Hi All,

Installed the new xtrons headunit today and it is a SWEET unit.

There is one really annoying feature though and that is lack of subwoofer control on the headunit.

No biggy I figure I'll just crank the gain on the sub amp (these preouts would be lucky to be 2v).

Unfortunately for me, when turning the gain up, I get a popping sound from my subs. Its like a short burst of pop pop pop everything second. When this happens the power light on the amp as well as the interior/dash lights dimm with the pops. The pops aren't even that loud, but it's obviously doing something to cause a power drain in the electrical system. This happens with the car turned off and running.

I've been trying to narrow it down, but not sure what my problem could be:

My setup:
Headunit only has 1 physical output, so I need to use 3 Y splitters to get 4 outputs (going into a 4ch amp).

If I turn down the gain on both channels (so 4 ch bridged into 2) the popping goes away (lower the gain, the softer the pop). Raising the volume on the headunit DOES NOT change the volume of the pop, only adjusting the gain does.
If I unplug 1 of the 4 inputs going into the amp, the pop softens. If I unplug all but 2 (no matter what configuration these 2 are in, e.g. 2x half bridged, or 1 full bridged channel) the popping goes away.

If I remove one of the splitters, and plug just the 1 plug into a spare port, I get the same popping volume as if I had used 3 plugs and all the splitters.

Any ideas? This is killing me as the only way I can get the subs turned up is if I turn up the gains, no subwoofer out control on the head unit :(.

I should also mention that If I turn the volume down on the headunit to 1, I still get the popping sound at the same volume as on MAX, HOWEVER if the headunit ceases to generate any sound, the popping goes away (e.g. on mute, in a menu with no song playing).

when you say one output, do you mean 1 channel?
dont split a signal more than once.
my first deck had 1 channel out, it went into a sub input, the amp for it was pass thru, so then the output RCA on that was split once to make up 4 channels for my 4 speakers. really this is a cheap option.
best is to have a Deck with a dedicated sub output

when you say one output, do you mean 1 channel?
dont split a signal more than once.
my first deck had 1 channel out, it went into a sub input, the amp for it was pass thru, so then the output RCA on that was split once to make up 4 channels for my 4 speakers. really this is a cheap dogey option.
best is to have a Deck with a dedicated sub output

Yeah 1 channel for subwoofer out. It has 3 outputs (front/rear/sub) but the sub only has 1 channel instead of 2.
Without using an inline RCA amplifier I don't see how else I can do the splitting.

I'm guessing because of the splitting of the RCA, the signal quality is dropping, combined with a more "sensitive" gain is picking up interference. If I can work out where the interference is coming from, this may also be a solution. Given the testing I've done I have no idea what could be the cause.

OK This is just getting strange, If the car revs above 1000 rpm, the popping stops, HOWEVER the subs are still really quiet. This would indicate an issue with power somewhere right? Whatever the interference is it's independent of the stereo volume.

If I only use 1 splitter and plug straight into 2 of the bridged channels, I get OK volume from a sub, but it's being drained out heavily by the in car speakers which have dedicated outputs and aren't hitting any where near the same amount of loss as the sub output.

I think I have 2 problems here (1 not so much a problem, but worse because problem 2):
1) There is interference somewhere in the RCA, but is only noticeable when the RCA signal strength drops because of splitting
2) The signal strength coming out of the headunit is woeful, and the only way to fix this is either replace headunit (would rather not) or get an inline rca amplifier

I've been looking around and perhaps an equaliser may help here? Considering the Headunit doesn't have much in the way of signal control.

The other option is to run an RCA cable from my "4 speaker" amp output and split that into the inputs for the sub amp. Is there a way you can use the input for an amp to go out as an output and back in again? Or will this cause a noise loop?

Everytime you split the signal the quality and strength drops. Id say this is the cause

TO clarify:

You have a 4 channel amp.. this is powering what? speakers, 1 sub bridged over 4 channels? 2 subs?

If you are only running subs off the amp, then you do not need an RCA in every input.. say you are running 1 voice coil bridged off 2 channels... either 1 of these channels needs a signal input, the other does not.

I assume that everything bar the head unit is existing, and ran fine before the installation of this new head unit? Try running one of the RCA lines from the front or rear channels to the sub and see if the popping remains.

If it is only happening once you turn the gains to a certain point, there is a chance there is an electronic fault with the amp, if you have another amp at your disposal to test in place of the current one this will also help to determine the cause.

My old Eclipse 4 channel that was powering a dual coil sub over all 4 channels developed a rhythmic tapping noise through the sub and took me a while to notice, it turned out to be a failed channel on the amp, I canned it and bit the bullet to buy a new set of matching amps.

Finally, if you are using a 4 channel to power a sub, I highly recommend changing over to a monoblock.. multi channel amps really weren't designed to run subs and you will find that a mono is a lot more pleasing to listen to and has a hell of a lot more control over your sub... it also means you wont have to split any signals :)

By splitting the Signal 3 times, you have degraded the signal quite significantly, and on top of that the Signal from the "Xtron" head unit wouldn't be anything flash. While this is fact, after reading some more i dont think this is your issue.

What Headunit did you have before and what model amp do you have?

There could be an issue with the Voltage depending on what amp you are running.

TO clarify:

You have a 4 channel amp.. this is powering what? speakers, 1 sub bridged over 4 channels? 2 subs?
I have 2 x 4ch amps, a soundstream 4x130wrms and the jaycar 4x130wrms amp. The interior speakers (front and rear) are running off the soundstream, and the front/rear RCA outputs from the HU are plugged into this.
The jaycar is running in 2 ch mode with each sub (2 x12 inch) running off one of the bridged outputs.


If you are only running subs off the amp, then you do not need an RCA in every input.. say you are running 1 voice coil bridged off 2 channels... either 1 of these channels needs a signal input, the other does not.
Hmmm this I did not know, I was under the impression that both bridged channels (so 1/2 and 3/4) needed both inputs. Would having 1 or 2 plugged in make a difference to sound level output? (IE louder with 2 inputs over the 1)


I assume that everything bar the head unit is existing, and ran fine before the installation of this new head unit? Try running one of the RCA lines from the front or rear channels to the sub and see if the popping remains.
I don't believe this is an issue with the output signal (other than the fact it's weak) as I don't get the popping with it split only once.


If it is only happening once you turn the gains to a certain point, there is a chance there is an electronic fault with the amp, if you have another amp at your disposal to test in place of the current one this will also help to determine the cause.
This was my first thought, but if that were true it'd do it no matter how many rca's were plugged in.


My old Eclipse 4 channel that was powering a dual coil sub over all 4 channels developed a rhythmic tapping noise through the sub and took me a while to notice, it turned out to be a failed channel on the amp, I canned it and bit the bullet to buy a new set of matching amps.

Finally, if you are using a 4 channel to power a sub, I highly recommend changing over to a monoblock.. multi channel amps really weren't designed to run subs and you will find that a mono is a lot more pleasing to listen to and has a hell of a lot more control over your sub... it also means you wont have to split any signals :)
Yeah I had a monoblock but it was way too underpowered, had the jaycar sitting here and it has some decent power output, If I can get this setup working I'd prefer it.

By splitting the Signal 3 times, you have degraded the signal quite significantly, and on top of that the Signal from the "Xtron" head unit wouldn't be anything flash. While this is fact, after reading some more i dont think this is your issue.

What Headunit did you have before and what model amp do you have?

There could be an issue with the Voltage depending on what amp you are running.

Running the jaycar response 4x130wrms. Headunit before was a Panasonic (was quite a good HU, 3d dot matrix display, had 3 sets of 5volt preouts with the sub having TWO rca plugs as well).

OK I've actually tried something different.

The soundstream amp I have powering my interior speakers does not have an RCA output, bugger!
So what i've had to do is, run the FRONT and REAR preouts from the headunit straight into the ports on the sub amp (jaycar), and then used the RCA out on this to split the signal into the speaker amp (I've made it so I have left/right fade, but no front/rear, which I can control via gains anyway).

And it actually sounds really good, and LOUD. No popping/interference noises and the subs/interior speakers go well. No noticeable drop in sound quality with this either which is surprising!

So that's my workaround for now, seems to be working OK, but if I can set it up a better way I will. Can anyone forsee any issues with the above setup? All my LPF/HPF frequencies are set (not sure how well lol, but enabled).

So that's my workaround for now, seems to be working OK, but if I can set it up a better way I will. Can anyone forsee any issues with the above setup? All my LPF/HPF frequencies are set (not sure how well lol, but enabled).

I dont see any major issues what so ever, with the said if this is working for you now, i wouldn't change it especially with the head unit your are running.

I probably wouldn't want to have a stereo signal being sent to my subs to be honest. Front/rear will never be exact output voltages, and as they are controlling 2 different subs this will result in cancellation, or, if both subs are in the same air space, 1 sub driving the other sub slightly which can cause issues with the voice coil.

Multiple subs should always be controlled via the same signal. If you say that the amp works fine with only 1 splitter, why not do what I said and only run 1 RCA into the channel 1/2 bridge, and the other RCA into the 3/4 bridge? This is the most practical solution.

I probably wouldn't want to have a stereo signal being sent to my subs to be honest. Front/rear will never be exact output voltages, and as they are controlling 2 different subs this will result in cancellation, or, if both subs are in the same air space, 1 sub driving the other sub slightly which can cause issues with the voice coil.

Multiple subs should always be controlled via the same signal. If you say that the amp works fine with only 1 splitter, why not do what I said and only run 1 RCA into the channel 1/2 bridge, and the other RCA into the 3/4 bridge? This is the most practical solution.

I'll have to try this tonight, I just hope the volume doesn't drop on the subs doing it this way too much.
Will report back :).

If it does, I'd suggest investing in a cheap line driver to up the voltage :)

If it does, I'd suggest investing in a cheap line driver to up the voltage :)

This was what I wanted to know in my original post lol. wheres the best place to get one suited?

Gaycar would have one surely, I've never actually bought one myself but Jaycar would be my first step.

Gaycar would have one surely, I've never actually bought one myself but Jaycar would be my first step.

Can't see anything on their website, I might pop into autobarn/jb on the way home and see if they have anything suited.

I believe my best option here given the current headunit, is convert back to my previous setup, but have the line driver powering up the sub output enough to be split.

agreed

OK Some interesting results.

If I plug 1 sub input into the 1/2 channel, it is softer than when I plug both into the 1/2 channels. I now have done what you said and plugged 1 in each of 1/2 and 3/4, increased the gains a little bit. I've also managed to find a setting on the headunit called "dbas", not sure what that is exactly but bass gets alot louder, had to tune the HPF on my speaker amp much higher as it was draining out the sub.

After all this is doesn't sound too bad at all, I know it can louder with a better headunit, but any louder and i'll probably lose my hearing in 10 minutes :P.

Thanks all for your help with this one!

Glad to hear it sounds good, just be careful that along with increasing the bass it isnt clipping or anything, depending on the headunit, 'dbass' or similar generally boosts the signal voltage for a set frequency range, somewhat artificially, and can often cause problems if used irresponsibly.. it also sometimes lowers the listening frequency of music, so that music that isnt usually very bass heavy can sounds much more so.

If it is working for you, as long as it isnt doing any harm by clipping or whatnot, then use the hell out of it and enjoy your sound system I say :D

Just an update on this. It's funny our minds work, when you want something to sound good, it starts to in your mind.
Went to autobarn and they let me try out a line driver (guy was pretty confident that it would only amplify a shit signal).....and it did. Got massive clarity issues, and the fact that the line driver was almost $200, yeah forget that it didn't even work. He explained they were mostly used for amplifying a GOOD signal across cable distances, not really designed for what i intended.

Anywho so it was either spend 1-200 getting a line driver, or just suck it up and buy a new headunit.

So that's what I did, gave up on the quest for a touch screen/dvd player, for specs I wanted they were way out of budget.

Ended up buying a Pioneer DEH-8350SD, has every feature I could ever dream of, and WOW, the sound quality of the music is incredible. Really showed how bad (even at normal volumes) the xtrons was SQ wise. Which is a shame because it does everything else really well.

So I've learnt a few good lessons in all of this, and am now enjoying the new pioneer deck :D.

What does everyone else think of the pioneer deck? good choice?