Peer Reviewed by Gary L. Zandstra: Rolls MA2355 stereo mixer/amplifier; Price: $320 MSRP
Peer Reviewer: Gary L. Zandstra, CTS, sales and marketing manager, Parkway Electric and Communications, Holland, MI. Parkway Electric and Communications specializes in developing customized communications packages, including improving local computer networks, voice-based client solutions, cabling infrastructure, fire alarms, and security systems, and supplies AV, telephone systems, unified messaging, and VoIP systems.
Rolls MA2355 stereo mixer/amplifier, $320 MSRP
What I Like About It:
The Rolls MA2355 mixer/amplifier offers a big bang for your buck. It's easy to configure — when preassembling the racks, our installers only had to set a couple of dip-switches and wire up the unit.
The product's terminal connectors for the speakers also made it easy to make the final speaker connections in the field.
I Would Change:
I would add variable level on ducking to the MA2355, which would allow for the system to be set so that ducking levels could be set to sound more natural when the teacher speaks over program material. In addition, a smoother ramp up and ramp down rate would also help it sound more natural.
Where I Used It:
Byron Center Public School, Byron Center, MI. The MA2355 is the mixer/amplifier for the school's AV systems in 100 classrooms.
Input Impedance: 600 ohms XLR balanced (mic); 22K ohms RCA (source); 22K ohms 1/4 -inch TS unbalanced (insert)
Max Input Level: -14 dBV mic level max (mic); 24 dBV (source); 24 dBV (insert)
Connectors: (2) XLR, (6) stereo RCA, (3) 1/4 -inch TRS, (1) 1/4 -inch TS
Phantom Power: +12 VDC
Max Gain: 60 dBV (mic); 26 dBV (source)
Tone Controls: + 12 dB, 100 Hz bass, + 12 dB, 11 kHz treble
Noise Floor: - 80 dBV
S/N Ratio: 96 dBV
Priority Attenuation: 60 dBV
Recommended Load: 8 ohms
THD: 0.06 percent typical
Power: 120 VAC, 50 to 60 Hz
Weight: 5.5 pounds
Dimensions: 19 x 1.75 x 5 inches
On this Byron Center Public Schools project, we were challenged with providing audio playback, microphone support for both teacher and student wireless microphones, the ability for the audio playback to duck when the teacher is talking, and the ability to have all of the inputs mute when a page or announcement takes place over the school intercom system.
When we first started the design of this project, we looked at using a mixer and a separate amplifier. While the concept looked great and the school loved the functionality, the price wasn't in its budget.
The school was very interested in the teacher being able to talk over all of the various inputs, so that control of the content and classroom discussion could be facilitated. As a design team, we were worried about the teacher showing a video clip on industrial processing (with audio playback reaching levels of 95 to 100 dB) and having an emergency page from the school's paging system go by unheard.
As our design progressed, I had a discussion with Rolls about our concerns. Together, we came up with the idea of putting an inline transformer on the 25 V paging line to bring it to a line level signal to go into the mixer, giving it priority over all of the other sources. By doing this, the teacher could shut off the local mixer, and the page could still be heard over the school intercom system.
Rolls then proceeded to modify an existing product to create the MA2355 mixer/amplifier. The ducking, muting, amplifying mixer/amplifier unit can serve many functions in many different applications. The results were the successful deployment of more than 100 of the MA2355s throughout the Byron Center Public School.
The final classroom configuration consisted of an IP-controlled video scaler/switcher, a handheld wireless microphone (student) and a headworn wireless microphone (teacher), DVD/VHS combo unit, ceiling speakers, and the MA2355. The ducking is effective when showing video clips with audio because the teacher can add valuable spoken information over the existing audio program.
The muting works well, too. It recently enabled a “lockdown” at the school to happen flawlessly. When the page came over the school intercom, the classroom audio system muted so the page could be clearly heard and understood.
Overall, the school was very happy with the price, performance, and value that the Rolls MA2355 mixer/amplifier was able to provide.