Rating: 
Summary: Shady Engineering
Review: A long time mp3 user, I was real excited to use this little gizmo with my car stereo. Shortly after acquiring the iRock, I had a major problem. The wires between the jack and the unit easily severed. Too difficult to splice the wires back together, the unit is now useless. I discovered this engineering flaw too late. Would not recommend it. Really disappointed. I hope they fix this flaw as the unit would create a ton of utility.
Rating: 
Summary: Improving the performance of IROCK 400FM
Review: A small modification to the IROCK 400FM, is needed in order to improve performance. Signal strength is inversely proportional to the square of the distance of the transmitting antenna to the receiving antenna, so the closer are the antennas to each other, signal strength can be considerably improved. The transmitting antenna of the IROCK 400FM is located within the audio cable, and to access this white wire, it is a simple matter of cutting about a 1½ inch slit along the sleeve near the stereo connector. Be careful not to damage the wires within the sleeve, and about one inch of the white wire can be pulled out. Attach about two feet of wire to the end of the white antenna wire so it can be placed in close proximity to the receiving antenna. In most cars, the radio antenna is imbedded within the rear window above the defroster, and the extended IROCK 400FM antenna can be taped right next to the cars radio antenna for optimum reception of IROCK 400FM transmitted signal.
Some electromechanical MP3 players produce high frequency noise which causes annoying hissing sounds in a vehicle application of the IROCK 400FM. This can be eliminated by using a Radio Shack AUDIO SYSTEM GROUND LOOP ISOLATOR (p/n 270-054) between the MP3 player output audio connector, and the input connector for the IROCK 400FM .
These modifications should provide the clear reception expected by the user, and is good alternative to cassette type adapters.
Rating:
Summary: Better than old 300W version...
Review: About 1.5 yrs ago i bought the old 300W version (i think that's how it's called) and i was pretty disappointed with it. The reception was pretty poor and spotty. Sometimes i had good reception, and sometimes i didn't. And when i didn't i always thought it was because my batteries were running low. I ended up hardly using it. Last week i dug it out of storage and tried it again. The reception was so bad it was unusable... but then i realized that the part of the chord that pluggs into the headphone jack of your music device was broken! So that i'm sure explained the horrible reception i had lately. So i decided to try the new model (400FM). I thought that the power from the car adapter might improve things. And also i was hoping that a newer model would just have better quality sound/reception. Wow, what a difference. The sound is pretty good. It totally overrides the set radio station (88.7 for me) with no static and bleed through. It's certainly not CD quality... close to radio quality though. But definitely good enough for me to enjoy music. I get the same decent quality whether or not the Car adapter is used. I am VERY surprised at how much better this model is over the old model. Design wise, I like how it now includes the car adapter. Having to replace batteries was a pain. But now i can't use the car adapter for my mp3 player. Oh well! Also, the power button is harder to accidentally press. It's flush flat with the exterior, not like a button sticking out. It would be better if the button were depressed a little. Overall, i'm very happy with my purchase.
Rating: 
Summary: A functional product, but not the best
Review: Actually, I'd like to give the iRock a rating of 3.5 stars, but settled on 3 stars. I bought the iRock to go with my 40GB iPod. Overall, I'm quite happy with it. Here are the plusses: *easy to use/install
*small (takes up only a little space)
*coiled power cord (helps!)
*uses very little power (with the batteries)
*reception is quite good on all 4 settings in a medium/large metro area (Twin Cities, Minnesota) with a lot of radio stations Here's the minus: I was disappointed in the clarity of sound produced by the iRock. I don't know if the decreased clarity is due to the iRock or my car stereo (an Alpine in my Honda CRV), but the sound produced by the iRock simply isn't as good as the sound I get listening to the iPod with a cheap pair of headphones. If the clarity was a bit better I'd probably give the product 4 to 5 stars. [I have discovered that I can improve the clarity of sound if I keep the volume on my iPod low and use the car stereo to adjust the volume. The clarity is 'fine,' but isn't great.]
Rating:
Summary: Disappointing
Review: After reading the reviews, I was disappointed to find that the iRock 400 gave a distorted, sibiliant, bass-light, hissy and squelchy sound. I have used this with my iRiver ihp140 and have tried a number of radios both in the car and at home. The iRiver is great, the iRock not. Anyone want to buy it?
Rating:
Summary: Pirate Radio
Review: Arg...I bought me this nice little gadget to use with my new iRiver iHP-120 MP3 player. It's small and light and comes with a coiled cigarette lighter power adapter (top selling feature for me). A red led indicates that the unit is on. It can transmit on one of four selectable frequencies. Choose the frequency with the least noise and you're golden. It packs away nicely in my armrest storage or glove compartment. I found that the quality of the reception depends greatly on the quality of the car stereo picking up the transmission. I find that in my Civic the reception is a little scratchy, but still very listenable. In my wife's Contour, parked next to my Civic, the reception is near perfect. Here's a hint for those of us without EE degrees interested in boosting the quality of transmission. The antenna is the wire that attaches to the headphone jack of the music player. If you add an additional couple feet with a headphone cord extension, you'll get a stronger signal. Just don't tell the FCC.
Rating: 
Summary: Does what it is supposed to quite well
Review: Based on some of the reviews I read I was primed to send the unit back when I received it, but the IRock worked very well and I am enjoying the convenience. I hooked it up to my laptop, put it downstairs and was able to get good sound on the stereo downstairs, the one upstairs, and on my car stereo in the garage (2100 square foot house). 83.3 had some distant signal, but the IRock overpowered it no problem. It even overpowered the local NPR station on 88.7 as long as the unit was within 6 feet of the receiver. Driving around town with it hooked up to an iPod proved to be problem free as well. I have a hard-wired jack for connecting to my home stereo. I haven't compared the sound using both methods, but I'm sure an audiophile would choose the hard-wired connection. None the less, if you have been able to survive with FM radio all these years, I'm sure this will do the trick. I have read about modifying the antennae for more range, but even just draping a 3 to 5 foot wire over the unit increases transmission range. On accident I discovered that touching my headphone jack to the pin on the 12 volt jack of the unit increases the range and clarity even more.
Rating:
Summary: All depends on what you use it for...
Review: Fed up with local radio, and not yet willing to dish out the money required for satellite radio equipment, I decided to purchase the iRock 400 for use with my iPod. Since the iRock plugs only into the mini-plug with no other connections, I found it to be more useful than products such as the iTrip, which can only be used with the iPod. After a month of usage, my feelings about the product are mixed. First of all, before you decide to purchase the iRock and use it in your vehicle as a radio replacement, make sure to check that the four frequencies are clear and free of adjacent interference where you plan on using it. The best way to do this is to go to www.radio-locator.com, which is a database of all radio stations in the United States which even provide coverage maps. In the primary vehicle I drive, a Kenwwod receiver with a CD and radio with very low sensitivity is installed. Typically, I have no problems at all using the 88.1 frequency with the iRock. Although I have to crank up the volume greatly, the quality isn't much less than a typical FM station... and much better than cassette. A local channel at 88.3 stops me from using the iRock there, since the interference is way too much for me to handle. For some reason I have yet to discover, I am unable to get a Stereo signal from the iRock on 88.5 and 88.7, which leads me to using the 88.1 frequency exclusively. Although my luck wasn't too bad with the Kenwood, I tried the iRock in another vehicle with a factory installed stock radio, and was very disappointed... At 88.1, the signal kept coming in and dropping out... the best strength from the iRock came when I had the end of it farthest away from the iPod. However, since all it takes is one turn for the unit to move, it was a disappointment. The interference on 88.3 was even worse with the stock radio, and 88.5 and 88.7 were once again only in mono. In the home, however, the iRock works great. When plugged in the back of my laptop, I can hear the sounds crystal clear on my Awia home stereo approximately 10 feet away. I also plugged the iRock into my television/VCR, and the sound quality was just as good as the RCA cables to Auxilary set up. I also no longer had the problem of 88.5 and 88.7 giving me a mono signal... and the 88.3 interference was non-existant. All in all, for the price the iRock is not a bad product. Keep in mind the unit costs less than $25. If you are serious about listening to portable music players or anything else in your car, your best bet is to spend an extra $15-30 and get a true FM Modulator... or to get a cassette adapter. Although my reciever doesn't have a cassette player, I have heard an adapter is the best way to go.
Rating:
Summary: irock fm transmitter, works well
Review: first it comes w/ d/c chord for power and work well in my car. it hasnt cut out once or given static. transmition quality is good, not great..but its fm not digital
definately worth it
Rating: 
Summary: sound is garbled and staticky
Review: FM-broadcasting music from my mp3 player to any radio sounded like a great solution for listening to my music in the car and the gym. Unfortunately, THE IROCK DOESN'T WORK WELL.
In the gym: I *physically put the irock on top of the radio's antenna* and the music is still garbled and full of static. It seems like for it to work, there has to be *no* other transmission on the frequency you select (and the irock only offers 4 frequencies). I'm in Boston - if you're somewhere without radio stations, maybe you'll be in luck.
In the car: Most cars have their antenna integrated into the rear windshield. The irock comes with a power adapter for the cigarette lighter. Which is nice. But it doesn't let it reach to the back window! Plus, even if it did, the music would sound bad, given my experience in the gym.
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