I'm dropping in a lil 6 band eq for the mids/highs and am having the strangest issue!!
the symptom can be described as what happens when you run power and RCAs next to each other, but to isolate variables i have all RCAs ran out of body panels and away from all wires.
ok-
RCA deck to interior amp is GOOD
RCA Deck to EQ is GOOD
RCA EQ to sub/mid amps is GOOD
RCA EQ to Highs amp is BAD
everything works fine until the RCA connection between EQ and interior amp is connected- trying to figure out how this problem only occurs for that one connection even though each works fine when connected to other devices.
-Drew
**edit amp has slight issues when ran from the HU but some jiggling of the RCA inputs solves it
Replies (14)
Victor on 08/8/2008 21:09:43
Seems like the either the "RCA outs in your EQ" or the "RCA ins of your amp" are not grounded well......
swez on 08/9/2008 00:57:51
Victor is probably right. The tweeter amp may have issues with internal grounding of the RCA's inputs.
Try testing this amp on full range speakers off another set of RCA outputs from the EQ. If you hear a steady hum at MB frequencies, it's probably a internal amp ground problem.
If the present tweeter amp has been around the block a few times, I would probably remove the covers, carefully clean the PCB with IPA and a toothbrush, then examine the traces and solder joints for contaminations, cold solder joints or loose connections at the RCA input panel. Resolder as needed w/ fine gage 60/40 Alloy, rosin core flux solder.
Tech tip: Use a bright lamp to backlight the board and a 10X magnifying lense. Look for gray and grainy solder joints, loose soldering joints. Clean the board after touch ups with IPA. (Rubbing Alcohol)
Swez
newB on 08/9/2008 05:10:29
0.o
oh i like it!
one of my fellow Sound Techs at Six flags does board work on the PA amps we run i'll ask him to take a look at it!
i was thinking it might be the rca grounds on the EQ- although i dont hear anything obnoxious from the other RCA outs, it may just be because the drivers are bigger and frequencies are lower, how would i go about making sure all my rca grounds are good?
(i've tried connecting the outer rim of the rca to ground with no effect, am i doing that right?)
the step i took to check the amp was to run the RCA from deck to amp with no buzzz, if it was an internal issue on the amp would the symptom still show itself with two different sources?
-Drew
swez on 08/9/2008 06:50:22
Drew,
Hum, have your buddy look at this tweeter amp and hope he spots something simple and can do a good repair if/as needed. It's possible the HF outs from this EQ are a bit flakey too. But test the HF amp on another output from the EQ and full range speakers anyway.
Also, if you really want to get ambitious, try the MID/HIGH outputs from the EQ to the suspect amp and see what turns up. If that is quiet, then test the HF outs from EQ to another known good amp and see what that result might be.
This group of tests will confirm amp or EQ out problems.
Swez
PS What HF tweets are you running off this amp? (Make and model #?) I ask this as some tweeter circuits a very reactive Capacitive loads. Some amps don't handle that type of load well and your's may be one of them.
Victor on 08/9/2008 17:33:37
Just doing some loud thinking...
""""RCA deck to interior amp is GOOD
RCA Deck to EQ is GOOD
RCA EQ to sub/mid amps is GOOD
RCA EQ to Highs amp is BAD
everything works fine until the RCA connection between EQ and interior amp is connected- trying to figure out how this problem only occurs for that one connection even though each works fine when connected to other devices.""""
what do u mean by interior amp.....?
1 - you have connection between the deck and the interior amp
2 - connection between eq and interior amp
trying to figure out how this problem only occurs for that one connection even though each works fine when connected to other devices.
apart from checking the amps....
if you can draw a rough sketch of the wiring diagram and upload it..
Victor...
PS: when using an external EQ , with 3way x overs you really dont need to let the HU send a direct signal to any amps or speaker.... By the way what Brand/Model No: EQ are we dealing with here..... ?
also what Brand/Model No: is the amp in question here ???
reason i ask this.... RCA input - output voltage and impedance, between 2 electronic components connected, need to be compatible.
newB on 08/10/2008 18:22:06
sry i've been out this weekend- i've decided its the EQ and the noise is coming out of the midwoofs and sub its just so faint that its not as annoying as the buzz from the highs.
and victor thats my fault for changing my terms in the first post
interior amp = highs amp
Kenwood 200w ------ 2 6x9s and 2 5.25s
crunch 400w ------ 2 8" mids
Kicker 400.1w ----- Eclipse 10" woof
-Drew
Victor on 08/10/2008 18:46:39
can we chat realtime on this one...
victorginger@yahoo.com
victorexports@hotmail.com
swez on 08/11/2008 09:00:50
Have you tried re-grounding the HU and EQ to the same location? (Not the harness ground, but a known good ground in the dash, firewall or floor panel)
Swez
newB on 08/11/2008 09:54:14
YUP!!!!
GRIN
-Drew
swez on 08/11/2008 16:52:08
Huh... what Make/Model is this EQ and how old do you think it is?
Since the noise issues prevail on all outputs, one has to think twice on this scenario and consider other option. If this were say a product from Audio Control, it's worth digging deeper. But if a low budget brand of dubious destinction, it may not be the right fix for your future goals.
Comments?
Swez
newB on 08/11/2008 20:55:41
its brand new in box, but a cheapo so as stated in victors email i will be returning it and purchasing an audio control unit sometime in the near future to accomplish what i need it to.
-Drew
Victor on 08/11/2008 23:01:49
if your EQ has a metallic chassis and cover.. try grounding them to the Car...
Victor...
newB on 08/12/2008 17:13:11
it did- wish i would have tried it but i can do much better for the money.
any recommendations?
-Drew
swez on 08/13/2008 02:07:31
What features do you need from the EQ and how many bands? (7-10 bands are plenty in a mobile system)
Swez
the symptom can be described as what happens when you run power and RCAs next to each other, but to isolate variables i have all RCAs ran out of body panels and away from all wires.
ok-
RCA deck to interior amp is GOOD
RCA Deck to EQ is GOOD
RCA EQ to sub/mid amps is GOOD
RCA EQ to Highs amp is BAD
everything works fine until the RCA connection between EQ and interior amp is connected- trying to figure out how this problem only occurs for that one connection even though each works fine when connected to other devices.
-Drew
**edit amp has slight issues when ran from the HU but some jiggling of the RCA inputs solves it
Replies (14)
Victor on 08/8/2008 21:09:43
Seems like the either the "RCA outs in your EQ" or the "RCA ins of your amp" are not grounded well......
swez on 08/9/2008 00:57:51
Victor is probably right. The tweeter amp may have issues with internal grounding of the RCA's inputs.
Try testing this amp on full range speakers off another set of RCA outputs from the EQ. If you hear a steady hum at MB frequencies, it's probably a internal amp ground problem.
If the present tweeter amp has been around the block a few times, I would probably remove the covers, carefully clean the PCB with IPA and a toothbrush, then examine the traces and solder joints for contaminations, cold solder joints or loose connections at the RCA input panel. Resolder as needed w/ fine gage 60/40 Alloy, rosin core flux solder.
Tech tip: Use a bright lamp to backlight the board and a 10X magnifying lense. Look for gray and grainy solder joints, loose soldering joints. Clean the board after touch ups with IPA. (Rubbing Alcohol)
Swez
newB on 08/9/2008 05:10:29
0.o
oh i like it!
one of my fellow Sound Techs at Six flags does board work on the PA amps we run i'll ask him to take a look at it!
i was thinking it might be the rca grounds on the EQ- although i dont hear anything obnoxious from the other RCA outs, it may just be because the drivers are bigger and frequencies are lower, how would i go about making sure all my rca grounds are good?
(i've tried connecting the outer rim of the rca to ground with no effect, am i doing that right?)
the step i took to check the amp was to run the RCA from deck to amp with no buzzz, if it was an internal issue on the amp would the symptom still show itself with two different sources?
-Drew
swez on 08/9/2008 06:50:22
Drew,
Hum, have your buddy look at this tweeter amp and hope he spots something simple and can do a good repair if/as needed. It's possible the HF outs from this EQ are a bit flakey too. But test the HF amp on another output from the EQ and full range speakers anyway.
Also, if you really want to get ambitious, try the MID/HIGH outputs from the EQ to the suspect amp and see what turns up. If that is quiet, then test the HF outs from EQ to another known good amp and see what that result might be.
This group of tests will confirm amp or EQ out problems.
Swez
PS What HF tweets are you running off this amp? (Make and model #?) I ask this as some tweeter circuits a very reactive Capacitive loads. Some amps don't handle that type of load well and your's may be one of them.
Victor on 08/9/2008 17:33:37
Just doing some loud thinking...
""""RCA deck to interior amp is GOOD
RCA Deck to EQ is GOOD
RCA EQ to sub/mid amps is GOOD
RCA EQ to Highs amp is BAD
everything works fine until the RCA connection between EQ and interior amp is connected- trying to figure out how this problem only occurs for that one connection even though each works fine when connected to other devices.""""
what do u mean by interior amp.....?
1 - you have connection between the deck and the interior amp
2 - connection between eq and interior amp
trying to figure out how this problem only occurs for that one connection even though each works fine when connected to other devices.
apart from checking the amps....
if you can draw a rough sketch of the wiring diagram and upload it..
Victor...
PS: when using an external EQ , with 3way x overs you really dont need to let the HU send a direct signal to any amps or speaker.... By the way what Brand/Model No: EQ are we dealing with here..... ?
also what Brand/Model No: is the amp in question here ???
reason i ask this.... RCA input - output voltage and impedance, between 2 electronic components connected, need to be compatible.
newB on 08/10/2008 18:22:06
sry i've been out this weekend- i've decided its the EQ and the noise is coming out of the midwoofs and sub its just so faint that its not as annoying as the buzz from the highs.
and victor thats my fault for changing my terms in the first post
interior amp = highs amp
Kenwood 200w ------ 2 6x9s and 2 5.25s
crunch 400w ------ 2 8" mids
Kicker 400.1w ----- Eclipse 10" woof
-Drew
Victor on 08/10/2008 18:46:39
can we chat realtime on this one...
victorginger@yahoo.com
victorexports@hotmail.com
swez on 08/11/2008 09:00:50
Have you tried re-grounding the HU and EQ to the same location? (Not the harness ground, but a known good ground in the dash, firewall or floor panel)
Swez
newB on 08/11/2008 09:54:14
YUP!!!!
GRIN
-Drew
swez on 08/11/2008 16:52:08
Huh... what Make/Model is this EQ and how old do you think it is?
Since the noise issues prevail on all outputs, one has to think twice on this scenario and consider other option. If this were say a product from Audio Control, it's worth digging deeper. But if a low budget brand of dubious destinction, it may not be the right fix for your future goals.
Comments?
Swez
newB on 08/11/2008 20:55:41
its brand new in box, but a cheapo so as stated in victors email i will be returning it and purchasing an audio control unit sometime in the near future to accomplish what i need it to.
-Drew
Victor on 08/11/2008 23:01:49
if your EQ has a metallic chassis and cover.. try grounding them to the Car...
Victor...
newB on 08/12/2008 17:13:11
it did- wish i would have tried it but i can do much better for the money.
any recommendations?
-Drew
swez on 08/13/2008 02:07:31
What features do you need from the EQ and how many bands? (7-10 bands are plenty in a mobile system)
Swez
Copyright ClubKnowledge 2009 * All Rights Reserved
