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Replacement tweeter compatibility and thoughts

post #1 of 12
Thread Starter 
I was recently able to pick up an older receiver and some newer floor speakers on the cheap. Testing them out, there's a solid midrange and bass, but the tweeters are kinda crappy.

Speakers Model: Boston Acoustic Classic II CS260
Receiver: Sony STR-GX900ES

Given that I picked the floor speakers up for $160 (for the pair) they're certainly not bad. I'm just wondering what I need to know in order to find a replacement tweeter, or if I should try at all. Here's the specs I could find easily:

Tweeter type: Soft dome
Dome Size: 1"
Tweeter/cutout Size: approx 2 & 7/8"
Sensitivity(speaker): 89db
Impedance(speaker): 8 ohms
Frequency range(speaker): 46Hz - 25kHz
Crossover: 2.8kHz

If I missed some thread about this in my google searches or if this is out of place please feel free to just drop a link and be on your way.
post #2 of 12
Any tweeter you put in there is really going to be a complete shot in the dark, you really should contact BA and see if it's possible to get a replacement. I'm assuming your tweeter is shot, if it is just the sound quality you dont like that's a different story. The easiest way to make the speaker brighter would be to pull the crossover out and replace the resistor on the tweeter filter with a lower value.

If you really do want to still try a different tweeter, you're going to have measure the outside flange diameter, and thend you might be able to find a drop in that fits here.

http://www.parts-express.com/cat/tweeters/17
post #3 of 12
Thread Starter 
It's more I'm not liking the sound. I think. Issue 2 is iffy

The tweeters have a decent amount of floor noise, which isn't a huge deal, mainly only noticeable when you're "closer" than you should be at a certain volume level. Plus it's impossible to get rid of floor noise, but the way I understand it the less "sensitive" a speaker is the less noticeable the noise.

The "right" tweeter kinda... cracks... at one particular frequency. Not both, and not based on volume. So I'm guessing it's a hybrid of the tweeter having a slight defect and the only song I noticed the crackling in happens to have the crossover frequency or some other the tweeter would be bad at. If it had to do with the crossover freq, would changing the resistor affect that?

Besides those, they just kinda seem weak, not that sharp. Well, to be fair, I mainly only noticed when I had Mozart/Beethoven piano and orchestra pieces playing to really test the limits - and those things have a crap ton of staccato highs. For regular music they're plenty good, and given the fact that the minimum I would have to pay for another pair of decent floor speakers would be about $250-300, it's certainly not deal breaking.
post #4 of 12
Can you test that track with a crackling sound on a different set of speakers, or swap your left and right speakers to make sure it is that specific speaker that is the problem?

Changing a resistor will simply raise the tweeter output, that is assuming the tweeter is padded down, most speakers require this but not all.
post #5 of 12
Thread Starter 
Well, I feel rather silly now.

I had my current speakers hooked up since I was having issues with the new ones so I tested the track on them, no static or crackle. Hooked up the new speakers again, with reversed positions from last time as you suggested... Nothing but music from either speaker. Played the song at least 3 times to be sure, then tried with others.

Maybe I just had a bad connection that first time? I hate these screw up/screw down fasteners as opposed to the old tension clip style haha.

I will probably go ahead and replace the resistors, though. I never knew you could do that, so I at least got something out of embarrassing myself. I assume it would have to be rated to a certain wattage, like these?

Thank you very much for the help smile.gif
post #6 of 12
The tweeter sees very little actual power, so that rating isnt very important. You need to find the ohm rating. If it has for example a 4 ohm resistor, changing to a 3 ohm will net you approximately 1.5 db (it could be more or less depending on other variables). Grabbing a bunch of resistor values in .5 ohm increments would be a good idea since they are so cheap. Unless you are very familiar with crossovers, please post a pic of the xover with notes showing where the +/- connections to the terminal and tweeter are, and I can tell you which resistor to change.
post #7 of 12
Quote:
Originally Posted by caboose rvb View Post

Tweeter type: Soft dome
Dome Size: 1"
Tweeter/cutout Size: approx 2 & 7/8"
Sensitivity(speaker): 89db
Impedance(speaker): 8 ohms
Crossover: 2.8kHz
That's all you need to know. Compare that to what's available here and you're good to go:
http://www.parts-express.com/cat/tweeters/17?kg=621|4017
post #8 of 12
Quote:
Originally Posted by Bill Fitzmaurice View Post

That's all you need to know. Compare that to what's available here and you're good to go:
http://www.parts-express.com/cat/tweeters/17?kg=621|4017

Really Bill? So the actual measured impedance and frequency response of the tweeter doesnt matter? As long as the claimed specs on both sides match it will work just fine? That's not right.
post #9 of 12
Quote:
Originally Posted by Jay1 View Post

Really Bill? So the actual measured impedance and frequency response of the tweeter doesnt matter? As long as the claimed specs on both sides match it will work just fine?
If the OP could actually obtain that data for the original tweeter it would be best to do so. He'd sooner see peace in the Middle East than to get that information from BA. He might be able to track down original tweeter if he pulls it, but probably not. Considering the price of the speaker I doubt that it's more than a $10 OEM special, and that he'd get a far better result from from a $20-$30 tweeter with no alteration to the crossover, which I also would be shocked to find to be either impedance optimized or of high quality. It's not like he's working with a B&W here.
post #10 of 12
Thread Starter 
Thanks for the replies smile.gif

I'm actually an EE major going into my senior year. I've done a fair bit of work on a different type of crossovers, but crossovers nonetheless and plenty of resistor/solder work. I also, naturally, have a multimeter around, so the resistance of the tweeter itself is a simple thing to find.

I might end up trying a different tweeter instead of working with the crossover, though. The crossover is at a point where I would need to tear or saw open the cabinet in order to reach, something I'm not overly fond of right now. These look like they might be worth a shot. Very similar specs (have to check the resistance), looks like I could even use the same screw holes.

I've also considered simply getting some decent bookshelf speakers to provide more mid and high end sound. My DA sub-1200 more than handles the bass for my tastes.

herpderp forgot the link: http://www.parts-express.com/pe/showdetl.cfm?partnumber=264-900
Edited by caboose rvb - 7/22/13 at 9:18pm
post #11 of 12
Still dont think you should mess with the tweeter, you will have better luck with this one

http://www.parts-express.com/pe/showdetl.cfm?partnumber=264-822
post #12 of 12
Quote:
Originally Posted by caboose rvb View Post

the resistance of the tweeter itself is a simple thing to find.
Resistance is futile. Impedance is what matters. However, where tweeters are concerned they don't have the impedance rise in the region of the crossover as woofers do, the result of the woofer voice coil inductance, so high pass filters seldom require the optimization that woofer low pass filters do.
Quote:
I might end up trying a different tweeter instead of working with the crossover, though. The crossover is at a point where I would need to tear or saw open the cabinet in order to reach, something I'm not overly fond of right now.
I've only opened up one BA speaker, so this may not apply in your case. But the one I did work on for a friend, a 6.5 inch two-way, was loaded with a ten dollar woofer, a five dollar tweeter, and a first order/first order crossover with a 20ga LP inductor and NPE high pass cap. After replacing the woofers (the surrounds were toast) with $20 Parts Express drivers and a real 2nd LP/3rd HP crossover with the original tweeters the difference was night and day.
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