Speaker enclosure dimension

[Dr.EM]

I'm interested in putting one of these drivers into a suitable sealed enclosure to form a test speaker and eventually perhaps a satellite speaker for a PC soundset;

**broken link removed**

I want to do it properly, so am using this to calculate the enclosure volume (top calc):

http://www.mhsoft.nl/spk_calc.asp

And come up with Vb -.157L (they are all negative for some reason?), fc 153Hz. Qtc isn't listed so this is using thier 0.707 number.

Anyhow, assuming that is the correct volume, I just can't seem to figure out the dimensions from it. A litre is 10cmx10cm, so if I wanted the front of the case to be 5cm accross, how would I calculate the depth for it? I keep thinking of under 2cm, which can't be right.

 

[audioguru]

It is a cheap, tiny little earphone, not a speaker.
Its resonance is 320Hz so don't expect to get any bass from it.
It isn't very sensitive (only 81dB for the mid-range frequencies) and its power rating is very low.
Its upper frequencies are much more sensitive creating poor frequency balance.
The manufacturer's frequency response curve doesn't mention the size of the test enclosure so the curve is meaningless.
I haven't seen software for designing an enclosure for a tiny satellite speaker.

 

[Dr.EM]

I was partially waiting for that answer

I'm aware of what you've said, I just thought it might be a little challenge to get a decent response from one. Sort of an experiment with case design/build without spedning lots of money on materials. As a test speaker (I have one, a coaxial car speaker in a poorly built case, but it's big and awkward for general use) I think it might be respectable; and coupled with a "sub" should sound better than many PC speaker systems available. I suspect the drivers they use are worse and the cases are undamped plastic boxes, quite probably not even the right size.

I can sort of visualise 0.157L in terms of if I took a 1L plastic bottle and cut 15.7 percent of it away, that would be the size; but I can't figure out the maths

 

[audioguru]

It has the bass response of a telephone: none!
Its response doesn't go low enough to be used with a sub-woofer.
Its high frequencies will shriek at you.
That is the opposite to a decent response.

 

[Dr.EM]

Ok, ok! I won't bother, lol

How do you go about working out dimensions from the Litre's though? In the case you know the size of baffle you want, and need fo figure out the depth?

I'm sure these must use something similar, looking at the size of the satellites, and they have recognition from what Hi-Fi and are generally regarded as the best 2.1 PC speakers available. What makes them sound so good (I know were not talking hi-fi here, but in PC speaker terms), I see they have metal enclosures;

**broken link removed**

The Visaton make seems to make some very high quality units too, hadn't really heard of them before.

 

[audioguru]

I clicked on the link of the speaker system that uses two of those tiny Visaton mid-range speakers. It is a tiny speaker system the size of a small book with a tiny "woofer" that doesn't go low enough and a tiny tweeter. People buy that junk??

I looked at the Technical Specifications for the Aego speaker system. It doesn't have any spec's.

 

[Dr.EM]

I think it's just a design you can follow. For the application of PC speakers I expect they are better than many of the systems available. Some of thier high end drivers look nice.

The Aego's are interesting. I never found specs for them either, but to be honest, I quite like that point. Most PC speaker sets have some baloney specs anyway. My brothers current set (he doesn't like them at all, I agree the sound quality is terrible) quote 72W RMS total power output. The power adapter is labelled 13.5vac, 5A. So what does that mean really; even if it were real, it is pretty irrelevant without knowing the sensitivity of the speakers. I think with the Aego set, they just let the sound and reviews speak for themselves rather than either making up stupid specs or putting the real ones on and people thinking the are underpowered.

The reviews I've seen everywhere of them are very complementary, from owners of them on another forum I'm on, and from magazines. My brother wants to change his. I suggested a set of small bookshelf speakers for which i'd build him one of my little amplifiers, but he thinks even small Hi-Fi speakers will look too big on the desk, so he may well end up going with these Aego ones. We're both pretty critical of the sound, so if he does, i'll do an honest review myself.

 

[audioguru]

Hi Dr. EM,
Go to www.diyaudio.com and look at the Fullrange forum. Guys are making speakers with 8cm and 10cm little drivers with a cabinet big enough so they produce good mid-bass. There is a new Chinese (Taiwan?) driver that most guys like and these drivers are much more sensitive than the one you found.

There is an American stereo company called Bose that have some pretty expensive two satellite speakers and a little subwoofer systems with built-in amp including EQ. They don't have deep bass and don't have the upper highs but sell by the millions. Google has topics called "Bose-bashing" about their defficiencies. They are made from junk.

 

[Dr.EM]

Yeah, making full range systems with one driver is popular among DIY builders. It is supposed to avoid peaks at the crossover frequencies or something. Horns are also popular and can produce very high sensitivity speakers. I would like to build some but don't know the maths or have much skill/tools for wood cutting.

I've seen all the Bose slating yeah. They are massively overpriced as they seem to be very similar construction to PC sound sets which retail at a 10th of the price. Big movies do require big speakers imo, I quite like seeing them anyway, rather than hiding them away. It inspires more confidence in the system . You could buy a very nice system for the cost of one of those Bose acoustimass/lifestyle sets, especially if you bought it all second hand.

I remember seeing a project where someone built a horn subwoofer into the ground out of concrete etc. It used 12 18" drivers I think, and achieved dangerous output with 6W of power. Can't find the link now, but will look for it

 

[audioguru]

I attended a Bose demonstration at a fair. I was amazed how good and loud it sounded. Then two pretty ladies removed the "big speaker" covers over the tiny satellite speakers and it made my hair stand up! They must have EQ'd the heck out of that system and hid many more speakers somewhere.

 

[Nigel Goodwin]

I attended a Bose demonstration at a fair. I was amazed how good and loud it sounded. Then two pretty ladies removed the "big speaker" covers over the tiny satellite speakers and it made my hair stand up! They must have EQ'd the heck out of that system and hid many more speakers somewhere.

It's the sub-woofer that handles all the power, the main speakers only handle mids and highs, so have no need to be large - plus you only need one sub-woofer, there's no stereo information at low frequencies (or at least your ears can't hear it).

A guy who used to work with me had a theatre sound system, with small satellites, but the sub-woofer was also a glass topped coffee table, so you didn't notice it was there - apart from your coffee jumping up and down!

 

[audioguru]

It's the sub-woofer that handles all the power, the main speakers only handle mids and highs, so have no need to be large

My home speakers have pretty powerful tweeters and I have worked with tweeters that are much more powerful than the cheap little satellite speaker drivers used in home Bose systems.
For the demonstration of their satellite speaker system that I attended I think they hid some real speakers from their professional series that are used in stadiums. The sound was from all around, not just from the two little satellites.

 

[olivergw]

I attended a Bose demonstration at a fair. I was amazed how good and loud it sounded. Then two pretty ladies removed the "big speaker" covers over the tiny satellite speakers and it made my hair stand up! They must have EQ'd the heck out of that system and hid many more speakers somewhere.

Thats because Bose use transmission line technology, essentially a small in diameter pipe, but very long, i have a bose wave system at home, the diameter of the speakers is about 6cm, and there are 2 but it has 30 inchs of solid tubing, for each speaker weaving about inside the box which creates the bass range, there is no need for a subwoofer, it is basic physics, but very difficult to tune the transmission line to create the deep sounds and get it in a small box, hence the large price tag,

 

[Dr.EM]

It's the sub-woofer that handles all the power, the main speakers only handle mids and highs, so have no need to be large - plus you only need one sub-woofer, there's no stereo information at low frequencies (or at least your ears can't hear it).

Thats the theory yeah. A lot of the time now, subwoofer simply means woofer. A proper one is just designed for what the actual speakers can't handle (sub 40Hz or so). Some are effective down to 14Hz, but are very expensive.

I still think you can tell where bass is coming from though. I know music doesn't place it anywhere, and film soundtracks probably don't either, but I made stereo recordings of rain and at one point, and a bus parked for a while outside making a very low frequency sound. When played back, even on speakers, it sounds like it's at the side of the house where it was in the recording; where as in mono this doesn't happen.

 

[audioguru]

The "low frequency" sound from the bus probably had some higher frequencies for you to hear its direction.
I like stereo subwoofers because some low frequency sounds are out-of-phase when in stereo but are cancelled when in mono.

 

[Dr.EM]

I find this interesting. It is the reccomended design for a Fostex driver:

https://www.fostexinternational.com/docs/speaker_comp/pdf/recom_enclose/206e_enclrev.pdf

It seems quite an elaborate design, but looking at the frequency response graph it doesn't seem very flat at all, or have very low extension? How would something like that sound; how much "wobble"needs to be in the response graph so it becomes noticeable/distracting? I'd like to see a response for my own speakers since I know how they sound, but have never found one.

 

[Nigel Goodwin]

Looks pretty horrible!, it's a very crude representation of a horn! - obviously to make it simple to build, but this will comprimise performance considerably. Most folded horns are a comprimise, but that's probably the poorest I've seen.

I wouldn't get too carried away chasing horn designs, far simpler bass reflex designs can give pretty impressive performance, and efficiency isn't too much of a worry with high powered drivers and cheap amps.

 

[audioguru]

I think the frequency response of the fairly cheap, low power, 8" (20cm) FE206E speaker with wizzer cone is pretty good. The curve is valid only on-axis since the wizzer cone beams the high frequencies straight forward. Sharp peaks or dips in the response might have been smoothed out.

If the treble tone control is turned down slightly, its frequency response is plus and minus only 4dB from 52Hz to 17kHz. Very good speakers deviate 3dB.

The folded horn enclosure would be a nightmare to make, wouldn't it?

 

[Dr.EM]

Yeah, it covers the range quite well for a single driver, just doesn't seem awfully flat about doing it.

There are some nice horn designs over at that diyaudio site. They have made curved ones with special bendy board and then presumably smoothed it all with sawdust and resin mixture.

Here is a nice horn, however it is a bit different. It is apparently sealed end and transmission line of some sort rather than one with an opening. It's purpose seems more to extend low end (at 25hz it does a good job too). Oddly, it uses 4 drivers. Don't look for the price tag

**broken link removed**

 

[audioguru]

I have laughed at the odd-looking B+W speakers for many years. Some people like them.