online-shashki Forum Sound System of the Week: 140 dB of DIY

For this first-ever online-shashki Forum Sound System of the Week, I selected a system that speaks to me and gets to the heart of why I love the online-shashki Forum community so much. The fully DIY speaker system built by forum contributor Mike Masunas—aka @eng-399—is a study in how to achieve as high a price/performance ratio as possible by tapping into the knowledge found in the forums.

While discussing his current system—which was nominated by numerous other online-shashki Forum members in the DIY section—Mike noted that his journey started when he gave the surprisingly capable Behringers B215XLs (which I wrote about four years ago) a shot. He built four DIY subs to go with them (18-inchers at that!) and from that point forward, he was hooked on high-sensitivity speaker systems and DIY builds.

One thing led to another, as it often does when the AV hobby grabs hold of you. And before you know it, Mike had added “DIY speaker and sub box building” to his forum profile’s list of interests, and also found himself in possession of a system that can reach 140 dB of output.

Mike’s words

“My journey started with four Stereo Integrity HT18 D2 subs in four 20 cubic-foot boxes, each tuned to 17 Hz, and Behringer PA speakers. I decided to build the subs after reading many threads on online-shashki Forum, especially since everyone was raving about how these drivers were such a big bang for your buck. This is what got me hooked on building everything DIY going forward.”

“So, after about a year of using the HT18 drivers, I decided to embark on a complete redo of the room, especially since I enjoyed building DIY boxes so much and had seen how much money I saved versus store-bought subs. Building DIY sub boxes does take a bit of time, but in the end it’s well worth it. ”

“When I built the subwoofer cabinets for the B&C drivers I use now, I had to get to know how to use WINISD software for modeling subs, although folks not comfortable with using it will find many guys like myself are happy to help out.”

“Once you’ve worked out the enclosure, you plan out your cut list for whatever wood you decide to use which is 3/4 inch MDF for all my boxes. I use either wood glue or PL construction adhesive to attach all the panels together. I shot a few brad nails into them to hold the panels together while clamping them in place.  I also like to use my router to create 3/4 inch roundovers on the port panels, both inside and outside of the box, to reduce chuffing.”

“I’ve built around 80-100 boxes now for myself and online-shashki Forum friends and love building every one. It’s so much fun to see what you created, and able to hear the end result once completed. Once I started building DIY speaker and sub boxes, I knew I’d never buy anything from a store again; you save a lot of money doing it yourself. Plus, you have bragging rights when it’s pulled off right.”

“I think I saved well over $10,000 (to date) by taking a DIY approach. has many of the drivers all us DIY guys look at to see what kind of numbers (peak output, etc.) each one produces, and the site provides real third-party TS parameters on each driver.”

“All my other boxes followed the same approach. Now, if you are able to get a flat pack from DIYSG, it definitely speeds thing up, but I like building everything myself from scratch.”

“By the way, my calibrated mic clips at 130 dB, so I can’t get an exact reading what the room hits its peak. But, according to the speaker designer Matt Grant (aka @MTG90 on online-shashki Forum) at frequencies of around 30 Hz to 60 Hz, my system should hit peaks in the low 140 dB range. Not too bad for going DIY!”

– Mike Masunas aka @eng-399 on online-shashki Forum

The Speakers

High-sensitivity speakers have an inherent advantage when it comes to reproducing realistic levels of dynamic range, be it for music or movies. For the front L/C/R channels of his DIY speaker system, Mike went with (DIYSG) Titan 615-LX 3-way speaker kits, which sell for $542.00 each including free shipping (which is an insanely good deal, BTW).

Titan 615-LX kits consist of: One 15″ Eminence-made neo-magnet woofer ($196.36), one Celestion CDX-1731 compression driver ($139.99), one 6.5″ Eminence Alpha 6CBMRA midrange ($44.99), one Denovo 2-way waveguide ($36), one set of crossover parts: ($90.56), two 4″ Precision Port flares ($27.00), one 3/4″ thick Baltic birch CNC cut front baffle ($22), and one set of screws and gaskets ($1.50).

online-shashki Forum Sound System of the Weelk
The front L/C/R channels and 21″ subs of the first-ever online-shashki Forum Sound System of the Week.

These speakers offer jaw-dropping specifications. Sensitivity is rated a 99 dB (2.83v/1M), recommended power is 50 watts up to 2000 watts going into a 6-ohm load, and frequency response is 38 Hz to 20 kHz. That’s right… for under $600 per speaker.

Surround duties in Mike’s system are taken care of by four DIYSG HTM-10 2-way speakers. These kits cost $267.24 each, including shipping. Here’s the breakdown: 1- 10″ Eminence Deltalite driver ($120), one Denovo DNA-325 compression driver ($69.20), one Denovo SEOS-12 waveguide ($28), one set of crossover parts ($54.57), two ports: $4.50, one 1″ thick CNC-cut front baffle ($15), and a set of screws and gaskets ($1.50).

Mike’s four HTM-10 speakers that are used as surrounds.

With the HTM-10 you get a very capable speaker for the money. Sensitivity is rated a 95 dB (2.83v/1M), recommended power it 10 watts up to 500 watts going into an 8-ohm load, and frequency response is 60 Hz to 20 kHz.

This is an Atmos-capable system, after all it’s located in a home theater. But, this is not Home Theater of the Month… I’m here to just talk about sound!

For height duty, Mike chose four of the DIYSG V-6 Volt ($121.38) plus the Volt-6 angled flat pack ($18). These satellite kits each come with one custom 6.5″ coaxial driver ($63), one Denovo DNA-150 compression driver ($19.75), one crossover board ($9), one set of crossover parts ($17.36), one slot port ($2), one CNC cut front baffle ($8), one set of screws and gaskets ($.50), and the angled flat pack.

Ceiling-mounted V-6 Volts take care of elevation channel duties.

The Volt 6 has what it takes to keep up with a powerful Sound System of the Week such as this. Sensitivity is rated a 93 dB (2.83v/1M), recommended power it 10 watts up to 300 watts going into an 8-ohm load, and frequency response is 65 Hz to 20 kHz.

The Subwoofers

High-sensitivity pro-style speakers like the DIY models Mike uses typically eschew ultra-deep bass extension for added output. So, it’s no surprise that it takes a powerful collection of subs to keep up with the speakers, but this system is up to it.

This rig uses both standard and nearfield subs. The regular subs are four 18.5 cubic-foot slotted-port enclosure units tuned to 15 Hz. These use B&C 21DS115-4 drivers ($573.13) which are 21″ 8-ohm subwoofer drivers.

Just one of the B&C 21″ drivers takes up a whole kitchen table.

The B&C 21DS115-4 is a monster, capable of handling 3400 watts of power. It has a 4.5″ diameter voice coil and a 16.5mm of (one-way) excursion when operating optimally. Beastly!!!

The nearfield units consist of six Legacy Audio Xtreme XD drivers installed into two 10.5 cubic-foot slotted-port boxes, each tuned to 12.5 Hz.

Here’s a clear view of one of the two nearfield sub enclosures.

The Electronics

While the electronics are not DIY, they are necessary to bring Mike’s system to life.

Power for the passive subs comes from several Behringer iNuke units. The B&C subs get two iNuke 6000s, with each of the four subs sucking 2200 watts of juice out of a channel for a total of 8800 watts. The nearfield subs each get one iNuke 3000 running in bridged mode (two total). Combined output is in the 6000 watts range, or 1000 watts per driver.

A Marantz SR7010 AVR acts as the surround processor for this rig, an Emotiva UPA 700 7-channel amp  (80 watts per channel) powers the surrounds while a Carvine DCM20004L 4-channel, 500 watt-per-channel amp takes care of L/C/R duties. Three AC Infinity rack fans keep things cool.

Finally, Mike uses a miniDSP processor to handle all the delay, filters, and levels for the subs.

Congratulations on your system being chosen as the first-ever online-shashki Forum Sound System of the Week, Mike.


online-shashki Forum members, are you proud of your stereo or surround-sound system? Here’s your chance to show it off at its best. Whether you are into two-channel systems, multi-channel surround-sound, or 3D immersive audio, you are invited to submit your system for consideration. Please click here to find out more.

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