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bulding the ultimate diy system

A

anjora

pfm Member
Hopefully i can offord:

Tweeter http://www.loudspeakershop.eu/raal-14015d-p-1797.html i haven't found any better at any price

The choice of woofers+midrange is a bit harder but http://www.audiotechnology.dk/iz.asp?id=4|a|132||| has some interesting products. i think 4 midranges+4 woofers is optimal, this will give me 16 times the output with 4 times the power(magic isn't it?).

I plan to cross the woofer and subwoofer electronically while the tweeter and midrange being protected with passive XO, two channel amps could be used where one channel drivers the midranges+tweeter and one channel for the woofers.

I wan't flat frequency responce down to 1 hz and 16 http://www.data-bass.com/data?page=system&id=90 of these + linkwitz transform/biquad should do the trick, and i also need some class D amps. the room gain will give the disired preasure at really low frequencies but it won't give me the air movemeant, fans should solve this issue but this is something i might add later.

A measuremeant microphone is needed, i found earthworks qtc-50 with the frequency responce of 3hz to 50khz, i plan to get a real studio microphone since i might use it for other purposes as well.

to get flat frequency responce between 1hz and 100khz i need to adjust the room accustics and use active bass absorbers.
 
I hear Dignitas in Switzerland can offer an alternative route out if you decide that death by 1Hz might be a bit upsetting for your loved ones.
 
According to the measurements there, you will need something like 6.5kw of power to get 100db/1m at even 10hz out of these speakers. 1hz is not possible.

Why on earth do you care about 1hz and 100khz anyway?
 
mcai7et2 said:
According to the measurements there, you will need something like 6.5kw of power to get 100db/1m at even 10hz out of these speakers. 1hz is not possible.

Why on earth do you care about 1hz and 100khz anyway?
Click to expand...

100kHz to provide 'bat music' for the bats running away from the 1Hz shaken trees nearby.
:)

Michael
 
If you use multiple midranges, how are you going to handle lobing of the polar pattern?

With woofers, there is no problem, as all the drivers are within a wavelength, but at say 1kHz, the wavelength is a foot. Two points that are 6" apart are separated by half a wavelength - this gives destructive interference.
 
Preferred crossover for the tweeter is 4th order L-R. Doesn't this imply active filters. If so I would suggest the tweeter falls off quite quick at it's lower limit.
 
I intend building a sports car.

I have decided to use 12x 6.0 litre V10 engines to ensure I get the best performance.

will this be enough?
 
mcai7et2 said:
According to the measurements there, you will need something like 6.5kw of power to get 100db/1m at even 10hz out of these speakers. 1hz is not possible.

Why on earth do you care about 1hz and 100khz anyway?
Click to expand...
below 10hz room gain kicks in so i only need eq down to 10hz, wider frequency responce offers better transients and you can feel these low frequencies.

difraction problems is ofcourse challening, however 4 6 inch midranges could be mounted around the tweeter using the mounting holes the tweeter has(each corner). then the distance between the midranges should be about 200mm which should be fine, at the crossover frequency the tweeter should help a bit so i may be able to cross it as high as 5kHz(second order).

if i'm skilled i may be improve it futher by adding waveguides below and above the midrange units. i think i will place the tweeter at the centre so all frequencies will be heard at the same height(and width).

i don't have any plans to use active filters to the midrange units or the tweeter, only the woofer.
 
I'll be interested to see how this project pans out, sound a bit of a mess at the moment. I presume you have lots and lots of speaker building practice?

Stefan
 
At 5kHz, the wavelength is 60mm. With 4 150mm midranges clustered round even a small tweeter, your source size will be more like 350mm edge to edge, so you will get intense lobing. The highest crossover frequency you can use with spatial coherence in that layout would be about 800Hz.
 
PigletsDad said:
At 5kHz, the wavelength is 60mm. With 4 150mm midranges clustered round even a small tweeter, your source size will be more like 350mm edge to edge, so you will get intense lobing. The highest crossover frequency you can use with spatial coherence in that layout would be about 800Hz.
Click to expand...
yes but it's the distance between the centers that matters, with 200mm distance and 4khz wavelenght the first angle for the minimum is 12°

I am thinking of using http://www.audiotechnology.dk/iz.asp?id=4|a|135||| only with notch at 5khz and second order highpass.

since i don't yet have practical experince with speaker building yet so i will keep it as simple as possible, this means everything sealed. i am considering installing the midranges+tweeter in a seperate boxes, this will be a bit trail and error, mabe just mount it without box and try to find a obtimal crossover.
 
Because you have an array with empty centre, it is actually edge to edge size that counts to first approximation.

To really get it right you need design software, as a lot of factors interact.

If you haven't previously designed speakers, you want read Vance Dickason's Loudspeaker Designer's Cookbook, and probably the Martin Colloms book as well.
 
With all due respect, I'd experiment with cheap drivers to get a feel about driver layout before I'd sink significant resources into this project.

If you absolutely must spend a lot of money on drive units, I'd get a 15M Illuminator rather than one of the Audio Technology units for the midrange.
 
Markus S said:
With all due respect, I'd experiment with cheap drivers to get a feel about driver layout before I'd sink significant resources into this project.

If you absolutely must spend a lot of money on drive units, I'd get a 15M Illuminator rather than one of the Audio Technology units for the midrange.
Click to expand...

yes i might start using cheaper midrange+woofers or less amount, also i doubt i will be able to cross as high as 5000hz even if there is tricks to minimize difraction problems such as placing stuff infront of the midrange drivers to spread out the sound waves in a preferable way.
 
sybil said:
I hear Dignitas in Switzerland can offer an alternative route out if you decide that death by 1Hz might be a bit upsetting for your loved ones.
Click to expand...

No need, I seem to recall that the resonance frequency of the brain inside the scull is about 8.5Hz :eek:
 
So, you haven't learnt to swim and you want to doggy-paddle cross the Atlantic?

I'll bring popcorn and a pair of life-savers.

In all seriousness, whilst I admire your ambition, you're missing the most difficult part of loudspeaker design: the crossover. Read the books first, then start with a simple 2-way system.
 
James said:
So, you haven't learnt to swim and you want to doggy-paddle cross the Atlantic?

I'll bring popcorn and a pair of life-savers.

In all seriousness, whilst I admire your ambition, you're missing the most difficult part of loudspeaker design: the crossover. Read the books first, then start with a simple 2-way system.
Click to expand...
It's very simple to to built a passive XO, making it good is ofcourse harder. I plan to use second order effectivly, something like:
-second order passive xo to the tweeter, this is done by connecting a capacitors in series, some notch filters will also be needed.
-shelving highpass filter to the nidrange, this is simply done by connection a resistor paralell to the capasitor
-shelving lowpass is used to the woofer, no highpass is used, this is done electronically.
-the subwoofers(8 per channel) helps the woofers at the really low frequencies.

I think room acuostics will be more challenging. It's pretty hard to find giid diffurors. BTW: i might start building the midrange+tqeeter, it should work pretty well as a speaker.

the power handling scan speak 15m-4624g00 offers is only 75W crossed at 200hz, however this increases up to 40 times when crossing at 500hz and up to 16 times crossed at 400hz, however this is unlikely to be the case since the midrange will burn before it reaches 1200W, the advantage with crossing higher is still much lower distortion. i appreciate all opinions on the choice of woofers and midranges.
 
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