Home theatre design and build in Australia

fishparty

Member
2013-05-05 12:21 pm
Hi all,

I have been trawling around for information on building my own home theatre system for a few months now, thought I'd finally try to tap into some expert opinions...

I want to build a 5.1 system to go with a Yamaha RX-V673 (or 575 if I can find a good one on eBay). Ideally I would like to build speakers that can handle 150 watts at 6ohms with a reasonably flat response. Here's the catch though - I want to keep the build price below $1000 (excluding cabinets).

I have access to a workshop and so cabinet construction should not be an issue - providing that I can find cabinet designs that I can plug straight into the computer. I am proficient at electrical work (I do a fair bit of microcontroller prototyping), however would prefer to buy crossovers etc as complete units, or at least unassembled kits (unless anyone can provide a list of every specific component).

I would like to have two floorstanders (3 or 4-way?), two satellites and a passive sub.

So...can anyone recommend drivers, crossovers/components and cabinet designs for this idea? And also where to buy these from (preferably from within Australia - I'm in Perth)...?

Cheers everyone, I look forward to hearing your advice.
 

Brett

Member
2002-01-07 6:02 pm
I would like to have two floorstanders (3 or 4-way?), two satellites and a passive sub.
For a thousand bucks? Don't want much do you?

You're going to need established designs because you don't seem to be able to design xovers yourself so that limits what you can do. Something like the Tarkus would probably be OK for the mains, and there are plenty of smaller designs out there for surrounds. Subs in Oz are thin on the ground but the Daytons soon available at LSK or Alpine SWR1224 would do the job OK. Most AVR amp channels won't power a sub very well especially if any EQ is used so a dedicated sub amp is strongly recommended.
 

fishparty

Member
2013-05-05 12:21 pm
Hi, thanks for that. Yeah unfortunately the budget is limited to a grand as I've just bought my first home and cash is relatively thin on the ground. Wanted a nice little project for my new workshop that, for a change, isn't a robot of some sort. Yes, I've looked at the Tarkus model before, the site is very informative. What do you think of the Swope system? The frequency plot looks pretty jagged, but obviously I'm no expert.
 

Brett

Member
2002-01-07 6:02 pm
Hi, thanks for that. Yeah unfortunately the budget is limited to a grand as I've just bought my first home and cash is relatively thin on the ground.
I understand the feeling, but there's only so much you can get for the $, especially down here.

Wanted a nice little project for my new workshop that, for a change, isn't a robot of some sort.
I'm already looking for the next nerd project, post theatre, and I think it's time to dig out the aeronautics training and design something that flies. I already do a bit of embedded design.

Yes, I've looked at the Tarkus model before, the site is very informative. What do you think of the Swope system? The frequency plot looks pretty jagged, but obviously I'm no expert.
The FR looks quite decent in the plot lower down the page.

They are not my cup of tea (far too small) but they might do what you need within your budget. I'd still build a sub or two with a Dayton 15.

I'd also echo 3GGG's advice to do an Ewave design. I use a 3 way version of these for surrounds.

JBL WG's measure very well, are inexpensive and the designs with the DE250 can be swapped for the DLA360 CD for less. They'll do far better than a small 2 way direct radiator for mains.
 

fishparty

Member
2013-05-05 12:21 pm
Cool, thanks for the info. Yeah I like the idea of the ewave design, with a couple of woofers sitting underneath. Couldn't find the DLA360 online though...

Did you build the xover for your three-ways from scratch? I don't have any problem with putting the components together, but would have no idea where to start in designing one. I feel this is going to become a major problem if I decide to start customising this build.

Oh also Brett, you mentioned that the Swope was far too small for your liking. Couple of questions:

1) Too small in size, or volume? I'm seeing ~90dB on the plot, that is certainly less than I'd like...

2) The are 4-ohm drivers. Am I going to destroy the 6 ohm receiver if every speaker is drawing power at 4 ohms?

By the way, Arduino is a great platform for building flying things. These are fun. https://code.google.com/p/arducopter/wiki/ArduCopter

Thanks 3GGG for the heads up, any further advice very much appreciated.
 

fishparty

Member
2013-05-05 12:21 pm
Actually, you know what? I really like the Tarkus (maybe with a flat face though). Possibly with <a href="http://www.jaycar.com.au/productView.asp?ID=CS2560">slightly cheaper drivers</a> if I can (or even just build this kit) with nice cabinets. What do you reckon of these? Less chance of me killing the system in my first attempt...

So.

Satellites? (Cheap and decent please)
Centre ideas?
Powered or passive sub? Keep in mind the receiver has a dedicated sub output.
That said, the Tarkus has two 10" woofers...

Opinions on the Jaycar kit are very much welcomed, please remember the low budget for the build though...

Cheers guys
 

fishparty

Member
2013-05-05 12:21 pm
Thanks AllenB,

If anyone has the time to explain crossovers to a noob like myself, how customisable are they? To be specific:

Is it possible to buy a different inductor with a lower cutoff and solder it straight in to the crossover as a replacement?

Also, can you daisy chain crossovers in one unit?

Cheers
 
Forget jaycar, there are far better products out there. Just read up for a while on here.
Also look at Paul Spencer's offerings over at stereo.net.

As 3 GGG said ,check out Pauls blog ,work won't allow me to link blogs :rolleyes:
redspade audio

If moneys tight maybe look at building the system over time with mains & center then add the rest as budget allows .Decent movies don't come out every week :D .
Cheers
 
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AllenB

Moderator
Paid Member
2008-10-18 11:31 am
Fishparty, it is possible to do many things with a crossover. You can change the tone of a speaker, and equalise anything as required. A crossover point can be changed, one driver made more loud/quiet, act as if it is closer/further. You can chose the rate at which drivers are cut off (steepness of the cut), and the extent to which you smooth the response may only depend on how many components you can implement, or afford, or deem necessary for a worthwhile improvement.

Increasing the value of an inductor is a common DIY practice. In order to have two drivers working together it is necessary to understand (and generally to measure), that a tone produced by a driver has a frequency, a level, and timing (phase). Where two drivers are both producing a particular frequency and their phase at this frequency is not close, they won't work together well and you may end up with a rough response due to cancellations (partial cancellations). It is possible to make improvements on most crossovers although some work quite well already, but a well enough designed crossover can be made worse by changing values...of course, don't let this stop you :)

Daisy chaining crossovers is valid enough in principle, but taking completed crossovers and running one into the other is unusual and probably not a good idea.
 

fishparty

Member
2013-05-05 12:21 pm
Thanks for all the info everyone!

I think I will stick with established designs, but definitely have "the bug" for this.

Just a few more final questions...

With the Tarkus, I read:

The impedance load of the Tarkus is generally safe for most amplifiers. It does dip down to 5 Ohms a few times, but that's pretty normal, even for commercial speakers that call themselves "8 Ohm nominal." It goes without saying, the Tarkus like some power behind them. They will get to 106 dB @ 75 Watts, before xmax becomes an issue. However, having an amp with more Wattage than that allows for some headroom, which is a good thing.

The amplifier I am looking at has:

7-channel 805W = 115W x 7 (6 ohms, 1 kHz, 0.9 % THD, 1 ch driven)
560W = 80W x 7 (6 ohms, 20 Hz-20 kHz, 0.09 % THD, 2 ch driven)
945W = 135W x 7 (6 ohms, 1 kHz, 10 % THD, 1 ch driven, JEITA)

I don't understand what this means...should I be looking at the lowest value i.e. 80W?
I do understand that these are not the greatest stats, however I bought the receiver on impulse today and am going to stick with it for the time being...provided that it is powerful enough to drive the Tarkus.

Will this be enough to power the Tarkus up to 105 dB at 75 watts? Is there enough residual headroom with this receiver to avoid distortion during peaks?

Thanks for the heads up about Paul's blog also, very interesting reading.

Another question: what is the best method for joining cabinets? Are dowels okay, or should I try to join the cabinets with grooves?

Finally: do I have to dampen every cabinet with polyfill or similar, or only certain cabinets? My current sub has no damping whatsoever, however I am unwilling to pull apart my expensive monitors to check whether they have anything inside them.

Cheers everyone, appreciate the advice.
 
Alternative

Hi all,

I have been trawling around for information on building my own home theatre system for a few months now, thought I'd finally try to tap into some expert opinions...

I want to build a 5.1 system to go with a Yamaha RX-V673 (or 575 if I can find a good one on eBay). Ideally I would like to build speakers that can handle 150 watts at 6ohms with a reasonably flat response. Here's the catch though - I want to keep the build price below $1000 (excluding cabinets).

I have access to a workshop and so cabinet construction should not be an issue - providing that I can find cabinet designs that I can plug straight into the computer. I am proficient at electrical work (I do a fair bit of microcontroller prototyping), however would prefer to buy crossovers etc as complete units, or at least unassembled kits (unless anyone can provide a list of every specific component).

I would like to have two floorstanders (3 or 4-way?), two satellites and a passive sub.

So...can anyone recommend drivers, crossovers/components and cabinet designs for this idea? And also where to buy these from (preferably from within Australia - I'm in Perth)...?

Cheers everyone, I look forward to hearing your advice.

I would source drivers for your project from P-Audio as they are nearby and will deliver quality at a low shipping cost.

To keep close to your budget here is my recommendation:

.........................................Phase I Phase II Unit Cost (USD)
Front Three: SN8-250CX .......(2)..........(1)..........$200
Back Two: SN6-150CX.........................(2)..........$100
Sub-Woofer: SD18-1700N......(1)........................$500
Budget Total (USD)................$900......$400......$1300

Rather than use lesser drivers to reduce cost, do your build in two phases.

If you get lucky, you may not be much over budget with a single purchase.

Note: All front units should be the same, so that across-screen pans remain natural.

Regards,

WHG
 

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