Supertweeter experiment

[Reid Malenfant]

Awesome, thanks Mark.
If you think a forth order filter would allow better integration then I'll go along with that. The only thing I'm woried about with a forth order is that it's an aweful lot of components to change if I find I need to tweak the crossover frequency.

Part of me keeps thinking that if the supertweeters really are only producing frequencies above 20KHz then in theory I won't be able to hear if they're working, which will make testing tricky. So that makes me think I'd like them to dip just below 20KHz so I can at least hear them a bit. However I don't know how close to 20KHz I can actually hear. So perhaps the next thing I should do is test my hearing. At least I would then know what to aim for.

So I'll play some test tones tonight and see what I find. That should then give you a guideline to base the crossover frequency on. Does that sound sensible?

Cheers.

Jeez, everyone is Dave on here

Yes a 24Db/octave 4th order filter will help it integrate much better. I doubt you'd need to worry about effects in the range you can hear because if you are about 40 or more like myself it'd be pretty uncommon for your hearing to extend beyond say 16KHz at a reasonable volume level, which might make the experiment appear to be a waste of time at first glance... However sounds that you can't hear will probably affect those that you actually can in the audible spectrum & this is where the extra "air" might come from.

My guess is that you'd not need to tweak the components As long as you set it up correctly with a test CD or better still a function generator you'd be just about spot on, or lets say within a few DB, but as you won't be able to hear it directly anyway a few Db should be ok. If we were talking about where we can here then you'd want to match within 1Db

[HighFidelityGuy]

Thanks Mark.
I decided to test my hearing anyway as I was interested to know how high I can hear.
I could definitely hear 18KHz. 19KHz was just about perceivable. I thought I could very slightly hear 20KHz but I think I was tricking myself to be honest. So there's hope for me yet.
I'm 29 so I think that's fairly good to say I've been to a fair few gigs and festivals without any hearing protection. I do look after my ears fairly well though.

So if the super tweeters kicked it at about 18KHz or above then that should be spot on.

I've been reading a bit more about crossovers and I'm starting to wonder if using an active crossover before my amp might be a more refined approach.
However that would require quite a bit more work so I think I'll stick with forth order passive crossovers at this stage and then take it from there.

So Mark, is that enough info for you to sort out the parts?

Cheers.

[Reid Malenfant]

So Mark, is that enough info for you to sort out the parts?

Damn i wish i was 29 again & knowing what'd happen on my 30th birthday party I'd have a sh*t eating grin thinking about it biggrin.gif

Yes, not a problem as i already know the components you'll need for a 4th order crossover, or should i say roll in filter for the supertweeter

[HighFidelityGuy]

Lol, sounds like you had a good one. There's a possibility I may celebrate my 30th in Vegas, so that should be fun.

I'll leave the crossover in your capable hands.

Cheers.

[Reid Malenfant]

Hi Dave, i haven't managed to find time to dig out a load of capacitors & test the things to get you your 1% tolerance parts yet i'm afraid, too damn busy sorting things out this way.

However here is the circuit diagram...

4th order high pass filter.jpg

The component values are as follows:-

C1 = 1.055uf
C2 = 2.11uf
L1 = 0.02mH
L2 = 0.09mH


Now i reckon i can get to within 1% tolerance on those capacitors as the values are inside of the caps standard 10% tolerance, so it's just a case of testing a load until i find the magic numbers The caps i'm thinking of are 100V MKT type - film caps..

[HighFidelityGuy]

Hi Mark, thanks for the update.
I'm not in a major rush. I've finally been sent some parts that I need for another project, so I've got other things to work on. So just concentrate on getting your room sorted out for now. After that once you've got the parts sorted just let me know how much you want for it all or what you drink and I'll make sure you're compensated.

[Reid Malenfant]

The only thing i'll add at the moment Dave is that you won't really be able to set it up by ear As the filter is steep you'll need to set it up by measuring at the amplifier terminals (i recall you mentioning you'll use a seperate amp ).

What you need to do is find out the sensitivity of your Wharfedales & the sensitivity of the ring diaphram tweeters. At that point you can play say a 1KHz test tone into both amps & adjust the volume on the new amp to get the correct output voltage to match the sensitivities. So you'll need a multimeter & some kind of test record or CD or similar

[HighFidelityGuy]

I am using a seperate amp so that will simplify things. I have access to the speaker specs, test tones and a Fluke multimeter, so I think I should be able to sort it. Once I have everything together I'll let you know so you can explain the steps.

Cheers.