I have a Focal Vestia No.4. I have upgraded all the components on the crossover with their original values. They all consist of Jantzen Audio brand air core coils, capacitors and resistors. For testing purposes, I have only upgraded one of the towers. However, there is a decrease in the bass compared to the original. The bass of the other one, the original tower, is stronger. What could be the reason?
The values of all the components in the new crossover and the original crossover are the same, in other words, the coils and capacitors were all used at the same value. In fact, when they first arrived, I measured them all one by one with an LCR meter for confirmation and compared them with the originals. They are within a tolerance of 1-2%.
Why might the bass be weaker? The bass speakers in the original crossover were connected with reverse polarity, so I did the same. I wonder if I reverse the polarity again and connect them with straight polarity, will it be fixed?
The values of all the components in the new crossover and the original crossover are the same, in other words, the coils and capacitors were all used at the same value. In fact, when they first arrived, I measured them all one by one with an LCR meter for confirmation and compared them with the originals. They are within a tolerance of 1-2%.
Why might the bass be weaker? The bass speakers in the original crossover were connected with reverse polarity, so I did the same. I wonder if I reverse the polarity again and connect them with straight polarity, will it be fixed?
Hate to state the obvious, but have you double checked that everything is rewired correctly? It's always worth a 2nd look.
Inductors are measured by the inductive value, but also have a DC resistance that's not always stated, but is typically stated in the specs, or can be measured. If the DC resistance of the inductors is significantly higher than the originals it could cause somewhat reduced output.
Just grabbing at straws, other possible causes could be that some internal stuffing has covered the port.
Inductors are measured by the inductive value, but also have a DC resistance that's not always stated, but is typically stated in the specs, or can be measured. If the DC resistance of the inductors is significantly higher than the originals it could cause somewhat reduced output.
Just grabbing at straws, other possible causes could be that some internal stuffing has covered the port.
Last edited:
This is unlikely to be a polarity issue.
As knotscott implies, changing crossover components (such as substituting an air core woofer inductor for an iron core one) can actually make the speaker's response worse rather than better. This is because the manufacturer will have carefully tuned the crossover function to match the particular crossover components they decided to use.
Details of the before and after components relating to your "upgrade" may reveal some useful information.
As knotscott implies, changing crossover components (such as substituting an air core woofer inductor for an iron core one) can actually make the speaker's response worse rather than better. This is because the manufacturer will have carefully tuned the crossover function to match the particular crossover components they decided to use.
Details of the before and after components relating to your "upgrade" may reveal some useful information.
Everything has been checked many times. Everything is as it should be, but the bass is not.
Before ordering the inductors, I made sure that the dc resistance was lower than the dc resistance of the original inductors.
Normally, in a second-order crossover, the middle frequency should be connected with reverse polarity, am I wrong? Focal did this for the lower frequency.
You should check the mid and tweeter crossover values and polarity.
If it's a bass issue replace the new inductors with the old ones.
If it's a bass issue replace the new inductors with the old ones.
So should I use the original inductor for the bass? Does it make sense to replace the electrolytic capacitor with a film capacitor?
I suggest that you simply reintroduce the original inductor and listen for the difference.
In a 2nd order crossover, the midrange driver should be connected in opposite electrical polarity to the woofer(s) so that they will be acoustically in phase.
Sometimes the tweeter is also wired in opposite polarity, so there is room for experiment there.
Whether it is desirable to replace a bipolar electrolytic capacitor with a film capacitor may depend on its position in the crossover circuit.
A bipolar electrolytic capacitor offers more 'series resistance' than the equivalent film capacitor, and that series resistance may have been taken into account by the crossover designer.
If you have a crossover schematic then post it here.
I attach a simple 3-way, 2nd order crossover schematic to emphasise the opposite electrical polarity requirement.
In a 2nd order crossover, the midrange driver should be connected in opposite electrical polarity to the woofer(s) so that they will be acoustically in phase.
Sometimes the tweeter is also wired in opposite polarity, so there is room for experiment there.
Whether it is desirable to replace a bipolar electrolytic capacitor with a film capacitor may depend on its position in the crossover circuit.
A bipolar electrolytic capacitor offers more 'series resistance' than the equivalent film capacitor, and that series resistance may have been taken into account by the crossover designer.
If you have a crossover schematic then post it here.
I attach a simple 3-way, 2nd order crossover schematic to emphasise the opposite electrical polarity requirement.
Attachments
Last edited:
You could swap the old inductor back in just to see if that's a possible cause. It shouldn't be, but for lack of other ideas, it could be worth it.
I tend to prefer decent polypropylene film caps over electrolytics for better overall clarity,. Not everyone would support that change, and sometimes they're not very practical, but it should be most audible in the mids vs woofers. What's audible from swapping caps is a variable, but if the whole system is well evolved, and the room and setup are good, it could indeed be audible.
Last edited:
Bass should always be positive connected.
Woofer moves out with battery across the terminals red is positive.
Woofer moves out with battery across the terminals red is positive.
That may be the norm, but I believe it is not essential as audio signals are AC and have no fixed polarity.
Would it make a difference to the working of the crossover I attached in post #7 if the input + and - terminals were swapped over to make the woofer electrically out of phase with the midrange and tweeter?
The DC battery test is simply a means of ensuring consistent assembly if the woofers should happen to have unidentified terminals.
After replacing it with the original inductor, the bass frequencies became relatively louder. I was surprised that this was related to an iron core inductor. But my other original speaker seems to be better at the lower frequencies.
If I reduce the number of spirals in the air core inductor and lower its value from 4.6 mH to 4.4 mH, will there be an improvement in the lower frequencies?
Last edited:
I didn't say it because it should be 4.4 mH, I said it as an example. Actually, my aim is to highlight the lower frequencies, but I think such an action will highlight the upper frequencies more. So it will be a wasted effort.
That is worse than useless and actually I feel insulted that you ask for advice, but don't want to put in the effort to reverse engineer the schematic.
First off, what made you decide to "upgrade" the filter? What components failed or could be improved?
Secondly, it is not normal what you see/hear. You "upgraded" the components with components with equal values. So something is out-of-the-ordinary.
The best way to start looking at this is have a schematic, understand the circuit. Connect a signal generator to the input of the filter and measure the outputs. Both with the bass speaker connected or a load resistor. A load resistor is not a good replacement for the complex speaker impedance, but differences in filter characteristic certainly show up.
Once you see these differences between the filter with old and new components. Check the schematic and see which components could have an influence. Then you could check the exact values of the components. With exact I mean inductance, R, magnetic field distribution and hysteresis. Both the old and the replacements. And lastly see if there is any interaction between inductors on the PCB. For air inductors that is different than for iron-core.
Any random changing of component values without exactly knowing the function or influence is useless. There are too many variables.
I must say that the original Focal crossover appears to have been built to a high standard.
E&E appears to have contracted a particularly virulent case of "crossovus upgraditus" which is doing the rounds on this forum!
To undertake such a task without access to a crossover schematic and measuring equipment is simply asking for trouble.
Sorry E&E, these are tough words, but I feel they have to be said for the sake of others contemplating similar upgrading projects.
E&E appears to have contracted a particularly virulent case of "crossovus upgraditus" which is doing the rounds on this forum!
To undertake such a task without access to a crossover schematic and measuring equipment is simply asking for trouble.
Sorry E&E, these are tough words, but I feel they have to be said for the sake of others contemplating similar upgrading projects.
