looking to build a high efficency, small speaker.

[demogorgon]

Originally posted by VvvvvV
Small full range drivers on modern micro hi-fi's sound pretty amazing, especially in the midrange. gets a really good 5" full range. I would be tempted at doing some kind of foldaway design.


You might even consider a micro transmission line with something so small like that all the efficiency is transferred into bass . Perhaps you could use some PVC gas pipe because it sounds a lot better than wood with something that size.


You could even buy a malfunctional micro hi-fi online and just keep the speakers and the amplifiers and turn it into a micro transmission line.

Wouldn't the line in a TL have to be 1\4 of the resonant frequency of the driver? to be honest, i have considerd TL a lot, but always i have come to the conclution that's it's out of my reach, Kings papers on the TL design theory's could very well be writen in urdu for all i understand of it

Foldaway?

Good idea trying to find some ready made stuff though, as my standards for this system isn't to high, but then there's the problem of finding thiele small parameters.

-Marius

[Richard Chiang]

I am trying to build a magnetizer for my speaker project. I need help on designing coils. Can anyone pointed me to the right direction or formula to calculate the current and turns?
Thanks

[planet10]

Originally posted by Richard Chiang
I am trying to build a magnetizer for my speaker project.

Warning: These things are VERY DANGEROUS because the pack HUGE amounts of energy. Anyone attempting to build one without an absoulutely thorough grounding in them is a candidate for a darwin award (ie a pine box, death, premature creamation...)

That being said, you can find some info in the JoeList archives (with more warnings & specific dangers -- ie fuses for these are substantial pieces of metal)

dave

[Rademakers]

but i thought all respons chats are made in anorechtic chambers

IMO response charts are best for 300 Hz and up. For the frequencies below that the manufacturer will probable use some overly big and low tuned enclosure, while used in 4pi or just 2 pi (unless they mount it 50 ft up in the sky).

Perhaps I'm not seeing this clearly but if the enclosure, roomsize, placement, roommodes, reflections, filtering and roomgain are so totally different from the place you're going to use it, than what does it tell you exactly?

Wkr Johan

[bogoes]

Originally posted by demogorgon
but at the same time, a double\triple TB W4-1320SB is looking good as well, as i'l get away without a crossover and the usage of multiple drivers guarantee lower distortion that simply using one.
i cant afford a mtm with the aurum, considering both the monetary costs as well as the cost in ocupied lugadge room. I could with the TB bamboo, but what will be gained in contrast to a simple 2\3 driver paralell coupling? you reffer to lobing?

Marius -

Lobing occurs whenever you have 2 distinct sources producing the same sounds. Since the sounds are not eminating from the exact same location, cancellation will occur at various listening angles. MTM designs use this occurence to reduce floor and ceiling bounce and keep the sound focused. This is also why you will hear repeatedly that although they are the most popular, MTM center channels laid horizontal are not the best bet because you will get response anomalies when sitting off-axis. The best way to minimize this effect is to ensure that you use a single tweeter to handle the highs and to make sure that your woofers are no more than 1/2 wavelength apart (center to center measurement) at the crossover point - and less is better.

In a 3 speaker full range setup, you have the shortest frequencies (treble) emanating from 3 spots on a vertical plane - with a 4 inch speaker, each will be close to 5 inches apart, with a 10 inch gap between the top and bottom speakers. 10 inches is the half wavelength for about 675Hz (calculator here) so all sound above 675Hz will exhibit some lobing problems on the vertical plane (i.e. they will sound very different standing up and sitting down). When you use a tweeter to handle the treble, you assign a single point source for the high frequencies and avoid the lobing errors in that region.

Clear as mud?

Originally posted by demogorgon
You altso refer to BSC, could you please clarify?

BSC = Baffle Step Compensation which has been mentioned numerous times in this thread concerning the dipole speakers but never explained. Essentially, at the frequency where the sound waves start to wrap around the speaker instead of project forward from the baffle only (distanct from center of driver to edge of cabinet frequency - about 4500Hz on a 6" wide speaker) the bass will drop off about 4dB depending on speaker placement (less in corners and against walls). BSC compensates for this by lowering treble to the proper levels to match.

Good luck.

[Geenius]

I have used this one and was pleased with the result:

PHL 1280

[MegaMe]

beat me to it I was just about to recommend a phl driver...
I have large doubts about the sonic qualities of some of the pro audio drivers...
but here the 1120 is tested and it doesn okay, considering it is compared to some pretty good drivers: http://206.13.113.199/ncdiyaudio/mar...20/PHL1120.htm


I also dont think they need very large enclosures, but I havent used one myself.

[planet10]

Originally posted by bogoes
BSC = Baffle Step Compensation which has been mentioned numerous times in this thread concerning the dipole speakers but never explained.

Dipoles? We were discussing Bipoles. Dipoles are a completely different beast.

Here is an intro http://www.t-linespeakers.org/tech/b...intro-bds.html -- it links off to other articles that cover off more detail.

about 4500Hz on a 6" wide speaker)

actually it will be about 1,000 Hz.

dave

[demogorgon]

been out of the loop for a day or two and lots of new replies, goody

I'm gonne have to digest this tomorrow, right now i'm to tired, 9-5 type of jobs really suck the life out of you

thanks
Marius

[demogorgon]

Well, sorry to inform those of you who contributed to this thread, i can no longer go ahead with the speakers.
the reason is that my economical situation has had an upturn, and so i'm buying my first car, a 85' golf mk2 GTi as a project car
and so i can safely asume all monetary recources to be dircted into that.

those of you who frequent the caraudio forum here will probably see me from time to time though

thanks for all your help though!
at the very least, i learned a thing or two

-Marius