Cube Audio Upgrade, Making a 2.1 cube speaker system Options Menu

[H3NRY]

Messing around with the cube speakers, I wondered how much potential the H-K "eyeballs" have. First thing I noticed, they have a resonance around 150 Hz due to the undamped enclosure. So first experiment was to stuff some of my wife's makeup remover cotton rounds into the recesses inside.



That really helped. It looked a bit funky, tho, so next step was to cut some pads from grey felt and put them in.





Now the sound is clean, but thin on the bass. Need a woofer. I had an old IBM/Cambridge Soundworks woofer which had promise, but needed retuning to match the H-Ks. The amp needed to be modded so the headphone jack and speakers are on together - the woofer is to be fed from the headphone jack.








Adding a jumper across the headphone switch pads under the board fixed that. (Red line.)

Now for the woofer itself, I bought a cube enclosure. What better match? Cut a piece of 3/8" plywood to size and covered the top with sticky-back foam. This is the block-off plate for the holes in the top of the cube.



Another square of plywood forms a mounting plate for the driver and amplifier. It's a loose fit, about 3/16" clearance around the edges. Foam weather strip is wrapped around the outside to form a seal and hold the works in by friction.





After testing, it was taken apart and some silver colored paper was added to dress things up a little. Et voila!



I'm afraid the weatherstrip doesn't really hold the woofer plate solidly enough. It vibrates under the pressure of low bass, so next step is to drill holes in the case and screw the plate solidly to the plastic. It sounds very nice with bass extension to 35Hz, and some output below that.

(edit) Refinements:
Added damping pad (carpet) and attached works with 4 screws. The guts had fallen out a couple of times with really low notes! Also moved the woofer's input low-pass filter frequency down 2 octaves. The H-K balls cover a wider frequency range than IBM's multimedia speakers did, so the woofer doesn't need to fill in mid-bass.







This post has been edited by H3NRY: Jun 22 2008, 04:39 PM

[Fangsuede]

Messing around with the cube speakers, I wondered how much potential the H-K "eyeballs" have.

Henry,
You are fun to watch in action

I'm glad a few members of Cubeowner understand electricity, I sure don't.

[H3NRY]

Didja notice the keyboard?

[Fangsuede]

Didja notice the keyboard?

My Panic button is about worn out

[iCube]

Impressive work Henry! I really enjoy close up pics of projects in progress, thanks for posting.

This post has been edited by iCube: Jun 22 2008, 11:14 AM

[MacRob]

great pics. That subwoofer is sooo cool

[Cube Over]

NOW, FINALLY, some people will be right when they see the Cube for the first time and make a remark like "wow, that is one cool sub you have there!"

[H3NRY]

I added a white LED to the amp board, which illuminates the Apple logo. The bassbox design software really works, or I got really lucky. Those 32 ft organ pipes and subterranean synth notes roll forth in glory.

[youfo]

I just found your post while searching the forum for info on Cube speakers. Very cool mod. Tempts me to do something similar with a spare Cube case I have.

Do you have any tips on opening the amp case without damaging it? Were you able to pry it open, or did you have to cut along the seam with a Dremel or other tool?

Any further advice would be appreciated.



This post has been edited by youfo: Feb 20 2009, 09:21 PM

[H3NRY]

Do you have any tips on opening the amp case without damaging it?

I just stuck a knife blade in the seam at one end and pried. Fortunately, it cracked open along the seams. Nothing else particularly secret. As you can see, I cut the speaker wires about 6" from the amp and put RCA jacks on it and RCA plugs on the speakers so I can experiment with other speakers (like SoundSticks) hooked to the Cube amp. I could have made a little circuit to drive the woofer from those jacks, but I'd already taken the amp apart to see what makes it tick, and the Cambridge woofer used a headphone plug for its input. Do note that the speaker leads are both hot, like a car radio - neither one is grounded. It's a BTL circuit.