Speaker Cabinet Design Question From Hell!

A

AreEss

2[H]4U
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Jul 5, 2005
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Okay, before we get started, if you don't know what a crossover is, you don't belong in this thread. Seriously. This is arguably audiophile stuff. Okay. So it is.Oh well! You've been warned! People will bite your head off if you make silly suggestions like buying Altec-Lansings or Cambridge Sound-used-to-work.

That said, here's the situation. I'm building myself a mildish setup for my computer. Sorta. Kinda.
Yeah. It's over the top. Custom power with two-stage decouple, active filtering, custom amplifiers based on some good reference designs (just putting them onto a single PCB, taking out some 12V higher up, etc.) Active crossovers, the works.
Total freaking overkill. HEY! I'm allowed! :D

Aaaaaaaanyways, I've got ugly space considerations from hell, and I really, really do NOT want to deal with the room acoustics on top of it. In fact, I'm just not going to. (Purists may now feel free to bite me!) It's low-powered near-my-head not-crap speakers, and what they do in the complete soundstage? I don't care! So there.
The soundstage is, simply put, my computer desk. And these speakers need to fit on it. And I kind of have a stupid-large CRT. So I need cabinets that are somewhere in the neighborhood of 4" wide (+-.5"), 5" deep (+-1"), and 12" (+-2") tall.

Soundstage? Well, you've got about 30" between my ears and the speakers.And the speakers sit on the desk which has the keyboard so dispersion thattaway *points down* is kinda who-cares. Same for vertical. I'm going for fairly narrow dispersion overall.

Yep. I suck. Find me some more bad design things. Yeah. I know. Aaaanyways.

The ebil plot largely consisted of 'hey cool, Fostex FT7RP's on sale!' offering 3500-48kHz, backing those with probably Tang-Band low-mids, and a mild woofer. Total power output? Well, not that much. It's 30" from my head. Either way, a nice wide reproduction that I can tweak with the EQ as needed. My hearing is good still; I have low end loss, no high end loss - I can hear up to around 28kHz. (Yay for not suffering the typical high-end loss with aging!) Yes, I'm going to make a point of listening to the speakers first to make sure they're what I want. But, I am fairly committed to ribbons for the highs. They fit the dimensions. They fit the range. They just don't, uhm, like magnets for shielding. And these are less than 6" from a 21" CRT-of-doom.

So, I need help. I need help with cabinet design, to shield and NOT make ribbons sound like utter crap. Anyone out there up to the task?
 
Check out tangband 3" drivers. Would fit quite well in those space limitations. Tack on a tweeter for upper end, and you should be able to get some nice monitors.
 
While I'm not normally a Hi-Vi fan, I'd recommend them over TB for 3" full-rangers: http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=297-428

They will need a little EQ, they're not flat stock. But they sound good.

Try to stick with neodymium drivers and you should be OK. The driver I linked is shielded so it works (though neodymium is still cooler).

Unless you're looking for ultra cheap, a line-array might be good for you. You can get near field and far-field performance using smaller drivers like 3"s + suitable tweeters (and ribbon tweeters actually work pretty well here if they're neodymium).

Or you can try a REAL full-range driver like the CSS FR-125. http://www.creativesound.ca/


Also, disregard AVSForum for this. www.diyaudio.com
 
dandragonrage said:
While I'm not normally a Hi-Vi fan, I'd recommend them over TB for 3" full-rangers: http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=297-428
They will need a little EQ, they're not flat stock. But they sound good.
Click to expand...

Well, as I said, I'm gonna have to listen first. I have weird tastes in performance; I prefer a very flat out-of-the-box response, and spending a stupid large amount of time tweaking it to my tastes. Nothing set in stone yet.. though I'm absurdly disappointed about not being able to shield the FT7RP's properly. Those are absolutely perfect for the crispness I prefer on the highs. (Especially set up for a 4500-5000 entry with a 36-38kHz cutoff.)

Try to stick with neodymium drivers and you should be OK. The driver I linked is shielded so it works (though neodymium is still cooler).
Click to expand...

I'm not too worried about temperatures, because I don't tend to drive my speakers very hard at all. I've never managed to smoke a set. So really, I'm gonna have to listen before I'm totallly sold on neody. Plus I'm worried about sharpness 1200-5000 range, which irritates me a lot. (One of the reasons I don't think I could stand the Davis carbon composites.)

Unless you're looking for ultra cheap, a line-array might be good for you. You can get near field and far-field performance using smaller drivers like 3"s + suitable tweeters (and ribbon tweeters actually work pretty well here if they're neodymium).
Click to expand...

I was actually thinking about just dumping the FT7RP's and 3" wides, and go with double or triple B-G Neo3-PDR's in each satellite. With the backcup, lot less hell in the cab design, and they're already shielded. But, they're wide range planars, so I have my worries about how they're going to actually sound across the range. I've always preferred three-way to two-way, just a matter of personal preference there.

Or you can try a REAL full-range driver like the CSS FR-125.
Click to expand...

I don't like full-range drivers, just personal preference. That's why I'm so leery of the Neo3's. Full-ranges always tend to have one area where they just grate on my nerves. Though this really is nothing in comparison to the utter crap that Creative shoves out the door these days on all fronts, but still rather annoying. ;P
 
While we are talking about full range drivers, aurasound should be mentioned, I think they are still on madisound.com, and I'm too lazy to check.
 
dandragonrage said:
I recommended neodymium because they don't have much stray magnetic field.
Click to expand...

Probably should've mentioned; I'm not overly concerned about stray magnetic field because these are gonna be shielded no matter what. Arguably, I'm going stupid-overkill; everything's shielded. That includes the cabling. (Yes, the cabling will have copper EMI/RFI shield sleeving overtop.) The amount of magnetic, EMI, and RFI noise in here is unbelievable. This is my work area though; it's not uncommon for me to have a dual Opteron with an unshielded mag-drive pump running with open sides.

What I'm thinking about now is a semi-line-array though. I really am gonna have to hear the Neo3's, but basically something like: low-power mid, mid/high power tweeter, low-power mid. The problem is that it introduces all kinds of screwball fun with chambers or porting even if the tweeter's got it's own chamber. (And I may end up doing the 'feh' route and putting all the crossovers in one box.)
 
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