Hi all,
today is a bad day. I've decided to take a look inside my $2000 Focal's. I've owned them for almost two years (and I mostly like the performance), but for a price tag like that it's not what I expected to see:
C'mon, magnetic core coils and electrolyts in a speaker that claims to be high-end? I guess I was too naive to believe that anything that's commercially made still can be GOOD (or at least - proper made) these days.
And then...you know the rest. I want to upgrade them :] Can I have your opinion on that? Is it worth doing by swapping part for the same value, just higher quality?
Resistors - I think they're quite ok, at least they look like ones I used in several crossovers I made previously (sorry, been some time, need a refresh 😉 ).
Caps - a switch to polypropilene/mylar ones should give a real result, I guess?
Coils - a complete switch to air-core (or we could leave woofers coil in, if it gets too unpractical to change). Especially when I have some questions about these speakers mid-range performance, and there are two of these chose on mid driver.
Any advice from guys who are much more knowledgeable than me would be a huge THANKS!
today is a bad day. I've decided to take a look inside my $2000 Focal's. I've owned them for almost two years (and I mostly like the performance), but for a price tag like that it's not what I expected to see:
C'mon, magnetic core coils and electrolyts in a speaker that claims to be high-end? I guess I was too naive to believe that anything that's commercially made still can be GOOD (or at least - proper made) these days.
And then...you know the rest. I want to upgrade them :] Can I have your opinion on that? Is it worth doing by swapping part for the same value, just higher quality?
Resistors - I think they're quite ok, at least they look like ones I used in several crossovers I made previously (sorry, been some time, need a refresh 😉 ).
Caps - a switch to polypropilene/mylar ones should give a real result, I guess?
Coils - a complete switch to air-core (or we could leave woofers coil in, if it gets too unpractical to change). Especially when I have some questions about these speakers mid-range performance, and there are two of these chose on mid driver.
Any advice from guys who are much more knowledgeable than me would be a huge THANKS!
Dear God! 😱 I own a pair of Chorus 826Vs also. I don't really care for how they sound in full range mode, but I've been happy with them when crossed over around 65 Hz and up. Everything below 65 Hz goes to a pair of DIY subs.
I'll be watching this thread with interest to see what direction you take.
I'll be watching this thread with interest to see what direction you take.
There's nothing wrong with cored inductors if designed properly. Chances are if you try to substitute air cores you will need a lot of physical separation and will be massive and expensive coils and still probably not quite achieve the DC resistance the originals have.
Don't do any rash changes. If you change coils to air and caps to foil, you will certainly hear a difference, but most of this difference will come from modifying the transfer function of the crossover.
I'm currently working on a redesign of a B&W Matrix 802s3 crossover, which also includes ferrite coils (4 of them) and electrolytic caps (3 of them). It's a minefield.
The least you can do is to exactly (+-0.03 ohm) match the DCR of coils, and compensate for ESR of the electorlytic capacitors by including series resistors.
B&W claims that when exchanging cored inductor for air inductors, you should also compensate for the inductor losses caused by Eddy currents. Currently I do not know how to do this.
If the coil or capacitor already has a resistor in series, you can modify this resistor value to compensate for it.
If you increase or decrease the DCR of series coil of your bass drivers, you will modify the Q of the system. Lower Q = leaner bass, Higher Q = bloatier bass. There exists exactly one Q value for this speaker/cabinet/crossover system which gives the most linear response and it's very likely the constructor calculated the crossover for this value.
As to capacitors - you can calculate the effective ESR with the following equation:
R = d / (2π fC)
estimate d=0.05 for electrolytic capacitors and d=0.001 for polypropylene.
As you see, ESR is frequency (f) dependant. Make sure you know what is the functional frequency for the capacitor you are exchanging in the crossover to be able to accurately calculate its ESR.
... as you see, it really is a minefield. If you go ahead, make sure you do it right.
I used the excellent XSim crossover simulator to build a model of my crossovers:
http://www.diyaudio.com/forums/multi-way/259865-xsim-free-crossover-designer.html
This helped me understand the contribution of each component including its ESR/DCR even without knowing the exact parameters of drivers used in my loudspeakers (I use 8ohm loads for simulation). I first built the model of existing crossovers, then made the equivalent, then tweaked values to match the frequency AND phase response.
If you need help, I'd be more then happy to assist, but first you need to draw an accurate schematic of your crossover.
I'm currently working on a redesign of a B&W Matrix 802s3 crossover, which also includes ferrite coils (4 of them) and electrolytic caps (3 of them). It's a minefield.
The least you can do is to exactly (+-0.03 ohm) match the DCR of coils, and compensate for ESR of the electorlytic capacitors by including series resistors.
B&W claims that when exchanging cored inductor for air inductors, you should also compensate for the inductor losses caused by Eddy currents. Currently I do not know how to do this.
If the coil or capacitor already has a resistor in series, you can modify this resistor value to compensate for it.
If you increase or decrease the DCR of series coil of your bass drivers, you will modify the Q of the system. Lower Q = leaner bass, Higher Q = bloatier bass. There exists exactly one Q value for this speaker/cabinet/crossover system which gives the most linear response and it's very likely the constructor calculated the crossover for this value.
As to capacitors - you can calculate the effective ESR with the following equation:
R = d / (2π fC)
estimate d=0.05 for electrolytic capacitors and d=0.001 for polypropylene.
As you see, ESR is frequency (f) dependant. Make sure you know what is the functional frequency for the capacitor you are exchanging in the crossover to be able to accurately calculate its ESR.
... as you see, it really is a minefield. If you go ahead, make sure you do it right.
I used the excellent XSim crossover simulator to build a model of my crossovers:
http://www.diyaudio.com/forums/multi-way/259865-xsim-free-crossover-designer.html
This helped me understand the contribution of each component including its ESR/DCR even without knowing the exact parameters of drivers used in my loudspeakers (I use 8ohm loads for simulation). I first built the model of existing crossovers, then made the equivalent, then tweaked values to match the frequency AND phase response.
If you need help, I'd be more then happy to assist, but first you need to draw an accurate schematic of your crossover.
Glina, thanks so much for your response. I was sure that there was much more than swapping parts in this. While it's obvious the commercial manufacturers save as much as they can on quality parts - they also surely extract the maximum value out of them by doing advanced engineering, as they have access to much more sophisticated engineering tools and testing environments.
I'll make sure I dig deep into everything you wrote and I've already drawn the schematics, just need to de-solder the coils and measure their inductance (I have the meter) and the resistance to complete it with figures. We'll continue from there.
I'll make sure I dig deep into everything you wrote and I've already drawn the schematics, just need to de-solder the coils and measure their inductance (I have the meter) and the resistance to complete it with figures. We'll continue from there.
Chulia, what are the values of the 4 capacitors and 2 resistors on that PCB?
I'm not going to mess with the coils. Too much of a possibility of screwing things up.
I'm not going to mess with the coils. Too much of a possibility of screwing things up.
I'm guessing you had to take a woofer out to get to the crossover? There are no screws to allow the crossover plate to easily be removed from the back of the cabinet.
Yah, you need to take it out, then you can access plastic "legs" that hold crossover plate, pinch them and push it out.
Here we go with the schematics (without coils values for now):
Here we go with the schematics (without coils values for now):
Hi,
You've no hope of matching the DCR's of the inductors
without utterly huge air coils, way over ~ $2K budget.
L1 is the air coil, fair enough, C1 the film cap, fair enough again.
You can't sensibly up date L2, L3, and L4.
The series L2 has particularly chunky wiring.
C3 is in parallel and has 0.6R in series, c4 is in parallel,
arguably you'd gain very little up dating these.
Resistor power ratings look good for their values.
Which leaves C2 and C1 as the series caps worth looking at.
Possibly update C1, but reuse it to parallel an updated C2.
Forget about series R to compensate C2's losses,
that would just render L2's low DCR pointless.
My ten cents worth,
rgds, sreten.
You've no hope of matching the DCR's of the inductors
without utterly huge air coils, way over ~ $2K budget.
L1 is the air coil, fair enough, C1 the film cap, fair enough again.
You can't sensibly up date L2, L3, and L4.
The series L2 has particularly chunky wiring.
C3 is in parallel and has 0.6R in series, c4 is in parallel,
arguably you'd gain very little up dating these.
Resistor power ratings look good for their values.
Which leaves C2 and C1 as the series caps worth looking at.
Possibly update C1, but reuse it to parallel an updated C2.
Forget about series R to compensate C2's losses,
that would just render L2's low DCR pointless.
My ten cents worth,
rgds, sreten.
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Lots of good replies here but this pretty much nails it.
It's not an awe inspiring crossover by any means but you can see why they've done what they've done and it's all fair enough.
I'd agree with sreten with my usual plan of mundorf supreme for the tweeters and mundorf evo oil for midrange, in this case you're looking at a cost of about $250 - that would have probably added another $1000 to the RRP. I wouldn't worry about ESR unless sreten likes to give me a reason to 😉
Chulia, there is nothing bad in cored coils, but if you have issue with midrange and you do not like it, then better to build new crossover.
Take a look on the review here:
Focal Chorus 800 V Speaker System HT Labs Measures | Sound & Vision
826 is purpule line:
http://www.soundandvision.com/images/archivesart/208foc.4.jpg
The best advice is to sell speakers and build some proven DIY project.
Alternative way is to buld new crossover for 826, but you need to start from the beginning: measuremets with microphone, and some speaker designing software + many months.
Just changing caps/coils will have some influence on the sound, but it is not comparable to redesigning crossover.
If you want to pay with toys, you can change R1 to MOX, C1 to Mundorf MEO. C2 - you can try also MEO, but it is big and expensive. Do not destroy original caps, as probaly after replacement and listening you'll wish to revert to original.
This appears as though it could be a fool's errand.
I have a couple of Mundorf 68 uF electrolytic caps on hand that were intended for another project that never came to fruition. But I don't know how beneficial it would be to replace electrolytic with electrolytic provided the caps aren't 20ish years old. Also, the C1 caps are already some type of film cap so there's no real need to replace them either.
There is a downside to recapping these crossovers. There is the possibility that they may not sound as good as they are stock. I've had that happen to me when swapping caps in a new pair of Def Tech SM 350 speakers. I had a stock pair and a modded pair and twice in a row in a blind A/B listening test I chose the stock SM 350s over the modded SM 350s. 🙁 Screwed the pooch on that one.
Also, if one ever goes to sell their Chorus 826Vs, the buyer may want all original parts so it may hurt resale value. In the past few days I noticed a very good looking pair of 826Vs hit about $930 on ebay, which was below the seller's reserve price. That's not too much for what we have in them. I paid $1,619 from Music Direct over a year ago. I'd hate to eat over $600 without having gotten more - a lot more - use out of them.
I'm still pretty happy with mine as they are with the exception of how they handle low frequency content. Fortunately, I have a couple of subs to take care of that.
I think I'm going to bow out of the notion of swapping crossover components and watch this thread to see how it develops.
I have a couple of Mundorf 68 uF electrolytic caps on hand that were intended for another project that never came to fruition. But I don't know how beneficial it would be to replace electrolytic with electrolytic provided the caps aren't 20ish years old. Also, the C1 caps are already some type of film cap so there's no real need to replace them either.
There is a downside to recapping these crossovers. There is the possibility that they may not sound as good as they are stock. I've had that happen to me when swapping caps in a new pair of Def Tech SM 350 speakers. I had a stock pair and a modded pair and twice in a row in a blind A/B listening test I chose the stock SM 350s over the modded SM 350s. 🙁 Screwed the pooch on that one.
Also, if one ever goes to sell their Chorus 826Vs, the buyer may want all original parts so it may hurt resale value. In the past few days I noticed a very good looking pair of 826Vs hit about $930 on ebay, which was below the seller's reserve price. That's not too much for what we have in them. I paid $1,619 from Music Direct over a year ago. I'd hate to eat over $600 without having gotten more - a lot more - use out of them.
I'm still pretty happy with mine as they are with the exception of how they handle low frequency content. Fortunately, I have a couple of subs to take care of that.
I think I'm going to bow out of the notion of swapping crossover components and watch this thread to see how it develops.I was pretty much wrapping it around in my head in a similar way before sreten really summed it up :]
Woofer line - it would be too irrational to update anything here, as values are high and I'm already quite satisfied with LF response.
Tweeter - seems like a quality components already used there (air core choke and a decent cap).
That leaves us with only mid driver to mess with, if do that at all. Sreten, thanks for really narrowing it down to the single C2 worth looking at. I think I'll get Mundorfs to replace them and see (sorry, hear) the difference. Should it go wrong - well, I'll put the originals back in place and will sleep tight knowing I've done everything sensible there was :]
I'll keep it updated with the final result.
Woofer line - it would be too irrational to update anything here, as values are high and I'm already quite satisfied with LF response.
Tweeter - seems like a quality components already used there (air core choke and a decent cap).
That leaves us with only mid driver to mess with, if do that at all. Sreten, thanks for really narrowing it down to the single C2 worth looking at. I think I'll get Mundorfs to replace them and see (sorry, hear) the difference. Should it go wrong - well, I'll put the originals back in place and will sleep tight knowing I've done everything sensible there was :]
I'll keep it updated with the final result.
Here's my take on this:
C1 looks like a mylar cap judging by its small size. You could profit some by changing to a quality polypropylene (Mundorf Supreme, Jantzen Superior, Audyn Cap Plus). You may hear some change by changing R1 to MOX.
C2 + L2.
C2 is a high value - upgrading to polypropylene will be costly.
My guess is that C2 contributes approx 0.1 ohm ESR to the system. This means that if you upgrade to polypropylene, you can use a coil with correspondingly higher DCR without adding any series resistors. There's a chance air core may be realistic.
L3 - probably will be very costly to upgrade to air coil with compatible DCR.
C3+R2
If you upgrade C3 to polypropylene, you will have to increase the R2 by approx 0.3-0.4ohm.
I'd leave the woofer part as it is.
And as a complete alternative to all above - I'd recommend getting some K40Y9 russian PIO caps for bypassing your existing caps (except the 150uF on woofers, you wont hear a difference there). If you want more top end sparkle, consider also the russian teflon caps (FT-1, FT-2, FT-3). A good estimate for bypasses is 1/100 of original capacitor value. I had nothing but excellent results with these russian caps and they are by far the best bang for buck in audio. Bypasses this small have very little influence on the effective ESR, so you will not modify the frequency response of your crossovers.
C1 looks like a mylar cap judging by its small size. You could profit some by changing to a quality polypropylene (Mundorf Supreme, Jantzen Superior, Audyn Cap Plus). You may hear some change by changing R1 to MOX.
C2 + L2.
C2 is a high value - upgrading to polypropylene will be costly.
My guess is that C2 contributes approx 0.1 ohm ESR to the system. This means that if you upgrade to polypropylene, you can use a coil with correspondingly higher DCR without adding any series resistors. There's a chance air core may be realistic.
L3 - probably will be very costly to upgrade to air coil with compatible DCR.
C3+R2
If you upgrade C3 to polypropylene, you will have to increase the R2 by approx 0.3-0.4ohm.
I'd leave the woofer part as it is.
And as a complete alternative to all above - I'd recommend getting some K40Y9 russian PIO caps for bypassing your existing caps (except the 150uF on woofers, you wont hear a difference there). If you want more top end sparkle, consider also the russian teflon caps (FT-1, FT-2, FT-3). A good estimate for bypasses is 1/100 of original capacitor value. I had nothing but excellent results with these russian caps and they are by far the best bang for buck in audio. Bypasses this small have very little influence on the effective ESR, so you will not modify the frequency response of your crossovers.
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I suggest you leave the speakers as they are, beacuse they
aren't broken and by "upgrading" filter you are probably
going to find your peace for a shorter period of time.
Invest you money in a small project of new good value
drivers and learn about building in the process.
One day you might become wise enough to do the proper
modification of the 826's with a completely new filter.
Lojzek - I get your point and I would go with it in another situation. But this time - it's all about learning and hearing the differences myself, not only reading about them. In other words - process over the result this time. I can always revert to the stock configuration if it sounds best and leaves my "upgrade" parts on the shelf - that will still be money well spent for the experience received.
So, with all due respect, action plan :]
1) Nice idea with bypasses. As they cost so little - will surely try that in first place.
2) Change C1/R1, shouldn't cost a fortune.
3) C2 change. I expect the most audible result here, but seems this will come at at a great price. No series resistor will be added.
4) L2 change to air core. This one is very questionable - I'll see if it's sensible to do that (in terms of complexity and price).
5) R2 + C3. Should be a reasonably cheap one again.
One more question - how do you guys perform your A/B tests? Any relay-based jig? Replugging things? Any other techniques to take the subjective "it has to be better" out of the equation?
So, with all due respect, action plan :]
1) Nice idea with bypasses. As they cost so little - will surely try that in first place.
2) Change C1/R1, shouldn't cost a fortune.
3) C2 change. I expect the most audible result here, but seems this will come at at a great price. No series resistor will be added.
4) L2 change to air core. This one is very questionable - I'll see if it's sensible to do that (in terms of complexity and price).
5) R2 + C3. Should be a reasonably cheap one again.
One more question - how do you guys perform your A/B tests? Any relay-based jig? Replugging things? Any other techniques to take the subjective "it has to be better" out of the equation?
Hi Chulia, I just finished redoing my Profile 918's. While the parts quality was better, especially int he capacitors, the tweeter looks like it's about the same based on reviews from Stereophile and Sound and Vision. 🙂 I ended up replacing all the caps in series with the tweeter with Mundorf MKP's, ($6 each) and the caps in parallel with Axon's. I like the improvements a great deal myself, but not sure I'd go much more expensive than that.
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