wired FM modulator question

[Wallace]

Has anyone here had any success installing an aftermarket hardwired FM
modulator?
I'm looking to play my ipod through the car stereo. The head unit is stock
and doesn't have aux in's to plug the ipod into.
I've tried a couple of FM wireless transmitters (Griffin Road Trip and DLO
Transdock Micro) and found the fidelity to be less than satisfactory.
I'd like to avoid replacing the head unit so my next option is to add an FM
modulator that converts the signal coming from the ipod into a line in that
is inserted into the antenna lead.
Has anyone here had any experience with this and be willing to comment on
the quality of sound obtained this way? Brand recommendations?
thanks,
Tom

[e-nigma]

"Wallace" > wrote in message
. ..
> Has anyone here had any success installing an aftermarket hardwired FM
> modulator?
> I'm looking to play my ipod through the car stereo. The head unit is stock
> and doesn't have aux in's to plug the ipod into.
> I've tried a couple of FM wireless transmitters (Griffin Road Trip and DLO
> Transdock Micro) and found the fidelity to be less than satisfactory.
> I'd like to avoid replacing the head unit so my next option is to add an
> FM modulator that converts the signal coming from the ipod into a line in
> that is inserted into the antenna lead.
> Has anyone here had any experience with this and be willing to comment on
> the quality of sound obtained this way? Brand recommendations?
> thanks,
> Tom
>

Most wires FM modulators If used have better than radio quality, but less
than CD quality

[Matt Ion]

Wallace wrote:
> Has anyone here had any success installing an aftermarket hardwired FM
> modulator?
> I'm looking to play my ipod through the car stereo. The head unit is stock
> and doesn't have aux in's to plug the ipod into.
> I've tried a couple of FM wireless transmitters (Griffin Road Trip and DLO
> Transdock Micro) and found the fidelity to be less than satisfactory.
> I'd like to avoid replacing the head unit so my next option is to add an FM
> modulator that converts the signal coming from the ipod into a line in that
> is inserted into the antenna lead.
> Has anyone here had any experience with this and be willing to comment on
> the quality of sound obtained this way? Brand recommendations?
> thanks,
> Tom

Pioneer was one of the first I saw use this concept some 15 years ago, with a
CD-changer. Installed several of those, mostly in cars where users wanted CD
capability without replacing the stock system at all.

Frankly, the limitation is in the FM signal itself, rather than the wireless vs.
wired feed. The FM signal itself has very limited dynamic range (something like
60dB), and frequency response (60Hz-18kHz or so). It's also a multuplexed
signal: the main signal is mono, with a higher subcarrier containing the
differences between left and right channels.

When a stereo signal is broadcast, it includes a "pilot" signal, a low-level
tone at 19kHz. If the receiver detects this tone, it then knows a stereo signal
is present and can de-multiplex it by combining the two separate (mono and
difference) channels. The drawback is that this 19kHz tone can be audible and
can sometimes appear as hiss, so most radios filter the high end significantly.
Because of this process, stereo separation is also very limited in FM.

All in all, it means there's a pretty low "ceiling" inherent to FM signal
quality. There's just no getting around it.

[GregS]

In article <UX8Hg.459553$IK3.425108@pd7tw1no>, Matt Ion > wrote:
>Wallace wrote:
>> Has anyone here had any success installing an aftermarket hardwired FM
>> modulator?
>> I'm looking to play my ipod through the car stereo. The head unit is stock
>> and doesn't have aux in's to plug the ipod into.
>> I've tried a couple of FM wireless transmitters (Griffin Road Trip and DLO
>> Transdock Micro) and found the fidelity to be less than satisfactory.
>> I'd like to avoid replacing the head unit so my next option is to add an FM
>> modulator that converts the signal coming from the ipod into a line in that
>> is inserted into the antenna lead.
>> Has anyone here had any experience with this and be willing to comment on
>> the quality of sound obtained this way? Brand recommendations?
>> thanks,
>> Tom
>
>Pioneer was one of the first I saw use this concept some 15 years ago, with a
>CD-changer. Installed several of those, mostly in cars where users wanted CD
>capability without replacing the stock system at all.
>
>Frankly, the limitation is in the FM signal itself, rather than the wireless
> vs.
>wired feed. The FM signal itself has very limited dynamic range (something
> like
>60dB), and frequency response (60Hz-18kHz or so). It's also a multuplexed
>signal: the main signal is mono, with a higher subcarrier containing the
>differences between left and right channels.

You will find a response that goes down much lower than that but the high end
is likely to be less. Modulators don't have the stability a regular station has
and they are easy to overload, meaning the overall output is going to be low.
I installed an inline modulator long ago for a tape deck. Never used it much.

greg

[Chad Wahls]

I got a cheapie from ebay and had to re-align it. I was kinda thinking I
needed to do so from the date of order :)

The pilot was so high that it caused high end saturation, it also drifted a
bit, it was only like 15 bucks.

Fortunately I am a former broadcast engineer and own an RF spectrum analyzer
:)

Chad
"GregS" > wrote in message
...
> In article <UX8Hg.459553$IK3.425108@pd7tw1no>, Matt Ion
> > wrote:
>>Wallace wrote:
>>> Has anyone here had any success installing an aftermarket hardwired FM
>>> modulator?
>>> I'm looking to play my ipod through the car stereo. The head unit is
>>> stock
>>> and doesn't have aux in's to plug the ipod into.
>>> I've tried a couple of FM wireless transmitters (Griffin Road Trip and
>>> DLO
>>> Transdock Micro) and found the fidelity to be less than satisfactory.
>>> I'd like to avoid replacing the head unit so my next option is to add an
>>> FM
>>> modulator that converts the signal coming from the ipod into a line in
>>> that
>>> is inserted into the antenna lead.
>>> Has anyone here had any experience with this and be willing to comment
>>> on
>>> the quality of sound obtained this way? Brand recommendations?
>>> thanks,
>>> Tom
>>
>>Pioneer was one of the first I saw use this concept some 15 years ago,
>>with a
>>CD-changer. Installed several of those, mostly in cars where users wanted
>>CD
>>capability without replacing the stock system at all.
>>
>>Frankly, the limitation is in the FM signal itself, rather than the
>>wireless
>> vs.
>>wired feed. The FM signal itself has very limited dynamic range
>>(something
>> like
>>60dB), and frequency response (60Hz-18kHz or so). It's also a multuplexed
>>signal: the main signal is mono, with a higher subcarrier containing the
>>differences between left and right channels.
>
> You will find a response that goes down much lower than that but the high
> end
> is likely to be less. Modulators don't have the stability a regular
> station has
> and they are easy to overload, meaning the overall output is going to be
> low.
> I installed an inline modulator long ago for a tape deck. Never used it
> much.
>
> greg

[Matt Ion]

Chad Wahls wrote:
> I got a cheapie from ebay and had to re-align it. I was kinda thinking I
> needed to do so from the date of order :)
>
> The pilot was so high that it caused high end saturation, it also drifted a
> bit, it was only like 15 bucks.
>
> Fortunately I am a former broadcast engineer and own an RF spectrum analyzer
> :)

Heheheh, everyone should have one of those :)

I recently used a Belkin wireless FM modulator to feed my Treo and portable DVD
players' outputs to the moving truck's radio-only system on a cross-country
move... I was quite happy with its performance (considering the limited fidelity
of the stock system and the inherent limitations of the FM signal).