Overnight Sensations: Build Thread

[WWWJD]

Pics of completed speakers can be seen here:http://techtalk.parts-express.com/sh...d.php?t=213037

Over the course of my build of Paul's Overnight Sensations, I plan to post progress regularly.

Tonight's first order of business? Crossovers. In the original thread, I posted a layout, and I'm quite happy to report that these are probably the smallest crossovers I've ever seen with the component count involved, and I'm kicking myself for not doing this on the Usher 721 build.

I inserted my other bad habit in the picture for scale:


An overhead view showing C3 and C4 tucked inside the large coil:


The green brick is a new chunk of florist foam; it's working wonders. It holds the board and components with full length leads perfectly stationary while the epoxy cures. Another one of those personal victory/"ah-ha" moments.

And one more thing; I don't know how many of you have tried this PC-7 epoxy, but these particular cans have been shelved for about 6 months. The consistency is awesome for component placement; very thick, and extremely sticky, and I'm certain it'll beat hot glue hands down, regardless of surface.


I hope that The build goes well for me, and may prove useful for anyone else in the future that might wanna tackle a fully loaded compact build complete with integrated amplifier. If not... oh well. It's something to do.

[Mark65]

Hey great idea putting (most) everything vertical like that, and the caps inside the coil! I'd be interested to know whether the inductive field has any effect upon the capacitors in the center, or vice versa. Also, I love the florist's foam idea for holding everything in place, VERY imaginative!

Keep the pics coming!!!

Mark

[WWWJD]

I'd be interested to know whether the inductive field has any effect upon the capacitors in the center, or vice versa.

Mark

I'm sure I'll never know the difference. Maybe one of these days when I get around to not cabbaging someone else's design, I'll play around and find out... being lazy for the now.

[Wolf]

I'm sure I'll never know the difference. Maybe one of these days when I get around to not cabbaging someone else's design, I'll play around and find out... being lazy for the now.

It was recently stated in regards to the "new" RB kit, that the central capacitor in an inductor does not have any affect on the inside components.

I always strayed from that, because I feared the worst. Now that I know it's okay, I may be doing that too when I use air-cores.
Later,
Wolf

[williamrschneider]

Out of curiosity, I just measured the inductance of a 1.1mH coil with a couple different capacitors and a 16 ohm 10W resistor running through the core. Almost no difference in measured inductance between the empty core and populated core.

Then I hooked up my signal generator and applied small signal voltages @ 100Hz and 1000Hz across some capacitors and the resistor positioned in the inductor's core - again, no significant difference.

It's not an exhaustive test by any means (i.e. the case when stonger voltages are applied across the caps and resistors, potential for crosstalk), but it's certainly reassuring that the inductance isn't changing.

[tomzarbo]

Mark, those are nifty looking crossovers. Very innovative I think. I will see if I can use that space-saving method on my current project.
It seems like it could be a bit more challenging to lay out, depending on the parts count, but nothing a little thinking won't cure!

Nice.
TomZ

[Paul Carmody]

Mark,
It seems you're quite the pioneer in crossover layout! I'm really impressed how you were able to think so 3-dimensionally about it... I honestly don't know if I could do that.

Bill,
Could you please take a photo of your XO layout as well? I know you split it into two separate boards, which is a good idea as well. I did the whole thing on one 3x6 board (if I remember correctly). Unfortunately, I forgot to take a picture of the layout; no big loss, it wasn't very pretty. Yours, on the other hand seem to always be meticulously laid out, so I'm curious how you did it.

[Wolf]

Out of curiosity, I just measured the inductance of a 1.1mH coil with a couple different capacitors and a 16 ohm 10W resistor running through the core. Almost no difference in measured inductance between the empty core and populated core.

Then I hooked up my signal generator and applied small signal voltages @ 100Hz and 1000Hz across some capacitors and the resistor positioned in the inductor's core - again, no significant difference.

It's not an exhaustive test by any means (i.e. the case when stonger voltages are applied across the caps and resistors, potential for crosstalk), but it's certainly reassuring that the inductance isn't changing.

I was actually more concerned about it the other way around...
The coils' generated field enacting more inductance on the internal components, or changing their values.
Later,
Wolf

[williamrschneider]

I was actually more concerned about it the other way around...
The coils' generated field enacting more inductance on the internal components, or changing their values.
Later,
Wolf

Wolf:
Good thinking, Wolf. I did that test this morning just before work, and didn't think about the effect of the coil on the other components.

I'll leave that bit of research for others though. I've got other fish frying right now.

Paul:
I only started assembling the crossovers last night, so they are still incomplete. I did plan out the crossover layouts on the computer and will indeed split them into the tweeter section and woofer section. I won't clutter WWJD's thread with my photos, so I guess I'll start another thread with my build.

[WWWJD]

My amp kit shipped today; getting excited about that one. In the mean time, I've been thinking more about maximizing the usefulness of these things. The guy that sits next to me in the office has the same taste in music, so I'm planning on having a "community" plug on the front of the amplified cabinet for iPods (mine included). BUT... it's stupid to have these things on the desk, and then have the PC operating on a separate pair of dinky speakers. So on the back, I'm going to put a second second stereo input for PC in.

On the front, I'm going to flush install two of these knobs; one for power and main level, the second shall serve as an input 1 / input 2 mixer knob. Should be pretty cool..



I had originally talked to the guys at work about printing out the cabs, or the baffles; but then they quoted me at $4 per cubic inch of material, which put that idea to rest pretty quick. Instead, I'll exploit them to make a couple of really nice interface plates. One for the back with power, left channel speaker out, and PC in; the other for the front with both of these knobs recessed/flushed into the plate, and a power LED. Post a drawering of that tomorrow hopefully.

Mini update: Tested both crossovers tonight with a mix of Diana Krall and Pantera... not only am I now an emotional train wreck, but have concluded that Paul's crossover design ain't too shabby.. These things are going to have some serious output once they're backed up with a box!

[williamrschneider]

That was fast! That crossover will set the land speed record for "small and quick".

Yours will be a fantastic build with all the features you're adding. I'll be watching your progress enviously while I build ordinary rectangular boxes for mine.

[Paul Carmody]

Mini update: Tested both crossovers tonight with a mix of Diana Krall and Pantera... not only am I now an emotional train wreck

Hahaha. It's all good music! Coincidentally, I've been known to use both artists in voicing my speakers.

[Mark65]

Hahaha. It's all good music! Coincidentally, I've been known to use both artists in voicing my speakers.

Interestingly, I listened to some Pantera yesterday, and made a mental note to never, ever let them near my speakers when voicing. Way too bright and harsh. Seems to me that if you voice your speakers to sound good with that, then just about everything else will sound muddy. I realize that that is their sound, and I like their music a lot, I just feel that it would bias my speakers in the wrong direction. YMMV.

Oh, and I don't have any Diana Krall....what type of music does she play?


Mark

[donparsons]

Oh, and I don't have any Diana Krall....what type of music does she play?

Mark

She's a lot like Pantera...

[Mark65]

I'm listening now on her MySpace page, and you're right, very similar...but the guitars are a little muted

I actually need to get some of this, that's baby makin' music!



Mark

[WWWJD]

Went to a new place called Woodcraft today... I drooled.. an entire corner dedicated to veneer.. so many to choose from. Wow. Tools? I think they've got all of em. I picked up a Jasper circle jig, which surprisingly fit my POS black and decker router. I still have to use my home brew jig for anything larger than 7" or so.. but so be it. Aside from that, I got three sheets of 3mm Baltic Birch Ply for the sides.. total wall thickness will be 9mm; more than enough from the feel of this stuff.

Got the top and bottom plates cut, then the front and rear. Used the Jasper jig to cut out vent holes and got them perfect right out of the box. Good day all in all.







So now I've got to figure out how to bend 3mm plywood around a 7.5" radius. Joy. Love first times. I sense lots of clamping in my near future.

More than likely, I'll wind up kerf cutting that plywood; set the table saw at a 45 and try to go a millimeter or two into the material.. yea. Sounds like a plan.

[Paul Carmody]

I kept staring at that picture wondering how you'd cut the curves so nicely, and why it appeared you'd used a router to do it. Then I saw the pivot holes off to the side; very clever!

And yeah, Woodcraft is a really amazing store. One could spend a lot of money there.

[dbe]

And one more thing; I don't know how many of you have tried this PC-7 epoxy, but these particular cans have been shelved for about 6 months. The consistency is awesome for component placement; very thick, and extremely sticky, and I'm certain it'll beat hot glue hands down, regardless of surface.

PC-7 is great goo! I recently used it to add stiffeners to, and reinforce the basket/magnet junction of, a Fostex FE 206 fullrange. Like you said: consistency is awesome for holding things in place and not responding to the clutches of gravity.

It also drills and taps well.

Dave

[WayneN]

Went to a new place called Woodcraft today... I drooled.. an entire corner dedicated to veneer.. so many to choose from. Wow. Tools? I think they've got all of em. I picked up a Jasper circle jig, which surprisingly fit my POS black and decker router. I still have to use my home brew jig for anything larger than 7" or so.. but so be it. Aside from that, I got three sheets of 3mm Baltic Birch Ply for the sides.. total wall thickness will be 9mm; more than enough from the feel of this stuff.

Got the top and bottom plates cut, then the front and rear. Used the Jasper jig to cut out vent holes and got them perfect right out of the box. Good day all in all.







So now I've got to figure out how to bend 3mm plywood around a 7.5" radius. Joy. Love first times. I sense lots of clamping in my near future.

More than likely, I'll wind up kerf cutting that plywood; set the table saw at a 45 and try to go a millimeter or two into the material.. yea. Sounds like a plan.

Hi Mark,

Nice Work!

I’ve been following both yours and Bill’s builds; it’s amazing to see the difference in cabinet and crossover concepts of the same design. Crossovers to me are complicated enough yours blows me away. With regards to your cabinets, will you be using some form of frame structure or just wrapping the Ply to the Top and Bottom plates?

For clamping you might want to try Ratchet Straps, I believe you would have more holding coverage overall?

We have a place in Canada very similar to Woodcraft, Lee Valley Tools, a hobbyist Paradise

WayneN

[WWWJD]

With regards to your cabinets, will you be using some form of frame structure or just wrapping the Ply to the Top and Bottom plates?


WayneN

I'm hoping that kerfing the ply will relieve some of the headache with bending, while maintaining rigidity in the finished piece; I'll be doing three layers per side, so with the gallon or so of glue it's gonna take to do that, I shouldn't have a problem with stiffness. If the kerfing doesn't work, then I may indeed have to make a third profile piece for the middle of the enclosure to maintain shape under clamping pressure. (eek!)