RBtowers

3-way floorstanding loudspeaker 2x6"+5"+1"

Drivers: SB17NBAC, Scan Speak 15M4624, Satori TW29RN

Cabinets: net volume 48l woofers, BR

Sensitivity: ~90dB/2.83V/1m

Impedance: nominal 4Ω, minimal 3.2Ω na 130Hz

Frekvence -3dB: 39Hz

Client asked me to find the right drivers for those beautiful cabinetrs and to create crossovers. Due to narrow baffles I was looking for woofers with outter diameter ~170mm. From the first moment I was pretty sure I was going to use SB17NBAC. Basta modelling confirmed two of them can work very well in 48l volume. SB15 would be obvious choice for the midrange, but I was curious of 15M for a long time. For the tweeter Vifa XT25 was chosen, but during listening tests and after few crossover itterations I had to try different tweeter. Satoris were at home, and they fitted the cutouts. Quick measurement and simple crossover modification followed and I started the listening. Finally it sounded full, rich, and as one speaker.

TW29 RN

15M Discovery

2x SB17 in parallel

Crossover modelling

Whenever it is possible, I prefer using LR2 filters. It is also usually starting point for crossover modelling. As here we have straight baffle, I counted with using allpass filter for tweeter from the beginning.

LR2 filter brought very uniform off axis behaviour.