Gadget alert summary: inexpensive audio amp with built in micro SD mp3 player, works well as sound source for sweeps.
I’m always trying to make improvements to our sweep techniques and to find ways make our operations more efficient. Finding a compact but strong sound source to use during RF sweeps that does not drive people nuts can be a challenge (for both the sweep team and the client). A number of fellow tscm-ers have mentioned playing recordings of things like a cleaning crew with a vacuum cleaner, other office sounds, or just music. The goal, though, is to have a playback device that is compact and fast and easy to set up. I have seen guys take an iPod, mp3 player, or even their cell phone and connect it to a remote speaker. That can do ok, but it adds an extra step and extra wires to make the connections (hope you don’t get an incoming call while using your cell phone). It can also be a bit cumbersome when moving the sound source from room to room.
An additional challenge has been that the sound needs to be strong enough to trigger any voice operated microphones. That needs to be fairly loud. Sampled “office” sounds are difficult to make the proper volume and vacuum cleaner or machine sounds could drive anyone crazy in a short period of time. Music is always a good bet, as long as you have something worth listening to. Ideally I would like to select an appropriate sound source depending on the client environment. Classical music, acoustic guitar, techno, or my favorite is to play various informative pod casts. Many of them last up to an hour on quite a variety of topics. Occasionally I actually learn something from them while sweeping.
So to do that, my wish has been to find a small, decent mp3 player WITH a built in speaker with robust audio.
Out with the old:
The first item I found was known as the Dream Box. It basically did what I wanted but had a few problems. The size was good, smaller than a TV remote, and a micro SD card for mp3 files. Problems were: a.) there was no display to know what mode you were in; b.) the volume control tended to get stuck in an ever increasing or ever decreasing position – the volume would grow until it maxed out, or would decrease until it was zero- i.e. constant fiddling required; and c.) there were a few other unneeded options that sometimes got turned on by accident- so without a display someone unfamiliar with the unit could not figure out how to reset it. My other techs complained about that. The Dream Box has now apparently been discontinued anyway, as I cannot find them for sale any longer.
The new item: Monoprice (the well known discount importer) has a unit, sold as a 5 W Guitar Amp, that also takes a micro SD card for playing mp3 files, has an LED display for seeing which file you are on along with playback time, and the audio can be quite loud.
This unit is much larger than my earlier Dream Box device, but for what it offers I think it will be my player of choice.
Some other features include an easy to use volume knob. It is an actual rotary potentiometer with on-off switch. Simple for any new-be tscm tech to figure out. There are multiple audio input jacks- 1/8″ sub mini jacks for Mic and Aux, as well as a 1/4″ phone jack for a guitar input. Since the unit is actually sold as a portable guitar practice amp, the guitar input has level and tone controls but they do nothing for the mp3 playback.
- headphone, aux in, mic in jacks
There is also a record mode. The idea being that you can record your guitar playing and play along with yourself, or play along with an mp3 music track.
What this means for us, is that the unit can double as an back up amp for audio testing. Add some alligator clips, battery, and maybe a capacitor for isolation and you can use it testing wires for mic audio. It also has built in belt clip to use hands free.
Micro SD memory card for mp3 playback- and for recording audio.
- Belt clip (cheap plastic) and lanyard loops
Volume and audio quality is good and loud. The build is fairly solid, but clearly made with inexpensive Chinese Monoprice plastic. The battery is integral to the unit and cannot be removed. Battery gets charged by a mini USB jack, the same jack that connects to PC for reading the SD card. There are no screw holes for disassembly, so if you want to hack into it you may have to do some damage.
The micro SD card lets me keep many different types of recordings in a very small space. I picked up a holder that stores 8 micro SD cards with a regular SD adapter in the size of a credit card. That way I can have multiple styles of recordings at my fingertips, to please even the most discerning client or tscm technician.
Price is just $30.23, so I’ll probably end up with two or three. Oh, and if you play electric guitar, you can also use it for that, but probably not during a sweep.