2.1 Computer/Desktop Speaker Design

[pirate121]

Hi all,
I'm designing some new computer speakers and was wondering if you had any thoughts/suggestions.
The speakers will primarily be for rock music, so I want it to be punchy and energetic, so "coloured".
It's a 2.1 system:
Satellite: Sealed ~3L
Tweeter = Aurasound NT1 (Aurasound NT1-204-8D 3/4" Titanium Dome Tweeter)
Mid = 2 x Fountek FR88EX 3" in parallel Fountek FR88EX 3" Full Range

Subwoofer at feet: Sealed
Subwoofer = 2x Peerless SLS 8" Cones Peerless SLS 830667, 8" Paper Cone Woofer in parallel compound. Pretty much doing parallel compound for fun.


Driver choice seem OK? Needs to be from the vendor Madisound. I'll use the madisound crossover service for the tweeter/mid satellites when I've figured out what drivers I want to use. Can't go any higher than 3" mids as they'll make the desktop speakers too big.
Current amp for use: Stereo = Microlab 35RMS per channel. Both the fountek and the aurasound have a power handling of 15RMS. Sensitivity of aurasound is 88.5 dB (1W/1m) and the fountek is 84.4 (+3 for parallel?) = 87.4 dB.
Sorry for the following noob questions, but is this OK? 15rms rated power handling seems a little low, will I be disappointed? Or is the sensitivity good enough? It's not going to be for partys, but I like cranking music every now and then. Also, in regards to the amp's 35RMS per channel, how is that used by the drivers? Is this cumulative? As in having 2 drivers rated at 15RMS each in one satellite can take 30RMS from an amp? Please explain!
Don't really need to worry about the subwoofer, it's somewhat of an overkill and I have a decent sub amp to go with it.
It's a 2.1 system so lower end should be fine as it's covered by the subwoofers. Although I'm wondering about the tweeter. For rock sound you generally have a louder low and high end with a subdued midrange. With the sub I can change it as I please, however, I was wondering if I should increase the SPL of the tweeter to match this "rock" sound? What do you think? Can I just mess around with the crossover post set up and adjust it to my tastes? Or should I get a more sensitive tweeter (Horn?) or just leave it to the computer equalizer?
Sorry for the barrage of questions,
Answer what you can!
Thanks,
Andrew

[BobEllis]

Driver choice seems reasonable for computer desk use. Even with a pair of mids don't expect to get terribly loud cleanly unless you cross to the sub very high.

The 15W driver rating is it's thermal limit. Yes, theoretically you can handle 30W per satellite, but depending on frequency and box design you may run out of linear excursion long before you get to 30W.

I've been thinking of doing something similar starting with Zaph's B3S project and some buyout tweeters. Zaph|Audio Good information about integrating a 3" and a sub.

You might consider putting the woofers in separate enclosures on ore near each end of the desk running stereo, sort of an M/T with bass bins setup. That would allow you to cross higher and therefore get louder on occasion.

[sdclc126]

It doesn't look like you'll need a tweeter at all with the Fountek - seems redundant - the small 3" woofers are really mid-high drivers that cover the tweeter range by themselves.

[planet10]

I'm with sdclc on the need for a tweeter. It (and the XO) will probably subtract more than it adds.

dave

[BobEllis]

Try it both ways - for a few bucks in tweeter and parts it's worth seeing which you prefer. My Zaph B3S project sounds a little fuzzy on top (compared to an RS150/27TDFC active), which makes me want to try a tweeter. I've never been a full range aficionado like Dave, so YMMV.

[preiter]

How are you planning to cross the sub with the satellites?

[sreten]

Hi,

See Fountek info here : Zaph|Audio

TBH I think you only need one Fountek per channel for nearfield.
For farfield possibly a 2.5 way system might be easier.

rgds, sreten.

http://sites.google.com/site/undefinition/diy
http://www.zaphaudio.com
http://www.rjbaudio.com/Audiofiles/FRDtools.html
http://www.rjbaudio.com/
http://speakerdesignworks.com/
http://www.htguide.com/forum/showthread.php4?t=28655
http://www.humblehomemadehifi.com
http://www.troelsgravesen.dk/
http://www.quarter-wave.com/
http://www.frugal-horn.com/
http://www.linkwitzlab.com/
http://www.musicanddesign.com/

[pirate121]

Hi, Thanks for the replies.
BobEllis: Yeah I've read most of Zaph's things, including the B3S. Basing a lot of my stuff on it. With the two subwoofer boxes, it's a good idea, not really what I want for this though, I want to try compound . Also, if location is a problem I'll just centre it. So larger box, larger linear excursion?

The driver choice of the fountek was based off of Zaph's small driver round up as previously posted (Zaph|Audio). He recommended adding a small cheap tweeter because the top end was a little ragged.
I agree I don't need two Founteks per channel, but it does increase the SPL to the tweeter (even though now I don't know if I want that :P) but it also makes it look cooler . It's going to be a small tower configuration so the tweeter will be at ear level. And it will mostly be nearfield.

I've got a reckhorn A-402 at home that I want to use as the bass amp. It has variable satellite low cut off and sub high cut so I can mess around with that to get what I like.

Thanks for the help,
Andrew