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Help? designing a DIY loudspeaker


Major Contributor
Oct 10, 2020
Sweden - Слава Україні
"Warning ⚠ English is not my 1st Language AND I tend to be very OCD and verbose when writing.

Before I continue, after listening to a variety of speakers at my local audio shops, ranging from 1000 to 12000 euros, I have not yet found something that fully satisfies me. Out of all the speakers I heard, the Klipsch Forte 4s left an impression because I liked how 'fast' they sounded (transient response), they had a very interesting sound; however, they lacked bass (and had other weird characteristics). I could elaborate on this all day, but here's the TL;DR:

I want to design and build a 2 or 3-way speaker for both music and home theatre use (I know, pretty different applications). My room is 32m2 with a 3M tall ceiling (4.9m x 6.4m x 3m). I want to keep driver and crossover costs at a budget level, around 500~ euros per speaker, or around 1000 euros for a pair, not including cabinet costs.

After hours of obsessing and reading online, including a book I had at home about loudspeaker design, I came to a few design decisions:

1. MTM? (not 100% sure if needed in my case)
2. Closed OR passive radiator midsection
3. Passive radiator bass/sub 'tower'?
4. Analog Crossover (DSP is out of budget)
5. Good vertical and horizontal directivity
6. Fast transient response
7. Possibility for future Expansion (bass module?)

I chose the drivers below based on their characteristics, as well as simulations in Vituix Cad (although I'm not 100% sure about my accuracy), and insights from other people's posts and builds online, and in magazines like Klang+ton.

- Tweeter: SEAS Prestige 27TBCD/GB-DXT - H1499-06 (€99.95) x1
- Midrange/Woofer: SB Acoustics SB15NBAC30-8 (€79.95) x2
- Passive Radiator: SB Acoustics SB15SFCR-00 (€32.95) x2

The reasoning behind driver choice:

- I chose the DXT because I saw how well it performed in the R1 Directiva as well as DXT mon, DXT wave, and others, as well as tests by Heissmann Acoustics.
- The two SB15s have a nice flat response in a passive radiation enclosure that would make it easier to blend with the tweeter at a 2nd order crossover of 1.8KHz, as well as being a good budget driver.
- The two SB15FCRs should have enough surface area to dissipate the energy of the two 'mids,' as well as allow the group delay not to skyrocket.

Shortcomings/issues in my Thought:

- I'm trying to design a speaker and crossover without:
- Full FRD+ZMA files as well as directivity measurements.
- The actual response of the drivers with the baffle I designed and the box, so I know how to design the crossover.
- Am I expecting too much?
- No actual experience in the field of designing speakers aside from setting up and listening.
- Pretty low budget considering Directiva was 500 just for a woofer. :(
- Hyper obsessing on the project made me unsure about my decisions (ADHD + Autism is a pain).

Compromises willing to be made:

- Driver choices Mid/Woofer/PR
- Size, they could be big or small. WAF is not an issue.
- Low-end response, a 2-way with 2x5-inch can only do so much without extra reinforcement.

What are you asking from US? You might be asking:
- Help me with:
- Driver integration/Box
- Teach me new stuff because it's 100% inevitable that I'm gonna learn A LOT of new stuff from this post (thankfully)
- Crossover Design
- Baffle Size/Simulation
- Baffle Step
- Time Alignment T+M OR T+M+Future Basstower Or T+M+W

Inspirations for the project:

- DXT-Wave (Heissmann Acoustics)
- DXT-MON (Heissmann Acoustics)
- Directiva R1 (ASR + Rick Sykora)
- Nebular Monitor (Tony Gee humblehomemadehifi)
- NeXT-Monitor (Klang&ton)
- 8c (Dutch& Dutch)
- A700+A400 (Buchardt)

Thanks for taking the time to read my post. <3
SB15 you say. Here's an exciting project:


A few months ago I began designing, building, and testing 3d printed speakers using the SB Acoustics SB15 and SB26 aluminum drivers. The tweeter on all three designs use the Somossonus (AKA Augerpro) waveguides, but with some structural modifications.

These speakers can all be printed without supports, with the exception of the center unit on the MTM model. All models do benefit from tree supports, so I highly recommend they be used on the woofer overhang and the tweeter cabinet ceiling overhang.


You can find more information and measurements on them in this thread:

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