The Seriphus is a sealed enclosure, powered subwoofer that employs the Peerless 10" CSC-X (850146) woofer with a Parts Express 250W plate amp that is intended to be used as a speaker stand with a side firing woofer. The PE plate amplifier has a built in 6dB bass boost at 30Hz which compensates for the natural rolloff of the Peerless woofer and extends the bass response. The Peerless woofer sells for around $64 and the PE plate amplifier usually sells for around $130 which puts the total cost including building materials well under $250 per subwoofer. This design is intended for primarily for music use because the 10" CSC-X woofer is not a true subwoofer and is not made to handle home theater level bass signals. However the Peerless woofer offers excellent performance as a music subwoofer and provides deep, tight bass at a low cost.


Peerless 850146: 257 SWR 39 115 SDX 4L AL (10" CSC-X Woofer)
The CSC-X line of woofers have many innovative features. The Composite Sandwich Cone improves accuracy and consistency of sound reproduction over the entire frequency range, creating a more musical driver. Enlarged basket windows minimize rear deflection interference. The new Linear Restoring Force spiders maintain consistent frequency response over the entire power range - even at the lowest volumes. Inverted, non-reflecting dustcaps minimize distortion created from edge interference.
High-end 10" woofer with a 5 layer "Sandwich" cone, extra heavy magnet, extra long 4 layer coil and distortion killer shortcirquit ring in the magnet system. This gives exceptionally good linearity and very deep and clean bass. Also, remark the very smooth response.This CSX 10" woofer is recommended for very versatile use in closed as well as vented boxes. In a reflex box of 100 ltrs. with tunings around 23 Hz it keeps level down to 30 Hz. A remarkable characteristic is the very robust extra thick iron plate basket with a nice structure lackering.

Parts Express 250W subwoofer amplifier w/6dB bass boost @ 30Hz (#300-796)
High power Class AB amplifier
Variable phase adjustment
Rumble Filter
Bass Boost
Gold plated connectors
High pass filter for satellite speakers
Auto On/Off
This high performance amplifier has all the power and advanced features that you have been looking for! The adjustable phase control provides flexibility in subwoofer room placement. It allows the user to "shift" the phase and fine tune the subwoofers output to their particular room environment. Until now, this feature was only found on high-end subwoofer systems costing thousands of dollars!
Specifications: Measured power output: 180 watts RMS into 8 ohms @ .1% THD, 272 watts into 4 ohms @ 0.2% THD. Signal to noise ratio: 101dB (A-weighted). Dimensions: 10-3/8" W x 10-7/16" H x 3-1/4" D. Enclosure cut out: 9" W x 9-1/4" H. Voltage: Selectable, 115/230V, 50-60 Hz, 450W. Net weight: 12 lbs.

Cabinet Design

The Seriphus cabinet measures 24"x10"x16" (HxWxD) which gives it an internal volume of almost 40 liters with the internal bracing taken into account. The woofer is placed near the floor while the plate amplifier is located on the upper part of the opposite side. The enclosure is heavily stuffed with Acoustastuff to enhance the bass performance. The enclosure is heavily braced with several internal braces on all sides making it very acoustically dead and solid. Both the plate amp and the Peerless woofer have built in foam gaskets which insure a well sealed enclosure. The enclosure was designed to be used as a stand for a typical bookshelf speaker and has a height that puts most design's tweeters at ear height. The footprint of the Asterion design including the front grill matches the footprint of the Seriphus subwoofer perfectly which converts the bass limited Asterion into an attractive, true full range speaker.


Based on simulations, the Peerless driver yields a -3dB point of around 50Hz in this enclosure but with the +6dB boost at 30Hz the -3dB point drops slightly below 35Hz as shown in the nearfield frequency response plot below. As mentioned, the plot below reveals that the Seriphus subwoofer has a -3dB point around 35Hz and a -10dB point around 25Hz which isn't bad for a 10" woofer in a sealed enclosure. I am currently using a pair of Seriphus subs as speaker stands for my Asterions. For this configuration I plug the ports of the Asterions which converts them to a closed box design with a shallower but sooner rolloff in the bass response. I have the source amplifier speaker output signals sent to the high level inputs of each plate amp which gives me stereo bass output. I set the plate amp crossover frequency to about 100-120Hz. The subwoofer level adjustment is set a tad past the 9 o'clock position for the best blend with the Asterions output level.

Using the Asterions as satellites, the Seriphus subwoofers do a great job of extending the in-room bass response well below 30Hz which is plenty deep for most of the music I listen to. The blend between the satellites and the subs is pretty good but it can be tricky to get the levels set just right because the subwoofer amplifier level adjustment is very sensitive. The bass produced by the Peerless woofers along with the PE plate amps is very clean, tight and deep which can be attributed to the closed box design. The crossover point is low enough that the side firing location of the woofers isn't really an issue when it comes to localizing the bass notes. Considering a pair of Seriphus costs less than $500 and the Asterions cost less than $600 you'll have a hard time finding a pair of commercial speakers for under $1,100 that can compete with them.