Audio set up: Thumping subwoofer

[guysy]

Ive got a 8" Vibe space passive sub woofer,

And i bought a vibe blackbox:3 Amplifier second hand off eBay, the condition of the amp is questionable it looks rough...

Ive laid down 10awg power cable that's got an in line 30a fuse that was put it once all the wires where in place, my original ground of the ISO fix is when i tested and had the thumping, ive just taken out the rear passengers side seatbelt bolt, wire brushed it to bare metal, and greased it with a round crimp terminal around the bolt, i do have two ground wires in line crimped because they weren't long enough... but it should be a good ground now?

The thumping doesn't happen with the RCA leads out? does that mean i have the ground problem? i have a pioneer head unit, but its a new ish one... ive heard about the ground problem...

The RCA leads where in the box when i had them, look like good quality but im not sure tbh...

Night mare, wanted it to work straight away! the only thing im questioning is the amp, RCA's, head unit outs or ground... but which? :S

 

[wallop]

Hi mate,

Long time since I been on here lol...

The fact the 'thumping' isn't present till you connect the RCA leads indicates the issue is before the amp..

Try removing the RCA leads from the Head Unit but connected to the amp, if the sub thumps the RCA leads are faulty...

If the sub doesn't thump until the Head Unit is connected then the issue is with the Head Unit or its associated wiring...

 

[guysy]

Ok mate cheers, the RCA's just look like cheap gold plated blue ones, the amp has a slight dent in the corner so i think it could be that... then again the subwoofers in mint condition but is also second hand, would the sub thump if it had a problem?

Ill try the RCA test soon.

Hoping my earth is good, its a crimped terminal, and 2 10awg wires in line crimped because the cable was too short, should bed a decent earth but maybe not.

 

[Dink]

imho 8 awg should be the minimum for any audio setup that contains a stand alone amp

i'd have a guess you may have fried the rca output of the head unit by not having decent earth on the amp.

i'd redo the earth with a complete piece of cable and reconnect removing all grease until the very end

 

[guysy]

Well for the first earth i used the ISO bolt, i ground off the coating to bare metal on the nut and tbh it may have been a decent earth... im not sure yet ive heard other people using that point, but now the earth is at the seatbelt bolt, bare metal with copper grease to prevent rust, all tight...

I think it could be the RCAs or the amp, i ill wait till my longer ground cable has arrived and all is secure untill i try again, cheers.

The amp is only 200w RMS bridged at 4ohm, the kit i bought said up to 350w so should be ok really?

 

[wozzaa]

You have to be careful with these amp wiring kits.

Especially cheaper ones as they might say they are a certain gauge but most of the time they are under what they say they are. Although a couple are actually very good, just have to check them carefully. Seen 4AWG kits that in reality were closer to 8AWG.

 

[guysy]

Whilst having trouble before with the thumping, i removed the RCA leads from the back of the head unit, it stopped the thumping, i tried another set of leads, still thumping, I tried the earth track fix all round the pre outs, still thumping.

Today i recieved my longer earth, however i found what ive been looking for (clearly not hard enough) one of the rear light earths which i found when removing the lower boot plastic...

I cleaned all contacts very well and bolted the light earth back so this should be a very good earth now... i put the earth wire straight into the terminal with no crimp just to make sure it was a good connection..

I re connected everything, RCAs last.. now i can hear faint and slightly crackly some music and also a whine...

Amp? the condition of it i would say so, or still possibly RCAs and head unit track?

For the track fix i earthed it on the head unit chassis so should have worked if it was that at fault?

 

[Dink]

try an mp3 player plugged into the amp to eliminate any faults with head unit/rca leads

 

[guysy]

Good idea, Id have to rest at the head unit end wouldn't i so i need a female red and white to 3.5mm jack dont i? ive got one somewhere.

 

[Dink]

get one like this so it just tests the amp

 

[dave_rudabar]

I wouldn't have bothered with the copper grease on the earth bolt, for what its worth.

 

[guysy]

Ok, so i found the right cable in the loft, and plugged my ipod in, i dont know what settings i should have had it on, but i turned everthing down, then put the gain up slightly,

In the picture i had it on LP... think thats right? But on the other switch i had it on Bridged and should be on mono?

Im a noob to this so sorry, the music played ok, didnt have any punch to it, but is this because its just mp3? i tried a few settings, turned the gains up slightly and the bass up, didnt get any bass at all really, and on one switch setting i got a noise, but this could be because its on the wrong setting?

The engine wasnt running for any of this.

If you listen to the video at the end you can hear the whine, excuse the music.

 

[Dink]

where was that music coming from:S did you have it pluged into another amp at the same time:S

you should only be getting getting bass from the sub

you would probably have to set the gain quite high with an mp3 player plugged in

 

[guysy]

Nope it was plugged straight into the amp!

Ive never had anything to do with amps before, so im probably doing something wrong... but 0 gain nothing, half gain, quiet music... but yeah i could hear it like it was playing on my pc speakers... no bass just tinny music...

Edit if i try again tomorrow with LPF mode set and mono set, is that the right settings? can you tell me what i should dial in and what i should listen for?

Cheers for helping.

 

[Dink]

yeah it should be in LPF mode with the little button out and the dial set to about 80Hz

leave bass enhance at 0 and leave the other switch in bridge.

 

[guysy]

Ok cheers, im going to try those settings with the head unit and RCA cables tomorrow...if im still getting crackling even with a replacement set of RCAs, its the head unit?

the amp played the ipods music, just not with any bass, ill see what tomorrows test comes up with.

Ill try with the engine on etc and see if there is still crackling or background noise.

 

[guysy]

Well some good progress Dink, i followed the settings you said to switch to and it worked although whilst holding the amp i accidently pushed the little button in... so i was still hearing a slight buzz until i checked again and the button was in, pressed it out and the noise went, i had the gain and bass on 0, and the other on 80Hz and i all i got was some very slight noise.

Before this i switched the RCAs to different ones, now i had clear but quiet sound i switched back to the original RCAs and had no problems so i dont think its the RCA's or head unit anymore.

So then with clear quiet sound, no crackles or buzz i turned the gain up and turn the bass up (using the head unit sound not mp3 anymore) its only when i got the gain to about 70% and the bass up around half way it sounded more like a sub woofer should sound? was the minimum gain and bass or using the mp3 to test? or should i hear good bass with the gain and bass set to 0?

Cheers.

 

[Dink]

you should set the head unit to how you will listen to it day to day but at the max volume

imho i would not turn any bass up on the head unit (apart from a sub level control and that would be set to max)

i'd try and get hold of a 50Hz @ 0dB test tone play that on repeat

then you set the gain on the amp until it starts to distort then you knock it back to where it doesn't then a tiny amount more.

 

[TIG ACM]

does sound like your amp isnt set correctly. I have a 50Hz @ 0db mp3 post your email and ill send you it..

 

[guysy]

PM'd TIG cheers

So i need to turn the head unit up to the maximum id sort of listen to day to day, and adjust the levels so it sounds right?

Is sub level control on the head unit settings? i have subwoofer: on/off/reverse and then i select on from that and it goes into the Hz settings... theres 3 of them

When im using this 50Hz cd on repeat what am i aiming to do? set it so it sounds bass'y enough at a high volume ?

Cheers.

 

[Dink]

turn the head unit up to the point where it starts to distort then turn it down a notch

the sub level control might not be on your head unit. (on my alpine i had it).

you are looking to match the sub volume to speaker volume with the 50Hz test tone. (say you have half volume on head unit your sub is also at half)

 

[helloimjammie]

Ive got a 8" Vibe space passive sub woofer,

And i bought a vibe blackbox:3 Amplifier second hand off eBay, the condition of the amp is questionable it looks rough...

Ive laid down 10awg power cable that's got an in line 30a fuse that was put it once all the wires where in place, my original ground of the ISO fix is when i tested and had the thumping, ive just taken out the rear passengers side seatbelt bolt, wire brushed it to bare metal, and greased it with a round crimp terminal around the bolt, i do have two ground wires in line crimped because they weren't long enough... but it should be a good ground now?

The thumping doesn't happen with the RCA leads out? does that mean i have the ground problem? i have a pioneer head unit, but its a new ish one... ive heard about the ground problem...

The RCA leads where in the box when i had them, look like good quality but im not sure tbh...

Night mare, wanted it to work straight away! the only thing im questioning is the amp, RCA's, head unit outs or ground... but which? :S

Just wondering mate, how was the ground you used? The one which the rear lights are ground to? I'm deciding whether to do that or not?

 

[tarmacmuncher]

Just wondering mate, how was the ground you used? The one which the rear lights are ground to? I'm deciding whether to do that or not?

Im using the ground to the back lights, its not ideal, but its ok if you are not running a missive set up

 

[guysy]

I think I bought a better earth and used a seatbelt fixing to earth, can't remember to be exact though.

 

[helloimjammie]

Im using the ground to the back lights, its not ideal, but its ok if you are not running a missive set up

I've only got an active 10" sub? 750 watt output and 250 RMS? Will that be okay? Does it matter if I still have the original light earth connected too?

 

[tarmacmuncher]

I've only got an active 10" sub? 750 watt output and 250 RMS? Will that be okay? Does it matter if I still have the original light earth connected too?

Yeah should be fine with that, im running 500 watt rms from it.

And yes you can leave it connected too, thats how i have done it

 

[helloimjammie]

Ahh brilliant cheers for that INFO mate great help!

 

[tarmacmuncher]

Ahh brilliant cheers for that INFO mate great help!

You're welcome

Pm me if you need any more help

 

[helloimjammie]

You're welcome

Pm me if you need any more help

Cheers bud will do!