Designer:

Taylor Hansen

Project Category:

Bookshelf Speakers

Project Level:

Intermediate

Project Time:

20+ Hours

Project Cost:

$100-$500

Project Description:

Piano studio monitors

Design Goals:

These loudspeakers were built with one application in mind: nearfield studio monitors for an upright piano. They needed to be accurate and articulate to extract each instrument out of the mix clearly, without the need of excessive volume. They also needed to be decoupled from the piano’s vibrations, sit at ear level, and fit the top of the piano. Challenges to overcome would be insetting a rectangular driver, obtaining a smooth off axis response with a large diaphragm tweeter, and completing a full HVLP spray paint job from start to finish.

Driver Selection:

Dayton Audio PT2C-8 Planar Tweeter
Dayton Audio RS150P-4A 6″ Woofer

Enclosure Design:

The ported enclosure resulted with a net internal volume of 0.5 cubic feet and was tuned to 45Hz. Port alignment was first simulated in winISD based on DATS measured T/S parameters of the RS150P-4(s) – later verified in the enclosure with DATS and OmniMic measurements. 3D modeling was completed in SketchUp, and CutListOptimizer helped minimize waste when breaking down a 4’ x 8’ x ¾” MDF sheet.

Crossover Design:

A 3rd order low pass filter and a damped 3rd order high pass filter were implemented, along with a shunt resistor in parallel with the tweeter to lower its Fs. This produced a smooth driver and phase integration at 2.5kHz, resulting in a nice deep reverse null. Minimum impedance only reached 4.1 ohms, making this safe for (most) 4 ohm rated amplifiers. The crossover components used were Dayton Audio 10W 1% resistors, Dayton Audio 20AWG Air Core Inductors, and Audyn 400V metalized polypropylene foil capacitors. Layout was first drafted by pen and paper, followed by a 3D model to ensure the crossover boards would fit inside the base of the enclosures. All components were secured with Zip Ties to the 3/8” MDF crossover boards, and connections were soldered beneath the board. Risers were later added to help mount the board to the enclosure.

Tips & Tricks:

The 0.25mH inductors I needed were backordered, so I ordered 0.3mH inductors instead. I unwound the coils slowly, measuring after each loop until I hit 0.25mH. It’s a great way to keep your project going without significant redesign. Remember, DATS still has the capability to measure resistors, inductors, and capacitors!

Conclusion:

These nearfield studio monitors look and sound incredible on my piano. Their contemporary aesthetics, characterized by a modern white finish and bold black accents, contrasts strikingly with the classic woodgrain of the piano and the warm glow of the tube amplifier. The planar tweeters pull an exceptional amount of detail from the mix, allowing for clear discernment between instruments – even at low to moderate listening levels. With a near seamless transition to the 6” woofer, the system exhibits tight cohesiveness from top to bottom – digging deeper than one may expect. The boundary reinforcement from the rear wall makes the bass surprisingly substantial, and results in a remarkably enjoyable experience, even without a subwoofer. These loudspeakers met all the requirements needed for their specific application, and have completely exceeded my personal expectations for the system. I’m very proud of these loudspeakers, and am excited to continue using them daily.

About the Designer:

Taylor Hansen is an electrical engineer specialized in power electronics for the aerospace industry. He has found that speaker building is a great way to couple his professional skills with his many hobbies such as fine woodworking, home theater, and live sound reinforcement. When not tinkering with electronics in the lab or sanding MDF in the shop, he can often be found serving as a pianist for his local church in Fort Wayne, Indiana. But perhaps most importantly, Taylor finds fulfillment in his wife and son, who serve as constant sources of motivation and love.

Project Parts List: