Adding Tweeter to Full Range

[ttan98]

I am wondering whether there are any major improvemnets in ths sound quality by adding a tweeter to a full range driver.

An example would be Fostex FE167E, Fostex suggests in their phamplet of adding their own Fostex tweeter. Does this prove benefitial?

I am sure some of you out there have tried this combination. If you have found it to improve the sound quality then let us know what type of tweeter you picked and why.

thanks.

[Sjef]

Adding a tweeter can help to bring some more air and detail to the sound. It's not as easy as it might seem though. While you whil certainly get more detail there's also the chnge that the coherence in the sound get's lost a bit. The whole sound spectrum can shift upwards, wich means that you will probably start noticing that your full-range driver has limited bass output as well.

I have had pretty good resulst with tweeters like the Beyma CP21, the Fostex FT66A. Don not get tempted to try a dome tweeter, most won't integrate wich fullrange drivers, totally different dynamic character.

[Pit Hinder]

Yup, time coherence is the problem here. By adding a tweeter you have the same problems you have with any other multipath - horror to fullrange fans.
Not digging deep into that problem here, there are threads galore dealing with this - it's the "first wave front" problem. Your brain uses transients to determine location of the sound source, thus getting able to reassemble the signal. If your FR and tweet are not time coherent that means your grey matter has a hard job - two disagreeing infos competing.
The trick with adding a tweeter to a fullrange is pushing it out of the detection time window, which is only ~20 milliseconds wide. Have the screecher beam upwards and/or backwards. Sounds crude, but works fine. The additional "airiness, detailing" or whatever you want to call it is there, but it doesn't spoil your FR's performance.

Cheers,
Pit

[ulfheden]

Originally posted by Pit Hinder

....The trick with adding a tweeter to a fullrange is pushing it out of the detection time window, which is only ~20 milliseconds wide. Have the screecher beam upwards and/or backwards. Sounds crude, but works fine......

I don't disagree that a rearwards fireing tweeter sounds as you describe. But I don't understand how your figures adds up. If the detecion window is 20ms and the speed of sound is 330m/s, then the tweeter would have to be 6.6 meters away to be outside the dection window.

Best regards

Peter

[Pit Hinder]

Peter,
you got me there - trying a quick-and-dirty explanation always means you expect people are as lazy as you and accept without thinking.
Let me try it this way: the detour via rear wall - ceiling - side walls arrives plenty late within the "time window", and it arrives several times, so it is smeared, no longer a sharply defined transient. Do you have measuring equipment? (ARTA is free, and quite good) Try measuring step response with too wide a time window, allowing wall-bounced sound in. Add a pair of piezo tweeters aimed backwards/upwards and try to tell their influence from general room influence. No good explanation, I know...do you by now know why I never tried to become a teacher?

Pit

[Cal Weldon]

Looking beyond the technical side, the easy way is to get a cheap tweeter like a piezo and try it forward, backward and to the side. See what you like, the option is yours regardless of what a machine tells you is good or bad. The ears are the only instrument that really matters in the long run. If you like the effect, consider getting a better tweeter. Room placement is a huge factor. In some cases you won't like it and in others you'll wonder why everyone doesn't do it.

[gychang]

Originally posted by ttan98
I am wondering whether there are any major improvemnets in ths sound quality by adding a tweeter to a full range driver.

An example would be Fostex FE167E, Fostex suggests in their phamplet of adding their own Fostex tweeter. Does this prove benefitial?

I am sure some of you out there have tried this combination. If you have found it to improve the sound quality then let us know what type of tweeter you picked and why.

thanks.

I tried a piezo ($1.50 /each at PE) on the new metronome with L-pad and put it in the rear of the cabinet see it here:

metronome minidisaster!

It is worthwhile since I do notice airy sparkle that can be adjusted. I recommend it (one can always turn it off)

gychang

[paba]

Hi all,

generally if you "help" your wideranger at the top you will most likely need to "help" it as well at the bottom or your basically just cranking the treble knob like in the 70's when we had treble knobs....my opinion anyway.

Pointing the tweeter to the back is worth trying it gives interesting results in some cases.

Putting a tweeter on top of the box is a challenge to time align and also to match the output volumes of the 2 drivers.

cheers
paba

[Pit Hinder]

Cal, gychang (strictly in alphabetical order, to those who can read and are PC minded, ie stupid)...I wonder why people in a DIY forum shy away from things like piezo tweeters - they are affordable, so they must be bad? Fuggit, they are the easiest screechers to build a Xover for, and they cost next to nothing - try if your ideas work, costs you two bucks!

Pit

[tinitus]

Here should be something about piezos, havent read it myself and personally I would use a ribbon

http://www.planet10-hifi.com/piezo-XO.html