Reply
 
Thread Tools Display Modes
  #1   Report Post  
Ben Rakestraw
 
Posts: n/a
Default Possible amp repair? Please help...

Hello,

I have a rockford fosgate 800a4, 100x4 @ 4 ohms, 200x4 @ 2ohms. When using
the RCA inputs to the amplifier, the amp sends a horrible high pitched
squeel to my full range speakers, even with the car's engine off. When
using the high level inputs on the amp, the noise goes away. Using another
amp I had around and a test speaker, I have determined that the problem is
not the head unit, noise coming into the RCA's, nor noise coming into the
speaker wires. I have also tested the ground by moving it, and it does not
appear to be the problem either. The sound is not noticable with subs
hooked up, as they can't play that high of a noise. The amp has been in
storage (cold garage) for the past two months. The last car I had it hooked
up in, the amp made some noise with the engine on (alternator whine), but
never with the engine off.

After my testing, I believe the problem is in the amp itself. So, does any
one with some electronics background know what the problem might be? Ball
park estimate of what a repair might cost me? I read some posts by a guy
called ampdoc, what do you think? I can continue using the high level
inputs for now, it sounds pretty good, but this is not ideal. Any info is
very appreciated.

Thanks,
Ben


  #2   Report Post  
wicked1
 
Posts: n/a
Default Possible amp repair? Please help...

ampdoc is very nice to deal with and very reasonable pricing give him a
call. He has his phone number in his signature. He has another amp of mine
right now.
"Ben Rakestraw" wrote in message
news:wabPb.91187$5V2.212729@attbi_s53...
Hello,

I have a rockford fosgate 800a4, 100x4 @ 4 ohms, 200x4 @ 2ohms. When

using
the RCA inputs to the amplifier, the amp sends a horrible high pitched
squeel to my full range speakers, even with the car's engine off. When
using the high level inputs on the amp, the noise goes away. Using

another
amp I had around and a test speaker, I have determined that the problem is
not the head unit, noise coming into the RCA's, nor noise coming into the
speaker wires. I have also tested the ground by moving it, and it does

not
appear to be the problem either. The sound is not noticable with subs
hooked up, as they can't play that high of a noise. The amp has been in
storage (cold garage) for the past two months. The last car I had it

hooked
up in, the amp made some noise with the engine on (alternator whine), but
never with the engine off.

After my testing, I believe the problem is in the amp itself. So, does

any
one with some electronics background know what the problem might be? Ball
park estimate of what a repair might cost me? I read some posts by a guy
called ampdoc, what do you think? I can continue using the high level
inputs for now, it sounds pretty good, but this is not ideal. Any info is
very appreciated.

Thanks,
Ben




  #3   Report Post  
Mark Zarella
 
Posts: n/a
Default Possible amp repair? Please help...

Spend the $40 to have it professionally installed.

"Ben Rakestraw" wrote in message
news:wabPb.91187$5V2.212729@attbi_s53...
Hello,

I have a rockford fosgate 800a4, 100x4 @ 4 ohms, 200x4 @ 2ohms. When

using
the RCA inputs to the amplifier, the amp sends a horrible high pitched
squeel to my full range speakers, even with the car's engine off. When
using the high level inputs on the amp, the noise goes away. Using

another
amp I had around and a test speaker, I have determined that the problem is
not the head unit, noise coming into the RCA's, nor noise coming into the
speaker wires. I have also tested the ground by moving it, and it does

not
appear to be the problem either. The sound is not noticable with subs
hooked up, as they can't play that high of a noise. The amp has been in
storage (cold garage) for the past two months. The last car I had it

hooked
up in, the amp made some noise with the engine on (alternator whine), but
never with the engine off.

After my testing, I believe the problem is in the amp itself. So, does

any
one with some electronics background know what the problem might be? Ball
park estimate of what a repair might cost me? I read some posts by a guy
called ampdoc, what do you think? I can continue using the high level
inputs for now, it sounds pretty good, but this is not ideal. Any info is
very appreciated.

Thanks,
Ben




  #4   Report Post  
ampdoc
 
Posts: n/a
Default Possible amp repair? Please help...

It sounds as if the ground pins of your RCA jacks have broken loose from the
PC board in the amp. It shouldn't be a problem to repair, you could do it
yourself if you feel comfortable taking the amp apart & are good at
soldering. Try GENTLY applying pressure to the RCA's with the amp on and see
if the noise goes away. If you don't feel comfortable fixing it yourself,
feel free to send it to us. We call with an estimate before we fix it.

--
Jammy Harbin
J & J Electronics, Inc
227 S. 4Th St.
Selmer, TN 38375
731-645-3311
"Ben Rakestraw" wrote in message
news:wabPb.91187$5V2.212729@attbi_s53...
Hello,

I have a rockford fosgate 800a4, 100x4 @ 4 ohms, 200x4 @ 2ohms. When

using
the RCA inputs to the amplifier, the amp sends a horrible high pitched
squeel to my full range speakers, even with the car's engine off. When
using the high level inputs on the amp, the noise goes away. Using

another
amp I had around and a test speaker, I have determined that the problem is
not the head unit, noise coming into the RCA's, nor noise coming into the
speaker wires. I have also tested the ground by moving it, and it does

not
appear to be the problem either. The sound is not noticable with subs
hooked up, as they can't play that high of a noise. The amp has been in
storage (cold garage) for the past two months. The last car I had it

hooked
up in, the amp made some noise with the engine on (alternator whine), but
never with the engine off.

After my testing, I believe the problem is in the amp itself. So, does

any
one with some electronics background know what the problem might be? Ball
park estimate of what a repair might cost me? I read some posts by a guy
called ampdoc, what do you think? I can continue using the high level
inputs for now, it sounds pretty good, but this is not ideal. Any info is
very appreciated.

Thanks,
Ben




  #5   Report Post  
Ben Rakestraw
 
Posts: n/a
Default Possible amp repair? Please help...

Tell me o wise one, what might a 'professional' do that I have not? I
thought this group was supposed to be helpful. Anyone else have some
constructive insight?

Ben

"Mark Zarella" wrote in message
...
Spend the $40 to have it professionally installed.

"Ben Rakestraw" wrote in message
news:wabPb.91187$5V2.212729@attbi_s53...
Hello,

I have a rockford fosgate 800a4, 100x4 @ 4 ohms, 200x4 @ 2ohms. When

using
the RCA inputs to the amplifier, the amp sends a horrible high pitched
squeel to my full range speakers, even with the car's engine off. When
using the high level inputs on the amp, the noise goes away. Using

another
amp I had around and a test speaker, I have determined that the problem

is
not the head unit, noise coming into the RCA's, nor noise coming into

the
speaker wires. I have also tested the ground by moving it, and it does

not
appear to be the problem either. The sound is not noticable with subs
hooked up, as they can't play that high of a noise. The amp has been in
storage (cold garage) for the past two months. The last car I had it

hooked
up in, the amp made some noise with the engine on (alternator whine),

but
never with the engine off.

After my testing, I believe the problem is in the amp itself. So, does

any
one with some electronics background know what the problem might be?

Ball
park estimate of what a repair might cost me? I read some posts by a

guy
called ampdoc, what do you think? I can continue using the high level
inputs for now, it sounds pretty good, but this is not ideal. Any info

is
very appreciated.

Thanks,
Ben








  #6   Report Post  
Mark Zarella
 
Posts: n/a
Default Possible amp repair? Please help...

Tell me o wise one, what might a 'professional' do that I have not? I
thought this group was supposed to be helpful. Anyone else have some
constructive insight?


Ok then don't. Just keep in mind which one of us is in here asking newbie
questions. I hear your question all the damned time, and 95% of the time it
turns out to be solvable by an experienced installer.

Oh yeah, did you try messing with your HU ground? Probably not...


  #7   Report Post  
Ben Rakestraw
 
Posts: n/a
Default Possible amp repair? Please help...

No, I did not try messing with the head unit ground, thank you for
suggesting it. What about the head unit ground would make the noise thru
RCA's but not hi-level inputs, even when the engine is off? A ground loop?
As I said in my first post, any info is appreciated.

This group is full of DIY'ers. If you are that experienced, please use it
to help us, not disrespect our newbie questions (which btw, I have seen far
more basic and obvious questions answered in this group).

Ben

"Mark Zarella" wrote in message
...
Tell me o wise one, what might a 'professional' do that I have not? I
thought this group was supposed to be helpful. Anyone else have some
constructive insight?


Ok then don't. Just keep in mind which one of us is in here asking newbie
questions. I hear your question all the damned time, and 95% of the time

it
turns out to be solvable by an experienced installer.

Oh yeah, did you try messing with your HU ground? Probably not...




  #8   Report Post  
Soundfreak03
 
Posts: n/a
Default Possible amp repair? Please help...

No, I did not try messing with the head unit ground, thank you for
suggesting it. What about the head unit ground would make the noise thru
RCA's but not hi-level inputs, even when the engine is off? A ground loop?
As I said in my first post, any info is appreciated.


Ground loops are funny sometimes. The addition of the RCA's could actually
cause the ground loop, your HU could be attempting to use those as a ground. Or
you could have bad RCAs with a break in the cable somewhere. Try the HU ground
and try a different set of cables. Pay attention to the results of each and
then in combination, that way if it doesn't work you can tell us what exactly
happened.

Les


  #9   Report Post  
Mark Zarella
 
Posts: n/a
Default Possible amp repair? Please help...

No, I did not try messing with the head unit ground, thank you for
suggesting it. What about the head unit ground would make the noise thru
RCA's but not hi-level inputs, even when the engine is off? A ground

loop?
As I said in my first post, any info is appreciated.

This group is full of DIY'ers. If you are that experienced, please use it
to help us, not disrespect our newbie questions (which btw, I have seen

far
more basic and obvious questions answered in this group).


I gave you my best recommendation. You rejected it. Instead, I'll suggest
that you make sure that the problem is with the amplifier first by trying a
different low-level source. A portable cd or mp3 player perhaps?

Although the evidence so far points to the amp, you need to explore all
avenues first as most repair shops charge you just to look at an amp.


  #10   Report Post  
Mark Zarella
 
Posts: n/a
Default Possible amp repair? Please help...

I think he's assuming the cables are fine because the other amp worked with
it. Not an unreasonable assumption. But I've seen stranger things happen.
It's not at all uncommon to get noise out of a perfecty working amplifier or
signal processor, even when plugging in another type gets rid of the noise.

"Soundfreak03" wrote in message
...
No, I did not try messing with the head unit ground, thank you for
suggesting it. What about the head unit ground would make the noise thru
RCA's but not hi-level inputs, even when the engine is off? A ground

loop?
As I said in my first post, any info is appreciated.


Ground loops are funny sometimes. The addition of the RCA's could actually
cause the ground loop, your HU could be attempting to use those as a

ground. Or
you could have bad RCAs with a break in the cable somewhere. Try the HU

ground
and try a different set of cables. Pay attention to the results of each

and
then in combination, that way if it doesn't work you can tell us what

exactly
happened.

Les






  #11   Report Post  
Shane Metzler
 
Posts: n/a
Default Possible amp repair? Please help...

Mark,

Why is it not uncommon to get noise out of a perfecty working amplifier or
signal processor, even when plugging in another type gets rid of the noise?

Thanks,

Shane
"Mark Zarella" wrote in message
...
I think he's assuming the cables are fine because the other amp worked

with
it. Not an unreasonable assumption. But I've seen stranger things

happen.
It's not at all uncommon to get noise out of a perfecty working amplifier

or
signal processor, even when plugging in another type gets rid of the

noise.

"Soundfreak03" wrote in message
...
No, I did not try messing with the head unit ground, thank you for
suggesting it. What about the head unit ground would make the noise

thru
RCA's but not hi-level inputs, even when the engine is off? A ground

loop?
As I said in my first post, any info is appreciated.


Ground loops are funny sometimes. The addition of the RCA's could

actually
cause the ground loop, your HU could be attempting to use those as a

ground. Or
you could have bad RCAs with a break in the cable somewhere. Try the HU

ground
and try a different set of cables. Pay attention to the results of each

and
then in combination, that way if it doesn't work you can tell us what

exactly
happened.

Les






  #12   Report Post  
Mark Zarella
 
Posts: n/a
Default Possible amp repair? Please help...

Why is it not uncommon to get noise out of a perfecty working amplifier or
signal processor, even when plugging in another type gets rid of the

noise?

Some pieces are more susceptible to ground loops and other types of noise
sources than other pieces.


  #13   Report Post  
Shane Metzler
 
Posts: n/a
Default Possible amp repair? Please help...

Ok Thanks!
"Mark Zarella" wrote in message
...
Why is it not uncommon to get noise out of a perfecty working amplifier

or
signal processor, even when plugging in another type gets rid of the

noise?

Some pieces are more susceptible to ground loops and other types of noise
sources than other pieces.




  #14   Report Post  
Ben Rakestraw
 
Posts: n/a
Default Possible amp repair? Please help...

A portable cd player plugged into the amp resulted in no noise, so I guess
the amp is fine. Once I get time this weekend, I will play with the head
unit ground. Do I have to ground the HU at the same point as the amp, or
will a good ground up front suffice?

couple random questions:
Do the power lines to the HU sometimes give noise like a bad ground would?
Do power filters, ground loop isolators, noise supressors, etc work? How?
(I plan on fixing the real problem before trying one of these band-aids, but
am just curious)

Thanks for all the replies!

Ben

"Mark Zarella" wrote in message
...
No, I did not try messing with the head unit ground, thank you for
suggesting it. What about the head unit ground would make the noise

thru
RCA's but not hi-level inputs, even when the engine is off? A ground

loop?
As I said in my first post, any info is appreciated.

This group is full of DIY'ers. If you are that experienced, please use

it
to help us, not disrespect our newbie questions (which btw, I have seen

far
more basic and obvious questions answered in this group).


I gave you my best recommendation. You rejected it. Instead, I'll

suggest
that you make sure that the problem is with the amplifier first by trying

a
different low-level source. A portable cd or mp3 player perhaps?

Although the evidence so far points to the amp, you need to explore all
avenues first as most repair shops charge you just to look at an amp.




  #15   Report Post  
Mark Zarella
 
Posts: n/a
Default Possible amp repair? Please help...

A portable cd player plugged into the amp resulted in no noise, so I guess
the amp is fine. Once I get time this weekend, I will play with the head
unit ground. Do I have to ground the HU at the same point as the amp, or
will a good ground up front suffice?


No, just aim for a good ground. As you may have heard before, eliminating
noise is more of an art than a science, so I wish you luck. Some cars and
some equipment is more difficult than others. That's what I meant when I
suggested you had a professional look at it. Not that you're incompetent or
that you couldn't figure it out. But rather, it can be a real pain in the
ass to finally figure out and they don't charge extra to do it.

couple random questions:
Do the power lines to the HU sometimes give noise like a bad ground would?


No.

Do power filters, ground loop isolators, noise supressors, etc work? How?


They can. They work by isolating grounds.


Reply
Thread Tools
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Help-Realistic Repair rob General 5 June 8th 04 12:37 PM
Sony Repair Suggestions Geoff Wood General 43 May 7th 04 03:11 AM
Repair services in SFBA notbob General 0 December 28th 03 04:34 AM
Rockford Amp Repair? Shane Metzler Car Audio 2 August 6th 03 03:17 AM
mb quart repair? nakamichi Car Audio 0 August 1st 03 08:56 AM


All times are GMT +1. The time now is 11:27 PM.

Powered by: vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AudioBanter.com.
The comments are property of their posters.
 

About Us

"It's about Audio and hi-fi"