rear speaker?

With regards to coding side of getting fader working; i have a friend who has the pro version of OBDeleven - i know this is more in depth than carista, so i have borrwed his dongle and login and had a look at it and am wondering if this would be a viable option to get the fader coded? I've seen posts of doing it this way but just wondering if anyone can tell me if this works before i go playing with it to no avail

Thanks for all the help so far, slowly plugging away at getting this sorted, so much appreciated!

Mark

 

[Deaky]

I fitted an inphase dual sub a few years ago for my son. We had exactly the same issues, connected it as per the instructions but had poor performance from the sub until the audio output was faded to one side or the other. I checked all. My connections and they were correct. I just reversed the polarity of one of the inputs and it worked as expected.

 

[CJW]

What a coincidence. Mine is a USW10 too. However it’s part of an Audison DSP controlled system that I installed and tuned myself with a reference mic etc and I didn’t try it without the DSP so haven’t witnessed this effect.

I suspect that it’s ‘destructive interference’ you’re witnessing - it’s out of phase with another speaker or speakers in the van.

 

[Marbzy]

@Deaky , thanks for info, I’ve connected the speaker outputs all ways and I think when I had the polarity correct on one side but wrong on the other is when performance was terrible! So I envy you getting it working this way

@CJW that’s mental mate ha. Don’t suppose you have the aforementioned cables to tell me hi level pin out? I assume you’re using RCAs if you have a separate amp

Thanks guys

Mark

 

[CJW]

I’m using one RCA from the DSP as it processes sub to a mono channel.

I bought this loom to replace the one that should have come with the speaker but the seller didn’t recover it from his car before it was scrapped. The listing description says what they’re for - live, earth, remote etc.

10 Pin Power Speaker Harness TO In Phase USW10 USW12 10 & 12 ACTIVE SUBWOOFER | eBay

THE LAST 4 ARE SPEAKER LEVEL INPUT.

www.ebay.co.uk

I did find an online manual but I can’t lay my hands on it just now. Will look later when home.

 

[Marbzy]

@CJW if you could mate that would be amazing. Can’t find any info for a definitive answer so anything you have would be a huge help

I also messaged the seller of the item you posted and he gave me a pin out that differed from what I followed first time around so I’ll have to have another fiddle and give out the latest results!

Thanks

Mark

 

[CJW]

That EBay fella is great. Def worth following his pin out.

I’m beginning to think I’ve got the paper version of the instructions as I can’t find it anywhere on my machine. Will keep looking.

Just out of interest, what happens if you connect just one of the speaker inputs? I.e. left or right? Others might say different but my understanding is that sub frequencies are usually panned dead centre in a mix.

 

[CJW]

As @Deaky suggested above - if one pair is reversed then you’ll get destructive interference when L&R are merged into mono.

 

[Marbzy]

@CJW no dramas mate was worth an ask,


If I connect just the L or R on its own then it seems to work fine on a single channel basis. But if I connect both then I seem to lose one side. Starting to think that the sub itself is dropping a channel when both are connected for some reason. Makes sense that sub would work on a mono signal but I don’t see the point of having both L and R connections if only one works?

Based on this, might sound silly I know but is there any scope of connecting both L and R from the HU together and then all into the connectors of the sub to retain a signal on both sides? Or am I talking absolute nonsense?

Thanks
Mark

 

[CJW]

With that new pinout you’ve got, you should be able to work out which pair is the wrong way round and then it should work.

As an aside though, have a look at this:

Center That Sub! (A Guide to Monoing Your Low End) - Written - Flotown Mastering

If you’re into audio and have spent any time on the internet (which, given that you’re reading an audio blog, seems more than a little likely), then you’ve probably heard that it’s REALLY, REALLY IMPORTANT TO MONO YOU LOW END… (at least, sometimes). Heck, maybe you’ve even watched a few YouTube v

flotownmastering.com

It is the norm for mastering engineers to mix sub frequencies to centre, so the signal is equally present on both L&R channels.

Are you tapping the front speaker signals for your sub?

 

[CJW]

Found the blighter.

 

[CJW]

This implies using chassis earth as negative????

EBay fella’s loom has four wires not two - white pair and black pair. Maybe this manual is for a slightly older version and it’s been replaced by a four wire version that uses the speaker negatives instead of chassis ground?

Just to restate - I used RCA output from the DSP so didn’t come across this.

 

[Howzat]

This implies using chassis earth as negative????

Thats's for the power. Yellow pos (fused) and Black neg (chassis)

 

[CJW]

Thats's for the power. Yellow pos (fused) and Black neg (chassis)

The grey pair are shown connected to the positives of the right and left speaker - no equivalent wires to the speaker negatives, therefore it must be using chassis earth instead of speaker negatives.