Help with 3 way Focal BOX design!

[silver00spike]

I bought a pair of each

10w6411 -10" woofer

6w4311 -6.5" woofer

TC120TD5 -tweeter

I don't have any specs for what kind of enclosures these need, except my assumption that the tweeters don't matter that much.

I've built a vented box for a 5ws subwoofer before, and it sounded like absolute crap, so I'd like to stay away from those if I can. Unless someone can show me an easy one to make

Also, I don't know how to wire them together (parallel/serial what to what?), and which amp under $400 on ebay to power them!



http://www.falcon-acoustics.co.uk/Units2001/6w4311.pdf
http://www.partsexpress.com/pdf/297-533.pdf
http://www.falcon-acoustics.co.uk/U...01/TC120TD5.pdf

are the specs

 

[BobEllis]

Those are some nice drivers, and deserve a good crossover and better than a $400 ebay amp, but lets take a quick stab at a rough design.

First, I suggest making your crossover external, so that you are more likely to keep tweaking to get the best out of your system.

You'll need to go vented with the 10W if you want any sort of bass extension. Try something in the neighborhood of the alignments suggested in the data sheet to get you deep enough for most music. You'll probably want a sub for HT, but if you tune it a little lower than suggested you may find that room gain gives you nice flat extension to under 30 Hz. You can play around in WinISD to figure out the details. Care to post details of your 5W design so we can help figure out where that went sour and help you avoid similar mistakes?

Your 6W should have its own sub-cabinet, around 15L sealed will give you an F3 of around 100Hz. A second order electrical high pass ought to give you a 4th order acoustic XO at 100 Hz. You'll need to measure to be sure, see www.audua.com for speaker workshop. It's free software that does measurement and crossover design tweaking. you might also consider raising the crossover point anywhere up to around 250 Hz, although the design process might be a little more involved.

The tweeter is sealed and does not need a sub-enclosure. I've had good results with crossing it to the similar 6W4254 at 2400Hz/ 4th order electrical. You may want a notch filter on the mid side to take care of the peak in the woofer response at around 3KHz, or start rolling off the 6W a little earlier than the tweeter comes in.

Summary of my suggestion - 10W in a60L vented box tuned ~38 Hz, crossing over 4th order LR 100-250Hz to the 6W in 15L, crossing over at 24-2500 Hz 4th order LR to the tweeter. If you can pick up/build some decent amps, I strongly encourage you to try an active XO, expecially between the 10W and 6W.

For me, parallel crossovers are easier to design, so I haven't played with series. Poke around here and the rest of the web for some good instruction on crossover basics.

good luck

 

[silver00spike]

I have custom crossovers on tis way here from ebay, made by focal for 1", 4", and 6.5" speakers. For the sub, I was hoping to find an amp that has a low, and high pass filter.

http://www.diyaudio.com/forums/showthread.php?postid=394241

this guy pretty much used the same components, but I'm not sure how he made the sub box, it looks like a wall with 4 holes in it cutting the box in half. I don't even know if its stuffed with anything.

Thanks for your help Bobellis, but most of the tech terms you used are way over my head

 

[BobEllis]

I hope the crossovers work out for you. Ideally the crossover is designed for the particular drivers in the particular cabinet and room. You may get lucky on the mid to high crossover, but you'll probably want to do some tweaking on the woof to mid, to add baffle step correction if your cabinet is a different width. It's not too hard to follow the directions others have posted on the web to measure and get better results than textbook filters, even if you cannot comprehend the math behind the derivation.

The wall with four holes you mentioned is cabinet bracing, also important to good sound. a single layer of MDF should not span more than 6-7 inches without a support. You'll need to make a sealed chamber for your mid. the simplest way is to add three pieces the width of the cabinet above, below and behind the mid. Stuff the mid chamber generously to absorb the mid's back wave.

good luck

 

[silver00spike]

Where do I buy the actual ports? And how do I know which sizes I need?

 

[BobEllis]

Ports can be self made or purchased at someplace like Parts Express. For a 10" driver, a rule of thumb is use a 4" ID port, or two 3" ports. For more specific recomendations download WinISD and model the driver in your box at rated power. Make the port big enough to keep the vent speed under 17 m/s (.05 Mach in other programs) and you should be fine.

one way to make a port is to mount a piece of PVC pipe to the inside of the cabinet (front or rear) and use a flush trim and or roundover bit to make the hole smooth. You can also make the port square or rectangular - WinISD will tell you how long to make it. Simulation isn't always exact so it's a good idea to make the port a little long and trim to fit.

edit: I was curious so I plugged it into WinISD. You'll want 2 - 4" ports about 17" long in a 65 L box for an alignment that will give you an F3 of 39 Hz. Don't forget to add back the volume occupied by the ports, driver and bracing to determine how big to make the box.

 

[silver00spike]

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here are the crossovers, they just came in today. Do they seem to be OK for my mids and highs?

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This is the box I made for the 5ws subwoofer. It sounded very quiet, and lots of port noise.

Is there any way somebody could draw up a quick diagram for me so I can start building the enclosures?

 

[float]

Hi Silver,
with those drivers and some skill and effort you could have speakers that sound like 10000 bucks.
Balls it up and you'd be lucky if they sound like $100.
Those crossovers won't do the job, but you could connect them up without breaking anything, so dont be afraid to have a listen.
It'll sound pants.
You could probably reuse some components, and maybe the board, but you need to do some research on this one.
Spend some weeks searching for any info/designs using these drivers. Learn more about speaker building in general.
You wont believe how much info is out there. Enjoy

The 5ws is a small sub and wont give much volume in the home.
However, your box looks a bit small- allowing for the driver and port it looks like you've only got about 2 litres there. Try a box of about 8 litres (ported or sealed).

 

[BobEllis]

Why not just use the diagram that you have and adjust the dimensions to suit?

You'll need a little more volume than that for your midrange. I'd go sealed for that.

The crossover you have probably will not give satisfactory results. At best it will give mediocre sound. The ferrite cored inductors and electrolytic caps don't do your drivers justice. I suspect that those resistors are not low inductance types. It looks like is has some driver specific EQ included on the woofer and mid, but you aren't using the ones it was designed for. The woofer filter has some baffle step compensation built in but it is for a narrower baffle than you'll be using.

Read up on crossover design, post a rough design here (try a standard 3rd order electrical XO at 300 and 2500, add a zoebel to the mid and woofer, add baffle step compensation and an Lpad on the tweeter to get close) and someone will probably help you improve it.

 

[Al.M]

Hope you will do a better job than the 5w sub box (whats the brown bits at the bottom, looks like chicken droppings))

WINISD seems to suggest 60 litre vented box with 100 x 180mm port, perhaps go for 80L to give few extra hz extension down to 35hz f3 point with 100 x 120mm port (you can always fill the bottom and reduce internal volume).

I would go for a 1m tall cabinet about 30cm wide and adjust depth to 34cm suit 80L volume, position the tweeter at the top around seated position of your ear or just above, midrange spaced 1cm down followed by woofer, off set tweeter inwards of listening postion. Enclose midrange in separate recommended volume (add stuffing). Situate port either front or rear depending on how close you will position to rear wall ) if too close then position front below woofer (can use a telescopic port to change and adjust to tuning of your choice).

As everyone else points out the crossover will be harder. You could start with a pre-made generic crossover from one of the electronic shops which might give typical crossover points of 500hz & 3000-5000hz, or build from scratch as recommended but you should read up on something like Vance Dickasons Speaker Design Cookbook. The learning curve might take some weeks or months. 2nd or 3rd order crossover should be tried before before going to more complex and expensive parts count higher order crossover but take note of what others are saying here.

I havn't seen many or any DIY designs using that exact combination of drivers but once finished it will be very impressive sounding.

You can read this website and links for some general ideas:

http://www.geocities.com/diyproac25/

 

[silver00spike]

Please keep in mind I know very little about speaker terminology.

So everybody here agrees that the crossovers I bought are crap?

The things in the 5ws box are left overs from ferret food. Those things like to flip their bowls over, and this box is the perfect feeding dish. Except for the port

I don't want to spend months reading up on crossovers, so I'd rather have a costum set made for me. What is a fair price for a set of custom made ones, and what components should I request be used in building one? Inductors and caps wise.

How do I make a port out of PVC pipe that would have as little port noise as possible? Does a square hole have less port noise?

I really appreciate all your help so far guys/girls

 

[float]

I don't want to spend months reading up on crossovers, so I'd rather have a costum set made for me. What is a fair price for a set of custom made ones, and what components should I request be used in building one? Inductors and caps wise.

How do I make a port out of PVC pipe that would have as little port noise as possible? Does a square hole have less port noise?

A fair price would be $5000. Paypal me the funds and I'll start today

As always, its not that simple. To get it right you need the drivers in their box for listening and measurement. Any "virtual" design would be very lucky to be optimal.

There are many on this forum who could run a simulation based on traced spl and impedance curves, and could suggest a box design, but some hours of work are involved. Maybe you could offer the job and see what happens?

If you're looking for an easy solution, sell your drivers and use the proceeds to buy something ready built. At least this way youd know what sound you're getting.

As for the port, bigger would be quieter, but would also need to be longer.

 

[hayenc]

PVC Ports

I also bought a pair of those crossovers, thinking Focal used better components in their commercial crossovers. Have not tested them yet, but will comment later.

As for PVC ports, this is what I found to be useful:

http://www.audiodiycentral.com/nt_porttube.shtml

My box for the 10W6411 uses two of these with 3 inch PVC, 7 in long in a box with ID of 10 1/2, 17 3/4, and 32 1/2 and a simple 300 Hz low pass. It is still breaking in, but sounds clean so far.

 

[float]

Re: PVC Ports

I also bought a pair of those crossovers, thinking Focal used better components in their commercial crossovers. .

Well, these days they do, but us DIYers would turn our noses up at the components in most commercial designs. Ferrite coils, cheap caps and ceramic resistors are the order of the day for 99% of the marketplace.

Silvers crossovers are for the column 444 kit; it may be that focal only supply the boards, and the distributor ( or previous owner) populated them.

Anyway, I know I'd want better bits...

 

[hayenc]

Re: Re: PVC Ports

Silvers crossovers are for the column 444 kit; it may be that focal only supply the boards, and the distributor ( or previous owner) populated them.

The documentation is Focal (in French) and the parts drawn in the document look like what is on the board. At least they used reasonable caps for the tweeter. Their 5K313 in the kit is sealed and the tweeter is in the middle.

I intend to try them in the 10V6411 (should have said V earlier, not W--more difficult to make work), 5V323, T90K setup that I just about have finished and see how they compare with the crossover I designed with parts more to a diy's liking. Part of the joy of experimenting is to see how different things sound, bearing in mind their board is for K's and not V's.

 

[BigSmooth]

Years ago (before I knew better) I too tried one of the focal crossovers without have the EXACT same drivers as listed. The speakers worked, but the sound was far from optimal. Please keep in mind, just because you have the same size driver, a V,K or W cone focal have completely different TS params. In many cases, the only thing they have in common is the manufacturer....

If you are going to spend the big $$$ for focal drivers, make sure you don't ruin the project with incorrectly designed crossovers.

 

[hayenc]

I fully appreciate your concerns. As I mentioned I have a correctly designed crossover for the drivers I am using. It may seem unappealing to some, but a lot can be learned from the mismatched crossover in picking out the problems. Sometimes the journey of learning is as important as the final result.

 

[silver00spike]

anyone here want to recommend which brand
components to use in a crossover

 

[BobEllis]

What is your budget? If your pockets are deep enough you can spend hundreds on pure silver inductors and "audiophile grade" capacitors.

Generally, avoid electrolytic capacitors like the plague. If the value required is too large for affordable film caps, at least bypass a non polar electrolytic with a decent film cap. Mylar or polystyrene caps are entry level, go for polypropylene if your budget permits. Some say that film and foil caps are better than metallized film, but they are more expensive.

Use the largest wire gauge air core inductors that you can afford. If you need to skimp, smaller coils will make less difference in the tweeter circuit (assuming parallel crossover) but either way be sure to model the coils DC resistance in your software. You can run inductors in series to get the sum of their inductance (it wil be higher if they are magnetically coupled. Use ferrite or iron core inductors only if the value you need is too large to find in air core.

Personal philosphy: If you need a cored inductor or electrolytic cap, the design is telling you that it wants to be actively crossed over. Actually, I prefer active all the way, but I have plenty of amplifiers.

Use non inductive resistors. Axon and Mills will cost about $4 each, Caddocks are more.

 

[silver00spike]

I wanna spend a max of $300 for the pair. Bigsmooth was nice enough to draw this up for me, and I was wondering if you guys think it looks good, and if it would fit my budget.

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Thanks again to Bigsmooth