Project: building a custom and flexible audio system

There are 4 replies in this Thread. The last Post () by Doppleganger.

    Part I





    Point is to design and build personal audio system to match your needs. Also my goal is to be flexible which means you will be able to take any of the components and use it elsewhere.



    Evry sound system can be devided to several common blocks - 1) source of signal; 2) amplifier/equilizer; 3) speakers. I gonna start from the "tail to the head" which means - 3) speakers.



    Because the whole system need to be flexible i decided to look at some parts target at car audio. In this way of thought i choosed a car type subwoofer speaker. Its not important does its a car speaker or just a standart one that you can find on the net aslong as the sensitivity and diameter of the speaker are high. Small drives, especially for low frequencies is just no good. Bigger is better. There is something else which you wont find on a standart speaker and this is the Dual Voice Coil. Evry speaker use one voice coil with fixed resistance (usually 4 or 8 ohm). Dual Voice Coil (DVC) speakers have two coils usually 2 or 4 ohm resistance each and four wires instead of two. Both coils need to be connected before speaker to be used. The advantage of DVC comes allowing you to connect both coils in different configuration to take the maximum of your amplifier. Lets take for example Pioneer TS-W256DVC. This drive match our requirements - 87dB sensitivity, 25cm diameter, 350W RMS, DVC with two 4 ohm coils and perfect frequency response for a subwoofer all this at good cost - 60 euros. Now depend on how you connect the coils (usually you get this into the user manual) you can 1x 8 ohm, 2x 4 ohm or 1x 2 ohm.



    to be continue ...





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    well i use KEF iQ9's as L/R fronts for point source sound, excellent base response too, with a ruark powered subwoofer, a pair of KEF iQ8d's as L/R surround for the same reasons, and a KEF iQ6c. but then i am a KEF fan!!


    i use a ROKSAN candyII DVD player as my source, and a yamaha RXV800RDS as my power amp(old but versatile).


    you dont need any additional equalization, you could go for an outboard DAC but unless you are a true audiophile its pointless, same with external power supplies.


    for a more affordable solution go for the iQ5's as fronts and some older Q80s' for rear surround with a Q80c for centre. all very affordable second hand.


    JUST PLAY IT LOUD!! :P


    btw m8 ive plenty of experience with car audio and you shouldnt use the same basic techniques with home audio. the listening evironments are too dissimilar, car audio speakers use different materials, impedences and methods to create thier desired sound. DVC subs are fine when running multiple subs in cars but in home audio you get to many phase variances with multiple sub setups, you lose sound rather than gain. just use 1 good quality sub. and most home audio speakers are rated at 6ohms rather that the usual 2,4 or 8 for car audio using multiple speaker set ups.


    just use good quality speakers and you wont need huge amounts of them to create your desired effect.

    I agree with Dop on this point i to love my home audio setup and i know of people who have tried to design there own speaker using car audio subs midrange and tweeters and to be honest not even a kicker sub can compete with my speakers my home setup i have 2 x Bose front speakers 2 x Eltax rear 1x Kef centre and running on a Sherwood DTS dolby surround Amplifier with Techincs CD and Sony Minidisk and Sony DVD i dont have the need for a Sub as my Bose speakers are more then adequate to shake and rattle most large rooms and do out perform my friends Kicker sub he runs on his Marantz Amplifier.

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    I have 8 channel surround system and verry good sound card but thats not what i have in mind. I belive you can build something on your own to use in the other rooms or places as i said something flexible at a good price and good quality. And you know whats the feeling when you made it on your own.


    So lets continue ...





    Part II



    There are in common two types of speakers when its about cars - 3.1) for enclosure use; 3.2) for free air use. There is nothing special about free air type of speakers - you just need to mount it on wooden (MDF) plate. Things are way more complex when its about creating a speaker box for enclosure speaker type. Usually speaker manual contains several common schemes like box with vent/port or box without vent/port and some dimentiones. This is also a matter of space you can spare (means in your car or to be comfortable to transport or place the box in your room). However if you're enthusiast you can take this even further - design your own speaker box. To do that you gonna need three things - your specific speaker parameters, program to simulate the overall sound effect (box + speaker) and good idea is to get a program for 3D design so you can see how it really gonna look and prevent later technical problems when you reach the assembling.


    First you need to start with the internal size of the box to provide atleast the recommended space for proper operation of the speaker. For our particular speaker recommended space is 22,6 liters for sealed enclosure box (no vents) and 31,1 liters for box with vents. If the size is below those values, speaker will be limited in reproducing some of the frequencies. If size is over those values an over excurse may occure which means, if you dont make your simulation to look properly with this box size you may blow up your speaker at sertain frequencies and imput power. So you need your speaker's specific technical specifications. I'll talk about that a bit later. Lets spend some time to design the speaker box. Bellow you can see design made in Solid Works - it really dont matter what program you use aslong you can see how the whole box will look.







    Keep in mind that you gonna change the look all the time untill you find what fits best sound/physical dimentions. What to expect from your speaker box with certain dimentiones and speaker combination will tell you your simulation which we gonna do with other program. Box you see above has following specifications:


    Wide: 360mm
    Height: 550mm
    Deep: 400mm
    Walls thickness: 20mm
    Wall isolation: 10mm
    External size: 79.2L
    Internal space without isolation: 58.75L
    Internal space with isolation: 49.98L
    Material: wood (cedar)



    As you see this is pure subwoofer with only one speaker, one vent port, and hole for terminal at the back and size exceeding nearly twice the size that is originally recommended. This brings its pluses and minuses which we will see at the simulation later.




    to be continue ...

    omg m8, now you are getting complicated and into the realms of the true audiophile.


    building your own speaker enclosures huh?!


    some variables to consider:


    resonant frequency of the individual drivers
    crossover complexity - activce, passive, crossover slope...
    enclosure construction - ie sealed, ported, bandpass, transmission line, horn loading, isobaric, passive radiators, etc..and materials used, granite/marble being the best accoustically^^
    the size of the listening room
    dimensions of the listening room
    objects in the listening room and thier construction
    object placement in the listening room
    construction of listening room inc floor....welsh slate being the best for the floors btw^^


    you could go on forever m8. car audio, comparatively, is simple in design to get the desired sound, but will never be up to the standards of a good home system.


    8 channel i assume you mean 7.1 digital?
    unneccassary imo to have that many speakers unless you own a cinema!!
    excellent sound can be achieved with a 5.1 set up using matched components and good quality source and amplification.


    stick with good quality english audio components and you cant go wrong imo. steer clear of the amps/sources that have loadsa buttons!!:P


    more gadgets= more variables = sooo much harder to get right


    btw m8, dont use vented enclosures for subwoofers unless you are just after serious volume and loadsa boom. go for a sealed enclosure for clarity, depth and accuracy