Related Manuals for ROSTEC LMA8
Summary of Contents for ROSTEC LMA8
- Page 1 Phone +45 3967 6438 Fax +45 3966 6438 Website www.rostec.dk E-mail rostec@rostec.dk LMA8 Mic/Line Preamplifier ROSTEC LMA8 8-channel Professional Mic/Line Preamplifier Revision 5, March 23, 2016...
-
Page 2: Table Of Contents
LMA8 Mic/Line Preamplifier General description Contents………………………………………………………..…. 1 Features ………………………………………………………..2 General description ……………………………………………… 2 Inputs and outputs……......……………………… 2 Insert points……………......……………………… 2 Simplified signal flow............... 3 Operational description Instrument/line inputs..……….……........4 Insert points ………...….……........... 4 +48 V Phantom Voltage………………….…………....4 Input gain adjust....………………….…………....5 Status indicators……………….…………………………….. -
Page 3: Features
The 8 instrument/line inputs are placed at the front panel General description for easy access and use 1/4" standard Jack connectors The LMA8 is an 8 channel ultra low noise and ultra low Switching between line input and mic input is automatic. distortion mic/line preamplifier designed with the When no Jack is plugged into the front connector, the professional sound engineer in mind. -
Page 4: Simplified Signal Flow
LMA8 Mic/Line Preamplifier... -
Page 5: Operational Description
LMA8 Mic/Line Preamplifier Operational description Insert point switch The toggle switch controls the bypass function of the insert point. The insert point exists electrically between the output of the preamp and the input of the digital module. When the LED is ON, the signal chain between the preamp and the digital module is “open”... -
Page 6: Input Gain Adjust
LMA8 Mic/Line Preamplifier Status indicators Input gain adjust These LEDs are status indicators for the digital interface module (USB or AES) and for Power Good. Turning the knob controls the input gain from minimum to maximum in one smooth movement. No clicks and no SYNC indicates a solid lock to the incoming word clock. -
Page 7: Mic Inputs
LMA8 Mic/Line Preamplifier Analog inputs (mic inputs) Analog outputs (line outputs) The analog input D-SUB connector is for the microphone The analog output D-SUB connector is for the balanced inputs. The maximum input is +30dBu. The input line outputs. The output buffers are of industrial grade impedance is 6 kohm transformerless balanced floating configuration. -
Page 8: Direct Inputs
LMA8 Mic/Line Preamplifier Direct input Digital interface slot The analog input D-SUB connector is for the balanced This is the slot for the optional digital interface module, direct line inputs to any installed digital module. shown here with the USB module installed With no digital module installed, the connector is inactive The inputs are electronically balanced. -
Page 9: Remote Ground Connection
"receive" the environmental noise. This additional noise signal is fed into the balanced input of the LMA8 at the negative input terminal, canceling out the noise signal at the positive terminal without affecting the sound signal from the instrument. -
Page 10: Front And Back Panel Quick Guide
LMA8 Mic/Line Preamplifier Front and back panel quick guide... -
Page 11: Mechanical And Electrical Specifications
LMA8 Mic/Line Preamplifier Mechanical and electrical specifications Dimensions with rack mounts: Width 19 inch, height 1U (44 mm), depth 210 mm Dimension as desktop: Width 420 mm, height 42 mm, depth 210 mm Weight: 5.0 kg Power: 180 - 253 VAC, 50-60 Hz, 15 Watts... -
Page 12: Technical Section
Impulse response The above snapshots show the ideal step impulse response of the LMA8. When subjected to at steep transient (in this case a step impulse with 5 nsec rise time), there is no ringing and no overshoot. There is only total control. The amp does NOT produce any signal itself when subjected to transient material. -
Page 13: Unwanted Hf Feedback
But not to worry; LMA8 has a mechanism in place to prevent such unwanted HF feedback. HF oscillation in complex studio installations is prone to occur when both gain and frequency response is high. The LMA8 uses a well established technique that employs a "constant gain/bandwidth product" function. In short; it works by reducing the upper frequency response when the gain is increased. -
Page 14: Noise Performance And Crosstalk
LMA8 Mic/Line Preamplifier Noise performance and crosstalk Input noise The graph shows the spectral density of the input noise by measuring with a sweeping 1/3 octave bandpass filter across the audio range. The input was terminated by 150 ohms and the gain was set to max (+70 dB) The noise spectrum is linear and smooth from 1 kHz and up and exhibits the typical characteristics of white noise. - Page 15 LMA8 Mic/Line Preamplifier Crosstalk The graph shows crosstalk between adjacent channels. A +16 dBu signal was sent to channel 1, gain setting +10 dB. The output level of channel 1 was +26 dBu. The input of channel 2 was terminated by 150 ohms, and the signal level was measured at the output of channel 2.
-
Page 16: Classical Distortion Analysis
The standard analysis of distortion in audio circuits has traditionally been "Total Harmonic Distortion + Noise". This method has only limited usefulness in this case, because the distortion of the LMA8 is so low, that it is masked by noise at higher gain settings. - Page 17 LMA8 Mic/Line Preamplifier Distortion + noise at +30 dB gain The THD+N is below 0.0008 % in the whole audio range. The measured THD+N result is very close to linear from 20 Hz - 20 kHz The input noise contribution at +30 dB gain corresponds to a level of approx. 0.0007 %.
-
Page 18: Fft Distortion Analysis
LMA8 Mic/Line Preamplifier FFT distortion analysis FFT analysis has the ability to detect distortion that is buried in the noise. Noise is a statistical phenomenon, and by reading several samples and adding them together, the FFT analysis is able reduce the noise to its average value, thus revealing the distortion components otherwise buried in the noise. - Page 19 LMA8 Mic/Line Preamplifier Gain +20 dB, frequency 1 kHz. The rms sum of all distortion components (THD) is 0.00014 %...
- Page 20 LMA8 Mic/Line Preamplifier Gain +30 dB, frequency 1 kHz. The rms sum of all distortion components (THD) is 0.00015 %...
- Page 21 LMA8 Mic/Line Preamplifier Gain +40 dB, frequency 1 kHz. The rms sum of all distortion components (THD) is 0.00025 %...
- Page 22 LMA8 Mic/Line Preamplifier Gain +50 dB, frequency 1 kHz. The rms sum of all distortion components (THD) is 0.00045 %...
- Page 23 LMA8 Mic/Line Preamplifier Gain +60 dB, frequency 1 kHz. The rms sum of all distortion components (THD) is 0.00118 %...
Need help?
Do you have a question about the LMA8 and is the answer not in the manual?
Questions and answers