– Voltage level: +/- 0.3 V resolution
– Sampling rate: 8 kHz
– Distortion Filters: 6 dB bandwidth of up to 1 kHz.
– Sample Rate: 200 samples per second with an optional resolution up to 50 Hz
– Calculation algorithm: The Linear Signal Combining (LSC) algorithm, which is the same algorithm used in professional analyzers
– Memory function: You may save a 4096 bytes long memory trace.
– Measurement period: You may choose any period between 1/16 of a second and 5 seconds.
– Output: A BNC connector for hardware test
– Input: Mic Input and Line Input for hardware test
– PCB: PC104 606
– Dimensions: 93mm by 73mm (B&W)
– OS Compatibility: Windows 2000 SP4 / XP SP2 / Vista SP1 / Windows 7SP1 / Windows 8
8/1/2014 08:55 PM
I’m writing this from the qrpf.net forum (
If you have any questions or want to know more, please let me know.
8/1/2014 08:58 PM
I have an analog distortion meter, but I’d be happy to upgrade to a digital one.
8/1/2014 09:01 PM
I have an analog distortion meter, but I’d be happy to upgrade to a digital one.
8/1/2014 09:02 PM
You don’t have to run out and buy one, or upgrade your existing analog meter.
You can get excellent results out of a free open-source software program called “FFT Demo” (File -> Open… -> FFT Demo).
I’ve used this program to test my audio gear and I haven’t purchased a digital distortion meter yet.
It’s available at:
8/1/2014 09:04 PM
I’m not quite sure what you mean by “sounds” as I dont know what you have
The RoMac Digital Distortion Meter Torrent Download is able to analyze your sound card’s distortion product signals. These levels are usually not visible by sound card monitor or oscilloscope screens. However, when they exceed your defined threshold, the sound card will try to lower the distortion to protect the audio system. In order to accurately measure the distortion levels and protect your listening system from self imposed distortion products, the RoMac Digital Distortion Meter automatically removes these artifacts. The Digital Distortion Meter’s ability to measure audio signals is based on the fact that a sine wave does not produce distortion products. Audio signals that do produce distortion products are most commonly a combination of sine, square, and saw tooth waveforms. These distortion products usually exceed the bandwidth of most sound cards. The Distortion Meter tests the band limited signal that the sound card passes to an audio amplifier. The Distortion Meter can be used to test either one or both channels of a sound card.
The Digital Distortion Meter can measure all types of distortion products such as multiple harmonics and IMD products. Audio Application Scenario 1: The Digital Distortion Meter can be used in conjunction with other Audio Signal processing tools to test a wide variety of audio system components. For instance, one might use the Distortion Meter to test the final output stage of audio amplifiers and Headphones. Amplifier design work can be greatly aided by testing the audio system before building and installing a new audio amplifier. The Distortion Meter will detect excessive distortion products caused by one or more of the amplifier’s internal components. Thus the Distortion Meter can detect a problem before it is too late and before the amplifier is built, tested, installed and operating. The Distortion Meter can be used simultaneously with the other tools on the other audio system components under test. The Digital Distortion Meter can be used to test both channels of a sound card. Audio Application Scenario 2: The Distortion Meter can be used to test the Audio Equalizer functions on a sound card. After the test, it can be used to easily dial in the EQ settings again. Audio Application Scenario 3: The Distortion Meter can be used to test the output stage of a Sound Card. It can also be used to determine if the sound card’s DAC level control has been adjusted too high or low. Audio Application Scenario 4: The Distortion Meter can be used to test the tone control functions on the sound card. Audio Application Scenario 5: The Distortion Meter can be used to test the volume controls on a sound
1. Frequency: 20 Hz – 15000 Hz
2. Resolution: +/- 13 Hz
3. Sweep Time: 1 Second
4. Wave Type: Sine
5. Test Signal: Amplified
6. Test Resolution: +/- 13 Hz
7. AutoLock: Yes
8. Input: Mic and Line
9. Output: Mic and Line
10. Output: Line In and Line Out
11. Input Strobe: Yes
12. Input Toggle: Yes
The new Logical Limit design from Motorola is not only “More Stable” but now it has “Robustness” to boot. The M0x4LMT and M0x4MMT make use of a new patented Multi-Mode Multi-Channel Low Noise Amplifier (LMNA) technology that boosts rejection to well above those of other amplifier technologies.
LMNA amplifiers reject common mode noise, such as those generated by nearby electrical devices and people. In addition, LMNA amplifiers dynamically adjust to line voltage and line signal levels, rejecting noise in a real-time manner. The result is a more robust amplifier that can withstand environments where ambient noise is particularly noisy, such as environments with many people or electrical devices near the amplifier.
Signal-to-Noise Ratio (SNR) measurements at different settings for high and low power modes, compared to a leading competitor’s amplifier measured with the same test signal and conditions, is shown below. The M0x4LMT and M0x4MMT provide SNR of 40dB or greater at all settings.
M0x4LMT: Average Line, Low Power: -54.0dB (SNR: 44.6dB)
M0x4MMT: Average Line, Low Power: -53.9dB (SNR: 46.9dB)
M0x4LMT: Average Line, High Power: -52.5dB (SNR: 42.5dB)
M0x4MMT: Average Line, High Power: -52.6dB (SNR: 41.5dB)
M0x4LMT: Average Line, High Power: -51.7dB (SNR: 41.3dB)
M0x4MMT: Average Line, High Power: -52.4dB (SNR: 41.1dB)
*Measurements are uncorrected.
*Measurement results may be incorrect if the measurement frequencies are too close to the carrier frequencies.
*Each measurement is an estimate of the distortion product, and is given in decibels to two significant figures.
*The distortion products will fall off at higher frequencies.
*The distortion products are allowed to pass through the measurement circuit in the audio path of the sound card.
*Up to four complete measurements can be saved to EEPROM for later use.
*Programming Counter will keep track of all frequencies and their corresponding signal level measurements.
*Test Frequency and Sweep Time (SMTP) is automatically written to the EEPROM at the end of the measurement.
*The level indicators will allow the sound card to not overload the audio path.
*The functions of the input audio signal and level indicator will allow for a normal audio system.
*Hooking up of the sound card’s audio input or output is not required.
*The computer must have a SoundBlaster compatible sound card and be in the PC compatible computer operating system.
*The software must be loaded into the PC via a floppy disk.
*The SoundBlaster must have a valid hardware DMA channel.
*The software may be loaded via a floppy disk.
*The Sound Blaster must be assigned to channel 2 or 2 channel devices may not work correctly.
*Reprogramming the EEPROM’s will allow the software to operate on PC’s with a different sound card.
*RoMac Software has dedicated a lot of research and development time to the creation of this product.
RoMac Software developed this software to be affordable to the Amateur Radio community and the audio experimenter. We hope that it will enable Amateur Radio Exceptions to operate on a budget.
*Below are the line graphics which are the Distortion Meter.
Figure 1 – RoMac’s Distortion Meter
Figure 2 – The Menu System of the Software
Figure 3 – Distance and Sweep Time
Figure 4 – Max Distortion Detection at 25ms
Figure 5 – Max Distortion Detection at 50ms
Figure 6 – Max Distortion Detection at 75ms
Figure 7 – Line Graph – Input Signal + Distortion
Figure 8 – Line Graph – Distortion Signal + Output Signal
Figure 9 – Draw Graph
Figure 10 – Draw Graph with Distortion Filters
Figure 11 – 12 – Audio Function Generator
Please note that the BOSS GP/SLIV are HARD! They are INTENSE! They are STRAIGHT AHEAD! They are UNFORGETTABLE! No this is not a typo or an error in the press release. The word INTENSE should be used to describe the BOSS GP/SLIV.
There is a third of a second of setup time from the start of the race to the player’s foot leaving the gas and breaking traction. The BOSS GP/SLIV are HARD! They are INTENSE! They are STRAIGHT