Speakers for a computer desk against a wall ?

[00940]

I know this kind of thing has been beaten to death but still... any suggestions for DIY speakers under these constraints ?

• the speakers will be used on a table, on both sides of a computer screen. About 70cm between the speakers, at arm's length from the listener. There is a wall just behind the screen so they will be at best 10 cm away from it.
• The room is kinda small, so there's about 3m between the two walls.
• It goes into an apartment, so thunderous bass isn't needed (and probably unwelcome). Still... some extension would be nice.
• Rather 2.0 than 2.1.
• 5" woofer ?
• It's for nearfield listening at reasonable levels so efficiency is of no huge concern. Amps will be lm3886 (40W/8r).
• Either active or passive. There is ample room under the desk for an external amp/crossover. If active, it'd be nice to stay under 2 channels of amplification per speaker (either a 2way or a 3 way with passive crossover between tweeter and mid). But if it's really worth it, I can go to 6 amps.
• If an active crossover is used, it probably will be with jriver and an ESI gigaport HD+. It will only be used on a computer anyway.
• Budget is about 500€/pair for the drivers and enclosures. If it isn't possible to beat a pair of focal shape 40 or the like for this price, it's not really worth it.

 

[Robh3606]

I would go with small active near field monitors and a sub. I use a pair of JBL 4208's and a powered Polk sub with 40 watt JBL/Urei amps driven by an I-Pod and it's damn nice. With the modern powered nearfield system don't see how you can go wrong. Much easier that DIY and probably better performance for the buck.

Rob

 

[chris661]

My small speakers would be perfect here:
Fostex FE126E in a small passive radiator enclosure. Tune as low as you want to go, and then EQ the result. Have 10-20w/ch available, and you're good to go.

FWIW, I got flat to 40Hz with that, but it needed a lot of cone excursion. Fine for sitting at a desk, but wouldn't fill anything bigger than a small room.

Chris

 

[00940]

@ Robh3606: yeah, but where is the fun in that ? Actually, the speakers are for my brother. He gets the speakers and I get the fun to build them.

@ chris661 : I'm a bit reticent to EQ the bass of a 0.35mm xmax speaker... It might be a prejudice but I don't have a lot of confidence in small fullrange under 100hz. A FAST maybe, with something like a pair of SLS-85S25CP04-04.

 

[DPH]

I've been playing with the idea of a waveguide loaded ribbon/planar tweeter coupled to an 5-6.5" driver that is wall mounted. Think wider and thinner than a usual box that could be mounted via a French cleat.

Reason for the ribbon/planer is to reduce vertical dispersion at nearfield since the desk is so close as far as reflections. Getting a woofer to be directional is nigh impossible within the "small" size constraint.

 

[Bicicletta]

If you use a thin wall box, consider where the hole in FR will fall. PE, for a 15 cm long box, you'll have a hole with a 30cm wavelength: 1133Hz. And probably below this frequency, a comb behavior, like this:

 

[chris661]

@ Robh3606: yeah, but where is the fun in that ? Actually, the speakers are for my brother. He gets the speakers and I get the fun to build them.

@ chris661 : I'm a bit reticent to EQ the bass of a 0.35mm xmax speaker... It might be a prejudice but I don't have a lot of confidence in small fullrange under 100hz. A FAST maybe, with something like a pair of SLS-85S25CP04-04.

The Fostex FE series overload very gracefully - you can get to about 10x Xmax before any problems start to show up.

For desktop use, it was fine. Any louder than that, though, and excursion was a problem.

Chris

 

[Cask05]

I'd go another direction entirely...

Why not get some fidelity and headroom without the need for much power? I'd look at a Crites CS-1 with just their woofers ($210USD pair), then put an ESS AMT-1 ($280USD pair) either on top (as a dipole above 800 Hz) or in the box (thus attenuating the AMT's backwave), then use a first order (a single choke and capacitor).

The net sensitivity would be something like 96 db/2.83V, with wonderful headroom/clarity, and a woofer that would allow you to EQ its response down almost an octave since it's a closed box woofer with reasonable xmax and low distortion. They have wonderful close-field response. Build the boxes as small or as large as you like, based on system Fs desired.

You could re-purpose the speakers for parties and other events easily, or let them eventually graduate up to a larger venue later on.

Chris

 

[Cask05]

Some performance plots using an AMT-1 and Cornwall bass bin with first order (EQed flat but no delay needed). You don't need a Cornwall bass bin, but some box size would be necessary to get full 12" woofer extension and fidelity with headroom. You could also decrease the woofer size and box size, but note the increase in modulation distortion and loss of headroom.

(See the red trace below for AMT-1 after break-in and no DSP delay)

 

[00940]

@Chris: that makes a lot more sense then

Still hesitating a bit. Right now, I've been running some sims with the peerless Peerless HDS 5.25" GF and the wavecor TW030WA12 . The idea is to use the woofer with passive radiators in a small enclosure and some EQ. Woofer and tweeter should cross without much problem at 1500hz.

 

[JR_W]

Not exactly what you are looking for, but I used Alpair 7 loaded Frugel Horns as both the speakers and rear legs of a computer desk. Not earthquake bass, but surprisingly more than I expected.

 

[eriksquires]

Have you seen the mini TL kits at Madisound? I've really wanted to try them.



Full Range Speaker Kits: Madisound Speaker Components

 

[jakeshields]

Wouldn't a concentric be ideal for nearfield from an imaging stand point?

 

[00940]

@ JR_W: cool setup. I can hardly ask my brother to cut off his desk but I must admit it's a nice idea if you have the freedom to do so.

@ eriksquires: I must confess I'm not a fan of fullrange drivers, especially in the days of digital crossovers. Why ask one driver to do what two are already struggling to do ?

@ jakeshields : yes, if you can find a good coax driver You're quickly on the path of a 3way with a coax though

 

[chris661]

A little while ago I took the 3" coaxial units out of some Kef egg speakers. They were pretty good.

One of those per side with a 6" mini-sub would be a nice little desktop system capable of useful LF output.

Chris

 

[stretchneck]

Jeff Bagby continuum has to be a consideration... images well when up close to a wall.

Or build yourself a pair of Trenner & Friedl Sun loudspeaker clones, SEAS L12RE/XFC is easy to come by.

Trenner & Friedl Sun loudspeaker | Stereophile.com

 

[00940]

@ stretchneck: those little Trenner & Friedl Sun are gorgeous. Their secret seems to be in the vents though. Maybe not that easy to clone correctly. Not quite sure about early reflections from the desk with such a form factor too.

In theory, my objections to the coax drivers are:
- the shape of the bass speakers isn't necessarily as good as a dedicated waveguide;
- they're fairly expensive for what you get compared to separate drivers (in terms of distortion, FR, bass extension).

But of course, you get point source behavior.

At this point, I'm very tempted by a pair of Seas CA15RLY in a 6l sealed box, paired with either the SB Acoustics SB26STAC-C000-4 or the Wavecor TW30WA11 crossed at about 1.5khz.

 

[mikejennens]

I went very simple, but enjoy my office system quite a bit. I have a pair of Baby Lab Red Eyes and a Drok amp. The speakers are about 8 inches away from the wall.
http://wodendesign.com/downloads/Woden-BabyLabs-241018.pdf

It's quite a compact system, but really does the job for me.
I've included a photo, so don't mind the state of mess on the desk (busy this time of year!).

Another great speaker I've used in a similar situation is the Mark Audio CHP-70 in Planet 10 Slim Classic GRs. Unbelievable sound-stage.
http://frugal-phile.com/boxlib/P10free/CGR-dKal-El703-301113.pdf

Mike

 

[LineSource]

You can get enough box volume for -F3 around 40Hz ported bass by constructing a TALL cabinet for your near-wall on-desk placement. Tang Band has 6.5" and 8" coaxial speakers which mimic a point source for close listening. You can locate the port on the outside panel of each cabinet to reduce garble on the close direct sound path. I would attempt to fit the 8", since I get great sound from a couple TangBand W8.
W8-2314 coaxial
W6-2313 coaxial

READ THIS DIY THREAD for crossover circuits and box volume requirements.
TB new line of Coax FR drivers

W8-2314 - 8” Paper Coaxial Full Range - TB SPEAKER CO., LTD.
W6-2313 - 6.5” Paper Coaxial Full Range - TB SPEAKER CO., LTD.

SUG2-25 - 6.5" 2 Way Coaxial Bookshelf Enclosure Suggestion - TB SPEAKER CO., LTD.

 

[00940]

Thanks for the ideas. I'm going to read that thread with more attention.

Honestly, 8" is really too big. 6.5" is big but might be feasible. I'm still a bit concerned by all the threads about the impact of the woofer excursion on the operation of the tweeter.