To start this thread off, I'm just going to post my pictures first.
The speakers:
The original crossover:
The naked crossover:
The replacement midrange crossover, moved to behind midrange/tweeter cavity. Original parts are above the board.
Finally, the replacements for the tweeter section
The speakers:
An externally hosted image should be here but it was not working when we last tested it.
The original crossover:
An externally hosted image should be here but it was not working when we last tested it.
The naked crossover:
An externally hosted image should be here but it was not working when we last tested it.
The replacement midrange crossover, moved to behind midrange/tweeter cavity. Original parts are above the board.
An externally hosted image should be here but it was not working when we last tested it.
Finally, the replacements for the tweeter section
An externally hosted image should be here but it was not working when we last tested it.
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So, the short story is that while evaluating DAC's at Music Lover's in San Francisco I got to listen to several different Wilson's. What I realized I was missing was the endless decay the Wilson's had with the right material. That is, it seemed as if my Focal's would cut off the trailing ends of notes and vocals long before they should. I also noticed a bit of glare as well.
Based on budget, space and time, I decided on the following approach:
Midrange Section
Move to an entirely new circuit board and replace everything. This would give me the room for the inductors and film caps. Inductors are Jantzen's, caps are Axon's.
Lessons learned:
- Jantzen coils have a lot more DCR than spec.
- Never use a hot glue gun late at night.
Because of lesson 2, I ended up with too little space, and almost caused a short in the resistor. I did add electrical tape after this shot was taken.
Tweeter Mods
Replace the film caps in the tweeter section. I went with Mundorf MKPs mostly out of cost but also out of space concerns. They are about the same size as the original Focal's so I could use them as drop in replacements. Based on the famous Humble Hi Fi cap review I was not expecting them to be as good as they turned out to be.
Replace all resistors with Mills. For the tweeter I ended up using 2 to get the right 2.4 Ohms and exceed the wattage.
Due to time and energy constraints, my first speaker was ready about a week before the second, so it's had time to break in. As an experiment, I went ahead and listened to my stereo with only one speaker modded. I can say without a doubt, they don't sound alike at all. 🙂 The moded speaker sounded quieter, but less congested. The original speaker had more treble output, but adjusting the balance just made things uncomfortable.
I now have two speakers moded, and I can say that I have achieved my primary goal of having much better decay, as well as ambient information is all much better now. I hear some glare when the volume gets turned up, but the speaker crossovers have a very uneven amount of break in time, so we'll see how they sound in a week.
Based on budget, space and time, I decided on the following approach:
Midrange Section
Move to an entirely new circuit board and replace everything. This would give me the room for the inductors and film caps. Inductors are Jantzen's, caps are Axon's.
Lessons learned:
- Jantzen coils have a lot more DCR than spec.
- Never use a hot glue gun late at night.
Because of lesson 2, I ended up with too little space, and almost caused a short in the resistor. I did add electrical tape after this shot was taken.
Tweeter Mods
Replace the film caps in the tweeter section. I went with Mundorf MKPs mostly out of cost but also out of space concerns. They are about the same size as the original Focal's so I could use them as drop in replacements. Based on the famous Humble Hi Fi cap review I was not expecting them to be as good as they turned out to be.
Replace all resistors with Mills. For the tweeter I ended up using 2 to get the right 2.4 Ohms and exceed the wattage.
Due to time and energy constraints, my first speaker was ready about a week before the second, so it's had time to break in. As an experiment, I went ahead and listened to my stereo with only one speaker modded. I can say without a doubt, they don't sound alike at all. 🙂 The moded speaker sounded quieter, but less congested. The original speaker had more treble output, but adjusting the balance just made things uncomfortable.
I now have two speakers moded, and I can say that I have achieved my primary goal of having much better decay, as well as ambient information is all much better now. I hear some glare when the volume gets turned up, but the speaker crossovers have a very uneven amount of break in time, so we'll see how they sound in a week.
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Parts Cost
Around $140 total. Caps, resistors, and air core inductors were about $6-7 each. Jantzen 14 guage copper foil inductors were around $35 (clearance price, probably all gone). Circuit boards were around $9 each from Madisound, cheaper from Parts Express.
Around $140 total. Caps, resistors, and air core inductors were about $6-7 each. Jantzen 14 guage copper foil inductors were around $35 (clearance price, probably all gone). Circuit boards were around $9 each from Madisound, cheaper from Parts Express.
The problem with some of the Focals (not the audiophile range) is that the crossover is in catenary i.e. commercial., for, the mid range loses... in this case. Check frq. measurements (?) for your model, besides any benefits you may get now.
Thanks, I'll keep that in mind. Truth is I wish I had better tools and time to completely evaluate the crossover, but lacking that I'm just replacing parts with equivalents for now.
Measurements shown here for the Profile 918 and Profile CC908 (link)
The speaker shows some problems that should be equalized at the factory/manufacturing. Not a project without some big mishaps?!
They don't get tired of selling junk, the sad part is that among them, there are good expensive components included in what looks like some type of a mixed salad. We should always measure all speakers for the sake of it and to know what is going on instead off talking about hypothetical benefits.
Focal Profile 918 Speaker System Measurements | Sound & Vision
The speaker shows some problems that should be equalized at the factory/manufacturing. Not a project without some big mishaps?!
They don't get tired of selling junk, the sad part is that among them, there are good expensive components included in what looks like some type of a mixed salad. We should always measure all speakers for the sake of it and to know what is going on instead off talking about hypothetical benefits.
Focal Profile 918 Speaker System Measurements | Sound & Vision
Attachments
Hi Inductor, I saw those charts. If you are looking at the Parts Express thread, the author, while acknowledging it was tongue-in-cheeck, they misunderstood how the Profile range works. If you look at the S&V review, please look at the 2nd chart. The Profile's were an experiment Focal has not repeated. As their documentation shows, and all the reviewers have concurred with, the Profiles use the speaker cover as an integral part of the treble dispersion control. The graph you are showing comes from the grill-off condition. With the grill on they do much better, and getting a stable image with Left to Right fill is nigh impossible without them.
Having said that, I would not mind playing around with the crossover in general to improve it even further, but as I mentioned, I don't have the equipment to measure them properly.
Having said that, I would not mind playing around with the crossover in general to improve it even further, but as I mentioned, I don't have the equipment to measure them properly.
Here is the chart with the grill on. MUCH better, but still has a shallow but wide depression centered around the crossover region. Definitely an area that could be improved.
An externally hosted image should be here but it was not working when we last tested it.
Focal 918 is a perfect example that cries outloud for a filter
modification. With the right technical approach, one can turn
it into an utopia model candidate soundwise.
modification. With the right technical approach, one can turn
it into an utopia model candidate soundwise.
Exactly! 🙂 For now I'm settling for experimenting with high quality parts. Perhaps in the future I will invest in some measurement tools.
Do you have recommendations? I purchased Xover Pro, but have yet to be able to install it successfully.
Erik,
I'm not familiar with that program of yours. Can you load
frd and zma files (textual files of a measurement or traced
graph) to simulate response?
Nowdays it's really easy and cheap to measure response
and impedance. A lot of info is present in this forum.
edit: I recommend you spend some time reading on the
measurements subject and then decide. People are able
to do a lot by just using free and powerful programs like
ARTA, REW and HOLM Impulse not to mention great free
simulation spreadsheets by Jeff Bagby(PCD and others) and
Xsim by Bill Waslo along with the Boxsim of Visaton. The cost
of a calibrated measurement mic and a mic preamp is peanuts
in comparison to high end filter parts that in reality bring
almost nothing.
I'm not familiar with that program of yours. Can you load
frd and zma files (textual files of a measurement or traced
graph) to simulate response?
Nowdays it's really easy and cheap to measure response
and impedance. A lot of info is present in this forum.
edit: I recommend you spend some time reading on the
measurements subject and then decide. People are able
to do a lot by just using free and powerful programs like
ARTA, REW and HOLM Impulse not to mention great free
simulation spreadsheets by Jeff Bagby(PCD and others) and
Xsim by Bill Waslo along with the Boxsim of Visaton. The cost
of a calibrated measurement mic and a mic preamp is peanuts
in comparison to high end filter parts that in reality bring
almost nothing.
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Good points into the measuring systems. A simulation could bring the drivers to sing.
I just opted for not changing my focals (factory), but, I use some shoulder pads on the tweeter, and the LF and midrange are much better after the first, second year. You can also test some sort of screens for the tweeter.
I just opted for not changing my focals (factory), but, I use some shoulder pads on the tweeter, and the LF and midrange are much better after the first, second year. You can also test some sort of screens for the tweeter.
I did some sleuthing and found a kit online that uses the same woofer (6W4359) at lautsprechershop.de. At least their claims are they get a very flatter frequency response above 1kHz than the Focal's. I used Digikey's Partsim online to simulate the two low pass filters. The one in the Profile and the one that lautsprechershop uses. Note that in the second one I also added a zobel network, so ignore differences just above 300mV. Sorry that Google sheets is not cooperating with a frequency axis, but you get the picture here. It seems Focal is rolling off later, but steeper, probably to better integrate with the 4th order high pass filter. What all of this tells me though is that the ragedness in the frequency response is all in the tweeter. :
The simulation ran with a 1V AC signal. The speaker was modeled as being 4 Ohms and 0.2mH in series. I exported the results of each run and plotted them together using Google Sheets. Sorry that I am also missing a db scale, but you get the picture. The low pass filter isn't the issue really so much as the tweeter performance.
The simulation ran with a 1V AC signal. The speaker was modeled as being 4 Ohms and 0.2mH in series. I exported the results of each run and plotted them together using Google Sheets. Sorry that I am also missing a db scale, but you get the picture. The low pass filter isn't the issue really so much as the tweeter performance.
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It's been almost a week since I've made my modifications and here are my observations.
The speakers have less glare and better, if not perfect, low volume resolution. The image has been raised, and pushed back. Some of this is coming from better ambient detail resolution. I have found myself compelled to sit and listen much more than before.
All is not perfect however. In exchange for more musical, smoother sounding I have lost some of the precision in the imaging. Images are now softer and less precise than before, however one could argue it sounds more realistic. Pinpoint imaging is not actually something we experience while listening to live music, so in that sense I have gotten closer to realistic.
I also feel like the speakers are more present in the room. That is, the sounds closest to left and right are more clearly coming from the speakers than before where they appeared to be behind them.
It's a mixed bag analytically, however I'm listening a lot more than before so clearly I've made progress as far as my emotional engagement with what I am listening to.
The speakers have less glare and better, if not perfect, low volume resolution. The image has been raised, and pushed back. Some of this is coming from better ambient detail resolution. I have found myself compelled to sit and listen much more than before.
All is not perfect however. In exchange for more musical, smoother sounding I have lost some of the precision in the imaging. Images are now softer and less precise than before, however one could argue it sounds more realistic. Pinpoint imaging is not actually something we experience while listening to live music, so in that sense I have gotten closer to realistic.
I also feel like the speakers are more present in the room. That is, the sounds closest to left and right are more clearly coming from the speakers than before where they appeared to be behind them.
It's a mixed bag analytically, however I'm listening a lot more than before so clearly I've made progress as far as my emotional engagement with what I am listening to.
So I've been looking more and more at the S&V review. I'm toying with the idea of adding an eq around the tweeter's 2.7 ohm padding resistor. I think around a 0.1mH coil with a 1 Ohm resistor. Ideas?
rookie question
Excuse my too simple question but how do you dismantle a Focal Profile 908 in the first place? I have 918 fronts, 908 rears and CC 908 centre and I looked all around, could not even find how to take out tweeters. Any help appreciated.
Thanks
Excuse my too simple question but how do you dismantle a Focal Profile 908 in the first place? I have 918 fronts, 908 rears and CC 908 centre and I looked all around, could not even find how to take out tweeters. Any help appreciated.
Thanks
Hi Serko!
I did a lot of work since then. You'll need a Torx bit of the right size and lots of time or a nice electric drill/driver. Make sure you keep the torque setting on the drill low! 🙂
Access to the crossover is through the woofer. Remove it and the crossover should be right behind it. The speaker connector plate on the rear of the speakers comes off with a single Torx screw. Make sure to keep it separate from the rest! It's not exactly the same size.
To work on the 918's crossover you'll need to remove the woofer, midrange and rear plate. Once there you will have access to the tweeter. You can leave it in place, but it will be easier to reconnect it if you take it out first. There's a thumb screw behind the tweeter, just use your fingers. You'll find a white nylon "gland" that screws the cable assembly through the midrange partition. Use your fingers to unscrew it. The entire crossover will come out with wiring in tact. There is no need to cut or desolder anything. You may need small pliers to grip contacts if too tight.
After doing a lot of work, and spending a lot of money on crossover parts, really, ridiculous amount, I have some advice for you. These are my suggestions after measuring everything and trying a number of other things, and spending at least a week of time in simulations. Feel free to go crazy, but what I present to you here is the most cost-effective, biggest bang for your buck. If you spend more money, we should talk about you building your own speakers or buying new. 🙂
1 - Replace Tweeter caps with Mundorf MKP's and resistors with Mills. These Mundorf's are smooth, but a little dark. The Cornel Dubelier 940C might be a good, less warm or dark alternate, but not tried it. The darkness of the Mundorfs may help to tame the Focal tweeter though. Try each before committing to all speakers and let me know. The original caps are probably Solen/SCR/Axon OEM's so whatever you use try something besides those. 🙂
2 - Add felt to the sides of the grills. You can just cut it to shape, and sneak it in behind the cloth. If you insist on listening without the covers, add black PSA felt to the sides around the tweeter. Check to be sure grill will fit back on later.
3 - Add adhesive backed felt to the tweeters. Use a 1.25" hole punch, and you'll be surprised how perfectly it fits.
4 - On the 918's remove the 195uF electrolytic capacitor and leave it out. Do not replace it with something else.
5 - On all speakers, check that the larger inductors are actually hooked up! The leads sometimes get installed too tightly and break after soldering. At least visually inspect the leads and use a pencil or something to make sure they're still attached.
If you want more information, refer to my blog post here.
At the least, here is the schematic for the 918's
The 195uF cap and the 8.8 Ohm resistors appear to be a sales trick to reduce the impedance and make the 918's appear to be more "discerning." Well, it's true, with impedances this low you'll need a beefier amplifier, but there's no benefit to you, or to the frequency response. You can eliminate this cap safely with no effect on the frequency response, but it may be easier on your amp and give you a more solid foundation.
Best,
Erik
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Forgot to mention. The crossover has 2 Philips screws at the top holding it in. That's it. The bottom of the crossover is just held in place by friction and the rubber boot. Pull out the screws, and rock it to remove.
Erik,
Thank you very much for all the valuable information you have shared. I managed to remove the woofer and tweeter. You are right, I found the 918s always a bit hard on the amp, didn't know even Focal would do these tricks. I use them with their meshes on but remove the tweeter covers. I have little experience with soldering however I will jump into this wagon when I have some free time.
Best regards,
Serkan
Thank you very much for all the valuable information you have shared. I managed to remove the woofer and tweeter. You are right, I found the 918s always a bit hard on the amp, didn't know even Focal would do these tricks. I use them with their meshes on but remove the tweeter covers. I have little experience with soldering however I will jump into this wagon when I have some free time.
Best regards,
Serkan
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