The Modern Minimus 7 build

[bcodemz]

I'm not saying that it couldn't work with only one passive radiator, just that the speaker will fall somewhat short of the capabilities of the active driver when it comes to the possible maximum SPL. It's just a compromise that everyone is free to make. 🙂

However, I would like to point out another possible problem, namely that the tuning frequency could be too low if only one passive radiator is used, even without an additional weight screwed on. The only way to raise fb would then be to use a second one.

In addition to the requirements regarding the displacement volume of the passive radiator, this could be another reason why I have not yet seen a Purifi build with fewer than two passive radiators per active bass driver (although I certainly haven't seen them all 😏).

Have you ever checked this with a simulation programme? The Enclosure Tool from VituixCAD is very well suited for simulations, even of constructions with passive radiators.

I'm not sure you realize just how small the enclosure is. The box is far smaller than the typical 4" build while simultaneously trying to tune much lower than a 4" is normally tuned to. The enclosure is so small that the issue is how much weight can the PR handle and how much rocking can the enclosure handle. It's really hard to tune low enough with an enclosure this small. The enclosure is much smaller than ideal, and the exercise is trying to make the most out of extremely small enclosures.

I built speakers using the Minimus 11 cabinets. I used a wave guide and big CD. I’m going to replace the wave guide with a flat ribbon tweeter just to get more internal cabinet space to allow the woofer to go lower. Just something to think about.

View attachment 1474944

Very cool. Nice job on those. I want to make a much smaller version of that.

I think you refer to Braun L300. I believe it is the smallest 3-way speakers : ).

What a cool tiny 3 way speaker! I love that concept. Thanks for showing.

 

[tktran303]

Yes. Thanks for sharing!

When @wolf_teeth made a tiny 3-way, I thought it was a novel concept. I had no idea it was done 50 years ago!

Machine Learning translated:

"This is a three-way shelf/wall speaker that can be placed horizontally, vertically, or even hung up. The housing is acoustically damped for better sound performance.

Technical Data:

• Frequency response: 45–25,000 Hz
• Music power handling: 50 watts
• Nominal power handling: 40 watts
• Impedance: 4 ohms
• Crossover frequencies: 600 / 3,000 Hz
• Crossover slope: 12 dB per octave

Connection:

• Built-in 5-meter cable with a standard plug

Drivers:

• 13 cm dynamic woofer
• 5 cm dynamic dome midrange
• 1.9 cm dynamic dome tweeter
• Coaxially mounted in front of the woofer

Housing:

• Wooden core encased in plastic with a removable front panel
• Available color combinations: black/black, brown/brown, or white/silver
• Weight: 6.0 kg
• Dimensions: 16 × 25.5 × 17 cm (W × H × D)

Special Features:
A remarkably compact three-way system with excellent electroacoustic performance, offering versatility in placement—standing, lying flat, or wall-mounted"



It was around this time that David Wilson released his first speaker using Braun and KEF drivers and Crown crossovers

 

[Arthur Jackson]

"It was around this time that David Wilson released his first speaker using Braun and KEF drivers and Crown crossovers"

@tktran303 Thanks for the link, and the history lesson!

 

[wolf_teeth]

I had not heard of the Braun 3ways either. Really, it is an advantage to not need the chamber for the midrange.

 

[LeoJar]

I still keep the Braun L630 with me and it still sound great even the foam had been replaced. In US, ADS is the name with similar design as Braun early speakers.