Question for the experts among us!

I'm "refurbishing" my 4th pair of Beovox 2500 cubes and this time I want to replace them with new tweeters which I bought from a shop in the US for just 2$ a piece. Now I need to know if I can use the same capacitor, or do I need another type/value. The tweeters are 8 ohms and the originals are 6 ohms. You think there's a (dramatic) change in sound quality? The new ones have a perfect fit in the cubes and are less deep as the original ones.

Btw, there's enough space in the cube now for capacitors using this new type of tweeter. Martin, can you supply me the right ones?

You work fast Leslie!

Those replacement tweeters are very close to the originals in terms of frequency range. Online I see that 2500Hz (the new tweeter's bottom end) can be crossed over with an 8uF capacitor - same as the orignal. That's where I would start.

Leslie search for crossover calculators, there are plentey on the net, as your cube is a tweeter I would make it up about 3000 or even 3500 Hz, but check the calculators, or start with 8 uf and increase.

Will give it a try with the originals, thanks guys, helpfull as always...

Søren Mexico:

Leslie search for crossover calculators, there are plentey on the net, as your cube is a tweeter I would make it up about 3000 or even 3500 Hz, but check the calculators, or start with 8 uf and increase.

Thats exactly where I crossed over my new reproduction pair of 2500s, 3500hz. I used a 10uF cap but that exact freq calls for a 10.36uF so currently I am actually operating slightly higher lower than I ought to be.

Rich has just sent me his overstock of capacitors to allow me to experiment.

Listening to my reproduction cubes, I think I would like to hear more, and adding 1000-1500 extra Hz at the bottom would probably give me what I want. Only problem is my tweeters are domes and wont like being stretched below 3500hz.

Hi Evan,

Sorry, but this is out of my knowledge Electronics is not my thing you know. Probably a stupid question but what type of caps do I need to use (Bipolar???). Can you give me a link where I have to look for regarding to specs? The site (thanks to you) were I bought the tweeters would be handy since I have to buy them again for my self made cubes.

Bipolar electrolytic will do.

Take a look here a 8 ohm tweeter, needs 6.3 uF for filter at 3000 Hz

Leslie:

Hi Evan,

Sorry, but this is out of my knowledge Electronics is not my thing you know. Probably a stupid question but what type of caps do I need to use (Bipolar???). Can you give me a link where I have to look for regarding to specs? The site (thanks to you) were I bought the tweeters would be handy since I have to buy them again for my self made cubes.

Don't worry Leslie, we will help you figure it out.

Soren is right, electrolytic bipolar is the type to use. That site, Parts Express, has many capacitors to choose from. A 6.63uF (exact value)capacitor will be hard to find by itself. First, you must make the call on exactly which frequency they will be crossed over at. What minimum frequency do you want the speaker to play at?

Are these cubes you are working on right now going to be used with the original BeoVox 3000/5000? If so, I would try and keep them as close to the original frequencies as possible. Which for you means 2500+. The capacitor value depends upon the lowest allowed frequency value you decide on.

Evan:

A 6.63uF (exact value)capacitor will be hard to find by itself.

...but 6.8 uF, which is in the regular E6/E12 value series, won't. Remember that conventional aluminum electrolytics (bipolar or not) are far from precision components. The specified tolerances can easily be 10-20% either way. And you'll never hear the difference between 6.63 and 6.8 (+2.5%) anyway!

I agree we should aim for the original specs if these are to be used with old Beovoxes that have an output for them. And if not, the exact crossover frequency is even more unimportant. After all, you're just going to bend the allover frequency response of the speaker system away from straight...

tournedos:

Evan:

A 6.63uF (exact value)capacitor will be hard to find by itself.

...but 6.8 uF, which is in the regular E6/E12 value series, won't. Remember that conventional aluminum electrolytics (bipolar or not) are far from precision components. The specified tolerances can easily be 10-20% either way. And you'll never hear the difference between 6.63 and 6.8 (+2.5%) anyway!

I agree we should aim for the original specs if these are to be used with old Beovoxes that have an output for them. And if not, the exact crossover frequency is even more unimportant. After all, you're just going to bend the allover frequency response of the speaker system away from straight...

I was going to jump straight to 7uF!

I'm pretty sure that the caps I bought for my reproduction cube project have at least 20% difference between them. They don't sound exactly the same!

tournedos:

Evan:

A 6.63uF (exact value)capacitor will be hard to find by itself.

...but 6.8 uF, which is in the regular E6/E12 value series, won't. Remember that conventional aluminum electrolytics (bipolar or not) are far from precision components. The specified tolerances can easily be 10-20% either way. And you'll never hear the difference between 6.63 and 6.8 (+2.5%) anyway!

And don't forget, the crossover frequency is where the response begins to get attenuated.  With a first-order network, that's 6 dB per octave of attenuation. A capacitor doesn't just cutoff all the frequencies below some magic number.

Also remember, crossover networks are designed as a system with the drivers to supplement the natural roll-off of each drivers response.

The connection from BV 5000 has a cap before the connector, 4.7 uF, the connector cut of the inbuild tweeters, but the inbuild tweeter has a coil, 0.2 mH, does the original cubes have a coil in the crossover ??

Søren Mexico:

The connection from BV 5000 has a cap before the connector, 4.7 uF, the connector cut of the inbuild tweeters, but the inbuild tweeter has a coil, 0.2 mH, does the original cubes have a coil in the crossover ??

No.

Wow, cannot mingle in this discussion Anyway, I'll start with the 6.8uF.....

Wow, cannot mingle in this discussion Anyway, I'll start with the 6.8uF.....

Leslie:

Wow, cannot mingle in this discussion Anyway, I'll start with the 6.8uF.....

I'm sure by now, you have already searched and found it, but just in case you haven't Parts Express does have one. Just search "6.8uF".

I would have linked it for you, but I am on my mobile now and it cant manage that.

Dont worry about trying to mingle Leslie, just ask questions if you  have them :)

http://www.parts-express.com/pe/pshowdetl.cfm?Partnumber=027-336