Hello,
I'm developing a new speaker with a Hypex FA plate amp therefore the whole crossover and all linear corrections can be done with a digital crossover. I am considering to use metal cone drivers. I have learned that the cone resonance should be better tamed with a passive crossover, since there is a reduction in harmonic distortion with this method. So this effect should also be present at other frequencies like the frequencies below the tweeter crossover frequency?! Passive crossover parts can also introduce a small amount of harmonic distortion or other none linear behavior so where should I avoid passive components and use digital filters?
So my general question is the following: which part of the crossover should be realized with passive components and which parts with active components to get the overall best results?
Best
Thomas
I'm developing a new speaker with a Hypex FA plate amp therefore the whole crossover and all linear corrections can be done with a digital crossover. I am considering to use metal cone drivers. I have learned that the cone resonance should be better tamed with a passive crossover, since there is a reduction in harmonic distortion with this method. So this effect should also be present at other frequencies like the frequencies below the tweeter crossover frequency?! Passive crossover parts can also introduce a small amount of harmonic distortion or other none linear behavior so where should I avoid passive components and use digital filters?
So my general question is the following: which part of the crossover should be realized with passive components and which parts with active components to get the overall best results?
Best
Thomas
He mentions that a series notch can tame it, but you can realise a series notch both passive and actively.
The speaker doesn't know if it is driven by a passive or by an amp preceded by a passive.
So I totally agree with your 1st line in your 1st post. Go digital!
Jan
The speaker doesn't know if it is driven by a passive or by an amp preceded by a passive.
So I totally agree with your 1st line in your 1st post. Go digital!
Jan
afaik the speaker will see a high impedance in case of the series notch filter mentioned in the purifi paper. You cannot replicate that (easily) with active filters.
(edit: included the reference)
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Actually, the idea of the Purifi blog post, is that the speaker does see a difference when it comes down to distortion.
There has been three topics now explaining and debating this in very great length.
It seems a promosing hypothesis, but more practical evidence and experiments are needed to close the loop.
Also, in this case some good performing amp are being used so it won't be as significant , but a passive filter does increase the noise floor. Which can be noticeable with high sensitive speakers/tweeters.
This is at least 6dB difference in bafflestep + the additional difference in sensitivity.
Hallo Thomas
The fact that it is not possible to eliminate non-linear distortions with DSP does not change this.
Once you have completed the project and you notice distortions, only then is the right time to address these distortions...
...with resistor, coil and condenser.
Grüße,
Bernd
Of course, DSP is the best way to a successful loudspeaker project.
The fact that it is not possible to eliminate non-linear distortions with DSP does not change this.
Once you have completed the project and you notice distortions, only then is the right time to address these distortions...
...with resistor, coil and condenser.
Grüße,
Bernd
That totally depends on the drivers being used.
If we can lower the distortion, this automatically means that there are more options all of a sudden.
Options one otherwise wouldn't pick maybe.
In the end it's a about the entire system.
See it as a tango dance.
If we can lower the distortion, this automatically means that there are more options all of a sudden.
Options one otherwise wouldn't pick maybe.
In the end it's a about the entire system.
See it as a tango dance.
I did some testing on this using a Seas aluminum cone (L16) driver. The relative distortion reduction using a passive notch filter is marginal at best.
If you have DSP capability already, I would use that generate your notch filter and avoid all the fooling around with a passive notch filter. A notch filter will necessarily be high-Q and you will need to take time and fine-tune the L/C values.
Dave.
If you have DSP capability already, I would use that generate your notch filter and avoid all the fooling around with a passive notch filter. A notch filter will necessarily be high-Q and you will need to take time and fine-tune the L/C values.
Dave.
Thank you for the replies.
As already mentioned the reduced harmonic distortion by using a passive filter vs. an equivalent active filter is documented. I don't completely understand why the higher resistance is beneficial. The current is reduced due to the higher resistance and therefore the coil motion hysteresis effects are less? Is this also true for tweeters and can a passive high pass achieve a similar effect?
You also have the advantage of amp self noise reduction when you use a passive filter but you can reduce the damping factor of the amp by serial resistance...
There has to be an optimal solution which at least in some cases is using some passive components. Of cause you have to be aware of the deviations af two or more passive crossovers, which can introduce a worse pair match and maybe other negativ effects?
What determines if passive components increase the noise floor?
Are there other effects which you have to take into account?
As already mentioned the reduced harmonic distortion by using a passive filter vs. an equivalent active filter is documented. I don't completely understand why the higher resistance is beneficial. The current is reduced due to the higher resistance and therefore the coil motion hysteresis effects are less? Is this also true for tweeters and can a passive high pass achieve a similar effect?
You also have the advantage of amp self noise reduction when you use a passive filter but you can reduce the damping factor of the amp by serial resistance...
There has to be an optimal solution which at least in some cases is using some passive components. Of cause you have to be aware of the deviations af two or more passive crossovers, which can introduce a worse pair match and maybe other negativ effects?
What determines if passive components increase the noise floor?
Are there other effects which you have to take into account?
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as far as i know (and I really don't know much about it!) you could try to achieve a similar "bonus" with current drive and without any passive x-over. however be prepared to start very emotional debate here on diyaudio.
you can follow heated up discussions in some other current drive threads!
that means increased "output" impedance as seen by driver and exactly what might be beneficial to the frequency range well above driver resonance frequency, according to the supporters of current drive.
never heard of that.
passive L-pads or series resistors can reduce effective sensitivity of drivers and by doing so reduce amp noise at the cost of efficiency and heating up resistors.
high sesnitivity horn drivers can be very revealing for amp noise.
another aspect of passive crossover components in active speakers would be including caps to protect drivers from any DC or low frequency in case of amp failure.
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I wouldn't assume there's an optimal solution. Everything we do usually involves trade-offs. (And you've just highlighted a few.)
With all due respect to Lars Risbo, I think this is a solution looking for a problem, in most cases.
if you have the ability at line-level to create an appropriate resonance notch filter, you are essentially solving the problem.
Dave.
if there is any problem at all...
the benefit of a passive filter is that you can reduce the resonance effects of breaking up cones not only for the fundamental frequencies (that are far above passpand anyway) but for harmonics.
so e.g. if you reduce a 4.5 kHz peak (outside used frequency range) with a notch you also reduce H3 for a 1.5 kHz tone in the useful frequency range.
My approach to combining active and passive crossover has been sorted out decades ago. I selected 150Hz as crossover point between woofers (two, not one sub) and two mid-tweeter boxes. Hence i have many active crossovers set at 150Hz.
Then i build many midweeter sections, easily swapable on top of the woofers, optimized with their own passive crossover. I use biamping, so difference in sensitivity between woofers and mid-tweeters is no issue. Other advantage is that small wattage amps are enough for top. Another advantage is no need to have way to many bulky floorstanding speakers around to clutter. Its easier to build and store mid-tweeters (bookshelfs).
Then i build many midweeter sections, easily swapable on top of the woofers, optimized with their own passive crossover. I use biamping, so difference in sensitivity between woofers and mid-tweeters is no issue. Other advantage is that small wattage amps are enough for top. Another advantage is no need to have way to many bulky floorstanding speakers around to clutter. Its easier to build and store mid-tweeters (bookshelfs).
Hallo Thomas,
You chose to title your Thread:
This is a remarkable completely right and well worded posting. I edited [passive component LCR] just for clarification "to hammer the point home".
There are two ways to cope with this:
1. dumbing it down to: "meh, current drive / resistor drive is ********",
or,
2. (I'm quoting myself here):
"Build a Loudspeaker!
Measure it!
I Did it!
That was very enriching for me!"
That was my conclusion on my own thread [Drive Current Distortion Measurement] on the "distorted electrical current" in Loudspeakers. Btw. this contraption plays music right now.
Thomas, do it!
Grüße,
Bernd
You chose to title your Thread:
"Combine passive and active crossover for better sound"
You are already given the best advice possible: Active crossover is the way to go anyway.please note :
This is a remarkable completely right and well worded posting. I edited [passive component LCR] just for clarification "to hammer the point home".
Not one person on the whole world is able to explain this in a few words. Me neither!
There are two ways to cope with this:
1. dumbing it down to: "meh, current drive / resistor drive is ********",
or,
2. (I'm quoting myself here):
"Build a Loudspeaker!
Measure it!
I Did it!
That was very enriching for me!"
That was my conclusion on my own thread [Drive Current Distortion Measurement] on the "distorted electrical current" in Loudspeakers. Btw. this contraption plays music right now.
Thomas, do it!
Grüße,
Bernd
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Hörnli, I understand your intention was benign, however please do not alter quotes directly since doing so can/has lead to misunderstandings (Rule 12). I have restored the quote to the original wording.On top of this it will be expensive, much moreso than an active filter.
IMO the only time a passive network is preferable is a 1st order HP cap for a tweeter.
"
This notch only works this way if it is done passive AND in series with the transducer.
I completely agree with you about avoiding passive components in speakers everywhere else."
Why series only???? Use parallel notches to do frequency compensation on compression drivers.
Rob 🙂
This notch only works this way if it is done passive AND in series with the transducer.
I completely agree with you about avoiding passive components in speakers everywhere else."
Why series only???? Use parallel notches to do frequency compensation on compression drivers.
Rob 🙂