Speaker crossover mod. Your advice?

I have removed the crossover from the speaker. Here is a link to the photos I took:

Focal 1027 crossover

I don't really know how to interpret what I'm seeing. Any help would be greatly appreciated.

Bryon

Thanks to everyone for your input. I have two principal concerns: the plan and the execution. As for the plan...

You can see a picture of the crossover here.

At the advice of another Audiogon member, I tested some of the caps on the crossover board to determine which one is associated with the tweeter. Here is what I did: I placed one lead of a multimeter on the lead of the capacitor, and the other lead of the meter on the tweeter's positive terminal. I got measurements of .4 Ohms and 4 Ohms for the two leads of the cap labelled "Focal 4.7J 250V" in the upper right of the photo. (I am assuming that the .4 Ohms measurement is really 0 Ohms, since I get the same .4 Ohms measurement when I simply touch the two leads of the meter together with nothing in between.)

On the basis of these measurements, the Audiogon member I've been talking to concluded that the 4.7J cap is the one for the tweeter. I have no reason to doubt him, since he seems like an experienced guy, but I would like to confirm with other folks that we (mostly I) didn't miss anything. There is another cap on the crossover, labelled "Focal 3.6J 250V" that, when I performed the same test, came back with measurements of 1 Ohm and 10.5 Ohms. Could that cap have anything to do with the tweeter as well? Is replacing the one 4.7J cap all I need to do for the tweeter?

Thanks,
Bryon

Thank you, Jeffrey, for your advice. I will attempt to remove the crossover board and trace it, to determine exactly what parts are in the tweeter's signal path. It may take me a day or two to get the time to do it. I will report back when it's done.

Bryon

Don't really have much of an idea what they are worth. The original MSRP was $8k. They were heavily discounted toward the end of their production run, when I bought them (new) for around $5.5k. That was roughly a year ago.

I looked at your outboard crossovers. Nice!

Bryon

Ok, I will make a schematic diagram and report back.

Bryon

I have created schematics for the crossover. It was tricky at first, but easy after I got the hang of it. Here they are:

TWEETER

MIDRANGE

WOOFERS

The following are the values of the caps and resistors for the various drivers, as labelled on the components:

TWEETER
C1 = 3.6J 250V
C2 = 6.8J 250V
R1 = 7W 5.6Ω JF

MIDRANGE
C3 = 56µF 63V
C4 = 12µF 63V
C5 = 4.7J 250V
R2 = 10W 6.8Ω JF
R3 = 10W 2.4Ω JF

WOOFERS
C6 = 220µF 63V
C7 = 440µF 63V
R4A = 10W 20Ω JF
R4B = 10W 20Ω JF
R4C = 10W 20Ω JF

What's next?

Bryon

Thanks, John, for your advice. I will take a look at the Mundorf thread. I don't know the first thing about caps, so hopefully that will help.

I think the plan at this point is to replace the 2 caps for the tweeter, and possibly the resistor for the tweeter. I am going to leave the inductors alone.

As far as the midrange, I may do that down the line, if I am happy with the tweeter results. But for a first step, I am going to restrict myself to the tweeter. With that in mind, I have a basic, possibly stupid, question as I look around for replacement caps:

The caps for the tweeter are labelled "3.6J" and 6.8J." Does the "J" after the number mean joule? In my preliminary search, all the caps I am seeing are rated in µF. I don't see any caps labelled with "J". Why is that?

Bryon

Thanks, Jeff. Just discovered this: "J" indicates a 5% tolerance, according to capacitor codes. In light of this...

Is it a safe assumption that the 3.6 and 6.8 caps are 3.6µF and 6.8µF? Are those typical values for caps associated with tweeters?

Also, finding a 3.6µF cap has been a little difficult. The caps I've found so far from various manufacturers are either 3.3µF or 3.9µF. I assume that using a different value will change the frequency of the high pass filter. Is that a bad idea? Or is the difference - .3µF - small enough to be ignored? Should I just keep searching for a 3.6µF cap?

Anyone?

Thanks, Al. I assumed the caps were uF, even though they are not marked as such. As this is my first attempt at a mod, I don't want to make a rookie mistake.

You are right that 1.8uF is a standard value, so connecting two caps in parallel might be an option. Do you know whether two caps can be connected in parallel to the crossover board, in light of the fact that the board has only one pair of holes for the stock 3.6uF cap? Do I simply place the leads from the two new caps into the same holes, so that each hole has two leads?

Thanks Al. I will keep that in mind, in the event I can't find or special order a 3.6uF cap.

John - Do you recommend Clarity MR for both tweeter caps? What about mixing caps from different manufacturers? Any rules of thumb here?

Also, do you think I should replace the resistor for the tweeter? If so, with what?

Thanks to all for the valuable input.

John - No sweat. I was about to send them to you when I saw your last post.

RE: Outboard crossover. Unfortunately, that's not in the cards. The room is not dedicated. Plus wife, pets, kids, etc.

RE: The size of the new caps. I was hoping to have the new caps "float" off the board a little, as in the following sketch:

FLOATING CAP

At least two problems that would need to be overcome in order to make this work:

1. Finding a cap with leads that are long enough to reach the board.
2. Finding a way to stabilize the cap.

Thoughts?

Bryon

Hi Jeffrey - Your advice is greatly appreciated.

RE: SoniCaps Gen 1 caps. They have a 3.6uF cap and a 6.8uF cap, but both are only 200V, whereas the stock Focal caps are 250V. So I assume that's not going to work.

RE: SoniCap Platinum caps. They don't come in the correct uF values, nor do I see any combination of 2 caps that sum to the correct values. Not to mention, they are, to use your phrase, more than I choose to afford. :-) I was hoping to do the whole project for $300-$500, so I need to find caps in the $100 range or so.

RE: MultiCaps RTX caps. Again, I don't see the correct values, nor do I see any combinations of 2 caps that sum to the correct values. Also, they tend to be 200V like the SoniCaps.

Hence the search for caps continues...

RE: Mills MRA-12 resistors. This is a stupid question, but I assume that replacing the stock 7 watt resistor with a 12 watt resistor is fine, provided that they have the same ohms rating (of 5.6). Is that correct?

Bryon

Thanks Jeffrey. Not trying to make things difficult. Trying not to make a mistake I will regret. To a pro, a rookie's caution may seem silly. But we are all rookies at one time or another.

Speaking of not making a mistake...

As Magfan pointed out, it's going to be difficult to mount the new caps to the crossover board, as they are MUCH bigger than the stock caps. Can anyone make a suggestion as to how the new caps can be secured to the board, which is mounted vertically inside the speaker cabinet. No, I can't go external.

BTW, I did discover that ClarityCaps MR will be available in March from Parts Connexion in the value I need - 3.6uF. I'm now leaning toward a combination of ClarityCap MR and Mundorf (not sure which one). Both have their proponents, so I may just split the difference.

Bryon

Face - Sorry, my last post wasn't that clear. The tweeter has 2 caps associated with it - C1 and C2 - that are 3.6uF and 6.8uF. What I was trying to say in my last post is that I'm currently leaning toward doing this:

1. Replacing the stock 3.6uF cap with a SINGLE 3.6uF ClarityCap MR.
2. Replacing the stock 6.8uF cap with a single 6.8uF Mundorf, (possibly silver/oil)

What do you think of that idea?

Bryon

...use a half-inch-square chunk of wood on the board as a spacer, cap on the wood, 3M foam tape holding all layers together, and a plastic ziptie thru the board.

Thanks, Jeffrey. I was thinking of doing something like this.

Last rookie question for you: To create the holes for the zip ties to pass through the board, is it ok to drill through the board with a regular drill bit?

Bryon

Thanks for the warning, Al. That's just the kind of rookie mistake I was hoping to avoid.

RE: The lack of room on the circuit board for the new caps...

Another poster suggested (in private email) that I build a small platform to go above the existing crossover board and attach the platform to the circuit board with wood blocks that are glued to the spaces created by the removal of the old caps. Then I can mount the new caps to the second platform, which would provide plenty of room for some of these big boys. I'm planning on using this approach.

RE: Which caps to use...

Obviously, folks have strong feelings about caps. I don't want to start a war, but I do want to elicit one last piece of advice about which caps to go with. Here is what I'm hoping to achieve: SMOOTHER treble. I would like to try to remove the last bit of grain and glare from the top end. In light of that...

-After reading about caps in other threads, the Duelunds sound perfect. But they are too much of a budget buster. :-(

-I have seen the Mundorf silver/oil caps described several times as "smooth." Hence my interest in them.

-I have seen the Clarity MR caps described as "neutral" and "transparent." Those characteristics are great, but may or may not involve greater "smoothness," which is the principal reason why I am changing the caps.

Thanks for any guidance.

Bryon

I have read a large fraction of the Mundorf s/o thread, the entire humblehomemadehifi shootout, and several others threads devoted to caps and crossover mods. I now have a plan...

1. Tweeter cap C1. Replace with a single 3.6uF ClarityCap MR.
2. Tweeter cap C2. Replace with a single 6.8uf Mundorf silver/oil.
3. Tweeter resistor R1. Replace with a Duelund CAST resistor.

My reasoning, FWIW...

--I would like to begin with the tweeter only. I very well may replace other crossover components in the future, but as a beginner, I would like to approach this in steps. Hence I will not be replacing any inductors at this time.

--I wanted to avoid bypassing caps, since several people warn about possible smearing effects. Hence each cap will be replaced with a single cap of identical value.

--I want to try to make the treble smoother and more liquid. Hence the choice of the Mundorf s/o for the 6.8uF cap. But the Mundorf s/o is not available in 3.6uF. Hence the choice of the ClarityCap MR for that position. I know that some folks discourage mixing caps from different manufacturers, but others report good results with that approach. So I will give it a try. My hope is that the liquidity of the Mundorf s/o and the transparency of the Clarity MR will combine to give me a pleasing balance of both characteristics.

--I cannot afford Duelund caps at the moment.

--I cannot go external.

That's the plan.

Bryon

Will do.

Just spoke with Jeff from Sonic Craft. Very knowledgable and very helpful. Here is what he recommended:

1. Tweeter cap C1. Replace with (2) Mundorf s/o in parallel (1.8uF + 1.8uF)

2. Tweeter cap C2. Replace with (1) Mundorf s/o.

3. Tweeter Resistor R1. Replace with Mills MRA-12.

4. Midrange cap C3. Replace with Jupiter Vintage Flatstack + Black Gate AC series in parallel (exact values TBD).

5. Midrange caps C4 & C5. Replace with Sonicaps Gen 1.

6. Bass caps C6 & C7. Replace with Axon or Solen caps.

Correct.

I have one lingering question regarding the values of the caps for the midrange. Here is how they are labelled on the caps themselves:

MIDRANGE CAPS
C3 = 56µF 63V, bottom right of this pic
C4 = 12µF 63V, bottom left of this pic
C5 = 4.7J 250V, top left of this pic

Notice that C3 and C4 are both SMALLER than C5, yet according to their labels, they are much LARGER values.

I am now wondering if C3, which is marked 56uF, is really a 5.6uF cap. Likewise, I am wondering if C4, which is marked 12uF, is really a 1.2uF cap.

Could C3 and C4 really be 56uF and 12uF and still be much smaller than C5 which is 4.7uF? Or can I infer from their small size that they are really 5.6uF and 1.2uF, even though there are no decimal points on the caps' labels?

I just don't want to order the wrong midrange parts.

Bryon

Jeff/John - I will get a meter to measure the capacitance of the midrange caps before replacing them.

Timlub - Thanks for the recommendations. I will take a look.

And thanks again to everyone for your input. I will report back after I have ordered and installed the parts to let you know how things turn out.

Bryon

Hi Louk - I have the same speakers that you have, the 1027be.

I'm not sure I understand your question. Are you asking about the crossover, the drivers, or the enclosure?

Bryon

Louk - The "s" in the first sentence of my post was simply meant to be plural, as in "my Focal ten twenty sevens." I had forgotten that Focal made a speaker designated 1027S. Sorry for the confusion.

In any case, I do indeed have the 1027be, and I can say that I don't have the same problem in the midrange that you are describing. I don't doubt what you are hearing, but I wonder if there's an issue elsewhere in the system. I have found that the 1027be is rather revealing of issues in upstream components.

Bryon

Louk - The serial number is 10E005493.

Which midrange chassis is built in your BE (my is as stated 6 W 4361)?

By "midrange chassis," do you mean the midrange driver? If so, I'm not sure what its designation is. I looked at the back of the driver and the information was so faint that it was unreadable. Here is a photo of the midrange driver:

midrange driver.

bc

The other midrange was too faint to read as well. Judging from your picture of the rear of your driver, I'd say our midrange drivers are the same. So I don't know what to attribute the difference to.

bc