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Project: Active Sound System Build

Problem Statement

I went to this concert at this guy’s house, kind of a house party and performance thing. And a lot of the other people remarked that the sound was really good and they could hear things that they had never heard before and they could really hear changes in the music that they didn’t expect. And that was because these speakers were high performance and tuned well and so forth. And I thought, I should have that for my music. So I talked to the person who had brought the speakers, he told me he built them 10 years ago and just carried them around to places. And so I was thinking that I should build my own speaker set and that’s because I’m interested in making my own music, modular synthesizer music but generated on CPU, because I don’t actually want to deal with a lot of the hard electronic stuff. And I figure if I can’t hear it well, then I need to come up with speakers that I can listen to and hear things properly.

And then I started reading about sound reproduction and I learned that home theaters are a big thing and that there are these Dolby Atmos systems that have height speakers and surround speakers and so forth. And in particular there was this video where he did it pretty cheap. And I thought, well, I should build a home theater system that can do Dolby Atmos, because that seems like the best way to get high-quality sound reproduction. And then I learned about active crossover and how that can improve the sound quality by allowing for more precise tuning of the speakers. And so I decided that I should build an active sound system with active crossover and multiple channels of amplification.

Near-term Goal

The focal point right now is buying a measurement microphone. So there’s a Dayton Audio iMM-6C measurement microphone for about $45 and it’s available on both Amazon and Parts Express. But Parts Express gives you a 10%-12% off discount off your order, they run specials a lot of the time. But to get free shipping at Parts Express, you have to buy at least $100 worth of stuff. And so I was thinking I should buy some speaker parts as well along with the microphone to get to the $100. And so the issue is that I have to have a decent idea of the system design to do that, before I buy the parts, because I don’t want to buy parts that are not going to be useful for the design that I end up going with.

Once I have the measurement microphone, I can start tuning my existing speakers:

I can also use the measurement microphone to measure the acoustic properties of my room, to help design the new speakers that I want to build. And then I also want to experiment with more complicated machine learning-based tuning. So overall, this is a step towards building a high-quality sound system that I can use for listening to music and also for producing music.

Core Strategy

The core strategy for making the system high-quality is to do active, software-controlled crossover, and drive each driver with its own dedicated amplifier channel. This allows for immense control and precise tuning of the system. Active crossover can adjust for many common issues with speakers:

This approach is more complex than a traditional passive crossover system, amounting to building a custom receiver, but the benefits seem worth it. The system can be tuned to perfection. Looking at the cost of parts, it even seems that with cheap DACs and class-D amplifiers, the cost difference is not that large - an active digital crossover is not really much more expensive than a passive analog one. It’s important to not get ripped off by low-quality 1% THD amplifiers, but it seems like it’s possible to get good quality for a reasonable price without spending a fortune for a high-end audiophile system.

However, even the physical design of the speakers cannot be ignored, even with active crossover. The drivers and the cabinet’s volume, shape, and materials all affect the sound, and a poor design can limit the system’s performance. DSP cannot fix physical damage or mechanical noise, and it cannot overcome severe distortion, reflections, or resonances. Essentially, if, when the speaker plays a test tone at a certain frequency and volume, there is an audible noise on top, such as an overtone, chuffing, etc., then really the DSP’s only option is to avoid that frequency band for that driver, and compensate with other drivers - it is like a piano with a broken key. There are some tricks with relying on masking effects, but these are ultimately band-aids over a fundamental problem. So the speaker design still matters, and I will try to choose good drivers and cabinet designs that minimize these issues.

Budget is all over the place. I want to keep it reasonable, but I also want to get good quality. DMS did it for 1800,aguyinthecommentssaysyoucanjustbuyareceiveranddoitfor1800, a guy in the comments says you can just buy a receiver and do it for 1,668. I’m aiming for something way less than that, but I don’t want to skimp on quality too much. I think the most important parts are the speakers, and I’ve read that DIY speakers can be much better than commercial ones for the same price. But I’m also lazy, so I might buy some pre-made speakers and modify them. The amplifiers can be cheap class-D ones, as long as they have low distortion and enough power. The DACs can also be cheap, as long as they have low noise and good dynamic range. The DSP can be done on a computer, so no cost there. Overall, I think it’s possible to get a high-quality system for a reasonable price, but it will require some research and careful selection of parts. And then, I’m not even sure I want to build a full 7.2.4 system right away, I’m going to start with a core 3.1 system + bass shaker, and then add more speakers later as needed. With so many options, and no hard requirements, it’s hard to pin down a budget. A reference point is that a Klipsch 5.1 system is 599,butit′spassive,sowiththeamplifierandDAC,itwouldbemorelike599, but it's passive, so with the amplifier and DAC, it would be more like 800. I want to say that getting it done for under $500 is a reasonable goal, but I don’t know if that’s realistic.

Speaker System Layout and Count

Format overview

A review of modern audio formats as found on Blu-ray discs and streaming services:

Of these, the 7.1 channel Dolby Atmos track is the most advanced and immersive format, as it combines a high channel count with object-based audio for height information. This allows for a truly three-dimensional sound experience when played on a compatible system. Supporting this format is a key goal for a modern home theater setup.

Surround Sound Configuration

The “AudioDome” system is a custom system with 91 KEF E301 speakers arranged in a geodesic-like sphere, and four subwoofers. They concluded in a paper that sound sources reproduced with ninth-order ambisonic panning are sufficiently focal such that two adjacent sources can be resolved at or below the level of normal human spatial acuity, and that their system was actually flawed, in that it did not reproduce high-frequency sounds correctly. The interesting graph is Figure 3/Table I, which shows that humans can discriminate 1 degree of sound up front, increasing to only 20 degrees at the sides. These are probably the best numbers available for human sound localization acuity, although there are similar results and probably more papers.

As far as practical speaker configurations go, this video is a good overview of Dolby Atmos speaker layouts. The most common home theater setup is 5.1, but the “gold standard” is 7.2.4, which has seven ear-level speakers (front left/center/right, left/right forward/back surround), two subwoofers, and four height speakers (front/back left/right). A 7.2.4 is set up like a normal 7.2 system but with 4 additional speakers above you (top left and right, back left and right) He says that’s what the movies are mixed for, and so it’s his recommendation. The angles don’t matter so much if you tune the system, just that the speakers are roughly in the right layout.

In practice the number of channels really depends on the room - for a small room, 5 channels probably is all that will fit, but for a larger room, 9 channels might be better than 7, and extra heights too. The heights are more important than the surrounds and really should be prioritized if you want Atmos sound. He says a 5.1.4 system sounds better than a 7.1.2 system. The extra subwoofer is also useful for smoothing out the bass response, but for movies it’s not as critical as the other speakers.

Overall, this question will depend on the room size and layout, budget, and personal preference. So for complete future-proofing, we’ll design it as an incremental progression towards a 7.2.4 system - it’s easy enough to build out part of it and add more speakers later, or just stop if it’s too complicated or expensive.

Incremental build plan

Stage 1: 1.0 (Mono)

Stage 2: 2.0 (Stereo)

Stage 3: 2.1 (The EDM Foundation)

Stage 4: 3.1 (Dialogue Clarity)

Stage 5: 3.2 (Club-Grade Bass)

Stage 6: 3.2 + Tactile (Feel the Drop)

Stage 7: 5.2 (Surround Begins)

Stage 8: 5.2.1 (Height Layer Opens)

Stage 9: 5.2.2 (Front Heights)

Stage 10: 5.2.3 (Rear Height Center)

Stage 11: 5.2.4 (Full Height Dome)

Stage 12: 6.2.4 (Rear Surround Begins)

Stage 13: 7.2.4 (Finale)

Speaker Matching Considerations

It’s important to understand that DSP and measurement can’t do perceptual matching at every listening position in the room. You can get a good match at a sweet spot or two, but other locations will hear mismatched power responses. This is especially true if the speakers have very different off-axis directivity patterns - no amount of DSP can change how sound radiates into the room.

Channel count

A basic breakdown of the speakers is:

The total channel count is 9 + 8 + 4 + 2 + 2 = 25 channels. The actual number may be higher or lower depending on the final design choices.

A standard A/V receiver will not have this many pre-outs or amplification channels. I will build a custom setup using multi-channel USB and amplifier boards.

Electronics chain

Bit depth and sample rate

The human auditory range is roughly 20 Hz–20 kHz with a potential dynamic range of about 120 dB in ideal conditions. Real-world listening, however, is limited by background noise, speaker performance, and comfort levels — nobody listens at the threshold of pain just to squeeze out a few more decibels. From this perspective, CD-quality audio (44.1 kHz sample rate, 16-bit depth) has long been accepted as sufficient for high-fidelity playback.

Digital signal processing (DSP) corrections, such as equalization and phase adjustment, are typically implemented with FIR filters. These don’t require a higher sample rate or bit depth than the source audio, so long as the internal precision of the DSP is sufficient. Professional production often uses 24-bit/96 kHz or more, but that is mostly to provide headroom for multiple processing stages and to reduce aliasing artifacts. For playback, dithering and proper gain staging already ensure that 16-bit/44.1 or 48 kHz remains transparent.

Machine learning-based DSP, which can attempt to correct nonlinear distortions in amplifiers and speakers, raises a more subtle concern. Nonlinear models can generate ultrasonic content that, in theory, could alias back into the audible range. But any well-designed playback chain includes low-pass filtering, and any amplifier or speaker that actually emitted ultrasonic noise at audible levels would be fundamentally flawed. In practice, then, even advanced DSP correction does not demand higher output rates. A 48 kHz signal suffices, and adding an ideal 48 kHz low-pass filter before the DAC would leave the audible result unchanged.

Bit depth often causes more confusion. A 16-bit DAC provides 65,536 discrete levels; at typical consumer line levels of 1–2 volts, that means each step is on the order of tens of microvolts. This is already smaller than most real-world noise sources in an audio system. While a 24-bit DAC has a theoretical dynamic range of 144 dB, practical designs rarely achieve this; even high-quality DACs are closer to 110–120 dB once noise and distortion are considered. Meanwhile, speakers, amplifiers, microphones, and rooms all have much higher noise floors and nonlinearities. In short: 24-bit precision is invaluable in production, but its benefits vanish in playback, where analog limitations dominate.

This reasoning matches what I found when I looked at the available hardware. Inexpensive stereo DAC audiophile dongles do exist, like the ES9018K2M or CX31993, but scaling them to 25 channels would require a dozen devices and an impractical number of USB endpoints. DIY boards and breakout chips also provide higher precision, but they require custom circuitry and are not plug-and-play. By contrast, the CM6206 USB audio chip offers six to eight output channels at 16-bit/48 kHz for just a couple of dollars. It fits within the USB Audio Class 1.0 standard, which avoids driver headaches, and it scales efficiently to the number of channels I need.

So both theory and practice converge: higher sample rates and bit depths don’t improve playback in a system dominated by speaker and room limitations, and the most practical, cost-effective solution — the CM6206 — already provides exactly the precision required for high-quality DSP-tuned audio. Yes, audiophile-grade DACs could sound better in theory, but the price/performance tradeoff is not favorable for a multi-channel system.

Tools and Materials Needed

skip the dayton 12 channel amp and use 6 mini power amps. 30-40forachifi50wpcampx6.DaytonMA1240a(amplifier)its40WattsperchannelRMSat8ohms…Or"half"poweredspeakersasPresonusErisE3.5([https://www.amazon.com/PreSonus−Eris−E3−5−Professional−Multimedia/dp/B075QVMBT9](https://www.amazon.com/PreSonus−Eris−E3−5−Professional−Multimedia/dp/B075QVMBT9?tag=hififorums−20)).Eachpairis for a chifi 50wpc amp x6. Dayton MA1240a (amplifier) its 40 Watts per channel RMS at 8 ohms… Or "half" powered speakers as Presonus Eris E3.5 ([https://www.amazon.com/PreSonus-Eris-E3-5-Professional-Multimedia/dp/B075QVMBT9](https://www.amazon.com/PreSonus-Eris-E3-5-Professional-Multimedia/dp/B075QVMBT9?tag=hififorums-20)). Each pair is 99, totalling around $500 for 12 speakers. The same DACs and software can be used. Only an active subwoofer is needed, witch can be bought cheap. Only problem would be weight for the cealing mounted speakers. But here the passive side of the pairs can be used.

https://www.amazon.com/Bluetooth-Digital-Amplifier-Channel-Audio/dp/B0875WY9TX/ref=sr_1_1_sspa?crid=OVW2YMPWP9N8&keywords=4+channel+amplifier+home+audio&qid=1670922589&sprefix=4+channel+ampli%2Caps%2C145&sr=8-1-spons&ufe=app_do%3Aamzn1.fos.006c50ae-5d4c-4777-9bc0-4513d670b6bc&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFPTFBXVTYxMDdPMlImZW5jcnlwdGVkSWQ9QTA1NDI3MjE4NklIWEZYWlQxN00mZW5jcnlwdGVkQWRJZD1BMDAyNzQ0ODIzN0NWRkxOUkY0U0Umd2lkZ2V0TmFtZT1zcF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

Parts express has lots of boards using class D amplifier chips like tda7498e or tda8954th. I happen to have a large lifepo4 battery at 24v in my house, and was thinking I could skip the costly AC to DC power supplies and just hook it straight up to the 24v battery (I assume similar to car audio, but I don’t have direct experience).

Software Challenges for spatial audio on Linux

Finding a software stack that can handle these modern audio formats, especially object-based formats like Dolby Atmos, on a Linux system is challenging. The Cavern project is the closest, they have an audio rendering engine capable of handling Dolby Atmos. Cavern supports using a microphone to perform an acoustic self-calibration of the listening environment, as will be needed when using the measurement microphone to tune the new speaker system. The Cavern project is open-source so it can be freely used and modified to suit specific needs.

However Cavern only handles audio decoding/playback with Atmos. It is primarily an ahead-of-time converter, meaning that it converts audio files into a multi-channel format. Linux support is not a primary focus of the Cavern project, although there are CLI-only Linux builds. There is a newer sub-project called CavernPipe that acts as a real-time converter, but it is not integrated with PipeWire. The developer of Cavern does not run Linux and has expressed their opinion that Linux support isn’t worth it.

The OpenAL Soft project has some support for 3D audio, so it might be possible to adapt it based on Cavern, but it is abandoned.

Overall, the software ecosystem for handling Dolby Atmos on Linux is still immature and fragmented. It seems it will require some custom development and integration work to get everything working together smoothly, probably involving forking Cavern and rewriting it from C# to C++. I don’t expect to play a lot of Atmos content, but I do want to be able to support it for future-proofing and to verify that I have obtained the best possible sound experience. I think the main goal is to be able to play back stereo content with high fidelity in a solid default configuration, and then if I can also decode and play back 7.1.4 Dolby Atmos content with Cavern or a fork of it, that would be a bonus.

For super-high frequencies, I’ll have to test my hearing - I might not even be able to hear above 15 kHz. But if I can, I might want to add a super-tweeter, like a ribbon tweeter, electrostatics, AMT, or even a plasma tweeter, although those are all expensive. The existing tweeters on the speakers I have might be good enough though - it’s something to measure.

Speaker Types

For the LCR speakers, custom-built cabinets are an option, but they’re expensive. Coaxial or MTM designs offer better imaging.

Amplifier Options

Possibilities: - Dayton Audio MA1240a 12-channel amplifier (x2) + additional 1-2 channel amp for subwoofers. $629.98 https://www.amazon.com/Dayton-Audio-MA1240a-Multi-Zone-Amplifier/dp/B003DKVZHQ

Speaker Options

12X (6 pairs) Dayton B452 airs - $45 for a pair - they where chosen for a combination of price/performance/size. they have nice drivers in a crappy box with none existent crossover(its like 1 cap or something). with help, they sound better then their price. and that crappy box weighs nothing, making it easier to hang. with say magnets from the ceiling

I wanna build some speakers. 12 to be exact. The goal is to get the parts for under 300,butinflationruinseverything.Definitelyhastobeunder300, but inflation ruins everything. Definitely has to be under 600. I’m looking at the Dayton Audio B452-AIR as a reference. Specs: Model Number: B452-AIR Description: 2-Way Bookshelf Speaker Pair Woofer: 4-1/2" polypropylene cone with 4-layer coil Tweeter: Mini AMT type with pleated Kapton diaphragm Finish: Black ebony pica vinyl on particle board Power Handling: 30W RMS/60W max Impedance: 6 ohms Response: 85 Hz to 20,000 Hz Sensitivity: 84 dB 1W/1m Crossover: First order high-pass Terminals: Quick-connect spring-loaded terminals Other: Keyhole mounting bracket Dimensions: 9.5" H x 5.5" W x 5.7" D Depth includes grill - Grill is removable, acoustically-transparent cloth

I’m just looking at parts express for now - I will check amazon and aliexpress later, but this is just seeing if it’s feasible.

So first off that woofer - not so many 4.5 inch woofers anymore. I found this one: Goldwood GW-204/8S 4" Shielded Poly Woofer 8 Ohm $17.98 also comes in a 4 ohm version for the same price. I honestly don’t know which is better.

but, way more common is 4" woofers. so I found this: GRS 4" Woofer Surface Mount Poly Cone 8 Ohm 4SMP-8 $14.49 again the 4 ohm version is the same price.

If I’m willing to go bigger there’s also this one: GRS 6PR-8 6-1/2" Poly Cone Rubber Surround Woofer $14.98

even an 8" for $16.98, but that might be too big to fit on my desk.

For the tweeter, the B452-AIR uses a mini AMT type with pleated Kapton diaphragm. It’s also reasonable to look at the non-air version, which uses a 5/8" polycarbonate dome tweeter with ferrofluid cooling.

But I think I found a reasonable one: Dayton Audio PTMini-6 Planar Tweeter 6 Ohm $10.98

the description says it’s a ribbon of heat-resistant Kapton material and an etched aluminum conductor, which sounds similar to the AIR.

As far as the particle board, I have no idea about how thick the Dayton speakers are, but you can get a 3/4-in x 4-ft x 8-ft Pine Sanded Particle Board for $38 from lowe’s. You can do the math to see how many speakers you can get out of that. I don’t feel like adding a vinyl finish, but I maybe I can spraypaint it or something.

So, crunch the math and see, what’s the total cost for 12 speakers?

Klipsch VB-15s 2 for $40 These bookshelf speakers deliver rich, powerful sound through 5-1/4" fiber-composite lightweight cone woofers and 1" aluminum dome tweeters. Handles up to 300 watts peak and 75 watts RMS (continuous) power @ 8 ohms. Tractrix horn technology. Bass-reflex MDF enclosure. 92.5dB sensitivity (although Klipsch is known for inflated sensitivity numbers). 8 ohms impedance.

Pioneer (model unknown, 80s) 2 for $60 15-inch woofers

Pioneer CS-C9000 x 2 + sony center speaker (unknown model) for $150 Type: 3 way, 3 driver loudspeaker system Frequency Response: 32Hz to 20kHz Max Music Power: 150W Crossover Frequency: 3000, 6000Hz Impedance: 6.3Ω Sensitivity: 90dB Bass: 1 x 300mm cone Midrange: 1 x 120mm cone Tweeter: 1 x 66mm cone Enclosure: bass reflex Dimensions: 380 x 800 x 330mm

Pioneer CS-R580 3-way speaker system 2 for $100 6 ohms 150 watts forums say “hard pass”

Sanyo SS V6-150 Floor standing speakers 2 for $50 max power 150 watt impedance 8 OHM 3 drivers with a big woofer (8") 5" and 3" Mid drivers are just a simple paper cone type, they’re nothing to write home about. The enclosure is in fact particle board with a Laminated vinyl finish. Not much insulating material inside. Simple low & high pass filter network. part of an ‘all-in-one’ rack system, produced from 1987-1988.

Sensitivity dB at 1 watt/1 meter Impedance ohms (Ω) RMS Power (watts) Peak Power (watts)

Theater Logic T2400 3 way floor standing speaker with 8" side-firing subwoofer impedance: 8 ohms minimum power: 20 watts RMS peak power: 200 watts “music power” sensitivity: 92 dB at 1 watt per 1 meter

Tweeter: 1" titanium ferrofluid Midrange: 5.25" x 2 Woofer: 8" modulus cone Frequency response: 30-25k Hz Crossover Frequency: 800, 5kHz Tuned ported cabinet Digital Ready Dimensions: 9.25" w x 14.37" d x 40.95" t

left/right matched set

The Drivers: The individual drivers (woofer, midrange, and tweeter) are likely the cheapest components available from bulk manufacturers in Asia. A reasonable estimate for their bulk cost is a few dollars each. So, a total of 6 drivers across two speakers might be worth about $15 to $20 in raw parts.

The Cabinet: The cabinet is made of thin particle board with a cheap vinyl wrap. The cost of materials and assembly is very low. You might be able to get $5-$10 worth of wood out of it.

The Wiring and Terminals: The wiring is likely thin gauge, and the terminals are cheap spring-clips. Maybe a dollar's worth of parts.

The "Crossover": It's likely just a single capacitor and a cheap coil, adding less than a dollar to the cost.

KEF 5.2

References
  1. Carlini, A., Bordeau, C., & Ambard, M. (2024). Auditory localization: a comprehensive practical review. Frontiers in Psychology, 15. 10.3389/fpsyg.2024.1408073
DSP Stuff
Measurement & DSP workflow
General Project
7.1.4 Home Theater System – Complete Component List