First time crossover design

[r0llinlacs]

I've decided to replace the tweeters in my less-than-stellar Sony tower speakers. The originals are 6-ohm and have a 1uf capacitor on the positive wire.

I've decided to go with these Beston 6-ohm ribbon tweeters, and I need an 18dB 3rd order crossover at roughly 3500hz.

According to a crossover calculator I found online, I need 5uf and 15uf capacitors and a 0.2mH coil to achieve 18dB 3500hz crossover point with a 6-ohm driver.

The reason I'm posting is because I'm not 100% sure I can trust the calculator. I was curious what the crossover point on the originals were, so I started inputting crossover values until the outcome was a 1uf capacitor. According to the calculator, the original tweeters have a crossover point of 25,000hz with a 1uf capacitor at 6-ohms, which obviously makes no sense at all. Is the calculator borked?


Does this look right?


Because this sure doesn't.

[Wolf]

Re: First time crossover design

First off- The Beston will have a BW5 acoustic rolloff with a second order filter due to its inherent response.

Second- if you don't know the response of the woofer and its xover, you can't really just have them meet in the middle with a hunch and a calculator.

3rd- the tweeter is 95dB on it's own and will need attenuation to compensate.

Can you provide more info?
Wolf

[bullittstang]

Re: First time crossover design

First, no you can't use an online calculator and get a good result, because the filter has to include the entire frequency range and impedance of the driver, which determine the actual filter/slope.

Also, you will need to know what your woofer is doing, otherwise you will have a mediocre result. i.e. if the woofer is crossing at 2k, you will have a huge gap from there to 3.5k where you are crossing the ribbon.

If you can give the model number of the Sony speakers and possibly a picture of the entire crossover and impedance of both woofer and tweeter, someone will be able to assist with something better than the online XO you have in your post. You will probably end of with a totally new design/XO, so the cost may become prohibitive if they were only mediocre speakers to start.

PS - first attachment isn't working, so not sure what that is a picture of.

Have you looked at some DIY designs yet?
Parts express has some good choices, as does meniscusaudio.com and DIYsoundgroup.com and if you need cabinets and everything, melbyaudio.com has some long-time favorite designs in the community.

[r0llinlacs]

Re: First time crossover design

First off- The Beston will have a BW5 acoustic rolloff with a second order filter due to its inherent response.

Second- if you don't know the response of the woofer and its xover, you can't really just have them meet in the middle with a hunch and a calculator.

3rd- the tweeter is 95dB on it's own and will need attenuation to compensate.

Can you provide more info?
Wolf

The towers are three-way Sony's. SS-MF400H

Tweeter crossover point is basically irrelevant because the mids have just a cap so essentially, no low pass to the mid, only high pass, so the mids scream with high frequencies they shouldn't be producing. The woofers have no cap/crossover at all, so free range. The speakers are as cheap as it gets.

Frequency response on the Bestons is 2000-40,000hz. I realize they have high sensitivity, but this is welcomed because the current tweeters are quiet, dull, and lifeless. I want them louder and brighter.

What more info would you like?

I just want to know if the calculator is correct, and if that combination of caps/inductor will net me 18dB 3500hz at 6ohm.

[r0llinlacs]

Re: First time crossover design

First, no you can't use an online calculator and get a good result, because the filter has to include the entire frequency range and impedance of the driver, which determine the actual filter/slope.

Also, you will need to know what your woofer is doing, otherwise you will have a mediocre result. i.e. if the woofer is crossing at 2k, you will have a huge gap from there to 3.5k where you are crossing the ribbon.

If you can give the model number of the Sony speakers and possibly a picture of the entire crossover and impedance of both woofer and tweeter, someone will be able to assist with something better than the online XO you have in your post. You will probably end of with a totally new design/XO, so the cost may become prohibitive if they were only mediocre speakers to start.

PS - first attachment isn't working, so not sure what that is a picture of.

Have you looked at some DIY designs yet?
Parts express has some good choices, as does meniscusaudio.com and DIYsoundgroup.com and if you need cabinets and everything, melbyaudio.com has some long-time favorite designs in the community.

Sony SS-MF400H

This is what I'm working with



As you can see, only a cap on the mid, and nothing at all on the woofer. Super cheap. Crossover points are basically irrelevant with this speaker.

I chose 3500hz because the reviews said that is the best cutoff for the best power handling on the Beston.


Here is the first attachment again, showing the supposed values for the capacitors/inductor I would need for 3500hz at 6-ohm.

[Wolf]

Re: First time crossover design

I just want to know if the calculator is correct, and if that combination of caps/inductor will net me 18dB 3500hz at 6ohm.

Nope- it won't.
Wolf

[r0llinlacs]

Re: First time crossover design

Nope- it won't.
Wolf

Care to elaborate? If it won't, what frequency will it cross at?

When designing a crossover, do I go by the impedance of the speaker, or by the final impedance of all speakers at the terminal?

Sorry but just saying no it won't doesn't help me, not even a tiny bit.

[chrisn]

Re: First time crossover design

Take a look here: https://sites.google.com/site/undefinition/diy-mfaq and here: https://sites.google.com/site/undefinition/diy it should answer some of your questions.

[Wolf]

Re: First time crossover design

Care to elaborate? If it won't, what frequency will it cross at?

I already said it would be BW5 with a second order filter, which means with a 3rd order, right components or not, it will be 6th order- and not BW3 as you asked. Without factoring in freq response and real impedance, along with baffle shape and position, as well as the adjacent driver data in kind; there is no way I can say that it will xover at 3.5k, let alone optimally.

Later,
Wolf

[r0llinlacs]

Re: First time crossover design

I can't find T/S params for the Beston tweeter, my multimeter isn't working correctly ATM so I don't know the impedance of the original mid or woofer.

Here's what I can find.

Original speakers:

Woofer - free range, no crossover
Mid - crossed at 2000hz, 2.7uf cap
Tweeter - crossed at 5000hz, 1uf cap

Beston tweeter "specs"



So, working with what I have and what information I can get, what can I do?

Nothing has to be perfect. I'd be half tempted to just throw a cap on it and call it a day, if the Beston didn't recommend an 18dB slope.

I'm not designing an elaborate 3-way crossover system, either. All I need is an 18dB high-pass crossover at 3500hz for a 6-ohm tweeter. It can't be that complicated. Nevermind the other speakers, they overlap anyways. I just want the tweeter crossed correctly as to not damage it.

[Wolf]

Re: First time crossover design

I can't find T/S params for the Beston tweeter, my multimeter isn't working correctly ATM so I don't know the impedance of the original mid or woofer.

Here's what I can find.

Original speakers:

Woofer - free range, no crossover
Mid - crossed at 2000hz, 2.7uf cap
Tweeter - crossed at 5000hz, 1uf cap

Beston tweeter "specs"

[ATTACH=CONFIG]61891[/ATTACH]

So, working with what I have and what information I can get, what can I do?

Nothing has to be perfect. I'd be half tempted to just throw a cap on it and call it a day, if the Beston didn't recommend an 18dB slope.

I'm not designing an elaborate 3-way crossover system, either. All I need is an 18dB high-pass crossover at 3500hz for a 6-ohm tweeter. It can't be that complicated. Nevermind the other speakers, they overlap anyways. I just want the tweeter crossed correctly as to not damage it.

I've used the RT003C with a second order filter, and it was fine, xover at 3.2k BW5 acoustic. If you have a hole in the response, then it just won't sound right. If you don't attenuate it- it won't sound right. Sure- it may be protected, but it won't be optimal.

AND- it really is that complicated to get it 'right'.

Later,
Wolf

[r0llinlacs]

Re: First time crossover design

I've used the RT003C with a second order filter, and it was fine, xover at 3.2k BW5 acoustic. If you have a hole in the response, then it just won't sound right. If you don't attenuate it- it won't sound right. Sure- it may be protected, but it won't be optimal.

AND- it really is that complicated to get it 'right'.

Later,
Wolf

Okay, now we're getting somewhere.

As it stands right now, the tweeters are hardly noticeable over the mids, due to the mids having no low-pass cross point. Anything will be better than how it is now. There can't be holes in response because every speaker overlaps anyways. I realize if I do a 3000hz cross point on the tweeters, overlapping will be even worse than it is now, but hopefully will drown out the harshness of the mids.

So you used a second order, I assume 12dB? What kind of power did you have going to it?

And sorry, but what the heck is BW3, BW5?

[Wolf]

Re: First time crossover design

Okay, now we're getting somewhere.

As it stands right now, the tweeters are hardly noticeable over the mids, due to the mids having no low-pass cross point. Anything will be better than how it is now. There can't be holes in response because every speaker overlaps anyways. I realize if I do a 3000hz cross point on the tweeters, overlapping will be even worse than it is now, but hopefully will drown out the harshness of the mids.

So you used a second order, I assume 12dB? What kind of power did you have going to it?

And sorry, but what the heck is BW3, BW5?

But you can still have breakups, cancellations, high harmonic distortions, mismatched driver levels, misaligned phases, and bumpy frequency responses. You can't just stab in the dark and turn on the lights.
12dB = second order, 18dB = third order; all done by a factor of 6dB/octave which is 1st order.

Remember that acoustic summation is done by the sum of the drivers' natural rolloff and the electrical transfer function. When I say the acoustic slopes were BW5, this means 5th order Butterworth acoustic. When I say the network LR2 , that is second-order Linkwitz Riley acoustic. When I specify the circuit or state electrical, this is referring to the electrical combination. The LR, BS, BW, etc refer to the alignment and Q of the acoustic rolloff.

Power is a big misnomer in audio, and many do not understand what it really means.

I think you really need to read Paul's FAQ pages if you have not, as referred earlier in this thread. You are to the point where you know enough to do damage, but really don't grasp the whole picture.

Later,
Wolf

[jhollander]

Re: First time crossover design

BW3, BW5 are crossover slopes. The advice we'd like to give is for something that will sound good. There's really nothing that you can add to improve your sony's sound.

My opinion/ advice would be to find a published 2-way design and reuse your box. You could be miles ahead if you scrolled down the page on that Beston tweeter to see the crossover for Wolf's Stance and used those parts, including the woofer.

[djg]

Re: First time crossover design

Bare bones kit is cheaper. Did you pick that tweeter because it fits the hole?


http://meniscusaudio.com/stance-pair-p-1353.html