rockin'Ru

That is strange.Assuming all power connections are good,I'd also suspect the head unit.
If it's at all possible,try a different hu or source,like a cd walkman.I've never heard a Genesis product but have heard nothing but good things about them so I must say that an amp problem takes the back burner.
Can you find an alternate signal source?You could even try a friends hu with long rca's jumped into your car.
If it's not wiring...

chiark

Hmm, running bridged will produce more heat in the amp, and also greater distortion.

It is either the HU or the amp - as Steve says, I'd try another head unit temporarily to see if that solves it.

Have you checked all power supply components, particularly fuses? A duff fuse that's only partially making connection can make all sorts of strange effects?

Nigel Bowles

Is the amp capable of being bridged?
Does it cut out after every 90 seconds or just once?

Sounds like the amp is getting hot and a cut out system is protecting it.

You could try getting an active cross over and running the mids on one channel and the tweeters on another. You can do this with a passive crossover if it came with the speaker kit.

steve McCulloch

ok, I have a £280 Alpine head unit with 2 preouts
1 Genesis miniblock and 1 genesis 4 channel

Dynn Audio fronts (6.5inch with tweeters) and 2 Subs

The 4 channel is running the fronts (not individually amped as this did not give enough power so they are being run through the the speaker with 2 channels bridged to run each speaker and tweater!!

I have a major problem.

For virtually every CD I play after about 30 seconds to 1 minute the sound on the disc goes into some sort of muffled mono - ie perfect stereo sound for a while then it goes all dull and crap. If I put the track back to the beginning its fine again for about 3o secs or so - then the same again - this is regardless of cd

This is also regardless of whether I'm driving, or on the drive with engine running or engine off

Yesterday the fronts went completely off for a minute and there was very little coming from the subs apart from some awful noise - like the subs were on 5% power or something

As the fronts and subs are being run from separate amps I cant see that its the amps?

I have noticed that if I keep the sound down there is never a problem - but when I crank up the noise to a high level the problem always occurs!

The Alpine unit is about a year old

Would I be correct in thining that its the head unit and that changing this may solve the problem - I have never come across this before!

Any comments on this one greatly appreciated

john banks

I have not heard of many recent amps that will not go down to 2ohms. Does sound rather like the headunit. I have successfully tested using a household CD players RCA outs straight into the amp at minimum gain - very quick test. Another thought - could it be that a speaker cable has been pinched in the body somewhere and grounded leading to very low impedance and amp shut off - puzzling that both amps are affected though.

Presumably running with an active crossover would be quieter for a number of reasons. One channel is being used for tweeters and would only really need to be about 10% of the power of the woofer channel - therefore the available power to the woofer is almost halved. Also, the removal of a lossy passive crossover would surely be less significant than the extra power gained from going to 2 ohms - especially with a quality amp like Genesis. With a Kenwood amp where the quoted power goes up only 50% when bridged (and even less clean power because for 2 ohm it is quoted at much higher THD and often at only 1KHz rather than full range), I am not convinced that you are really getting any genuine clean "free" power by bridging or running at 2 ohm, but Genesis will be a different matter, and in addition to the first reason above, I can appreciate why bridging is the way to go with your setup Steve.

(To save taking over your thread Steve, Nigel can you help on

rockin'Ru

While I'm not too familiar with Genesis amps,I'm going to ASSume(the mothu of all ****up's )that the 4 channel Genesis amp would be 4 ohm stable bridged as most,and NOT stable at 2 ohms bridged as mentioned.
But I don't know what speakers you're talking about.Dynn Audio?Do you mean Dyna Audio,or is this somthing I've never heard of before?(if so could someone please leave a link so I can take a peak?)
Also,you said that the subs were all but out too,which is why I'm suspecting the hu right now.What ever itis,it's effecting both amps,not just one.

steve McCulloch

Hmmmm

I didn't give the full game away I dont think on the first posting... I'll expand so as not to waste too much time

The front left speaker has gone walkies - manufacturing defect - glue has come unstuck on the design so its riggled out!

Therefore I'm running off one right speaker and tweater while the left hand side speaker is repaired.

Now I cant comment on the past workings as the car was in for an overhaul of ICE

I was originally running the Dyn's (these come standard in Porschs, but I dont know where a link would be - I guess Adam would know) with a 4 channel amp running the fronts and 2 rear subs.

The amp simply was not capable of this by itself (in fact it had a fault from day 1!)

In went the car to a Genesis dealer for new 4 channel with sub control and a miniblock

The miniblock for the 2 Diamond subs and the 4 channel for the fronts. All I know is running the fronts on separate channels did not produce enough power as the subs simply drowned out the sound

On taking the car home after some 2 minutes on a Dr Dre cd the front left speaker went - so I only have the front right while this is sorted.

I noticed that at low volume I got no issues - but cranking up over 23 on the volume produced the issues

I was very surprised though when at one point the front rights went completely and the bass pretty much disappeared.

I now partially suspect that its the amp shutting down - nothing has been done re the front left other than there is nothing currently there - it just puzzles me that at one point the subs went too - this only happened once

So it could be the amps shutting down or the head unit - probably still the hu!

If I get the same problem when the Dyn comes back then I'll know theres something dodgy

Car will be back in at the car hifi centre soon to check it all out

Apparently though everything was fine before my left side speaker wnet belly up

(oh... apparently this is not uncommon of the Dyn's - perhaps I would have been better to put in CD Technologies - but they were would have been £600 instead of £400!)

Chiark - no not the fuses
Nigel - Genesis should not have any problems running bridged - after the 30 secs or so it stays in 'crap mode'
Rockin - no issues that I can see with wiring

So perhaps this sheds a bit more light - hope I have not wasted too much time on this one!

I'll soon have the answer

I seem to have nothing but problems with my ICE - first a Genesis amp is faultly - then a speaker - great

Perhaps cheaper gear would have been the way to go!

kryten

steve, the system should be pretty awesome - i have dyns and soundstream amps on a similar setup and its great so i don't think its your choice of kit that is the problem (we all get unlucky with stuff that goes wrong now and again - the important thing is how well they sort it out)

to be honest, i'd let the car hifi centre check it out (i assume its them in cheltenham) - i'm sure they'll figure it out in not time, far easer than we can manage without seeing the system.

if you want to try things, then:

it _may_ be an amp shutting down. the Dyns are a tricky load to run and while Genesis amps are top notch there could be a heat buildup problem - do you have any cooling fans around the amps? how/where are the amps mounted? what guage of power/earth are you using?

it could be the headunit - try and get hold of another source (cd walkman) and see if it happens. that will prove if its the headunit.

steve McCulloch

I've been told its a load impedence problem - whatever that means - from having only the right hand side front working on the 4 channel amp

I do think its shutting down - as it only happens when I really crank up the volume!

Has anyone mounted the front speakers in special pods - ie that come out a couple of inches to get much better sound quality?

kryten

Most 4 channel amps are capable of working with only 1/2/3 channels being used, though it may be something specific to the genesis.

My Dyns are in door builds (done at Car HiFi centre). Helps get them a little more on axis than the standard location, means they aren't trying to come through the standard plastic grille and they have a solid baffle to mount to.

Didn't compare it with standard location, but I have in previous cars and always found an improvement when using a door build.

steve McCulloch

Kryten

Any chance of listening to your set up - having a look at the door builds, etc as you live fairly close?


Rgds

Steve