I previously built Valeria, a compact bookshelf speaker using pro-audio drivers, namely a 6.5" mid-bass and a 1" horn-loaded compression driver. The dynamics offered by this small speaker are impressive, if I may say so myself. It’s currently serving as the center channel in my home theater.
Lately, I’ve been thinking of building speakers with better bass response (a subwoofer will still be necessary though) and improved horizontal and especially vertical directivity. This necessitated using an 8" mid-bass driver, a compression driver that rolls off below 1 kHz, and a horn that can control directivity better than the B&C ME10 I used in Valeria.
The mid-bass driver I selected for Valkyrie is the Lavoce WAF082.00. It has a 2" voice coil, a paper cone, and a cast-aluminum basket. The compression driver, Lavoce DF10.171K, features a 1.75" voice coil and a polyimide diaphragm. As for the horn, I decided to use the RCF HF101, a cast aluminum horn with relatively compact dimensions, which is important to minimize driver-to-driver spacing and consequently improving vertical directivity.
I designed a compact cabinet with internal bracing that couples to the drivers, making the drivers part of the brace and reinforcing the front and rear sides of the cabinet.
The braces were made of 16 mm beech plywood. I attached the braces to the cabinet walls with 3M VHB tape instead of regular wood glue. The soft layer in between acts as constrained-layer damping to reduce resonances.
I decided to use a 3rd order LP and 2nd order HP for the crossover along with two notch filters for the compression driver. The crossover frequency is approximately 1 kHz.
It’s critical to add absorption material to manage the reflections and standing waves that form inside the cabinet. I lined the walls with felt and placed extra-thick 60 mm pyramid foam on top while leaving enough space for the drivers.
Pictured below: Valkyrie standing next to Valeria. Valkyrie’s dimensions are 24 x 42 x 21.5 cm (WxHxD), while Valeria measures 19 x 33 x 22.5 cm (WxHxD).
So, how is the sound? By itself, the bass is lacking, as expected. However, as soon as you add a subwoofer to the mix, the missing low-end is filled in, and what you get is effortless dynamics throughout the entire frequency range assuming the subwoofer can keep up with Valkyrie at higher volumes.
In listening tests, it’s immediately apparent that, compared to Valeria, the bass is considerably louder and deeper below 200 Hz. Otherwise, they’re well matched.
The impedance plot looks clean, with the exception of a resonance at around 300 Hz. This appears to be inherent to the mid-bass driver’s construction, as the free-air impedance measurements of the driver show it as well, albeit not as pronounced. The nominal impedance is 6 ohms dipping to 4.4 ohms at 210 Hz.
The frequency response is within ±3 dB from 100 to 20,000 Hz (quasi-anechoic measurement). The mid-bass to compression driver crossover frequency is quite low at 1 kHz to help make vertical directivity well behaved. A subwoofer is necessary for good bass response.
The horizontal directivity is ±45 degrees nominal, smooth down to 800 Hz. Below that frequency, the directivity quickly becomes omnidirectional. Thanks to the uniform directivity, the frequency response can be equalized without any issues.
The vertical directivity is ±35 degrees nominal, and it’s smooth down to a respectable 1200 Hz. As long as your ears aren’t below around 15 degrees of the horn’s center axis, the timbre of the speaker shouldn’t change noticeably regardless of where you sit or stand.
Last but not least, a complete build video is available below. Please let me know what you think.
Lately, I’ve been thinking of building speakers with better bass response (a subwoofer will still be necessary though) and improved horizontal and especially vertical directivity. This necessitated using an 8" mid-bass driver, a compression driver that rolls off below 1 kHz, and a horn that can control directivity better than the B&C ME10 I used in Valeria.
The mid-bass driver I selected for Valkyrie is the Lavoce WAF082.00. It has a 2" voice coil, a paper cone, and a cast-aluminum basket. The compression driver, Lavoce DF10.171K, features a 1.75" voice coil and a polyimide diaphragm. As for the horn, I decided to use the RCF HF101, a cast aluminum horn with relatively compact dimensions, which is important to minimize driver-to-driver spacing and consequently improving vertical directivity.
I designed a compact cabinet with internal bracing that couples to the drivers, making the drivers part of the brace and reinforcing the front and rear sides of the cabinet.
The braces were made of 16 mm beech plywood. I attached the braces to the cabinet walls with 3M VHB tape instead of regular wood glue. The soft layer in between acts as constrained-layer damping to reduce resonances.
I decided to use a 3rd order LP and 2nd order HP for the crossover along with two notch filters for the compression driver. The crossover frequency is approximately 1 kHz.
It’s critical to add absorption material to manage the reflections and standing waves that form inside the cabinet. I lined the walls with felt and placed extra-thick 60 mm pyramid foam on top while leaving enough space for the drivers.
Pictured below: Valkyrie standing next to Valeria. Valkyrie’s dimensions are 24 x 42 x 21.5 cm (WxHxD), while Valeria measures 19 x 33 x 22.5 cm (WxHxD).
So, how is the sound? By itself, the bass is lacking, as expected. However, as soon as you add a subwoofer to the mix, the missing low-end is filled in, and what you get is effortless dynamics throughout the entire frequency range assuming the subwoofer can keep up with Valkyrie at higher volumes.
In listening tests, it’s immediately apparent that, compared to Valeria, the bass is considerably louder and deeper below 200 Hz. Otherwise, they’re well matched.
The impedance plot looks clean, with the exception of a resonance at around 300 Hz. This appears to be inherent to the mid-bass driver’s construction, as the free-air impedance measurements of the driver show it as well, albeit not as pronounced. The nominal impedance is 6 ohms dipping to 4.4 ohms at 210 Hz.
The frequency response is within ±3 dB from 100 to 20,000 Hz (quasi-anechoic measurement). The mid-bass to compression driver crossover frequency is quite low at 1 kHz to help make vertical directivity well behaved. A subwoofer is necessary for good bass response.
The horizontal directivity is ±45 degrees nominal, smooth down to 800 Hz. Below that frequency, the directivity quickly becomes omnidirectional. Thanks to the uniform directivity, the frequency response can be equalized without any issues.
The vertical directivity is ±35 degrees nominal, and it’s smooth down to a respectable 1200 Hz. As long as your ears aren’t below around 15 degrees of the horn’s center axis, the timbre of the speaker shouldn’t change noticeably regardless of where you sit or stand.
Last but not least, a complete build video is available below. Please let me know what you think.
