Converting DIY Perks 5.1 Center Speaker to Passive for My AVR Setup

You can get X-over kits from manufacturers like Dayton (matched to their drivers) and from Ali Express for a more "one-size-fits all" approach.

One of the best kept secrets in cinema-sound is that (and this is unlike HiFi for music) the sound stage is dominated by the centre speaker. For sure, Dolby and DTS produce multi-channel systems up to 9.2 but the reality is that the guys mixing the sound are creatives working to produce a sound-stage dominated by the centre speaker. This is totally different to music where the sound stage is generally mixed for front-facing stage. The exception is in live music and some orchestral events where there are some directional cues but they're generally quite small.

Sounds a bit barmy but that's where the majority of the speech comes from right in front of us. A most actors stand to "stage right or stage left" a little of the actual centre but they're rarely speaking from off-stage (that's the screen). I won't delve into psychoacoustics which is the science of this, but this is why you see many high-performance systems with those tiny satellite speakers.

The centre speaker needs to be the best one in the kit, followed by the sub-bass. The other four are for directional cues and since LF information (below a few hundred Hz) isn't directional, we only usually need a single LF (sub-bass).

Those satellite speakers are responsible for higher frequencies - mostly above about 5KHz which are increasingly directional as the frequency rises.

This isn't just what happens in cinema - it happens in reality too due to the physics of how sound travels and our brains have been learning this over millions of years of human evolution. (Some animals, cats are a great example, can turn their ears on a swivel to detect positional cues, particularly sound from behind because they are a prey animal as well as predators.) Humans use the shape of our pinnea and you've learned since birth how the frequency of a sound from behind you is richer in HF than a sound from in front - the HF is partly attenuated by the pinna, but LF isn't.

What matters is the power that each speaker produces is more important than it's frequency response and your amp (probably) came with a measurement mic to do that for you to match your room acoustics.

The upshot of all of this is you can take any of Matt's designs (scale it up if you prefer) and use that as a centre speaker, including the current one with the lasers.

Thank you for the detailed explanation and insights!
I appreciate the effort you put into breaking down the importance of the center speaker and the science behind it.

Your point about the center speaker being the most critical in the system is precisely why I want to take my time and get this project right.

My current audio setup is a bit of a mix-and-match:

• Center, sub, and rear surround speakers: Part of the Harman Kardon HKTS 9 set.

• Front speakers: A pair of old Jensen Hifi Advantage 2000 that i got for free (the specs on the back specify 30-20.000 Hz / 4 ohms of impedance)

The Harman Kardon center speaker is decent, but I’ve been looking for a way to upgrade it.
That’s what drew me to Matt’s design—it’s compact yet looks like it could deliver great clarity with that tweeter placement.

I’ve also measured my room acoustics using the mic that came with my Denon AVR and the Audyssey calibration system. It’s helped balance my setup, but I still feel like the center channel could use an upgrade for better dialogue clarity and tonal balance with the rest of the system.

Regarding crossover modules, I’ll definitely check out Dayton and AliExpress for kits.

Thanks again for your help!

Yeah, I can't stress enough how vitally important it is to bust the wallet on your centre and sub and not worry too much about the satellites which are only effects speakers - 4-5 KHz upwards are crucial but if they can reach down to 300Hz they will pick up a little bit of speech . As a sound moves stage right and left (but still on screen) the satellites will kick in slightly but as it moves off screen (or over your head) psychoacoustics kick in and  our brain produces the illusion of a sound moving beyond the speakers.

It's important to makes sure your sub is well matched to the bottom end of the centre - the better ones have a phase switch (just in case) and an adjustment for the cutoff of the LPF. Typically a few hundred Hz.

In my experience speakers that claim to have a 20-20K coverage are often lying or have crossovers that are all over the place.

I can't recall if Matt has done a big sub recently but he's done some super work on folded  transmission lines which help correct the impedance of free air to that of the driver. (This technique is best known in the Bose Wave Radio and Wave CD).