I'm looking for a better solution to those cheap mp3 transmitters you can buy on ebay for connecting ipods etc and listening on FM on the car radio.

It seems they all have American 75us pre-emphasis, so they sound too bright on UK FM radios. They also sound pretty naff generally.

Does anyone know if there are any available that are better quality, or alternatively any reasonably affordable low power stereo exciters? - it would only need very low power. (I believe the Ebay jobs have to be lower than 50 nW to be legal). A slightly higher power would be Ok because I could reduce it down within reason with an inefficient antenna. A sprog box would be fine (if the audio quality was good enough for me), because the power would be low enough for it not to cause problems.

Any suggestions?

Most are going to sound very similar tbh. Most have the same components. It might be worth just getting a head unit with a 3.5mm jack in the front to get the best sound quality.

Direct connection is best for sound quality as Mr SDE says!
Bluetooth is an option too!
A quality VFO would sound good? but then you will need stereo encoder,PSU and a PLL to eliminate constant adjustment! LONG!

These cheap types are just a standard VFO mono circuit and sound a lot better than the cheap stereo PLL things.

http://www.ebay.co.uk/itm/4-Channel-LCD ... 3aad446efa

NOYB wrote:it would only need very low power. (I believe the Ebay jobs have to be lower than 50 nW to be legal). A slightly higher power would be Ok because I could reduce it down within reason with an inefficient antenna.

I wouldn't worry about it being over the specified power limit, even into the tens of mW. Ofcom are hardly going to be interested, even if they did know. Not sure how they would know...

Anyway, a much better way of doing it is to attenuate the output, as a crappy antenna causes matching problems. You can make pretty much any value of attenuator you could ever want with three surface mount resistors.

I don't have bluetooth in the car, and I don't really want to replace the factory fitted unit. So we think those Chinese 7w sprog boxes are same stereo encoder as the the cheapo mp3 transmitters then? Shame.

Yep I'm on save wavelength as you Wisepranker (excuse the pun) - I was going to say dummy load, but chose to say "inefficient antenna" - same thing really! I agree though it would also be possible to make an inefficient antenna with wrong impedance - I'll slap my wrists and never say silly things again!

I got one of these for the transit as it doesn't have mp3 input. It's better than the crap ipod things you can get but only problem is its audio is a bit quiet, so you turn up the radio and get blasted when the traffic news comes on!

http://www.maplin.co.uk/p/belkin-tuneca ... -mp3-a14kc

Steambod
Thanks - but I don't want to spend that much unless it solves the problem I'm trying to avoid. I'll see if it details anything about pre-emphasis in the manual.

The loudness I see can be adjusted on this unit (as well as your audio device obviously!). If it's still not loud enough, another reason is that your audio may not have any audio processing ie compression) which the FM stations will have. In my case I've got Stereo Tool running on the stream, so hopefully it will be near enough same volume.

Sorry Mr NOYB??
Im not sure what you are trying to achieve?? Those MP3 units will give you reasonable results for £29.99 what more do you want for that price?
Quality of MP3s will vary depending on how they were recorded? and what bit rate?
Also if you are streaming? that can effect your sound greatly!

Sinus - just trying to achieve a reasonable quality for either streaming or playing mp3's in the car.

I don't want to spend £29 if it's no better than the £5 ones on Ebay.

If it's good enough to be able to tell the difference between a say 128k and 256k mp3 or stream then that would be a real result. But all the ones I've tried so far even a wav file sounds awful. Combination of wrong pre-emphasis and generally naff modulator I reckon.

But if people generally rate the tunecast I might buy one. Alternatively for same sort of money I've heard it is possible to build an FM transmitter on a Raspberry Pi. As long as quality was OK it would not matter if it sprogged, because it would be low power and contained within a metal box (car).

Ahh ok i see!
id assume most of them mp3 transmitters are probly based on bh1417 style IC? which have decent stereo seperation but have quite a square and noisey pilot
If youre willing to spend a bit and box a proper unit? PCS Electronics, NRG, and Tugicom do some quality kit! a 1watt would be plenty for your needs!
Ive never used a raspberry before? but id think they may be a headache programming? also ive never liked the idea of digital gear producing sinusoidal signals

You are right Sinus - the Linux stuff is a bit of a nightmare - but you get a nice rewarding glow when you "defeat" it and make it comply!

I've just been rooting around in the loft and found an FM interface for a car CD jukebox I had in the mid 90's. It's Sony, so I'm hoping it will be OK quality....