Please help with crossover

[A Sanchez]

Hi,

The crossover frequency in my DIY speakers is calculated at 3000hz but still I can hear lots of sounds coming out from the tweeter that are supposed to be below the 3000 Hz range (according to charts like this one http://www.soundinstitute.com/images/tt58f2.gif ), like alto and even tenor sax or human voices. Isn't it there something wrong?? or this is normal and I should not use those charts as a reference.

Many thanks

Antonio

 

[richie00boy]

How about you tell use more info like what slope you have used, and circuit diagram.

 

[A Sanchez]

Hi,

This is the circuit diagram: http://www.diyaudio.com/forums/attachment.php?s=&postid=944432&stamp=1150796093

My aim is just to copy it. At the moment I am using slightly different resistors values because I could not find the exact ones yet but I suppose this should not be the problem. I am using 3.3 ohms for R2 y 8.2 ohms for R1 instead of 3 and 8 ohms.


Antonio

 

[PeteMcK]

that chart gives fundamental tones, but tweeters mostly reproduce overtones...

 

[richie00boy]

Are you using the same drivers as in the diagram?

 

[A Sanchez]

Hi Thanks for your replies.

that chart gives fundamental tones, but tweeters mostly reproduce overtones...

This makes sense.

Also now that I learned about cutoff and slopes it makes even more sense to hear a voice or a tenor sax sound coming out from the tweeter.

Are you using the same drivers as in the diagram?

Yes, I am using exactly the same drivers.

By the way the designer (Jim Griffin) said in another thread that the slope is high order (I do not how high) and that the design incorporates BSC.

Thanks

Antonio

 

[richie00boy]

Well remember that the filter is not a brick wall and that even 10dB down sounds could be audible.

 

[A Sanchez]

Yes, you are right thanks.

I was a bit concerned because I did not what to blow up the ribbon tweeters.

I have checked that the crossover connections are correct, so everything should be fine.

Regards


Antonio

 

[tinitus]

My tweeters are playing the top of voices too

 

[tinitus]

Maybe you need to play just a little with both attenuation resistors ?

 

[BlueWizard]

Just a thought, but is there a chance you have mixed up the 8 ohm R1 and the 3 ohm R2?

Do the tweeters sound generally loud relative to the woofer?

From a quick look, it seems the G2si is 6 ohms; 6 ohms in parallel with 3 ohms (R2) is 2 ohms. So, the overall impedance of the L-Pad Circuit plus the tweeter is 10 ohms. Simply math tell us that 80% of the signal is lost across the 8 ohm R1 leaving 20% of the signal across the tweeter.

If the resistors were reversed, the tweeters would generally sound louder than they should.

So, again, the 8 ohm should be in series with the tweeter and the 3 ohm should be in parallel.

It's probably not a problem; it was just a thought. I made the same mistake recently in rewiring my speakers.

Steve/bluewizard

 

[tinitus]

My thought too...something fishy going on with those resistors
but then, I suppose those tweeters are ribbons, and they may need lots of attenuation
Also, IF those resistors are right, the change they make are/should be incorporated in xo
Its not easy, but I have learned that a lot may be gained from playing a bit with those resistors

 

[richie00boy]

Have you actually listened to the summed output to make sure it sounds in balance? Just listening to one driver can be very misleading.

 

[A Sanchez]

Hi,

Thanks for all your replies.

Yes I have listened to the summed up ouput and also made sure that no resistors were mixed.

I think everything is all right and that all the problem was in my mind.

What happened is that I had been listening to the Jordan drivers as full range. Since the top end of these drivers is very linear and the speakers were placed too low, I got used to hear lots of mid and low frecuencies. Then at the sam time I added the ribbons and crossovers I placed the speakers in proper stands, which meant that the sound coming out from the system was just totally different and I felt that something was wrong. This is what made me listen to the tweeters and woofer separatelly as, as I said, I did not want to blow up my tweeters.

Anyway, now I have got used to the "new" sound of my speakers and I really like it and also I have played very loud music and the tweeters did not blow up. So, yes it was all my imagination.

Thanks again

Antonio