Hey guys, I'm fairly new here.
I love the DIY Perks Surround Sound Speakers, and I think they are a great project to start.
However, I already have a spare AV receiver and actually don't mind running cable lengths out to speakers. (an old Yamaha RX-V6A)
in fact, it's harder to get power out to the speakers with my current setup.
So, I'm thinking about how to convert the speakers to passively powered ones.
The amp from the av can do 100-watt, which should cover the 3 speakers (40watt woofer+ 40watt woofer + 20 tweeter)
It should be simple enough: replace the DSP and amp with a 3-way cross-over.
My issue is that I have never designed my own crossover before.
Would anyone be able to direct me to an easy guide/ calculator to design one that matches the cross-overs found in the DSP profiles?
Passive crossovers are a lot different to digital ones. Passive components have huge tolerances which the designers have to account for - not to mention (and something many beginners miss) is that the crossover should (ideally must) be designed to suit the specific speaker driver and cabinet, although that's speaking as a hi-fi purist.
In other words a passive crossover can have breakpoints that overlap quite widely, whereas a digital one can enjoy much tighter tolerance. Is that a good thing? That depends (pun incoming) what you listen to.
The mid-range is classically colourfully called a "squawker" not that you hear that much these days as most passive setups are just dual driver. This is in part due to improvements in speaker technology and assembly and partly because passive crossovers cause more problems than they solve to a large degree for reasons of that overlap.
Another "gotcha" with designing a crossover is the availability of the power inductors that are required. Sure, you can wind your own but that creates problems of its own.
You can get two-way crossovers from Ali Express (three way too, I would expect) across a fair bunch of of power ratings - and this is honestly the simplest, cheapest (and pain-free) way to do this.
An alternative is to use an active (not a DSP) crossover - which have an advantage that they can be "tuned" with nothing more than a small screwdriver. They're a whole lot easier to design as, at the simplest level, only require three operational amplifiers - low, band and hi-pass.
Take everything I say with a pinch of salt, I might be wrong and it's a very *expensive* way to learn!
Oh absolutely. This will have to be a 3-way custom job
There aren't really any great quality 3-way active cross-overs that i can find
I find that the DSP is a bit redundant when I have an AV receiver that will do that job; IMO if there is a clean analogue going out, I don't want to touch it again until I hear it.
I still do see a lot of expensive speakers use analogue passive cross-overs, though.
is it really not a great idea to adapt this design? i do like the surround mid-sub that DIY PERKS has designed in.
its upsetting that that DSP need power in
Analogue crossovers are fine if you're designing the whole shebang - which means you know the speaker loading and other characteristics which aren't always available. DSPs are tunable of course - which is what I think Matt's done because you can set these parameter's digitally and tweak as necessary. And I concur, his designs are just delicious.
If you really, really want to design a passive crossover there are a few sites I've happened upon that have handy-dandy calculators. I dare say we could probably do it here in the forum, assuming you have the speaker characteristic response curves. (That's not me being awkward, it's just that we need to know where the crossover points are or we're micturating into hurricane as it were.)
I did manage to find a great introduction with fairly well described theory which isn't terribly mathematical here. The presentation is appalling by modern standards but it's the text that matters.
https://www.calsci.com/audio/X-Overs.html
Are you intending on winding your own inductors or are you happy to use commercial ones? I haven't wound an inductor of any power since I made a transformer as an apprentice many decades in the dark past. I think I still have it actually.
I'm working a little blind here since I haven't built this project - not enough hours in the day unfortunately - but if you're OK to source the data sheets for the speaker drivers I'm sure we could have a crack at it.
OR you could save yourself a lot of pain with something from the experts right off the peg, bearing in mind that this might not have the correct points for the drivers Matt's used. Dayton are among the best and while these aren't "cheap" they do use quality components so they are more likely to perform as advertised!
https://www.daytonaudio.com/product/599/xo3w-625-5k-3-way-crossover-625-5-000-hz
the full selection is here (with some other manufacturers in there) Dayton are mostly the blue PCBs:
https://www.parts-express.com/speaker-components/crossover-components/assembled-passive-crossovers
Take everything I say with a pinch of salt, I might be wrong and it's a very *expensive* way to learn!