Distortion in Bass-managed speakers

[Ardrazzt]

Firts of all, I apology if this matter has already been discussed. I looked in the forum but I didn't found anything.
When we see the following picture in the speakers review like this.

What happens when the crossover is on? How the HP filter affects this graph?
Thank you very much in advance.

 

[puppet]

The HP filter lowers the distortion, that would be due to cone excursion, below it's set frequency. The "Q" of the filter, if that is used to lift the low end response, may add somewhat to the distortion readings above the set frequency as it slightly increases cone excursion there as well. In the higher amplitude graph you've shown the overall cone excursion is increased and the HP filter is, while still enabled, less effective in controlling cone excursion.

 

[ernestcarl]

IMD should be reduced as well, however, you will not see it in that type of graph. Multitone measurements can be performed to make the effect of mains HP and sub bass support more visible.

 

[617]

The reason why your tweeter has a crossover filter is to prevent excessively loud and excessively low signals from causing the tweeter to audibly distort (or be destroyed). A high pass filter on your woofer will do the exact same thing; harmonic distortion will be a smaller % of the total signal since it is playing more quietly.

 

[JohnnyNG]

IMD should be reduced as well, however, you will not see it in that type of graph. Multitone measurements can be performed to make the effect of mains HP and sub bass support more visible.

I've wondered about this. I would imagine that a HP reducing excursion would indeed lower IMD well above the HP frequency up to the bandwidth limit of the speaker's woofer.

 

[ernestcarl]

I've wondered about this. I would imagine that a HP reducing excursion would indeed lower IMD well above the HP frequency up to the bandwidth limit of the speaker's woofer.

Neumann has a helpful graphic illustration (mainly for a three-way) here:

Neumann – the reference since 1928

Good sound starts with Neumann. Professional Studio Microphones ✓ Stage Microphones ✓ Homestudio ✓ Studio Headphones ✓ Recording Studio✓

www.neumann.com

*Select the 800+KB PDF

You will notice the effect extends to the high frequencies as well.

 

[JohnnyNG]

Neumann has a helpful graphic illustration (mainly for a three-way) here:

Neumann – the reference since 1928

Good sound starts with Neumann. Professional Studio Microphones ✓ Stage Microphones ✓ Homestudio ✓ Studio Headphones ✓ Recording Studio✓

www.neumann.com

*Select the 800+KB PDF

You will notice the effect extends to the high frequencies as well.

Very interesting, thank you!

 

[abdo123]

Here you go! 5.25 driver Bass managed to two very capable 12inch subs at 100Hz, distortion increases below 30 Hz because of response roll-off (and also a couple of resonances that i later fixed).

 

[abdo123]

Managed to normalize distortion to fundemental level

 

[fineMen]

What happens when the crossover is on?

You could be able to evaluate that by yourself. Think of which data would be needed. A lot, I know, but which exactly? Reiterated, once you invest some independend thought it may come to you that at least the development of distortion with level at each frequency is of prime importance. But nobody is going to tell you about this dB by dB. Bad situation, except you are willing to take your own measurements, are you?

A general advice is to support small-ish speaker with additional bass boxes that may be used even up to 200Hz, hence them not being "subs" in particular. Please report back what you've accomplished.