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View Full Version : Mids and High's Question???????



cdog
11-09-2004, 03:41 PM
I've got 3 set's of MB Quartz 6.5's and they are run by a fosgate 551X amp. When I crank it up the amp shut's down after a while and then comes back on after 30 sec. or so. I belive it shuts down because of distortion. What shoud I do? I can get $200 credit for my amp as a trade in. Should I go with the JL or another fosgate and what modle exactly. A guy I know told me I need more power to the 6.5's. How much can I expect to pay for a better amp?

Havasu Hangin'
11-09-2004, 03:55 PM
How well is it ventilated?

cdog
11-09-2004, 04:01 PM
How well is it ventilated?
Pretty well. I have one of those stinger fans blowing over the amps and kept the end plates off of them. It did this in my driveway sunday while it was 65 degrees out side.

Havasu Hangin'
11-09-2004, 04:22 PM
Well, it sounds like thermal shutdown, but not if it's that well ventilated. Does it get hot? How are the speakers wired to it?
I'd put a minimum of 100 watts to those speakers.

phebus
11-09-2004, 04:31 PM
My Fosgate amp was shutting down due to low voltage (it was going into protect mode) It would come back on if power was shut off, then turned back on to reset it, but turn off again in about 30 secs. I don't know if the 551 will cycle on and off by itself if it goes into protect, but I would check to make sure your voltage isn't droping below 10.5 volts with a meter.

cdog
11-09-2004, 04:37 PM
My Fosgate amp was shutting down due to low voltage (it was going into protect mode) It would come back on if power was shut off, then turned back on to reset it, but turn off again in about 30 secs. I don't know if the 551 will cycle on and off by itself if it goes into protect, but I would check to make sure your voltage isn't droping below 10.5 volts with a meter.
The base amp did'nt shut down. It get's fed from the same 4 ga. source. It's a Bp1000 fosgate running 2 eclipse 12's.

phebus
11-09-2004, 05:45 PM
The base amp did'nt shut down. It get's fed from the same 4 ga. source. It's a Bp1000 fosgate running 2 eclipse 12's.
I have two Fosgate amps (1500 mono, 800 4ch.), and only the 1500 shuts down when my voltage drops. Bothh have the same voltage feed Can't explain it, but happens.

cdog
11-09-2004, 05:53 PM
Where are all of the stereo shop guy's? Did they get tired of giving away free advice?

cdog
11-09-2004, 06:02 PM
What i'm thinking right now is that each speaker has a RMS rating of 80-130 watts. The amp I have running 6 speakers has a RMS output of 275 watts. I was thinking of buying another amp with a RMS output of 550 RMS and split that among 4 speakers and using my 551 to run the other two. How does that sound?

cdog
11-09-2004, 06:58 PM
Bump?

riverbound
11-09-2004, 07:09 PM
Cdogg,
It could be a number of things.
1) thermal shutdown (not likely if you have fans blowing directly on it)
2) shorted speaker wire (Rockfords will play through a short to an extent
this seems more likely)
3) your speakers could be distoring causing a short which causes the amp to
go into protect mode (also very likely)
4) bad amp (it happens sometimes)
My advice would be to take it to someone who is familiar with these amps and can properly diagnose your problem. There are many shops out there that will look at it for a very nominal fee if not free. I know that IF we charge you to trouble shoot we will usually apply the trouble shoot fee to any purchese that is made to fix the problem. We have done many boats for board members and almost always use Rockford amps.
If you want us to take a look at it call Robert (909)481-8411 and tell him you are from ***boat, he will take care of you. Also "parker" here on the boards is in the shop everyday maybe get a hold of him and he can help you out.

cdog
11-09-2004, 07:18 PM
Cdogg,
It could be a number of things.
1) thermal shutdown (not likely if you have fans blowing directly on it)
2) shorted speaker wire (Rockfords will play through a short to an extent
this seems more likely)
3) your speakers could be distoring causing a short which causes the amp to
go into protect mode (also very likely)
4) bad amp (it happens sometimes)
My advice would be to take it to someone who is familiar with these amps and can properly diagnose your problem. There are many shops out there that will look at it for a very nominal fee if not free. I know that IF we charge you to trouble shoot we will usually apply the trouble shoot fee to any purchese that is made to fix the problem. We have done many boats for board members and almost always use Rockford amps.
If you want us to take a look at it call Robert (909)481-8411 and tell him you are from ***boat, he will take care of you. Also "parker" here on the boards is in the shop everyday maybe get a hold of him and he can help you out.
Thanks for your help. Does it sound like they are under powered? The 6.5's are the MB 160.19's.

Havasu Hangin'
11-09-2004, 07:23 PM
What i'm thinking right now is that each speaker has a RMS rating of 80-130 watts. The amp I have running 6 speakers has a RMS output of 275 watts. I was thinking of buying another amp with a RMS output of 550 RMS and split that among 4 speakers and using my 551 to run the other two. How does that sound?
I think you've kinda painted yoursef in a corner with that amp.
If you bridge that amp, it will put out 275 watts x 2 at 4 ohms. That's too much for those speakers...and you can't add another pair because it won't take a 2 ohm bridged load.
With that amp, the bottom line is that you can either give your speaker 70 watts (70 x 4 @ 4 ohms for two pair or 140 x 4 @ 2 ohms for four pair) or 275 watts each.
Might be time for some changes...
PS- I agree with riverbound...sounds like a shorted wire.

riverbound
11-09-2004, 08:15 PM
What i'm thinking right now is that each speaker has a RMS rating of 80-130 watts. The amp I have running 6 speakers has a RMS output of 275 watts. I was thinking of buying another amp with a RMS output of 550 RMS and split that among 4 speakers and using my 551 to run the other two. How does that sound?
This would be your best option, but make sure you dont have any shorts in the system. I have run that same setup many times, it is a little on the underpowered side. If it is tuned propperly and you dont listen to it too loud it will do the job. Most people are happy with the sound and performance.

cdog
11-09-2004, 08:17 PM
Do you think the shorted wire would cause me to get some engine buzz when the engine is on? I've checked all of the grounds and they're all good, but when the engine is on I get a buzz on the passenger side speakers only.

riverbound
11-09-2004, 08:32 PM
Do you think the shorted wire would cause me to get some engine buzz when the engine is on? I've checked all of the grounds and they're all good, but when the engine is on I get a buzz on the passenger side speakers only.
could be, but it would have to be looked at to know for sure.

cdog
11-09-2004, 08:46 PM
Shockwave installed all of my stuff and is telling me they don't know why it's buzzing when the engine is running. They say it's because of my custom engine that does'nt have any noise suppressors but to me that does not make any sense due to only the passenger side getting the buzz. Sounds like a short, probably on the ground side causing the buzz and when the volume is up and the amp is cranking there is more resistance and causes the amp to go into protect mode. What do you think?

riverbound
11-09-2004, 08:49 PM
Shockwave installed all of my stuff and is telling me they don't know why it's buzzing when the engine is running. They say it's because of my custom engine that does'nt have any noise suppressors but to me that does not make any sense due to only the passenger side getting the buzz. Sounds like a short, probably on the ground side causing the buzz and when the volume is up and the amp is cranking there is more resistance and causes the amp to go into protect mode. What do you think?
If it was some sort of induced noise it would affect both sides.

cdog
11-09-2004, 08:58 PM
If it was some sort of induced noise it would affect both sides.
That's what I told them. The only thing I did not check yet was switching the rca's while I had the buzz of the engine and see if the buzz changed sides. I get a little bit of noise from the stinger fan on the passenger side speakers also. Sounds to me more and more that I probably have a short on the pass side speaker wire. Now that I think about it I switched the rca's while the fan noise was present and the noise stayed on the same side. What ga. speaker wire should be run for the 6.5's?

Havasu Hangin'
11-09-2004, 09:20 PM
I have had ignition noise picked up by speakers before (MSD, HEI, etc). Make sure the speakers are not grounded.
Don't worry about the guage on the speaker wires (16 is fine)...there's not enough amperage to matter.

mbrown2
11-09-2004, 09:59 PM
I have had a 1500bd Rockford Hotplate go into thermal shutdown even with Stinger fans on it...Although they sound great and are good amps, there are better amps out there...
I run three sets of MB's in another boat, and have 200x4 (PG Xenon) amp driving the 3 sets of MB's...100 x 2 to 2 sets, and 200 x 2 to another set...the amp never shuts down and it don't even fans blowing on it, but has internal fans..