Stereo Clipper 15KHz LPF. Stereo audio clipper with active 15KHz filters

Transcription

1 Stereo Clipper 15KHz LPF Stereo audio clipper with active 15KHz filters Dimension (L x W x H): 62mm x 50mm x 15mm FMB stereo audio clipper with active 15KHz filters, is an audio board with professional class sound quality. It has been designed for use with audio limiters and compressors to eliminate overshoots and filter out all unwanted harmonics above 15KHz. It also combines analogue and digital techniques to use the best of both worlds. Features Unbalanced audio inputs Adjustable gain Designed for use width audio limiters / compressors Soft audio clippers Kristal controlled 15KHz switch cap audio filters Clean spectral output Low noise operational amplifiers Rev Page 1 from 6

2 Product description FMB stereo audio clipper with active 15KHz filters, is an audio board with professional class sound quality. It has been designed for use behind audio limiters and compressors to eliminate overshoots and filter out all unwanted harmonics above 15KHz. It also combines analogue and digital techniques to use the best of both worlds. Input amplifers: To be able to use a wide range of input levels, there is a preamplifier to set the right level for the audio clippers. For correct operation adjust the input level with the variable resistors to a point just before you can see the led light up, you should not hear the clippers in the audio, if you do, re adjust. About Clipping: To limit overshoot from analogue audio limiters or compressors or just to clip your audio, use the on board soft clip clippers to create a clipped audio signal. These clippers are soft clippers because they keeps round edges for a less digital sound. It also helps to keep your audio within 75KHz bandwidth. 15KHz filters: To be sure that audio and harmonics from the clippers does not exceed the 15KHz audio limit, we added two Maxim Integrated crystal oscillator controlled switch cap filters. These switch cap filters keep your audio below 15KHz and suppress the 19KHz from your audio with more than 55dB. Spectrum output of 3 cases Case 1: Output spectrum from a not clipped audio sweep from 20Hz to 20KHz with an 15KHz filter. Rev Page 2 from 6

3 Case 2: Output spectrum from a clipped audio sweep from 20Hz to 20KHz without an 15KHz filter. Case 3: Output spectrum from a clipped audio sweep from 20Hz to 20KHz with an 15KHz filter. Case 1 & 3 are plots from this clipper board with crystal oscillator controlled 15KHz switch cap filter. Case 2 is from a different clipper product without filter. In the 1 st and 3 rd case there is not a noticeable difference in output spectrum while in the 2 nd case, the clipped audio generates a lot of unwanted harmonics. Only the spectral output of case 1 & 3 should be used for broadcast transmissions. This is the reason we designed this product. Rev Page 3 from 6

4 Overall Electrical specifications min typ max Power supply Volt DC Supply current 280 ma DC Audio specifications Input impedance 10 K ohm Input level 0 +6 dbu Output impedance 1 K Ohm Output level 0 dbu Signal to noise ratio db Output 18KHz -50 db Output spurious >20KHz -60 db Overall absolute maximum rating Symbol Parameter Value Unit Vs Power supply 18 V dc Is Supply Current 350 ma dc Tstg Storage Temperature Range 0 / +60 C TC Operating Temperature 50 C Rev Page 4 from 6

5 Connections & settings Connections and settings explained input Unbalanced audio input, Connect your hot signal to the input pole and solder your shielding to the GND pole. Clipper on/off To limit overshoots from an audio limiter board or other audio compressor connect a short to these pins. Use of the soft clippers can also be used to optimise your audio compressing or keep your audio within 75KHz bandwidth. Gain adjust Adjusts input level to the correct clipper level V DC V DC input ( always use a DC regulated power supply) GND System ground ( = 0V ) output Unbalanced audio output, Connect your hot signal to the output pole and solder your shielding to the GND pole. Note: This pcs board has to be built in a metal or aluminium enclosure with a proper ground connection. Use metal standoffs, screws and bolds to connect the board at least 5mm above the bottom of the enclosure and use all 4 holes in the corners. For audio connections, use a good quality shielded audio cable. Connect audio shielding to the ground connection closest to the hot connection. Rev Page 5 from 6

6 IMPORTANT NOTICE FMBROADCASTPARTS RESERVE THE RIGHT TO MAKE CHANGES TO THE PRODUCT(S) OR INFORMATION CONTAINED HEREIN WITHOUT NOTICE. FMBROADCASTPARTS ASSUMES NO RESPONSIBILITY FOR ANY ERRORS WHICH MAY APPEAR IN THIS DOCUMENT. WARRANTY INFORMATION APPLICABLE TO THE PRODUCT IDENTIFIED HEREIN IS AVAILABLE UPON REQUEST. NOTHING CONTAINED HEREIN SHALL CONSTITUTE A WARRANTY, REPRESENTATION OR GUARANTEE OF ANY KIND. FMBROADCASTPARTS EXPRESSLY DISCLAIMS ALL OTHER WARRANTIES, EXPRESS AND/OR IMPLIED INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY, AND OF FITNESS FOR A PARTICULAR PURPOSE, USE OR APPLICATION. WARNING FMBROADCASTPARTS PRODUCTS ARE NOT INTENDED FOR USE IN LIFE SUPPORT APPLIANCES, DEVICES OR SYSTEMS. USE OF A FMBROADCASTPARTS PRODUCT IN ANY SUCH APPLICATION WITHOUT WRITTEN CONSENT IS PROHIBITED. No part of this document may be copied or reproduced in any form or by any means without the prior written consent of FMbroadcastparts. Rev Page 6 from 6