Wavecor TW030WA11 crossover freq?

[Sponge]

Hello, what is the opinion on crossing over this tweeter below 1000hz considering it's low fs of 410 hz.
Thanks. Glenn

TW030WA11_12

 

[Russdawg1]

Take a look at the usable frequency response. I’d cross somewhere in there personally. 1500hz up.

 

[Sponge]

Take a look at the usable frequency response. I’d cross somewhere in there personally. 1500hz up.

I am asking because this is what Parts Express responded to the question someone asked.

Can this tweeter be safely crossed over at about 1500hz?

chris t on Jan 10, 2019

BEST ANSWER: Yes with a second order crossover it can be crossed as low as 850 since the Fs is so low. So using a second order crossover at 1500 Hz will be fine as well. But I would not use less than second order, a first order might be pushing it a little for the roll off.

• Reply
• Inaccurate
• Greg T Staff on Jan 10, 2019

 

[Verdinut]

What midrange driver or woofer will you be using with it, its size and frequency range?

The crossover point has to be properly matched with the drivers. Also, using a lower filter frequency would reduce the power handling capacity of the tweeter. This driver has a frequency range from 1500 to 25,000 Hz.
Personally, I would suggest a minimal crossover frequency of 2000 Hz, and 2500 Hz would be even preferable, provided that the driver to be matched has a good response and dispersion up to that frequency at least.

 

[Swerd]

What about the cabinet you plan on mounting the tweeter in?

Even though this tweeter has a wave guide, it still may generate a peak & valley in it's lower frequency range due to diffraction. The data published by the manufacturer was made with the tweeter mounted in free air (no cabinet or baffle) or on an infinite baffle. You cannot assume there will be no diffraction when its mounted in your cabinet.

With tweeters with flat mounting plates, their interaction with cabinet edges can have a major impact on the crossover frequency selection. It depends on the distance between the tweeter and the cabinet edges. The only way to be certain what this tweeter will do is to see it's frequency response while mounted in your cabinet.

With small diffraction peaks & valleys there are effective ways to minimize them. Rounded edges, off-set tweeter mounting, or felt baffle surfaces can all help. But if the peaks & valleys are large enough in amplitude, the best way is to avoid the problem by increasing the crossover frequency.

Here is an example of a ¾" dome tweeter, with a flat mounting plate, on an 8" wide cabinet. Without a crossover, there is a broad peak between roughly 1500 and 2000 Hz, followed by a valley centered between 2500 and 3000 Hz. All tweeters will have a similar profile in this box. What will that Wavecor tweeter do in your cabinet?

For detailed explanations see these links:
https://www.linkwitzlab.com/diffraction.htm

Speaker baffle design, diffraction and baffle step - Audio Judgement

When people build a speaker box, they only factor the internal volume. The shape of the box, baffle design and driver placement are important

audiojudgement.com

 

[TLS Guy]

Hello, what is the opinion on crossing over this tweeter below 1000hz considering it's low fs of 410 hz.
Thanks. Glenn

TW030WA11_12

View attachment 32074

Parts Express is not a place you can look to for reliable advice. In fact that is the place to usually get the wrong answer.

You and they have made the mistake of looking at Fs isolation. You have to look at Fs with Qts. If Qts is is low it means the resonance at Fs is very narrow and that the unit can be driven below Fs. An example is the ATC mid dome. On the other hand if Qts is high then the resonance around Fs has a very wide footprint indeed. This unit has a very high Qts at 0.79 which is a close as makes not difference to 0.8. So this unit can not be driven anywhere near Fs. Also the back cavity is small and that gives you a clue that this unit is not suitable for low crossover.

The power against frequency is not stated in the specs. But for a small unit like that driving it below 1500 Hz is courting burn out.

If you use a second order crossover I would not cross that unit below 1500 Hz. Since the power handling versus frequency is not known, I would not use that unit with a crossover below 1500 Hz. The power demands of music rapidly increase below 2.5 KHz. If this unit is to be part of a high power speaker I would not cross below 2.5 KHz.

 

[Sponge]

What about the cabinet you plan on mounting the tweeter in?

Even though this tweeter has a wave guide, it still may generate a peak & valley in it's lower frequency range due to diffraction. The data published by the manufacturer was made with the tweeter mounted in free air (no cabinet or baffle) or on an infinite baffle. You cannot assume there will be no diffraction when its mounted in your cabinet.

With tweeters with flat mounting plates, their interaction with cabinet edges can have a major impact on the crossover frequency selection. It depends on the distance between the tweeter and the cabinet edges. The only way to be certain what this tweeter will do is to see it's frequency response while mounted in your cabinet.

With small diffraction peaks & valleys there are effective ways to minimize them. Rounded edges, off-set tweeter mounting, or felt baffle surfaces can all help. But if the peaks & valleys are large enough in amplitude, the best way is to avoid the problem by increasing the crossover frequency.

Here is an example of a ¾" dome tweeter, with a flat mounting plate, on an 8" wide cabinet. Without a crossover, there is a broad peak between roughly 1500 and 2000 Hz, followed by a valley centered between 2500 and 3000 Hz. All tweeters will have a similar profile in this box. What will that Wavecor tweeter do in your cabinet?

View attachment 32079

For detailed explanations see these links:
https://www.linkwitzlab.com/diffraction.htm

Speaker baffle design, diffraction and baffle step - Audio Judgement

When people build a speaker box, they only factor the internal volume. The shape of the box, baffle design and driver placement are important

audiojudgement.com

Thank you Swerd, those are very good articles about baffles. Will be very useful.

 

[Sponge]

When I first posted the question was after listening to my Heil Amts and have always realized that the vertical axis is very narrow.
I wanted to see if there was a driver unit available that could replace the Heil with the same crossover point that had a better dispersion.
My search led me to either a compression diver/ horn or changing crossover point.
The only other unit that comes close is the Fostex FT48D which they state will reproduce down to 900Hz.

 

[Sponge]

 

[everettT]

What is you target frequency?

 

[Sponge]

What is you target frequency?

The Heils cross at 800hz.

 

[TLS Guy]

When I first posted the question was after listening to my Heil Amts and have always realized that the vertical axis is very narrow.
I wanted to see if there was a driver unit available that could replace the Heil with the same crossover point that had a better dispersion.
My search led me to either a compression diver/ horn or changing crossover point.
The only other unit that comes close is the Fostex FT48D which they state will reproduce down to 900Hz.

Now I know what you are doing I see what the project is. That Heil speaker has a large woofer crossed at 800 Hz. I know that speaker as a colleague had one. Not a speaker I had a lot of regard for. I think a lot of the problem is that the woofer is crossed to high and the Heil AMT too low.

There is no moving coil dome tweeter that you can cross to that driver at 800 Hz. It is a waste of time looking.

Next point is that you don't just look at manufactures specs. They seldom tell the whole truth. Look at the graph of that Fostex unit. It is rolling off just below 1500 Hz. Therefore that unit needs crossing over at 1500 Hz. In addition units like that are not going to take the power required to cross below that. They will blow.

If you don't like those speakers sell them and then buy or build something else.

If you did want to mod those speakers it would be difficult and you would have only two options. You would need to make it a three way, or use a large compression driver with an appropriately sized horn. With either option you would be better off selling those speakers and starting a design and build from scratch.

Your current approach will give you far worse speakers then you have now, and make them worthless.

You are not embarking on a viable or sensible endeavor. That also goes for practically all speaker mods. They are pretty much uniformly disasters.

So one more time, your option is to buy or build new speakers. For the latter I think you have some serious study to do before embarking on it. However that option is brings a lot of joy and satisfaction, but you have to put in the work. Designing and building a good speaker is not an easy task and not for the faint of heart.

 

[everettT]

If 800hz is the target, I think Techonic has a new 1 1/8 BMR for around $11. Might be fun to play with as you could slightly modify the woofer circuit and cross around 300hz IIRC.

 

[everettT]

This is the one I was thinking of. IIRC Dennis Murphy commented somewhere about using them as a tweeter, I'll see if I can find it.

Home

Tectonic TEBM28C10-4/A 1-1/8" BMR Full-Range Speaker 4 OhmTectonic's TEBM28C10-4/A miniature BMR is a speaker driver with an extended frequency response and an extremely wide directivity. It combines the benefits of Tectonic bending-wave technology and pistonic modes of operation.The small...

www.parts-express.com

 

[Sponge]

Now I know what you are doing I see what the project is. That Heil speaker has a large woofer crossed at 800 Hz. I know that speaker as a colleague had one. Not a speaker I had a lot of regard for. I think a lot of the problem is that the woofer is crossed to high and the Heil AMT too low.

There is no moving coil dome tweeter that you can cross to that driver at 800 Hz. It is a waste of time looking.

Next point is that you don't just look at manufactures specs. They seldom tell the whole truth. Look at the graph of that Fostex unit. It is rolling off just below 1500 Hz. Therefore that unit needs crossing over at 1500 Hz. In addition units like that are not going to take the power required to cross below that. They will blow.

If you don't like those speakers sell them and then buy or build something else.

If you did want to mod those speakers it would be difficult and you would have only two options. You would need to make it a three way, or use a large compression driver with an appropriately sized horn. With either option you would be better off selling those speakers and starting a design and build from scratch.

Your current approach will give you far worse speakers then you have now, and make them worthless.

You are not embarking on a viable or sensible endeavor. That also goes for practically all speaker mods. They are pretty much uniformly disasters.

So one more time, your option is to buy or build new speakers. For the latter I think you have some serious study to do before embarking on it. However that option is brings a lot of joy and satisfaction, but you have to put in the work. Designing and building a good speaker is not an easy task and not for the faint of heart.

I was not going to mod the Heils, as I stated just wondering if there was a unit that crosses that low, that's all.

 

[Sponge]

These are the Heils that I made and listen to.

 

[everettT]

Not sure of the dimensions but this may work as well. Are they dipole?

Home

Bohlender Graebener Neo8S Planar TransducerThe Neo8S features a push-pull magnet system that has been designed with the help of Finite Element Analysis software to achieve optimum efficiency/cost performance. There are no heavy voice coils, spiders, glue joints, paper cones and surrounds. Hence...

www.parts-express.com

 

[Verdinut]

This is the one I was thinking of. IIRC Dennis Murphy commented somewhere about using them as a tweeter, I'll see if I can find it.

Home

Tectonic TEBM28C10-4/A 1-1/8" BMR Full-Range Speaker 4 OhmTectonic's TEBM28C10-4/A miniature BMR is a speaker driver with an extended frequency response and an extremely wide directivity. It combines the benefits of Tectonic bending-wave technology and pistonic modes of operation.The small...

www.parts-express.com

I don't think that using this speaker is a good idea. This driver has a very low sensitivity of around 80dB at 1 watt and is most likely less sensitive than the Heil woofer.
It is not recommended to use a resistor in series with a woofer where you lose amplifier power in heat, and the series resistor would also kill any amp's damping factor. That damping action is required to control the woofer's motion for good transients.

 

[everettT]

I don't think that using this speaker is a good idea. This driver has a very low sensitivity of around 80dB at 1 watt and is most likely less sensitive than the Heil woofer.
It is not recommended to use a resistor in series with a woofer where you lose amplifier power in heat, and the series resistor would also kill any amp's damping factor. That damping action is required to control the woofer's motion for good transients.

Thanks. I seem to remember Dennis saying something when the Cambridge bookshelf used one of the BMRs as a tweeter, just cant remember. After seeing the pics, it wouldn't work if it's a dipole anyway.

 

[Russdawg1]

Thanks. I seem to remember Dennis saying something when the Cambridge bookshelf used one of the BMRs as a tweeter, just cant remember. After seeing the pics, it wouldn't work if it's a dipole anyway.

He used the 3” BMR driver as a midrange in his Philharmonic BMR standmount speakers.

He looked into using it as a tweeter but decided against it as there were problems doing so.

Makes a great midrange though