Hi Dwayne, Comments within! On Mon, Jan 7, 2013 at 7:26 AM, Dwayne Reid wrote: > What you describe is something that I do regularly. One of my hobby > jobs is doing live audio (at our local football stadium) as well as > doing RF (wireless mics & wireless intercom) *and* production > intercom for both live TV broadcasts and large live events. For > example, the last large Intercom job that I did (late last summer) > was for the film crew doing a 3D movie with the rock band Metallica - > that was an RTS Adam digital-matrix system with just shy of 100 users > on wired and wireless headsets plus an additional 45-50 users on two > channels of half-duplex 2-way radio on something like 18 channels of comm= .. My intercom systems aren't usually that large, unless there's a film crew (broadcast or DVD) present. I'm lucky in that it's usually only one channel, simple Clearcom partyline. > Something that both myself and my users find very important is the > concept of spacial separation when monitoring multiple channels of > comm. One of my buddies does audio for live broadcast TV - he often > sets up several small (Fostex) speakers above and in front of him > (top left and right corners of the room) as well as at his feet and > behind him. This lets him identify which channel of comm > instructions are coming from - which lets him decide what to > ignore. He can't wear a headset when he is mixing live audio, which > makes the little comm speakers vitally important for him to do a good job= .. I do something similar, but on a smaller scale. In my right ear is an in-ear monitor. It's custom molded to my ear, so blocks external sound. It's fed from the audio system. In my left ear I wear a filtered earplug to drop the noise level down to something my ears can handle safely, then my intercom headset over that. If I've got my work kit with me, I use my Sennheiser headset. Radio is just a speaker mic held close to my ear before the show, and I usually give up once we start as I'm unlikely to hear it. I can tell when something said comes from the intercom or through the in-ear system based on which ear it appears in. > I regularly monitor 2 or 3 audio sources when I'm in front of my > intercom panel at the stadium - a walkie, the intercom headset and > program audio. But I cheat - I wear an IFB earbud from my 2-way > radio in my left ear, then have the intercom headset over top of that > ear. My right ear is either open (so that I can talk with people > coming into the audio booth) or has one side of Sony 7506 headphones > over it with program audio and/or monitor audio from the Wireless Mic > receiver racks. Both headsets get tossed when I have to go run and > deal with a problem but the radio earbud stays in my left ear. Thankfully I don't often have to wander. When I do, my in-ears are usually fed wirelessly. My intercom has to come off though. I'm working on a short range wireless solution so that I'm not dragging any wires, but that's on hold for the moment. > Can I suggest that you try using an IFB earbud in your ear for your > 2-way radio? You might be pleasantly surprised at how well it > works. The earbuds that I use come from Audio Implements (USA) - 125 > Ohm clarifiers with an air-tube to an accordion-style bud. Audio > from the intercom headset speaker has no problem getting past the > earbud into my ear. For what its worth, I'm using a Beyer-Dynamic > DT-108 single-muff headset when I'm sitting at that intercom panel. I find that I have to keep a filtered ear plug in my ear, mainly to knock down crowd noise, but also to keep the intercom from damaging my ear. Often someone will key in at an inopportune moment and their mic will pick up a lot of noise. I'd be hesitant to take that part of the equation out. > For Motorola radios, at least, you can get speaker-mics that have a > 3.5mm earphone jack. That works well with the 125R Audio Implements > IFB earbuds. I would assume that Kenwood and Icom (and other 2-way > portable radios) have similar speaker-mics available. I mostly work > with Motorola HT-750 radios. I usually use the same radios, and those are the speaker mics that I went through rather quickly. It seems that the earphone jack went intermittent rather quickly, which is a huge hassle. We only carry so many spares, so I ran out of them quickly too. > If you find the earbud to be too uncomfortable for long periods of > time, I've recently started using a small headset instead of the > earbud. Unfortunately, I don't recall the names (manufacturer and > model) of the unit - but I can find out. Its small enough that the > Beyer headset fits right over top of it. This headset replaces both > the speaker-mic and IFB earpiece. I used it for the first time last > season and quite like it so far. I'd be interested to know more about what you're using, if you get the chan= ce. > You can try the mixer approach - I've got a small PCB that mixes 4 > in-coming mono signals into a stereo output that I could send to you > (if I can find them - they were for Broadcast Talent boxes that I > built more than 20 years ago). These cards have individual dip > controls as well as pan controls - the dip controls dim each incoming > audio channel by an adjustable amount when that channel's dim control > signal is active. The card runs from a single +24V supply but will > probably work down to 12V. It uses TL072 and TL074 op-amps, which > limits how low the supply voltage can be. Interesting. What activated the dip circuit in its original application? > I hope this helps and I'd love to hear more about what you do. Everything helps! I tend to focus mainly on lighting, but I also do video, and general design. Josh --=20 A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .