1.2TLs and tweeter output

tugboat

Is each tweeter at a different crossover point, or just some of them? Will the crossover point make each tweeter in the same cabinet seem at a different output level? If so, will the crossover and ouput level in one speaker mirror the other speaker? For instance...if the bottom tweeter has the highest output level in the right speaker, will the highest output level tweeter also be the bottom one of the left speaker. I hope this makes sense.

Anyway, I started to notice the sound of one speaker started to dull a bit and things in mono didn't sound even. I turned down the bass, boosted the treble and went to each tweeter with a tube to my ear. I noticed that each tweeter had a different level in the left speaker and in the right speaker I found the thrid from the top tweeter to be dead. I checked it and it's a gonner. Now the working tweeters don't seem to exactly match their buddies in the other speaker, but they also don't appear to be damaged. Kind of like they're in different position than the other speaker.

Also, since upgrading all the tweeters isn't in the cards at the moment, does anyone know where I might be able to locate a working SL3000? I'm sure the RDO replacement wouldn't be the best fit unless I was changing them all.

Thanks!

Dennis Gardner

The third from the top is the main tweeter in the circuit and tends to go out first. They are mirrored left & right. I would replace the dead tweeter my moving a pair from another position into the third to give you a better matched pair in that position. Used tweeters come up pretty often around these parts for replacement.

tugboat

Dennis Gardner wrote: »

The third from the top is the main tweeter in the circuit and tends to go out first. They are mirrored left & right. I would replace the dead tweeter my moving a pair from another position into the third to give you a better matched pair in that position. Used tweeters come up pretty often around these parts for replacement.

Took your advice and moved the second from the top down to the thrid position to replace the dead one and put the dead one in its place. Night and day difference. I guess that's to be expected since the main tweeter wasn't working. I can now live with it until I can find a replacement, although, just knowing one isn't working is going to cause me to question everything I listen to. I'm also going to swap the second and third around in the other speaker.

Thanks!

heiney9

It's called a "progressive" point source. All the tweeters play a slightly differnt part of the frequency at differing output levels and when aligned and properly crossed over they project from a single point. It increases vertical dispersion and helps reduce reflection from/along the baffle.

If they didn't you'd get terrible phasing and comb filtering effects.

tugboat

heiney9 wrote: »

It's called a "progressive" point source. All the tweeters play a slightly differnt part of the frequency at differing output levels and when aligned and properly crossed over they project from a single point. It increases vertical dispersion and helps reduce reflection from/along the baffle.

If they didn't you'd get terrible phasing and comb filtering effects.

Okay, I think I get the idea behind it, but not the science. I'm just glad there are those in this world capable of thinking up and implementing such.

Thanks for the info.

ben62670

If you understand schematics this will help.
http://www.polkaudio.com/forums/attachment.php?attachmentid=26687&d=1186346402
H9 hit it pretty good. The tweeters do have different XO points, and output levels.
Ben

tugboat

ben62670 wrote: »

If you understand schematics this will help.
http://www.polkaudio.com/forums/attachment.php?attachmentid=26687&d=1186346402
H9 hit it pretty good. The tweeters do have different XO points, and output levels.
Ben

Now you've done it. You've confused me more. I'm no expert in reading schematics, but I'll be darned if this one doesn't show the + sided of the tweeters connected to the - binding post. It also shows the + binding post going to - on the second tweeter (through a resitor, cap and I beleive the poly switch I've read about here). So why is that? Why don't they follow polarity throughout? The mids seem to follow polarity matching.

Hopefully I'm making sense.

Thanks

ben62670

tugboat wrote: »

Now you've done it. You've confused me more. I'm no expert in reading schematics, but I'll be darned if this one doesn't show the + sided of the tweeters connected to the - binding post. It also shows the + binding post going to - on the second tweeter (through a resitor, cap and I beleive the poly switch I've read about here). So why is that? Why don't they follow polarity throughout? The mids seem to follow polarity matching.

Hopefully I'm making sense.

Thanks

Don't worry about that. That is just running them out of phase. The mids are driven by 12db XO's. The tweeters are mostly 18db slopes. These tweeter arrays are actually very complex to design. You don't see dome arrays hardly ever. If they ran them positive to positive then they would be out of phase.
6db matches 6db, and 18db.
12db matches 12db, and 24db.
If you have any other combination the phase can be fixed by running the tweeter out of phase(reverse polarity).
Ben

tugboat

ben62670 wrote: »

Don't worry about that. That is just running them out of phase. The mids are driven by 12db XO's. The tweeters are mostly 18db slopes. These tweeter arrays are actually very complex to design. You don't see dome arrays hardly ever. If they ran them positive to positive then they would be out of phase.
6db matches 6db, and 18db.
12db matches 12db, and 24db.
If you have any other combination the phase can be fixed by running the tweeter out of phase(reverse polarity).
Ben

I will nod, rub my chin and say, "I see." This in no way indicates my understanding of anything from above, but it helps me save face by giving the impression I do.

ben62670

Not many understand XO's. Actually nearly anyone does. This forum has taught me a lot. I thought I knew something when I joined, but stick around if you love audio there are some very knowledgeable helpful people here.
Ben

Systems

tugboat wrote: »

You've confused me more. I'm no expert in reading schematics, but I'll be darned if this one doesn't show the + sided of the tweeters connected to the - binding post.

Although they are hooked up electrically out of phase,they will be acoustically in phase with the midranges.:D


As well as changing the slope and crossover points and levels they have added a series coil on T4 to roll off its top end.

ben62670

GV#27 wrote: »

Although they are hooked up electrically out of phase,they will be acoustically in phase with the midranges.:D

Thanks for the short, and sweet GV. Did you see what DigiKey did to my order:eek:

tugboat

GV#27 wrote: »

Although they are hooked up electrically out of phase,they will be acoustically in phase with the midranges.:D


As well as changing the slope and crossover points and levels they have added a series coil on T4 to roll off its top end.

Back in the early '80s I had a couple of woofers and tweeters. I was really proud of myself for figuring out I need a choke for the woofer and a cap for the tweeter. Should have seen me digging through the bins of chokes thinking the biggest one would be the best. As for the cap, I stood there like a deer in headlights when the guy asked me what value I wanted. :eek: I told him what I wanted to do and he asked me what frequency I was looking to cut it off at. Again, deer in headlights! I took a few from him of different values and home I went. Well back then I thought I did really well. Now, I wouldn't be caught dead listening to what I created. From now on, I refer to the experts for anything beyond the basics.

I do, however, have this inner itch to rebuild my crossovers soon. I've found enough info here and have been practicing my soldering, so I should be in good shape when that day comes.

ben62670

If you recap your XO's replace one component at a time, and one XO at a time. If you need to use the other XO as reference you have it. Plenty of people here are willing to help.
Enjoy
Ben

tugboat

ben62670 wrote: »

If you recap your XO's replace one component at a time, and one XO at a time. If you need to use the other XO as reference you have it. Plenty of people here are willing to help.
Enjoy
Ben

Good advice. I was hoping it would be like when I work on my vehicle. I always end up with spare parts when I'm done. I figure if it went back together without them, they weren't needed!

Systems

tugboat wrote: »

when I work on my vehicle. I always end up with spare parts when I'm done. I figure if it went back together without them, they weren't needed!

Well it should be lighter therefore go faster...atleast for a short while.:D

tugboat

Thanks everyone for helping me understand the tweeter setup a little better. And a big thanks to Carl (Candyliquor35m) for parting with an SL3000 so I could get my dead one replaced! Thanks, Carl!

candyliquor35m

My pleasure. Glad to help get your music back on track.