Kenwood Amp

[Arnold]

Right, some of you know about my ongoing issue with my sub amp!

Its blown up twice now in the space of a month, and i've just had the same one fixed and returned to me this morning...

First of all, is there any way i can improve my setup to reduce the chances of this thing blowing up again, or, is it purely down to the fact this amp is rubbish, why it keeps going wrong.

Is overheating an issue with amps (its sitting on a carpet false floor) - or am i running it for too long? Its capable of 2x250W, which is what both my subs are. I think it blew up last time when i started my car! pop went the 40A fuse taking the amp out with it

So any advice on making this thing survive longer than a week would be apprechiated!

Arnold

 

[Monkey]

take all the wiring out and start again, making sure that no cales are broke and or touching body work (except the earth cable) suing proper cables etc

 

[Monkey]

right this is exactly what i would do:

Ask the person who repaired it what went wrong with the amp, what part of the amp went pop and why they think the amp went pop.

if he says its power related i'd:

rip out all the cabling and visually inspect it checking that the plastic is not broken at all (if it is replace the whole cable DO NOT JOIN IT AT ALL)

Power Cable Installation aprox 5m:

put one end of the power cable at the front of the car (DO NOT CONNECT IT TO THE BATTERY WE WILL COME TO THIS LATER) by the grill (making sure you have more cable than required you can always cut a cable to length but you cant extend it) find a hole in the bulkhead (the bit of metal between the engine and the inside of the car) and make sure it has a gromet (rubber/plastic bung) make a hole in the gromit and push the cable in to the car. it should come into the passenger side foot well, you may have to pull some carpet back to allow easy access. remove the door sill (piece of plastic running along the door apature at the bottom) and the piece of plastic in the foot well on the left. place cable under the carpet making sure that nothing can cut in to it. feed the cable in to the boot. whist you are running the power cable also run the remote cable from the headunit to the boot (DO NOT RUN THE RCA's (PHONOS) WITH THE POWER CABLE THIS WILL CAUSE INTERFERENCE)

find a place you want to mount the amp secure and not to the back of a sub box (unless the sub box is secured to the car)

mount the amp

cut the power cable to lengh and connect it up to the amp

connect the earth cable (of the same size as the power cable) and find a good earthing point (any part of the body, use a abrasive pad to scratch away the paint) and use a earth anchor 9ct gold plated.

Connect the remote cable to the amp

Speaker Cables:

now connect the speaker cables making sure that NO part of the cable can touch no other terminal on the amp or sub except the terminal it is intended to touch, and also taking care to get the polarity of the speaker round the right way

RCA's:

Run the RCA's from the headunit along the drivers side of the car using the same principle as running the power and remote cable, then connect the up to the am making sure the polarity is round the right way ie: red goes to red.

go to the front of the car and secure the power cable in the engine bay cut it so that there is no more than 12" of cable lengh to the battery put a fuse holder here (DO NOT INSTALL THE FUSE) making sure it is the same rating as the sum of all the fuses for all the amps you have installed not higher or lower this WILL cause problems. you will have now a cable that goes to a fuse holder that is secured in the boot and then no cable, connect the piece of power cable you have just cut off to the other end of the fuse holder (you shouls have 12" of cable) and connect it to the battery using a proper amp terminal block, you will have to cut the Nissan cables from the crap connector and put these in to the terminal block as well.

Check all connections again

put fuse in fuse holder it will spark dont jump its normal. then switch everything on. if you have followed thisyou will have no problems.

 

[Retepetsir]

" (DO NOT RUN THE RCA's (PHONOS) WITH THE POWER CABLE THIS WILL CAUSE INTERFERENCE)"

Incorrect, DC power cable cannot cause intereference in AC signal cable, a common misconception.

From when I looked at Arnolds car at JAE, the installation looked fine. The only thing I might want to do would be to upgrade the power cable to 4awg Arnold

If you can get hold of a multimeter (£5 from Maplin) measure the voltage at the amp terminals, using the 20V DC Voltage setting, then measure it at the battery. If there is a significant voltage drop between the two (i.e. 12V at battery and 10V at amp) then it might be worth upgrading your power cable as your experiancing quite a bit of voltage drop

 

[Arnold]

Cheers guys. The amp is in and powers up for longer than a second so its a good start, but i didnt have any CD's in my car to test the subs. Im hoping they didnt get fried when the amp went last time!

Monkey, the repair was done by Kenwood!

 

[Monkey]

" (DO NOT RUN THE RCA's (PHONOS) WITH THE POWER CABLE THIS WILL CAUSE INTERFERENCE)"

Incorrect, DC power cable cannot cause intereference in AC signal cable, a common misconception.

i will have to correct you on this

You are correct in saying that DC can not cause interference like ac can but noise does travel along the cable in electrical form. its altornator whine that causes a noise, and it can jump to the RCA's if they are close to the power feed (not on all cars but most) and that does happen.

the only way you can really put RCA's along with the power feed is if they are Sheilded (very expensive) to ground but i still dont recomend to do this


Check this link out

 

[Arnold]

How would i tell if the subs were dodgey? the amp is in and i've blasted the quad through it - and although theres still alot of bass / power, it just doesnt sound the same as it did!

then again, i may have blasted my ears so much, nothing sounds as good as it should anymore!

 

[Retepetsir]

i will have to correct you on this

You are correct in saying that DC can not cause interference like ac can but noise does travel along the cable in electrical form. its altornator whine that causes a noise, and it can jump to the RCA's if they are close to the power feed (not on all cars but most) and that does happen.

the only way you can really put RCA's along with the power feed is if they are Sheilded (very expensive) to ground but i still dont recomend to do this


Check this link out

That might just happen, but the strength/level of the noise usually is so little, that it has no effect. In all the installs that I have seen/helped with, and all that I have done, I've never had noise problems from alternator whine. Also, shielded RCA's are not expensive if you know where to get them from/where to get the cable and plugs to make them yourself! (CPC is a good place to start )

99% of interference problems are down to bad grounds.

Try having a browse/search on Talkaudio.co.uk, the free forums provided by caraudiodirect

Arnold, not sure what to suggest mate. If they got a nice dose of DC then thats something that speakers do not like very much!!!

If you can grab a multimeter, measure the resistance (ohms) accross the sub terminals and tell me what the results are

 

[Monkey]

i like to be able to porve what im saying and why im saying it (i am open to views as im not single minded), here is a few more website saying the same as me

check number 3
http://www.termpro.com/articles/noise.html

number 3 again
http://www.redrival.com/ixlnxtc24/ampkit.htm

http://www.carstereo.com/help/amp_instal.cfm

and explaination of alternator noise

http://www.carstereo.com/help/noise.cfm

other forums:

Talk Audio

http://www.talkaudio.co.uk/vbb/showthread.php?p=1528897#post1528897

the12volts.com very good and interesting website

http://www.the12volt.com/installbay/forum_posts.asp?TID=62951&PN=1

http://www.the12volt.com/installbay/forum_posts.asp?TID=62923&PN=1

United Cruisers

http://s10.invisionfree.com/unitedcruisers/index.php?showtopic=510&hl=

Ultimate Jap Car Club

http://domain839233.sites.fasthosts.com/forum//index.php?showtopic=12139

SXOC

http://www.sxoc.co.uk/vbb/showthread.php?t=172824

Tatsu

http://www.tatsu.co.uk/forum/viewtopic.php?p=21402#21402

Bit Tech

http://forums.bit-tech.net/showthread.php?p=1069258#post1069258

i have also phoned up Alpine technical (but they wouldnt put anything in writing as they are not installers they are manufacturers.

i asked,

"ive bought an alpine sub and amp and a one man band company is installing ti for me, he says he is going to run the RCA along with the power cable, is this ok as i have heard this is wrong".

the tech support bloke said:

Find your self another installer as this guy wont be in business for very long if he does things like this, this a bad practice in car audio installations.

ive emailed Kenwood and pioneer the same,(so i have it in writing)

this is a quote from the car audio direct troubleshooter,

Troubleshooter

RCA cables
One of the most common causes is the RCA cables which run from the head unit to the amplifier picking up interference. Always use good quality RCA leads (preferably triple shielded) and always try to run them as far away from any of your cars wiring harnesses as possible. Also run them separately from the amplifiers power feed. Try hanging the RCA lead loosely between the stereo and the amp (draped over the front seats for instance). Start the car, turn the volume to minimum and rev the engine. If the high pitched noise has gone then you know where the fault lies and you will have to be careful when running the cables down the car

 

[Retepetsir]

Notice on your Talkaudio post..........Black Cat is the friend of mine that I was talking about

But yes, good practice is seperating them if you can, but of all the installations I have seen and done (and I have seen and done many!) I have not once had a noise problem. And if there is a noise problem, then 99% of the time its down to poor earthing and poor car electrics.

 

[Retepetsir]

This is going off topic anyway, if you want to continue it further, either start a new thread or carry on with your thread on TA

 

[Arnold]

I've removed the blank posts

Also, i went back and had a fiddle around and with a few more adjustments on the head unit, i think its sounding ok! Also tuned it so i dont really need to touch the boost controller anymore

 

[Retepetsir]

Sounds good to me mate

Keep me informed as to how your getting on. I've just made my car undrivable, but sheering off a throttle body bolt inside the inlet manifold. Hoorahhhhhhhhhhhhhh!

 

[Ben]

arnold, i had same problem - i shat myself when i fried my amp that my sub would be knackered so like Pete said, whack the multimeter out and get a reading across terminals, also where is it earthed to? I had mine earther to rrear light bolt thing but second time round i sanded it all down to bare metal just to make sure

 

[Arnold]

arnold, i had same problem - i shat myself when i fried my amp that my sub would be knackered so like Pete said, whack the multimeter out and get a reading across terminals, also where is it earthed to? I had mine earther to rrear light bolt thing but second time round i sanded it all down to bare metal just to make sure

The earth, along with the earth for 2 other amps and a cd changer, go into a distribution block, which go into the bolt used to hold the boot latch on.

The thing was, when it blew, and the fuse changed, both subs would come out as far as possible, and make a really loud bass tone, before the amp cut out. The process happened everytime the amp was turned off and on. I rang Pete who told me if sounded like it was sending DC to them.

They seem to be sounding ok though!

 

[Ben]

im sure i managed to do that, was a long time ago but im sure it was when i had the setting wrong, like on 2 channels instead of 3

 

[Retepetsir]

The earth, along with the earth for 2 other amps and a cd changer, go into a distribution block, which go into the bolt used to hold the boot latch on.

The thing was, when it blew, and the fuse changed, both subs would come out as far as possible, and make a really loud bass tone, before the amp cut out. The process happened everytime the amp was turned off and on. I rang Pete who told me if sounded like it was sending DC to them.

They seem to be sounding ok though!

At least they sound ok atm, just take it easy for a bit