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RE: Four Focal 10K515 woofers, need ideas

Posted by Presto (A) on April 9, 2015 at 23:37:25

In Reply to: Four Focal 10K515 woofers, need ideas posted by 430cruz on April 9, 2015 at 12:48:48:

Neat... NOS Focal woofers!

The three-ways pictured in the other thread are a 'two of a kind' by the way - me and an old pal did a build, one pair for each of us. I had custom laser-cut router templates made for those - that's why the drivers fit so nicely like that. It's a WMTM with a 10V01 polyglass 10" woofs in a sealed box, and two 4" 5K4411's around the TC120TDX2 treated inverted titanium dome tweet. A friend bought them because I was going to DIY butcher them, and he liked them and... "saved them" from my evil DIY operating table. He still has them. They're like new! They need baffle step compensation redone - the mids and highs blend super nice though. I went over there and helped him use equalization to take care of the baffle step issue. He uses them with a sub, and a "one day" project is for me to build him a new sub cabinet with a "house killer" driver to use with his 2000W PA amplifier.)

As for your woofs:

They're screaming to be used with either a nice mid and tweet combo, or as you suggested - as woofer cabinets with a nice 2-way on top, with them filling in the bottom end.

Making a simple 2-woofer cabinet and popping a two-way on top sounds easier than a 2.5 or three way design... but only at first glance. If your two-way has proper baffle step compensation (aka, nice bass and midbass that is not too lean) then what you need is a SUB and not woofers that extend out to almost 2K. It would be a waste (and almost a misapplication) to cross these beauties over at sub frequencies.

I would want to go the WWMT 2.5 way route with a high efficiency mid and tweet, or even a WMTMW. With woofs that sensitive you might want to consider a nice Scan-Speak ring radiator. Those woofs could quite easily mate up with a mid-dome as well.

The problem with those woofers? They are so versatile there is no one right answer. What do you want to build with four capable woofs that extend quite far, are very flat, quite sensitive and have good low-end performance?

WMTMW would be my first choice, but I've never done a 2.5 way WWMT. lol.

Both sound like very challenging and fun projects.

Another route is find a nice two-way that sacrifices low end extension for small size and imaging ability and pop them on top of a dual woofer cabinet. It can be a simple cabinet made into a pseudo-3-way or it can be a 0.5 cabinet made into a 2.5 way. The trick in those cases is crossover work for the 2-way's midwoof. There is only one way, in my mind, to incorporate a low frequency driver using a 2-ways natural low end rolloff, and that would be a sub.

It would be a crime to use these as subs, although you could.

These things are screaming for a proper 2.5 or three way design.

Get 2nd and 3rd and 4th opinions! ;)

If you're a competent DIYer, you can go for that, or you can put them in a simple ported box and get the rolling with a 2-way on top using a standalone active or even PC/Mac-based DSP crossover.

Here is a more current design I am toying with... an old pic from a earlier stage in development. (They're all black now... and have different woofers...)

These now have Seas ER18RNX 8 ohm woofs instead of the Dayton metal cone woofs. Truth be known, the Seas woofs have a rise in the response that needs to be dealt with, but these are indeed some hi-fi sounding woofs. The mids are vintage Vifa MG10MD09-08 near full-range fiberglass cone, and they are truncated (by me) on the tweeter side only. The tweets are Vifa D26NC55-06 and sound very good for a small format neo tweet. ATC was using a similar tweeter in some of their best studio monitors. I think they changed to larger tweeters because many 'philes protested the existence of such an inexpensive drive unit next to their famous 3" mid dome drivers costing thousands alone. Crossover is all PC/DSP based and I play digital audio files right off the hard drive into the crossover/player into 6.1 channels (3-way stereo plus sub). They sound pretty good, and whatever "voicing" (equalization) I can dream up I can make happen. They're actually very flexible, but I've nailed down all of the sweet spots over the years. I have them dialed in and mostly just listen now. Fun experiments include switching from FIR based to phase-corrected IIR based crossovers... in seconds, and listening for differences! ;) Try that with passive boxes, right?!

Note the Cheap MTX car sub in the cheap slant enclosure (ran by a parts express plate amp) in the corner. I've used woofers costing ten times the price and often I still miss the tuneful and tight bass of that driver. It was perfect in an equalized sealed box, and if not driven beyond it's excursion limits could provide ample bass without pushing the 200W plate amp at all. Amazing little woofer. Not "super x max high output" but definitely a hidden gem. I now use a much better built and serious looking Peerless 12" drive in a sealed box with a newer plate amp, also with equalization. More authority, but truth be told I often miss that little paper cone 12. Either way, the bass vanishes. You can't tell the sub is on, crossed over at 60Hz at 24db/octave. Integrating subs is rather easy when used properly, within their range, with an adequately steep slope...

It's really all a bunch of junk... but what's amazing is how darned good it sounds considering there are no components there (audio wise) that are audiophile grade and the drive units used are good but not spectacular. It's all about integration and years of endless tweaking and experimenting. I like experimenting about as much as listening, so I do a bit of each... I have listening months, then experimenting months.

Cheers,
Presto

Edits: 04/09/15 04/09/15 04/09/15

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