SB Acoustics 3 ways

[cosmindaniel12]

Hello!

I bought about a year and a half ago some SB Acoustics drivers. I haven't found the time to build the speakers untill now. But I managed to get a 1 week vacation, got my best friend to help me build them (I have 2 left hands) and started to work.

The speakers are:

2 x http://www.sbacoustics.com/index.php...b29rdc-c000-4/
2 x http://www.sbacoustics.com/index.php...-sb17nrxc35-4/
4 x http://www.sbacoustics.com/index.php...-sb23nrxs45-8/

I have simulated the speaker using Boxsim and both the manufacturer's FR graphs and the graphs from http://www.zaphaudio.com/

Enclosure is 70 liters (2.5 cu ft) vented (30 Hz tuning, reflex port in the floor) for the woofers + 8 liters (0.35 cu ft) sealed for the mid driver.

Results:

Frequency Response:



Phase:



Directivity:



The crossover:



I considered that the simulations are looking good, so I started to build the enclosures:











My best friend can get the credit for the enclosure:

























And the crossovers:



We have started assembling them. I think I will increase the tweeter's attenuation with another 2-3 dB. I don't have a measurement mic, but the tweeter volume seems a bit high. Other than that, the sound is exactly how I imagined it...

[WilZirkle]

Nice! The are looking good so far, I can't wait for the finished photos.

[Face]

A measurement mic is worth every penny. Not just for speaker design, but for room setup/treatments.

Nice work so far!

[cjd]

That looks like fun!

How did you get sensitivity so high? I'd have guessed this would manage no more than ~90dB and this looks right up at 93dB. That probably plays into the question of how you simulated and included baffle diffraction for that baffle, since I'm also curious how you derived how much baffle step (or lack) was needed?

C

[cosmindaniel12]

Sensitivity is expressed at 2.83V, and impedance is pretty low (between 3 and 6 ohms). I have included baffle step and diffraction in the simulation.

[cosmindaniel12]

And the speakers are now complete. They sound great on classical music and jazz, but the tweeter is still a couple of dB too loud for rock, or other styles. I'll try some more different resistors, to find something that suits my very small and reflective room.
They were designed for a medium-large living room, but for the moment I use them in a small room (around 200 sq ft).

Cell phone pictures:

[Juhazi]

Not necessarily THE mini monitor! I really hope that you'll find a big room for these some day.

[cosmindaniel12]

A bigger apartment is one of my short-term plans.

[Juhazi]

Not necessarily THE mini monitor! I really hope that you'll find a big room for these some day.

[cosmindaniel12]

I have changed the tweeter and mid attenuation, moved the speakers around the room, found their best place in the room, and now I'm absolutely happy with them.

Final crossover:



Out of curiosity, I measured them using HOLMImpulse and my old mic, bonus for an ASUS motherboard:



The mic measures surprisingly linear. If I'm measuring the drivers independently, I get results within 2 dB from the simulation. The down side is that it only measures to 10kHz.

Frequency Response in the listening position, 1/3 octave smoothing:



THD:



2nd HD



3rd HD



4th HD



5th HD