Design a Bose-beater

[Variac]

So it seems that you need to aim for 100hz in order to fix the greatest problem with the bozzzze and get the better quality you are looking for.
I guess that means the very attractive HiVi (i suggest the ones with the round frame. )
I think you will need aperiodic loading and some serious equalization on the lower end, but because it is to be played at low volume this willl probably work, right ? anyone?

[Variac]

heres the new mini MOX active crossover thread. Might be helpful to get everything crossed over.

May I suggest thoose Speakon speaker connectors from Neutric to make hooking up the Sat speakers foolproof.

[sfx]

Just read the entire thread with a lot of interest, and now I think I have to throw in my 5 cents.

I think Variac's suggestion to use a Linkwitz transform is a good way to go. First, it's a trick that imho BÖSE doesn't use, and it helps to decrease volume without sacrificing LF response.

there is a project by Elliott Sound Products, that might be of some interest: click here
It's meant to be a HiFi - PC speaker system. The satellites are rather small, but not quite as small as requested (27x12x14 cm, or 10.6 inch x... ahh, do it yourself ), and the sealed subwoofer uses Linkwitz transform. It is 22 liters (/28, less than a cubic foot for imperialists...), and goes down to 30 Hz and below. The project also includes the amplifiers with 2x50 Watts and 150 Watts for the sub.

Now here's my suggestion: make the satellites a bit smaller, and use also Linkwitz transform on them to get them down to 100 Hz, and roll off below to avoid distortion. The high frequency response should remain untouched by this. For the sub, if 22 liters is too large, make it smaller, and either increase the power to achieve the same LF response (since it's only for low volumes anyway, a speaker with reasonable excursion would do). Or scrap the 30Hz and live happily with 45-50 Hz lower end. I'd prefer the low bass though - 30Hz is still better than most commercial much larger subs, and 22 liters is manageable.

I used the linkwitz transform circuit on my (much larger) 65 liter 12" subwoofer. Resonance for the sealed box is around 50 Hz - with that little trick, it now extends my system down to 15 Hz (-6db). Crossover is 40 hz, since my (also much larger ) 4-way speakers go down to 30 Hz already. The point is, Linkwitz's trick really does magic, and you get a much more responsive and much lower bass than with ported designs. For people who don't know what it is, here's the short version: Use a sealed box, and electronically compensate the predictable rolloff below resonance, to extend the bottom end. This is not just bass boost - the compensation has to be matched to the speaker. Downside is, you need more power, but, hey, chipamps are really cheap and small. You could even use a UcD400 Class D module, the 90% efficiency would make up for it, they have 400 Watts RMS, cost 100 Euro, and outperform many high end amps easily.

The amplifiers could go into the subwoofer, with a suitable heatsink as the back side. I'm not totally sure how linkwitz transform works on a 2-way satellite. Could be ok - the tweeter wouldn't really notice the extension of the bottom end. Opinions?

[Variac]

Well, I always like posts that generally agree with me!- even if I don't know what I'm doing . I was also proposing using the LT on the sats- my question was whether it works with aperiodic enclosures. I don't think it matters. I hadn't really gotten to the sub as Dave seems pretty clear on that. The ESP link is REALLY going to be useful!

Obviously the sats need to have enough excursion to handle the boost, and more area than a 2" driver, which is why I thought the HiVi drivers might be best.

Yes, one thing we have enough of is power - relatively speaking.
the LT will increase their power consumption a lot as well as their excursion. If the sats are using average of less than a watt, then they will possibly be getting their max power of about 15 watts

Now here's my suggestion: make the satellites a bit smaller, and use also Linkwitz transform on them to get them down to 100 Hz, and roll off below to avoid distortion. The high frequency response should remain untouched by this.

That sums it up IMHO

As Dave mentioned, the sub is more familier territory so we haven't really discussed it. Probably sealed with LT is the way to go.
45-50 hz really is fine, lower is fine too , but not essential as sfx mentions. Here's the ESP (Elliott) link for that and also explains LT for use in the sats.

http://sound.westhost.com/project71.htm

[Hezz]

Dave,

Today I saw some computer speakers a Circuit City that were really well designed and small. When I turned them on I was amazed at how good they sounded in relation to the other computer speakers. I think they were an exellent design. About as tall as the Bose satellites but only about two inches wide and 3.5 inches deep. They had two I inch wide range speakers mounted vertically at the top of the enclosure and one side firing 2 inch driver near the bottom. Coupled to the six inch subwoofer the combination was much better than you would expect from such small speakers.

I think you could use this topology and widen the speaker a little and make it more deep. Say four inches wide and five inches deep. You might even be able to add a little height as this gives the cabinet a more artistic look. They look much better than the Bose sattelites. Then you could use 1 two inch upper driver or two 1 inch drivers and a side firing 3 or 4 inch driver to supplement the bass.

With a well made rigid cabinet you should be able to get good sound down to at least 150 Hz and maybe lower to 100 Hz.

As you said the subwoofer is the easy part in this build. I will model a solid mockup to see if you like the idea.

Hezz

[sfx]

Originally posted by Variac
As Dave mentioned, the sub is more familier territory so we haven't really discussed it. Probably sealed with LT is the way to go.
45-50 hz really is fine, lower is fine too , but not essential as sfx mentions. Here's the ESP (Elliott) link for that and also explains LT for use in the sats.

I agree that the satellites are the tricky bit, but I disagree that the subwoofer is trivial - unless you want a 50-100Hz "subwoofer" (or rather 'boom generator'?) like in the BÖSE system, which doesn't deserve the name. I haven't seen a single commercial small subwoofer (up to 40 liters) yet, that satisfied me. They usually deliver a lot of "punch" at their resonance frequency, which usually dominates, but don't really go low, rarely 35Hz, and produce heaps of distortion and wind noise. Yes, it will boom, rattle and shake the floor, but that's not really HiFi reproduction.

Actually, I do think 30 Hz low end is quite essential - for me full range is still 20Hz to 20kHz - but I'm aware that many people think differently (expressed by the fact that most home theater subs roll of at 40 Hz. Even my main speakers go much lower than this...). Even worse, now after I built my own sub, I really got used to 16Hz bottom end. The extra octave down low is really noticeable. But that's hardly doable with a small system like this. 30Hz is doable, though, yet imho only with LT in sealed box. Vented 30Hz subs are huge.

It's possible to go even lower with a tiny sub, it's expensive though... I've once seen a design here using a rather tiny hexagon shaped enclosure with 12 (2 per side) Dynaudio woofers, and 1600 Watts amplification - also a way to do it. The sub can be even smaller (I don't think it was much more than 20 liters), and the membrane area is maximised by using several drivers. 12 is overkill, but maybe 2 or 4 woofers, perhaps a little cube with a speaker on each side? The only remaining problem is finding suitable small subwoofers, which won't distort (3rd harmonic) at low frequencies, and still have enough excursion (>5mm) and power handling capabilities (preferably >100Watt RMS). It's not about loudness here, but we'll need the extra power to extend the bass response low enough, due to the small size.

I'm looking forward to hearing about first results I was planning to build myself a small 'portable' system some day, that is able to surprise people...

[Hezz]

Dave here is a picture of those speakers,

Not highend sounding but pretty good for computer speakers in the tiny category. A slightly enlarged version might sound pretty good.

1 inch tweeter, two inch midrange and three or four inch side firing midbass driver.

Hezz

[dastardly]

Yeah, I know this thread has been dead for a week, but I was out of town.

It is a little bigger than 8"x8"x8", but may have the power handling to take the lowend boost for good extension.

A 10" Dayton titanic MKIII in a 0.4cuft sealed box with an amp that can give about 6db boost at 30Hz? I am not sure what amplifier boost curves look like so that boost number may be off. I though maybe an 12x12"x10" 3/4" stock. (12"x12"x8" + 2" depth for driver and amp volume?)

Don

[Czilla9000]

If you are willing to go non-DIY (which I realize you probably aren't) , I think I found the perfect solution. (Please read before discrediting)


I would try the Mirage NanoSat system.

The satellites are almost exactly the same size as the Bose (they are actually less tall) and they go much deeper. They also have a unique curvy design that I am guessing makes them look smaller than Bose. The subwoofer is the size you are talking about, and the system response is 30-20,000 Hz.

Best of all, they have some sort of technology that is supposed to completely emerse the room with a wall of sound due to some baazar driver angle placing. From the reviews I have read, the effect works as claimed. The sweet spot is also supposed to be HUGE, which is good if your girlfriend is walking around the studio while working.

The 'OMNIPOLAR' (as they call it) effect is supposed to be very blatant. In all honesty, your girlfriend would probably notice the special effect of the Mirage system more than the raw fidelity of the your DIY system. Mirage is also respectable among audiophiles, so there would be no shame in it. The fidelity of the Mirage system is also good from what I have read.

While I think that this is an excellent theoretical excerise in DIY audio design, I think the Mirage system would win her over more due to the blatant omnipolar effect which cannot be DIYed (can it?). It might also alert her to the differences in how speakers can sound, which might make her more open to larger DIYed speakers in the future.

Here is a review of the system:

http://miragespeakers.com/PDFs/curre...OSATreview.pdf

[Variac]

How could we have forgotten these- they got great reviews in the mags:

http://www.acousticenergydirect.com/aego.htm

At one time they were available in stereo but now seem to be only available in a HT config for around $600

Its hard to get an idea of their size from the photos, but I've seen them and they are TINY.