How to improve sound on a wired fm modulator?
April 20, 2010 5:36 PM   Subscribe

Today I had a wired fm modulator installed in my 2003 Lexus ES300. The one used was the "Farenheit Phase Lock Loop FM Modulator (EFM-01 / EFM01)." My issue seems to be that when the music is quiet/not busy, it comes through clear, but when the sounds pick up I get some seriously bad buzzing/distortion.

The shop I had it installed at is extremely reputable, and they assured me it'd sound better than my cassette adapter. However, if there is going to be this buzzing, it certainly isn't better. I have an on/off switch to disable the radio when i use the modulator, and there is also some little knob i can turn, though im not sure what that does. The station they have it using is apparently a good one (88.9).

I'm wondering what may be wrong here, or what I can do to fix/improve the issue. I'll probably call the shop tomorrow, but I'm interested in what you guys have to say.
posted by rbf1138 to Technology (7 answers total)
is this it?

are you just hooking in your device through its headphone jack? have you tried backing down the volume on the device a bit? I've noticed that having the volume up too high produces distortion in my setup (which is tape adapter + iPhone) - the headphone jack is amplified, so it can drive headphones (which can require quite a bit of juice to make work, depending on the kind you have), and your volume setting on your device might just be more than the modulator doohickey can deal with. (I've noticed similar effects on things besides just the iPhone + tape adapter setup - if you plug your device into your home stereo and crank the volume on the device, you'll probably get distortion out of that too, even if you turn the stereo itself down.)
posted by mrg at 5:57 PM on April 20, 2010

It's basically the same as that one, but a different brand. I am using my ipods headphone jack- maybe ill try my other player with a line-out. I don't think it's clipping/distortion based on volume, but I'll try making some adjustments with that, too. It seemed to be triggered by activity in the music itself.
posted by rbf1138 at 6:02 PM on April 20, 2010

So, it seemed somewhat better using a dedicated line-out. The best example of the problem I can give is that during the opening of Radiohead's Airbag, it's smooth until vocals come in, at which point they distort, seemingly primarily on the vocals themselves. Some issue with a certain frequency distorting when it goes through the system?! I don't know enough about the electronic/audio hardware to understand why this would be happening.
posted by rbf1138 at 6:30 PM on April 20, 2010

One suggestion that you've probably tried - when I have my iPhone running through an FM modulator in my car, it sounds awful if iPod's EQ is set to "Bass Boost", where I have it for my earbuds. Changing it to "Rock" sounds great.
posted by Jimbob at 6:36 PM on April 20, 2010

Nah, I'm positive it's something with the connection/setup, nothing with EQ. The dedicated line-out proves it. The car system solely controls the volume this way, with a direct, clean signal from the Cowon X5 im using.
posted by rbf1138 at 6:38 PM on April 20, 2010

I had an cheap aftermarket CD changer in a car once that you tuned into over the radio.

The sound was terrible until I found out how to turn what I guess you could call the "transmitter power" down on the CD changer. What seemed to be happening is that the CD changer's little FM radio transmitter was overwhelming the (also cheap) car stereo radio receiver.

Perhaps you can check and see if your gizmo has a power setting and try playing with that.
posted by tss at 9:08 PM on April 20, 2010

Oh, also, symptoms were very consistent with what you have described.
posted by tss at 9:09 PM on April 20, 2010

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