My Bach Grands were damaged by an accidental full-scale playback event, so rather than restoring them exactly to stock, I worked with Bill, a retired speaker builder in Granada Hills, to redesign them as a modern custom two-way while retaining the original Vienna cabinets.
The new drivers are an SB Acoustics SB17MFC35-4 midwoofer and a Wavecor TW030WA11 4-ohm waveguided textile-dome tweeter. Bill fabricated custom tweeter inserts, physically aligned the drivers, and designed an asymmetrical second-order crossover at approximately 2.2 kHz, allowing the tweeter to remain in normal polarity.
The crossover uses a 14-gauge Solen series coil, Jantzen, Audyn and CrossCap film capacitors, and a Mundorf copper resistor. He also removed the obsolete upper tweeter vent, repositioned the original felt damping to reduce the cabinet’s vertical standing-wave problem, and added rolled Dacron behind the woofer and remaining bass port.
Bill says the completed speakers exceeded his expectations and now disappear into the soundstage. They are no longer stock Bach Grands, but essentially a new loudspeaker built around the beautiful Vienna enclosure. I’m excited to get them home, measure them and compare them with the original design.
The new drivers are an SB Acoustics SB17MFC35-4 midwoofer and a Wavecor TW030WA11 4-ohm waveguided textile-dome tweeter. Bill fabricated custom tweeter inserts, physically aligned the drivers, and designed an asymmetrical second-order crossover at approximately 2.2 kHz, allowing the tweeter to remain in normal polarity.
The crossover uses a 14-gauge Solen series coil, Jantzen, Audyn and CrossCap film capacitors, and a Mundorf copper resistor. He also removed the obsolete upper tweeter vent, repositioned the original felt damping to reduce the cabinet’s vertical standing-wave problem, and added rolled Dacron behind the woofer and remaining bass port.
Bill says the completed speakers exceeded his expectations and now disappear into the soundstage. They are no longer stock Bach Grands, but essentially a new loudspeaker built around the beautiful Vienna enclosure. I’m excited to get them home, measure them and compare them with the original design.
