![panasonic wm-61a calibration file panasonic wm-61a calibration file](https://cdn.head-fi.org/a/11318390.png)
The approximate voltage gain from the external input is shown on the SPL range switch. Figure 1 also shows its frequency response. The old “A” and “B” responses were found to be generally unsuitable in practice and the ITU-R ARM is suggested as a replacement for both. Its use is still favored for subjective sound measurements especially at high SPLs. The “C” response attenuates the low and high frequencies (see Figure 1). The flat response is ☑ dB from 20 Hz to 20 kHz and is primarily set by the microphone cartridge rather than the amplifier.
![panasonic wm-61a calibration file panasonic wm-61a calibration file](https://www.mvaudiolabs.com/wp-content/themes/yootheme/cache/press_chamb_old_mic_schematics-582b3664.png)
There are three frequency weighting responses as selected by a front-panel rotary switch: FLAT, “C,” and ITU-R ARM. The spectrum analyzer amplitude value is the same as the displayed SPL. Although the display label is “Peak,” the reading is the mean or average SPL. But at each switch position the display has a 40-dB range (–34 to 6 dBu) so the overall SPL range is 16 dB (50 – 34 on the lowest range) to 136 dB (130 + 6 on the highest range). The useable range is about 30 to 136 dB because of the inherent noise in the amplifier circuit. This is the measured SPL when the graphic display MODE is set to “Peak dBu-Meter” and the reading is 0 dBu. The sound pressure level (SPL) front-panel rotary switch is numbered 50 to 130 dB in 10 dB steps. The lower (green) curve is the ITU-R ARM. The upper (yellow) curve is the “C” response. The external input impedance is 47 k and it is DC coupled.įigure 1: The Model 527’s weighting responses are shown. It has a built-in electret condenser microphone (ECM) and an external input to a female Bayonet Neill–Concelman (BNC) connector as selected by a left-side mounted toggle switch. The Velleman kit uses enough power (75 mA) that I think internal batteries are not practical. (It may or may not be a TDL Technology product.) The cast aluminum enclosure measures 6.73” × 4.76” × 2.17.” An addendum with full-size drawings, more photos, a parts list, and wire lengths is available at A 24-VDC wall power supply-or an external battery pack for operation away from power mains-powers the sound level meter. I opted to call my design the Model 527, because I wanted to keep track of all the drawings and photos. To convert the kit into a useful test instrument, I designed and built a sound level meter (see Photo 1). Photo 1: The completed Sound Level Meter includes a shaped aluminum microphone holder. The only specification that I may dispute is the “easy panel mounting,”but I will discuss that in more detail later.
#Panasonic wm 61a calibration file manual
(The voltage and spectrum analyzer modes have the same dynamic range.) The LCD shows the input as a bar graph and as numeric values. It also has a Setup Menu (a “long” press on the Mode switch) for language selection, auto, or manual range selection, display contrast, and so forth. More importantly, it has a 40 dB dynamic range, which means the voltmeter modes have a 15.5-mV-to-1.55-V (–34 to 6 dBu) RMS and peak range. Its sensitivity is –34 dBu which is equal to 15.5 mV RMS. It has a front-panel push-button Mode switch with six selections: Peak power, RMS power, mean (or average) voltage in decibels (dB), peak voltage in dB, linear audio spectrum (20 Hz to 20 kHz) and one-third-octave log audio spectrum (band centers from 31 Hz to 16 kHz). Originally published in audioXpress, December 2013įirst, I will review the specifications so you will know what the audio analyzer kit can do.
![panasonic wm-61a calibration file panasonic wm-61a calibration file](http://www.johncon.com/john/wm61a/graphics/wm61a-small.jpg)
It comes with a 15-page assembly manual and a user guide, which can be downloaded from the Velleman website. I found it easy to build and thought it would be useful in a project.
![panasonic wm-61a calibration file panasonic wm-61a calibration file](http://drc-fir.sourceforge.net/doc/figures/drc054.png)
It is a barebones kit with no enclosure or power supply, but for the price, it is very versatile. I designed my sound level meter and spectrum analyzer, the Model 527, around a Velleman Audio Analyzer kit (K8098).