Statement External X-Over?

[bigjohn]

My plan this fall is to build a pair of full size statements and while pondering a problem at work I came up with an idea for an external X-over and wanted to know if its a stupid idea or somewhat feasible.

So here it is; instead of building just a plain external box for the x-over i want to make it look like a piece of equipment i.e. an emotiva UPA-1 amp, complete with a cooling fan, indication light on the front and maybe even an analog VU meter. this would be powered by transformer which would be controlled by a relay which would be triggered in the same fashion as an amplifier.

my concerns are that the transformer has the potential to cause EM interference, and that this isnt as simple as i am initially thinking it will be.

What do ya'all think?

[engr_dave]

I like your idea of external crossover. I have done this in the past. No space constraints, easily accessible - makes repair or tweaking the XO easy, reduced likelihood of vibration-induced failures, etc. Also nothing wrong with putting it in an "amp-like" chassis.

As far as interference, you can use a shielded transformer like this

and you shouldn't have any interference issues. If you are concerned, you could use a wall wart and feed DC to the chassis.

A fan, IMHO, is a bad idea. The crossover doesn't need a fan. It won't work any better with a fan. So you will just be adding noise to your listening space. And the fan has just as much potential for generating electrical interference as the transformer.

Also a analog VU meter isn't as straightforward as you might think. VU meters are logarithmic, as they must be for audio signals. Panel meters are typically linear, so you'll need a circuit to convert the signal. I think you can "fudge" it with some passive components and the right meter movement, as Radio Shack did with their "APM-100" outboard stereo audio power meter in the 1980s.

If it were me (and I'm as much of a tinkerer as the next geek) I'd build or buy a nice "amp-looking" chassis, put some LED's on the front panel and just power them from the 12v trigger. They won't draw enough power to bother your system's trigger. Simple. Silent. Cool-looking.

[impala454]

Cool idea. Might be pretty slick (although pricey) to use some neutrik speakon connectors from the box to the speaker itself.

[cbark]

+1 engr_dave

[Face]

Cool idea. Might be pretty slick (although pricey) to use some neutrik speakon connectors from the box to the speaker itself.

+1

Their 8 pole connectors would be perfect for the Statement.

IMO, I would build a pair of matching cabinets to house the crossovers and place them behind or beside the speakers.

[alteredbeast77]

i was thinking of using something like this for my 4t build http://www.alliedelec.com/search/pro...px?SKU=2780300

[bigjohn]

Thank you for all the replies!

Engr_dave

I agree about the fan, it was more of a I have the room why not idea, and now i know why not to.

my original idea was just to power the lights off of the trigger source, but I'll need to do some current measurements to make sure the added LED's dont overload my pre-amp, if they do then I'll just add a shielded transformer.

I found an old Phase -Linear 400 at a garage sale for a steal, but it has a broken VU meter, in looking into a replacement i found a few places that sell the log calibrated ones, from my initial research it doesnt seem that involved to add one with a few passive components, but we'll see.

Impala454

the Seakon connectors are perfect for this build, and i have access to some sleeving so i can make custom harnesses that go from the x-over to the speakers. I know this isnt going to be the cheapest way to go but thats not the driving factor though its a close third.

Face

I thought about building smaller boxes that would go near the speakers, but the space factor has basically eliminated that, the way my room is situated where they will go is in front of my record storage and equipment rack, also i am building a new rack that will have plenty of room, 48'' wide by 72'' high,

[evilskillit]

Yeah this is really cool the only issue is increased cost. The cost of 8 pairs of binding posts per speaker, 8 runs of wire and the cost of the chassis for the crossover. But if none of that bothers you then go for it, it'll look sweet.

[impala454]

Another thought is if you're going to build it into an "amp like" box, you might as well put both XOs in the same box? IMHO that'd be even cleaner looking than two separate boxes. I wouldn't know about the electrical aspects of doing that though and whether it would introduce any interference. My guess would be no but perhaps someone else can chime in (Curt C?)

[Face]

Yeah this is really cool the only issue is increased cost. The cost of 8 pairs of binding posts per speaker, 8 runs of wire and the cost of the chassis for the crossover. But if none of that bothers you then go for it, it'll look sweet.

Where are you getting 8 binding posts from?

http://www.neutrikusa.com/fl/en/audio/210_93741/NL8FC_detailtechnical.aspx?title=NL8FC

http://www.neutrikusa.com/fl/en/audio/210_1107119658/NL8MD-V-BAG_detail.aspx

Cheaper than a quality pair of binding posts.

[Face]

Another thought is if you're going to build it into an "amp like" box, you might as well put both XOs in the same box? IMHO that'd be even cleaner looking than two separate boxes. I wouldn't know about the electrical aspects of doing that though and whether it would introduce any interference. My guess would be no but perhaps someone else can chime in (Curt C?)

Two crossovers in the same box wouldn't be an issue, mounting them in a metal box may be though.

[Curt C]

I think the idea is fine in principal, and there is no reason why both crossover shouldn't be in the same box. Just keep the inductor spacing appropriate. There are a couple of things to consider however:

A metal box would be OK, as long as it is not steel. Ferrous materials close to the inductors can substantially change their nominal values. A wood box with an Aluminum face plate might be good compromise of aesthetics and cost. -In the 'golden days' our amplifiers/receivers were considered like furniture, and many came with wood enclosures. -Although most all were fake walnut over particle board, some were real wood veneer...

All power stuff to drive ancillary items included in the box should be shielded. An aluminum 'bud box' would be good to reduce the RFI emissions, as well as good wire run management.

Passive power indications will have to be high impedance and primarily resistive in nature or the amplifier may be adversely loaded.

Hopefully I'm of some help here. Thanks Chuck for pointing out the thread! I've been a bit overwhelmed at work and home lately, with little time to frequent the forums...

C

[impala454]

No prob Curt, I know you're the Statements XO guru so figured you might have some good input

I'm really interested to see how this build turns out!

[bigjohn]

Thank you for the feedback Face, Curt and Chuck,

I hadn't considered the one box idea yet, but that would definitely cut down on the amount of work to be done.

I think my plan will be to use wood for the box and maybe get aluminum face plate CNC'd, I'll look into the passive VU meter circuits and see if i can find one that will work otherwise I'll stick with simple indication lights.

I'll post some pics when it gets all done, I got 2 projects ahead of this one though (new rack, and a sub build) so it could be awhile

[Face]

Just buy a McIntosh amp, problem solved.