Horrible sound through an FM modulator

[JHZR2]

I’m trying to backfit Bluetooth into my 96 Ram. I got an fm modulator and a Bluetooth adapter.

I use a Bluetooth adapter in most of my vehicles, I know their pros and cons and don’t have an issue.

Ive used switched on/off fm modulators many times. Ive used them for cd changers, aux inputs, etc. Ive not had issues with their sound. Maybe not perfect, but a car at speed has lots of sound flaws anyway.

So I set this one up into my OE chrysler stereo. The fm sound is just fine, no issues with speaker wiring or whatever else.

I tied the grounds for the modulator and Bluetooth dongle to the grounding bolt on the back of the head unit.
I powered the units from the switched power going to the head unit.

The sound is so poor, I don’t know where to begin… scratchy, not clear, low volume…

The station is set right, when the modulator turns on the sound from the stereo is silence. Full quiet. But inject any sound and it sounds like it’s on an AM station 100 miles away with a lot of static.

I don’t know where to start.

Thoughts?

 

[wwillson]

@MolaKule does a lot of work with radios, maybe he will know.

 

[Jimmy9190]

Sounds like a compatibility problem between the dongle and the modulator. Could be a problem with the signal being too strong from the dongle and it is overdriving the input to the modulator. It could also be that old Dodge radio just can not process a higher end/higher frequency modern bluetooth signal so you get a lot of distortion from it.

You could look into using a bluetooth FM transmitter, it would take the place of the modulator and all you do is tune it to the unused frequency same as you would with the modulator but it sends the input straight from bluetooth to the radio without the need for an FM modulator. There are a lot of transmitters to choose from, and they are pretty cheap on Amazon. Crutchfield has this one, it costs more than most on Amazon but Scosche is a very good brand, they have been around for a long time and they make good products that work well.

Scosche BTFreq™

Bluetooth® FM transmitter with USB and AUX inputs

www.crutchfield.com

That one has some handy features and even has a wireless remote. Your other alternative would be to replace the radio with a good aftermarket unit. Most all headunits now have bluetooth already built in, just pair your phone and go. Pioneer will give the best sound for the money. It is super easy to replace the factory radio in a Dodge Ram. There is an installation kit you use that fits the dash and they work out fine. You can buy a good aftermarket unit now for roughly $100.00, maybe less now that the holiday shopping season is here. Crutchfield will have more info and the best advice on that as well.

 

[JHZR2]

Sounds like a compatibility problem between the dongle and the modulator. Could be a problem with the signal being too strong from the dongle and it is overdriving the input to the modulator. It could also be that old Dodge radio just can not process a higher end/higher frequency modern bluetooth signal so you get a lot of distortion from it.

You could look into using a bluetooth FM transmitter, it would take the place of the modulator and all you do is tune it to the unused frequency same as you would with the modulator but it sends the input straight from bluetooth to the radio without the need for an FM modulator. There are a lot of transmitters to choose from, and they are pretty cheap on Amazon. Crutchfield has this one, it costs more than most on Amazon but Scosche is a very good brand, they have been around for a long time and they make good products that work well.

Scosche BTFreq™

Bluetooth® FM transmitter with USB and AUX inputs

www.crutchfield.com

That one has some handy features and even has a wireless remote. Your other alternative would be to replace the radio with a good aftermarket unit. Most all headunits now have bluetooth already built in, just pair your phone and go. Pioneer will give the best sound for the money. It is super easy to replace the factory radio in a Dodge Ram. There is an installation kit you use that fits the dash and they work out fine. You can buy a good aftermarket unit now for roughly $100.00, maybe less now that the holiday shopping season is here. Crutchfield will have more info and the best advice on that as well.

It was too strong of a signal.

The Bluetooth dongle I got is horrible. Absolutely horrible… so it will go back for other reasons, but what I’ve seen is if I set volume at my phone at full, the BT unit will power off. If it’s a lower volume, it will be overdriven and scratchy, until I set my phone to
So I can get reasonable sound by setting the phone output lower. I recall on my old bmw which had a switched fm modulator, that I had to limit the volume, but that was a headphone jack and somewhat different.

I’m still not happy.

I have used those broadcasting fm modulators, I have them in two of my cars. But the cars are Mercedes with power antennas, so I can control the antenna down and it receives a clear signal and works well. Somehow the volume is higher on those, but if my phone volume is set too high it will still clip and distort.

Not entirely sure how to proceed next. I hate the look of aftermarket head units. I had bought a professionally installed bt unit from eBay, but the install and sound quality were poor.

One of those kenwood bluetooth amps might be the best bet…

 

[GON]

I am trying to figure out what product you have/ how you have it configured. I am guessing you have both a wired Antenna Bypass FM modulator and a wireless bluetooth dongle?

I really like the wired Antenna Bypass FM modulators', as opposed to wireless transmitters as it seems I am always in a area the wireless transmitter competes with a local FM station. wired Antenna Bypass always wins that battle.

https://www.amazon.com/iSimple-IS31-Antenna-Modulator-Aftermarket/dp/B002U5XPBE/ref=sr_1_3

 

[MolaKule]

I am trying to figure out what product you have/ how you have it configured. I am guessing you have both a wired Antenna Bypass FM modulator and a wireless bluetooth dongle?

I really like the wired Antenna Bypass FM modulators', as opposed to wireless transmitters as it seems I am always in a area the wireless transmitter competes with a local FM station. wired Antenna Bypass always wins that battle.

https://www.amazon.com/iSimple-IS31-Antenna-Modulator-Aftermarket/dp/B002U5XPBE/ref=sr_1_3

I have seen some FM transmitters slightly off frequency so the BT receiver circuitry is attempting to pick up a station slightly off frequency with subsequent noise and distortion.

 

[JHZR2]

I am trying to figure out what product you have/ how you have it configured. I am guessing you have both a wired Antenna Bypass FM modulator and a wireless bluetooth dongle?

I really like the wired Antenna Bypass FM modulators', as opposed to wireless transmitters as it seems I am always in a area the wireless transmitter competes with a local FM station. wired Antenna Bypass always wins that battle.

https://www.amazon.com/iSimple-IS31-Antenna-Modulator-Aftermarket/dp/B002U5XPBE/ref=sr_1_3

Yes a wired fm modulator that I can switch on and off, and a “marine” Bluetooth receiver. The Bluetooth receiver which just connects when it sees power and outputs via rca connections is horrible. I can’t have the volume on my phone outputting higher than 50% or this thing powers off.

I had a radio shack fm modulator I found in my stuff unused. Was trying this all as proof of concept. This modulator has no gain setting that I can see. I’m going to try to open it up. I have to wonder if a superior Bluetooth dongle, like a tunai firefly, and a higher gain on either this modulator or another that had a gain setting that I can increase, might even be better.

I have seen some FM transmitters slightly off frequency so the BT receiver circuitry is attempting to pick up a station slightly off frequency with subsequent noise and distortion.

Interesting perspective. The modulator does cut out any static or signal on the frequency selected, and that tails off a few tenths higher and lower. I think it’s gain is low, not settable (will open it up hoping there’s a potentiometer in that), and so the combination of a horrible Bluetooth source, and needing to turn the volume on the head unit up to compensate for the modulator, which then amplified whatever other noise it gets…

 

[JHZR2]

It’s getting much better….

I used a tunai firefly and a headphone to rca adapter, and things work much nicer. The tunai firefly dongle with headphone cable doesn’t clip or distort at high volumes. It’s very clear. The RadioShack fm modulator has no gain control, even on the PCB, but I got an isimple unit that has a gain adjustment and a better overall output.

much, much better…

 

[GON]

Is this the modulator you went with?
iSimple IS31 Antenna Bypass FM Modulator for Factory or Aftermarket Car Radios

 

[GON]

BTW, iSimple makes a FM Modulator with built in bluettooh. I have never seen a unit like this before;
iSimple ISFM2351 Tranzit BLU Bluetooth Enabled Car FM Transmitter Music Stream

 

[brianl703]

Not entirely sure how to proceed next. I hate the look of aftermarket head units. I had bought a professionally installed bt unit from eBay, but the install and sound quality were poor.

Look into the head units for heavy-duty trucks, like the ones made by Aptiv and Panasonic. There's also a stock-looking Continental/VDO head unit out there. These almost all use an "ISO" connector which is the same connector that older VWs use for their head units.

 

[JHZR2]

Look into the head units for heavy-duty trucks, like the ones made by Aptiv and Panasonic. There's also a stock-looking Continental/VDO head unit out there. These almost all use an "ISO" connector which is the same connector that older VWs use for their head units.

I was able to find a beautiful “refurbished” OE head unit, and used an isimple FM modulator with a Tunai Firefly Bluetooth dongle. Much, much better. I installed a little toggle switch and it works great. Sound in the truck will never be perfect. It has speakers where it does and it’s a loud diesel. But the upgraded speakers and this solution is quite good. I’m very happy. I’m sure an integrated Bluetooth in a head unit would bring marginally better sq, but there is still the overall design of the truck, sound deadening, etc.

I’m happy.

 

[brianl703]

Look into the head units for heavy-duty trucks, like the ones made by Aptiv and Panasonic. There's also a stock-looking Continental/VDO head unit out there.

I was able to find a beautiful “refurbished” OE head unit, and used an isimple FM modulator with a Tunai Firefly Bluetooth dongle. Much, much better. I installed a little toggle switch and it works great. Sound in the truck will never be perfect. It has speakers where it does and it’s a loud diesel. But the upgraded speakers and this solution is quite good. I’m very happy. I’m sure an integrated Bluetooth in a head unit would bring marginally better sq, but there is still the overall design of the truck, sound deadening, etc.

I’m happy.

The one I ordered for my 1998 Nissan Frontier is this:

It includes a separate bluetooth microphone:

These heavy-duty radios are built very well, I've had previous versions in other vehicles and they don't break or wear out.