Mikbox: Getting a feedback loop and low-humming noises
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Mikbox: Getting a feedback loop and low-humming noises
Hi folks,
I have a 2000 CLK430 coupe with a digital StarTAC CDMA that I am upgrading to a Motorola V551. The MikBox install went OK and the car recognizes the V551 via the new cradle and MikBox.
The problem I have is that when I make or receive calls, I get a very annoying high-pitched feedback loop and need to turn down the volume almost all the way. This is the same type of feedback noise generated if you had a microphone too close to speakers.
I also get a low-pitch hum from the time you start making a call through the time the call ends. Some of you might know this noise if you have ever left your mobile handset near speakers. When the phone is ringing, or while the call is engaged, the speaker seems to resonate at the same frequency of the call.
I have attempted to use the telephone docked in the cradle and with the cable only. This way, I would be able to determine if this issue had anything to do with the external antenna.
The car used to have a StarTAC TDMA handset. After a couple of years, I purchased the CDMA handset to switch over to Verizon. As far as I knew, the only difference was the handset - I didn't have to change anything else out, I believe.
Does anyone know how to remedy either or both of these issues?
With the OEM stuff in place, these issues never existed - it's only appeared with the MikBox installed.
Here are my specs:
2000 CLK430 with COMAND factory-installed
StarTAC CDMA- old handset (OEM Mercedes)
Motorola V551 - new handset (Cingular)
PSE is Q682-0460
I've sent Mik an email about this, but if anyone has seen this before, I'd appreciate your help.
I have a 2000 CLK430 coupe with a digital StarTAC CDMA that I am upgrading to a Motorola V551. The MikBox install went OK and the car recognizes the V551 via the new cradle and MikBox.
The problem I have is that when I make or receive calls, I get a very annoying high-pitched feedback loop and need to turn down the volume almost all the way. This is the same type of feedback noise generated if you had a microphone too close to speakers.
I also get a low-pitch hum from the time you start making a call through the time the call ends. Some of you might know this noise if you have ever left your mobile handset near speakers. When the phone is ringing, or while the call is engaged, the speaker seems to resonate at the same frequency of the call.
I have attempted to use the telephone docked in the cradle and with the cable only. This way, I would be able to determine if this issue had anything to do with the external antenna.
The car used to have a StarTAC TDMA handset. After a couple of years, I purchased the CDMA handset to switch over to Verizon. As far as I knew, the only difference was the handset - I didn't have to change anything else out, I believe.
Does anyone know how to remedy either or both of these issues?
With the OEM stuff in place, these issues never existed - it's only appeared with the MikBox installed.
Here are my specs:
2000 CLK430 with COMAND factory-installed
StarTAC CDMA- old handset (OEM Mercedes)
Motorola V551 - new handset (Cingular)
PSE is Q682-0460
I've sent Mik an email about this, but if anyone has seen this before, I'd appreciate your help.
Last edited by juanvaldez; Oct 30, 2005 at 06:40 PM.
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2015 E250D
It is a very common problem with GSM phones. If you try a CDMA, that noise will be gone. I have done several MIKBOX installs and some have a loud annoying sound while others have low hum. Try a different phone as well.
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That's not good....
I always keep my car phone docked in the Mercedes and carry one around separately. Right now, all of my lines are on Cingular FamilyTalk, and this was the last one on Verizon that I wanted to move over, so that I could just pay $9.99 for the extra line per month instead of the $45 that Verizon charges.
Odd that nobody except me has reported this problem, unless most people are using CDMA handsets...
It seems like the microphone also becomes super sensitive with the V551/MikBox combo installed. If you switch to telephone mode and then rub your finger over the car's built-in microphone, you will hear loud noises from the speakers.
I always keep my car phone docked in the Mercedes and carry one around separately. Right now, all of my lines are on Cingular FamilyTalk, and this was the last one on Verizon that I wanted to move over, so that I could just pay $9.99 for the extra line per month instead of the $45 that Verizon charges.
Odd that nobody except me has reported this problem, unless most people are using CDMA handsets...
It seems like the microphone also becomes super sensitive with the V551/MikBox combo installed. If you switch to telephone mode and then rub your finger over the car's built-in microphone, you will hear loud noises from the speakers.
Originally Posted by sunman
It is a very common problem with GSM phones. If you try a CDMA, that noise will be gone. I have done several MIKBOX installs and some have a loud annoying sound while others have low hum. Try a different phone as well.
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Unfortunately the humming noise is normal on the GSM phones. Some cars have it louder than others. It depends on the combination of head unit and PSE. Usually when using the external antenna and compensator it is better, since the phone won't use as much output power (better signal).
The high pitch feedback noise you are talking about is not normal. So far there was one customer only who reported something similar. He used the SA200 amplifier, and without it there was no problem. But since you already tried to take the cradle out of the loop, it can't be the antenna circuit.
You possible have a faulty MB/Mot cable.
The high pitch feedback noise you are talking about is not normal. So far there was one customer only who reported something similar. He used the SA200 amplifier, and without it there was no problem. But since you already tried to take the cradle out of the loop, it can't be the antenna circuit.
You possible have a faulty MB/Mot cable.
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Thanks for the responses regarding the GSM humming. It's strange that this issue would exist, since the car used to have a TDMA handset, and there was no humming.
Unless I'm missing something, GSM and TDMA use the same frequency set, so I am wondering why this is happening with GSM.
Also, when the phone is docked in the cradle, and the antenna contact is made between the phone and the cradle, shouldn't the internal antenna be entirely disabled? It should have zero power when docked, no?
Unless I'm missing something, GSM and TDMA use the same frequency set, so I am wondering why this is happening with GSM.
Also, when the phone is docked in the cradle, and the antenna contact is made between the phone and the cradle, shouldn't the internal antenna be entirely disabled? It should have zero power when docked, no?
Last edited by juanvaldez; Oct 31, 2005 at 12:55 AM.
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...........check your connection between the PSE and the car. In addition to the male and female pins that connect together, there are two screws that need to be tightened, just as in a computer connection to a monitor cable. I had humming noise when my connection was loose. Long short, but see if it helps.
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