Radio 10 Does Not Contain Crossover -- Tweeters and Subwoofer Do

[fmaxwell]

There has been some conflicting information so I wanted to set the record straight:

The fortwo (451) in-dash factory tweeters contain crossover (electrolytic) capacitors. Driving them with a standard speaker output from an aftermarket head unit or amp should work fine and they will crossover at the correct frequency.

Similarly, the factory subwoofer has its own crossover (low-pass filter) built into it. It gets one channel from being wired in parallel with a door speaker and the opposite channel by being wired in parallel with a tweeter.

If there were a high-pass crossover for the tweeters in the head unit, the subwoofer would get no bass from input wired in parallel with the tweeter. If the radio had a high-pass crossover for the door speakers (to act as a bass blocker), the subwoofer would not get low bass from the input wired in parallel with the door speakers. Since the factory door speakers are just single cones (no tweeters or whizzer cones), they are incapable of reproducing high frequencies, so there's no need for the radio to roll off the high frequencies sent to them. Thus, I'm fairly confident that the radio has no crossover capabilities built into it.

When wiring an aftermarket head unit, one would normally wire the rear channel speaker outputs to the door speakers and the front channel outputs to the tweeters. Then the faders could be used to control how much, if any, treble was sent to the in-dash factory tweeters. This is where the factory subwoofer wiring becomes a problem. The signal going to the two channels of the subwoofer would vary in relationship to the fader setting. So if you faded back to reduce in-dash tweeter level, the channel of the subwoofer connected in parallel with a tweeter would also be reduced. The correct thing to do is to rewire the subwoofer so that it gets both of its inputs from the door speakers.

I hope that putting all of this information in one place helps those who need more information on the smart fortwo speaker wiring.

[Evilution]

Interesting thought, one which answers another question that I had going around in my head. On the 450, when you added the tweeters you had to activate the crossover.
I have messed with the 451 stereo and can find no crossover activation. Your statement explains why.

This is also a bonus for one of my other projects involving rear speakers.

[MB DNA]

"This is also a bonus for one of my other projects involving rear speakers."

Evilution,

If you crack the code on the 451 Radio 10, please share - especially with regard to adding rear speakers.

[John_H]

Before I removed them, I had the tweeters hooked up to the back channels of the 4-channel output of my aftermarket radio. When I did the fade all the way to the tweeters, I did not have the audio all starting at the 5kHz realm, but heard regular audio, not extremely peaked at the high end. Since I'm more sensitive to high frequencies than some folks, I'd think a crossover would have sounded *much* different than it does.

I'd love to see any info on the factory tweeters.

[Cruising n Coasting]

Does the stock Radio 10 have enough RMS power for a nice set of Focal 165 CA1 door speakers? Can I disconnect/override the subwoofer and install a Infinity Basslink powered subwoofer using the speaker line inputs?

[Evilution]

Originally Posted by MB DNA

If you crack the code on the 451 Radio 10, please share

There is nothing to crack here. The Radio 10 (and I assume the Radio 9 as well) has outputs for 4 speakers. 4 positive and 4 negative.

All 4 lines are full range frequencies and only the passive crossover attached to the speaker or the speaker dynamics will allow the correct frequencies to be used.

My idea is to disconnect the tweeters from connections 1,2,7 and 8 and wire the rear speakers into them. The front speaker connection 3,4,5 and 6 will go to a 2 way crossover where the frequency will be split into high and low and sent to the mid range and the tweeters.

The rear speakers could be coaxial speakers with built in tweeters, these have built in passive crossovers but you could again wire to a crossover and split the channels again.

This gives the chance to run 4 mid range and 4 tweeters if you wished although rear tweeters are a bit pointless as the high frequency needs to be aimed more towards the listener or the sound is lost. Better to have the front tweeters only and boost the output a bit.

Most crossovers have a tweeter boost output.

Fred - thinking further on the standard stereo, I wonder if the treble adjustment is actually a standard rear fader, as you fade more forwards it would reduce the signal to the "rear" speakers (or in this case, forward tweeters) making them quieter.

[Cruising n Coasting]

What a mystery?!? Nobody seems to have the answer on the Radio 10 power output.
I might as well just buy another radio since I don't have the gear to measure it.

[fmaxwell]

Originally Posted by Evilution

Fred - thinking further on the standard stereo, I wonder if the treble adjustment is actually a standard rear fader, as you fade more forwards it would reduce the signal to the "rear" speakers (or in this case, forward tweeters) making them quieter.

Good thinking! If I have a chance (no promises), I will hook up the Radio 10 to a benchtop supply and a scope and see if the you're right about that. I think that it's very likely that you are correct.

Originally Posted by Cruising n Coasting

Nobody seems to have the answer on the Radio 10 power output. I might as well just buy another radio since I don't have the gear to measure it.

You don't need to know the wattage. You just need to know if it's adequate to drive the speakers to which you listen to the level you want without clipping. You do that by listening, not measuring.

Don't get too hung up on wattage. If you want to worry about something, worry about speaker sensitivity. If you cut the speaker sensitivity by 3dB, it's like cutting the wattage in half.

[mvaldes]

Understanding that what speaker you choose depends on your "ear" and listening preferences, I also understand that I won't be driving in an audiophile's paradise (particularly with my DTH exhaust.) Given those considerations, what are my best options for door speaker replacements? I would like to keep to the same size as factory and keep the interior factory grills. Basically, take off the outside stuff for access, remove the old speakers and wire in new ones. Anyone have any suggestions including whether this speaker exchange would improve the sound quality enough to justify the work involved.
Thank you in advance from one (a non-audiophile and non-prefessional musician) who enjoys listening to and playing pretty much all types of music - classical, rock, country, bluegrass, pop, etc.,)
Michael

[Cruising n Coasting]

MValdes, the DTH exhaust is the quietest of the current available options. Do you have the side exhaust or the center exhaust? Do you think the power justifies the noise. I am just curious since I can't get an answer on the Radio 10 power output.