RexNuts Subaru Forums

Hey guys,

I have a JBL GTO75.4 amp, which ive had for a good 6 years.
Currently running 2 front speakers (splits) and a sub off the amp. Sounded damn good when i first put it all in and tuned it.
Over the last 4 months or so, the sound got quieter and quiter, and i found myself retuning the amp. At first i thought it was just my hearing going bad from all the loud music.. but im only 23 and i can hear other things perfectly (like the turbo whine ).

Now recently, the amp keeps going into 'protect' mode when i turned the volume more than 20 (out of 62) which is quiet.
Last night, i tried to see if there was something else that may be throwing the amp into protect mode (like a dodgy curcuit board on my speakers), so i took those channels out and tried to isolate the problem.
I disconnected EVERYTHING (RCA in and speakers out) and the amp is still going into protect mode.

Everything appears to be earthed correctly, and none of the fuses are blown.

Blown amp? I dont really want to fork out another $400 for the amp i want if this one isnt broken.. anything i can do to test it? Really need this fixed before the weekend as i dont want to go on his Kiama cruise with no music :p

Also, i might add.. the left speaker made a massive "pop" sound which made me jump at one stage last night.. and when the amp was 'just' working, a crazy amount of static was coming out of the speakers with the volume all the way down (both speakers, not just the one with the dodgy circuit board).

Sounds to me like you could have a faulty capacitor inside the amp...
Open the amp and look for something like this and let me know if this is the case.

Hmm, will have to have a look tonight..
I'm thinking of just replacing the damn thing with this: http://www.cadencestore.com/ProductCart ... roduct=557

Thoughts?

What's your speakers and sub rated at? Watts rms..
Is it just front splits and a sub?
How much is that amp?

Front speakers are Boston S60.. 35-45w rms apparently.

Cant remember what Sub is rated at either..lol. Its pioneer and cost me like $289?

Amp is $399

Maybe this could be another option with amps

http://www.lifestylestore.com.au/produc ... KAC-8404-/

Seems to have good specs and a remote sub volume control which is handy
Lets see what Mad89 thinks

Ended up just buying the bloody thing.. :p
Will see if it makes any difference Will post later..

As i posted in the other thread;

Sorry for the late reply mate, but it seems a bit too late now. lol. Looks like hes bought it already?

For future reference, i would have recommended SPL Dynamics S2604 for $399 RRP, conservatively rated at 4x65wmrs, with variable high and low pass filters (40-4000hz) and 24db slopes. Great bang for buck amps!

Or for some serious grunt, RE Audio XT800.4v3, which is 4x100wrms and full range Class DE for increased efficiency for $479 RRP.

Hope that helps.

Yeh that amp i got is Cadence Flash F600-4 which is apparently 4x100w rms.

Found the source of the problem, which wasnt the amp.. but this new amp is AWESOME! Im keeping it in
Did a much neater install too, so end of the day im $399 lighter in the wallet, but really really happy. This amp really shows the true sound of the Boston speakers too! Havent even hooked up the sub yet.. really doesnt seem necessary with how good it currently is!
Think i might just buy some more Boston speakers for the back of the car and hook them into the 2 extra channels and leave the sub out..

What was the problem? I'm curious.. bad earth?

With the higher end sets of Boston splits that ive used and installed (Pro60SE and SPZ60 mainly), ive found that they will happily take a bucket load of power and still deliver very good sound. Just be mindful when setting your highpass filter. I suggest around 70~80hz at a minimum, and appropriate setting of the amp gains to accomodate.

Depending on your listening tastes, a sub may not be needed, but dont forget, in that case, you'll be missing out on everything below about 80hz. If you're OK with that, then dont drive the speakers too hard, and im sure you'll be happy.

Yeh, thinking i may install the sub afterall. Some songs just dont really give me the bass im looking for when im driving :p
Just need to find a way to secure it in the boot so it doesnt slide all over the place.
Havent set HPF yet, will play around with the settings on the weekend... im sure im pissing off the neighbours ny now..

In your model Subaru, theres a support brace that runs under the parcel shelf, with some holes in it, etc.

Put a bolt through one of these and secure it tight, allowing about 10mm thread to poke through. From there, install an L shaped bracket onto your subbox, and then use a wingnut or similar to bolt it to the brace. It wont move, and you can easily remove it if/when needed.

I have a pic of what i mean if the above doesnt make any sense. I dont have it on me though, so would need to post it up later tonight for you, when i have access to my laptop again.

Or you could get one of these if you can find one in ebay... I paid about $90 late last year.

Ignore my messy boot

If you ever come across something like that again, please let me know. Exactly what i need.
How does it secure to the side tho?

I just placed some velcro strips and it doesnt move

They pop up on ebay from time to time..

At the moment I could only see one.
http://cgi.ebay.com.au/SUBARU-SPEAKER-S ... 2a082b493d

OK, so the farking thing isnt working again!
So, im leaning towards the headunit being the problem now..
This is pissing me off heaps! God dammit!

Ummmm - have you checked the earth on it?

What trouble shooting have you completed so far?

Triple check your earths, and then check them again. 9/10 times, amps going into protect is from voltage drop and/or poor earthing one way or another.

Either that, or you have short somewhere in your speaker wiring that is causing the problem.

Yeah I'm leaning towards a short in a speakers somewhere..
Check the speaker that popped... pull it out and test your system... I reckon the plug is possibly touching the metal part of the door...
This actually happened to me once too

Ok, ill go take everything apart again now..

So done so far:
- Changed amp.. which worked amazingly until a few days later when listening to loud(ish) music..
- Checked circuit board on left speaker (the one that popped) and put all cables back in again and used a lot of electrical tape!
- Disconnected left speaker from amp
- Amp is still lighting up.. dont know how you determine protect mode on this new one..

Havent checked earth, its under the back seat, connected to screw used for seatbelts.. untouched for about a year..
Where are you guys earthing to? Maybe i need a better spot..
Will try running cables from bros headunit into my amp to see if its my headunit thats busted (i suspect this atm, its a pile of Pioneer SHIT thats given me issues from day one.. $1870 could have been better spent).

Will report back shortly

Ok, so..

Amp is earthed as mentioned above.. connection is very tight.

- Connected RCA from headunit to brothers amp - worked.
- Connected iPod to speakers - worked.

- Connected brothers headunit to my amp - NOT working

There are no fuses on the new amp, nor is there any indication this ones going into protect mode. Tried adjusting all levels of input/output on amp.. still nothing. So it has to be the amp, right? Ive packaged it all up, and going to take it back to JB tomorrow.

Hey man I'm meeting up with another member most probably on Saturday to help him find the Fuel relay in his car around Blacktown... if you want to meet up with us I can take my tester and we can try to figure out whats going on with your system.
Let me know.

Yes, please!
I took the amp back to JB and got a replacement, so maybe i can install it with you!? All cables are there.. just need to plug them in, which will take all of 10mins..

Yeah no problems at all.
PM me your mob number and I'll let you know when and where.