AB2CD
Sun, 15 Nov 2009 18:45:17 -0800
Hey folks! I have struggled to find the right combination of settings for my 5K. Plagued with what some have described as crackling, crossover distortion, incorrect biasing, I have some observations to share. BTW I heard the same artifacts that many say are characteristic of the Flex. Although I agree, It's not too difficult to adjust to get it sounding spectacular. For what it's worth:
1) The Flex (for better or for worse) has its own mind when it comes to audio leveling, compression and ALC. Use it! You can't turn it off and using outboard compression creates a host of problems no one needs. 2) The balanced input can be overdriven with line levels approaching +4dbm. I suggest -10 dbm if you are using an outboard preamp/EQ 3) The input of the Flex is electronically balanced. Using both a 1:1 audio isolation transformer and a RF ferrite filter worked very well for me. The RF filter is easily made with some magnet wire and a split ferrite bead. 4) If you do use a transformer, you don't need to go crazy with a Jensen. A $20 Hammond 145B will work just fine. Enclosing both the ferrite filter and the 145B in a Bud box provides an additional level of RF shielding. 5) Be sure to terminate the Flex side of the transformer with a 600 ohm resistor. The Flex input Z is 50K. Without the resistor the transformer will not have a very flat curve. 6) Use the leveler. It works very well. Mike gains of 10-15 will provide great drive and lot's of punch to your signal. 7) Watch the Mic level! It doesn't need to constantly peak at 0. In fact, if you run the mic gain too hot, your audio will be crappy. Let the leveler and the Flex do its thing. 8) If you are running a microphone straight into the Flex, you might want to terminate the mic with a resistor to match its suggested load Z. An 1/8 watt resistor should easily fit inside the mike plug. If I'm not mistaken, the Flex Mike input is also 50K and if not terminated correctly, the mike (like the transformer), will not accurately replicate its response curve. My suggestion is to load the mike and use an EQ to adjust the response. 9) Finally, I went with a 96 KHz sampling rate and large audio and DSP buffers. I can't say for certain that this helped but it sure seemed to. A fellow Flex owner suggested I post my experiences to help others. Please except my suggestions in the spirit they are offered. It may be that next week will bring a different configuration but for now things are sounding the best they have since I had my Flex. If I can be of any help please don't hesitate to contact me directly. It will my pleasure to help you. Jim _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ Message delivered to arch...@mail-archive.com