Hello all,
the focal crossblock is one of the few parts I kept from my few years in caraudio.
It's a wonderful piece that served me a lot in the car, but also helpful in home environment in the variable setup I tried.
It is built, I assume, for 4 ohms drivers so of course with 8 ohms everything shifts, but the wide range of adjustment still allowed a compromise.
I used it few months ago between mids/highs on my OB setup, not optimal because with the drivers I finally chose it required heavy EQ, but ok just the time to find other amps/dsp.
I have now much better result active there too, plus gained time alignment.
I always wondered why there isn't anything like that for home, I mean with this flexibility and build quality, but maybe I’m just unaware of it.
DSPs are great and cheap now, but with 10 channels it doesn't hurt to simplify a bit, and I find it transparent sound wise.
I explored other active solutions like the k231 but they're a bit steep, and would require a bunch of spare cards for the same flexibility.
Anyway, I'm sure I will use it again one day, in the next version or next setup.
Or even right now I could use it to save two channels and maybe test new amps.
So the main question is: could I modify the crossblock itself, basically changing most components to better fit 8 ohms drivers?
I don't know much about crossovers, just how to use them but can't easily read/understand their schematics.
Once opened you can see how it's built (the 2 way version I have):
4 coils (big for woofers and small for tweeters?), few caps and a bunch of resistors, plus maybe few other things that I don't know (it appears two resistors have been replaced by the previous owner).
From left to right, 1st knob defines the low pass point, 2nd the Q factor, the 3rd defines the high pass point and the fourth acts as an L-pad.
I suppose each knob controls a specific routing for a combination of coil/resistor to get to the desired slope.
For the coil I'm not sure how it works, it looks like there's multiple soldered/entry points onto the pcb on their circumferences, is it possible that different pcb "tracks" arrive at different sections of the coil, for variable "rolled length"? If so it's not something I'm ready to change but I could still change the resistors.
The idea is to list all parts, find similar items but with half values for 8ohms (if I'm not wrong there), and solder them as replacement.
Do you think changing only the resistors would mess up everything? I assume the amount of combinations could still mitigate that.
There's thousands of settings once combined, just to give you an idea for basic slopes:
What do you think? I’m nuts or it could eventually work? Thx!
the focal crossblock is one of the few parts I kept from my few years in caraudio.
It's a wonderful piece that served me a lot in the car, but also helpful in home environment in the variable setup I tried.
It is built, I assume, for 4 ohms drivers so of course with 8 ohms everything shifts, but the wide range of adjustment still allowed a compromise.
I used it few months ago between mids/highs on my OB setup, not optimal because with the drivers I finally chose it required heavy EQ, but ok just the time to find other amps/dsp.
I have now much better result active there too, plus gained time alignment.
I always wondered why there isn't anything like that for home, I mean with this flexibility and build quality, but maybe I’m just unaware of it.
DSPs are great and cheap now, but with 10 channels it doesn't hurt to simplify a bit, and I find it transparent sound wise.
I explored other active solutions like the k231 but they're a bit steep, and would require a bunch of spare cards for the same flexibility.
Anyway, I'm sure I will use it again one day, in the next version or next setup.
Or even right now I could use it to save two channels and maybe test new amps.
So the main question is: could I modify the crossblock itself, basically changing most components to better fit 8 ohms drivers?
I don't know much about crossovers, just how to use them but can't easily read/understand their schematics.
Once opened you can see how it's built (the 2 way version I have):
4 coils (big for woofers and small for tweeters?), few caps and a bunch of resistors, plus maybe few other things that I don't know (it appears two resistors have been replaced by the previous owner).
From left to right, 1st knob defines the low pass point, 2nd the Q factor, the 3rd defines the high pass point and the fourth acts as an L-pad.
I suppose each knob controls a specific routing for a combination of coil/resistor to get to the desired slope.
For the coil I'm not sure how it works, it looks like there's multiple soldered/entry points onto the pcb on their circumferences, is it possible that different pcb "tracks" arrive at different sections of the coil, for variable "rolled length"? If so it's not something I'm ready to change but I could still change the resistors.
The idea is to list all parts, find similar items but with half values for 8ohms (if I'm not wrong there), and solder them as replacement.
Do you think changing only the resistors would mess up everything? I assume the amount of combinations could still mitigate that.
There's thousands of settings once combined, just to give you an idea for basic slopes:
What do you think? I’m nuts or it could eventually work? Thx!
I don't think they're making them anymore, but the Vidsonix VCB-100 was an interesting one.
https://audioxpress.com/files/attachment/2625
https://audioxpress.com/files/attachment/2625
I've built similar. For 8 ohms you might add some larger inductor values. I'd think about the intended crossover range to see whether you also want lower capacitor values.
I searched for it for a while years ago, but never saw one on the bay or others. I understand there’s little values for a company to pursue these nowadays, but still useful for a crowd that always play with different speakers.
"Inductors", that’s the right name thanks. I see, so they would have more effect?
How do you think it is built, just one big inductor with a fixed value or could they have built multiple inductors « russian doll » style for all possible settings?
But you’re right I should better define the range first. The tweeter section is wide enough and has always been sufficient to find a good response, even with horns.
It’s the woofer section that is much more limited with 8 ohms. For current setup I would only need to change the woofer lowpass, to get to a 2-3khz range instead of the usable 4-8khz right now.
It is possible to use taps on the inductors to get multiple values out of them, I didn't see that in the photos.
Yes, it comes down to the range. Larger inductors would push it down and that might be preferred.
Yes, it comes down to the range. Larger inductors would push it down and that might be preferred.
Yes it’s hard to see on these pics but I’ve seen at least 4 soldering points to the PCB. I’ll check below of there’s more.
Ok then, I’ll focus on the inductors, thx much!
Ok then, I’ll focus on the inductors, thx much!
I'd leave it as it is.
😆🤣 Don't trust it, said from a Diy'er ...!!!
I guess half of the resistors are for the Q in the woofer path ( attached to a leg of C after L) and the others for setting tweeter level.
The other switches are for selecting the different taps on the coils. ( I think I got it!!)
About the values of each component, I'd just keep the ones on the tweeter path - crossovers are most useful when separated, it helps also in the final wiring. Most tweeters come in the low Z ( 4Ω) format, so crossovers for 2 way speakers might use 8 Ω woofers and 4 Ω tweeters for matching the sensitivities.
Yes, I agree it would be best if it is better understood first.
When doubling the impedance of the speaker, you would want to double the inductance and halve the capacitance. Double inductance comes with 1.4 times the number of turns, in case you can't measure and have to look at the taps and guess.
Now I'm sure there are taps, it might be helpful to add information in case you wanted to rewire it rather than try to replace parts, which would be difficult as I'd expect you would need to locate and tap the inductors yourself.
When doubling the impedance of the speaker, you would want to double the inductance and halve the capacitance. Double inductance comes with 1.4 times the number of turns, in case you can't measure and have to look at the taps and guess.
My no-tech version is a boxful of single-quantity part-pairs (Jantzen) I had hoarded years ago during a major sale, and others salvaged from "hi-fi" kits. Since I can't replace them without breaking the bank (typically each can be more expensive than the driver I use it on), I don't solder but simply use electrician's twist cone-caps to "splice" wire leads temporarily (plus alligator-clip wires). It takes only a few minutes to try out a filter, or several filters. Resistor-chains are a pain though.
It would be very nice to build the OP's magic box. The fancy multi-tapped inductor coil can be replaced by a chain of small coils. Etc.
It would be very nice to build the OP's magic box. The fancy multi-tapped inductor coil can be replaced by a chain of small coils. Etc.
Good guess about half the resistors used for woofer and the other half for tweeter, since a lot of them have the same values!
The track/taps part is a nice piece of engineering, even if I don’t get it all 😛
Yes after more thinking, playing with these inductors might be out of my reach.
But I will still disassemble it carefully and check the bottom tracks. Make a drawing if I get it.
Too bad I sold another one I could have merged some of their parts (or even simply used both in serie, never thought of that).
What would be the use of the smaller ones on top, the ones horizontally placed?
I did try a bunch of crossovers I had from older sets, but it’s really rare that I find the right response.
I did try a combo of this box + passive and it worked fine, but just too messy.
Also I’m always frightned to only use one section only of an existing crossover.
If I understand, only the parrallel ones can be used this way, and since I don't read schematics I always fear for the amp.
The track/taps part is a nice piece of engineering, even if I don’t get it all 😛
Yes after more thinking, playing with these inductors might be out of my reach.
But I will still disassemble it carefully and check the bottom tracks. Make a drawing if I get it.
Too bad I sold another one I could have merged some of their parts (or even simply used both in serie, never thought of that).
What would be the use of the smaller ones on top, the ones horizontally placed?
I did try a bunch of crossovers I had from older sets, but it’s really rare that I find the right response.
I did try a combo of this box + passive and it worked fine, but just too messy.
Also I’m always frightned to only use one section only of an existing crossover.
If I understand, only the parrallel ones can be used this way, and since I don't read schematics I always fear for the amp.
It is a nice piece of a product particularly because of Focal Utopia designation, one should assume the retail price ought to be significant so it might pay off to sell and instead get the parts and magnet wire to build yourself an even much better universal crossover.