(Veneer is Figured Etimoe from veneersupplies.com)

Tweeter: Peerless XT25SC40-04

Waveguide: Visaton WG 148 R

Woofer: SB Acoustics SB16PFCR25-8

Dimensions: 9.5 (W) x 16.0 (H) x 11.25 (D)

Volume: Gross volume 0.65cf (18.5L)

Frequency Response (-3 dB): 52Hz to 20kHz

Sensitivity (2.83v/1m): 83.3 dB

Nominal Impedance: 8 ohms (minimum 6.9 ohms at 165Hz)

Crossover: 2,100 Hz

1. Background and Design Goals

2. Crossover

3. Measurements

4. Bill of Materials (BOM)

5. Miscellaneous

1.   Background and Design Goals

This speaker started out as an experiment of sorts. (1) I tried several “thumbnail” or “table edge” router bits to create a DIY waveguide with the Lavoce TN131.00 tweeter, and (2) I experimented with “slicing” the cone like Scan-speak revelators as explored in the popular Parts Express Tech Talk (PETT) thread How to Tame your PM180-8. I had some PM180-8s but wanted to start with an inexpensive driver. I did not originally find much about the SB16PFC woofer, but users PWRRYD and Geoff Miller spoke highly of it, and the price was right, so that settled it.

I took the speaker to InDIYana 2023 and Parts Express’ speaker design competition in 2023 and got positive feedback and decided to make a slightly easier to construct version. During this time Parts Express started carrying the Visaton WG 148 R waveguide, so I decided to go with that and switch to the XT25 tweeter, as the Lavoce is just a bit large for the Visaton waveguide (although I could have filed it down just a bit and made it work). I also decided to move to a version using just the off-the-shelf woofer and avoid slicing the cone.

I took the updated version to the CSS DIY get together in Detroit, Michigan, in the fall of 2023 and again received favorable feedback. I am quite pleased with them, and they have been in my regular speaker rotation for the last two years. They were quite inexpensive when I originally built them, but even after some global inflation the drivers and crossover parts are about $200 as of the end of 2025.

Cabinet Dimensions and Driver Placement

The cabinet is ¾-inch particle board from Menards shelving that often goes on sale for $4. All edges of the front baffle have a ¾-inch roundover. All walls except the inside of the front baffle are lined with 30mm Sonic Barrier Acousta-Blue denim fiber from Parts Express. (A few pics of the actual build are in Section 5: Miscellaneous.)

I went with an off-the-shelf Parts Express 2-inch adjustable port tube with the cabinet tuned to 42.5Hz with the port length of 4-1/4 inches. (Note, I did not need the “adjustable” portion of the PE port tube.)

2. Crossover

The crossover is LR4 at 2,100 Hz. Third-order electrical on both tweeter and woofer, with an L-pad on the tweeter, and both wired in normal polarity. See Section 5: Miscellaneous for a 3D printed xo board and point-to-point illustration.

Crossover Schematic

3. Measurements

Below are a lot of measurements that may (or may not) be interesting.

Note: SPL measurements are of the final speaker with a 2.83V signal measured at 2 meters (scaled to 1 meter SPL) and 1/24th octave smoothing. Distortion measurements are at 31.5 cm (96 dB and 106 dB) and scaled to 1-meter levels of 86 dB and 96 dB, respectively. Equipment is an Earthworks M23R microphone and Motu M2 audio interface. Impedance measurement is using a DATS V3.

4. Bill of Materials (BOM)

The BOM below shows xo components from Parts Express, as this would come with free shipping if purchased with tweeter and waveguide. However, I used components from Jule Fidelity (JF). The normal prices are great, but I got the components during their moving sale, and the prices were just ridiculously low. If you need xo components and are not familiar with JF Components, you need to get familiar with them.

5. Miscellaneous

I have gotten in the habit of designing 3D crossover boards for my builds, not only does it keeps things nice and tidy but additionally forces me to try to organize the components in an efficient manner. Everything fits easily on a 4-inch x 6-inch board. (I print the boards in ABS and have small stand-offs for the resistors since they can potentially get hot, and PLA gets soft at more modest temperatures than ABS). (HERE is the *.stl file that I used.)

3D Printed Crossover Board (Populated with JF Components Parts)

Of course, I could have just point-to-point wired the components on any 4” x 6” scrap of material.

The cabinet was made with a removeable baffle and has two “T-braces” connecting the sides and the back as well as a brace between the top horizontal brace and the top of the cabinet. All sides lined with 30mm Acousta-Blue denim damping material. The crossover was attached to the back as that was easier than putting it on the bottom and trying to work between the bottom brace and the bottom of the cabinet. Not shown, but before butting it all up, I wedged pieces of the denim material in front of the crossover and in front of the terminal posts in the bottom section.

Cabinet Lining and Bracing

To attach the tweeter to the waveguide I used the scrap piece of particle board left over from the woofer cutout and some M4 bolts from Lowe's.

Tweeter Attached to Waveguide and Woofer Hole Chamfered