Glen Trew Posted May 16, 2011 Report Share Posted May 16, 2011 Thank you, Ethan. Tom- Mike's explanation is essentially correct. One just connects the loops of wire in series so that, with multiple passes around the room or performance area, such a large length of wire is accumulated that impedance is raised sufficiently that the amplifier can run without risk of "shorting." In practice, I think it may be difficult to achieve 4 Ohms but most professional amps will operate without harm into a 2 Ohm load. Of course, best to check with the manufacturer before hooking up that wire. David If you use a 100' of small gauge wire for the induction loop, it would probably be difficult to get a 4 ohm load on the amp output. I've done it with many different amp types, high-end and not so high-end, and always had good results and there was never any damage. Regarding what playback equipment to use, in inexpensive Mac or PC notebook with Audacity (free download) will take care of most anything that doesn't need complex on-the-fly editing, for which you would want to hire a protools playback specialist who has their own gear. I've done tons of playback with Audacity and a computer, including special needs such as pull-up, 2x and 1/2x speed, etc, etc. Glen Trew Quote Link to comment Share on other sites More sharing options...
wolfvid Posted May 16, 2011 Report Share Posted May 16, 2011 i HAVE SOME LIBERTY BATTERY (or AC) POWERED SPEAKERS FOR SALE THAT ARE FINE FOR MEDIUM SIZED AUDIENCES. More info and pix at http://wolfvid.com/datasheets/Specials.pdf Quote Link to comment Share on other sites More sharing options...
cjh Posted May 17, 2011 Report Share Posted May 17, 2011 oh the comedy of online posts, I just spent the last half hr writing a reply to this thread only for it all to vanish when I had to re-login to publish it :-) In brief: 95% of my playback needs are covered with the use of a small system that is part of my standard kit, a macbook running Audacity (free online) and 2 x Acoustic Research "Powered Partners" which are small wedge shaped active spkrs that run off 12V. I get about 2 days worth of run time from one 65Whr v-lock battery, for their size and portability they sound the best I have heard from anything similar and they are very solidly built. I use them daily for onset Dir comms, dialogue and music playback, running them from a IFB Rx means no cables to worry about and repo'ing is very easy. The only time I need a bigger system is on very large stages or outdoors when there is high BG noise, wind etc and then prod just hires a bigger active spkr for those days. There is a valid point for having a bit more oomph available when doing playback for singing if the actor is a less confident vocalist as it helps them a lot, I tend to be doing the opposite for now which is running the playback low or using earpieces and recording clean enough tracks to be mixed into the prerecorded stuff, well that's how it's supposed to work! The only time I hire in big rigs is for bands or night club type scenes and then my first call is to talk to the art dept as they often need something for visual use and with a little prep communication you can kill 2 birds. The AR Partners are pretty hard to find (AR stopped making then in the 80's) but do come up second hand, you'll most likely need to re-cone them which I did to mine, easy enough and parts available online with a bit of google searching. Also try looking for "Advent AV570's" which I think are copies still being made and also pretty good though I've never heard them. Great post from RVD, I've never used a thumper but it would def be good for BG dance/dialogue scenes. Regards, Chris. Quote Link to comment Share on other sites More sharing options...
John Blankenship Posted May 17, 2011 Report Share Posted May 17, 2011 ...and 2 x Acoustic Research "Powered Partners" which are small wedge shaped active spkrs that run off 12V. I get about 2 days worth of run time from one 65Whr v-lock battery, for their size and portability they sound the best I have heard from anything similar and they are very solidly built... ...The AR Partners are pretty hard to find (AR stopped making then in the 80's) but do come up second hand, you'll most likely need to re-cone them which I did to mine, easy enough and parts available online with a bit of google searching. Also try looking for "Advent AV570's" which I think are copies still being made and also pretty good though I've never heard them. I agree they're really nice sounding speakers. Actually, the Advent AV570 speakers are not copies, they're the same speaker as the Acoustic Research AV570, but were renamed when the company was sold (the name is now owned by Audiovox). The only difference between the two models is the name and the knobs. http://www.amazon.com/AV570-70-Watt-Powered-Multimedia-Speaker/dp/B00005LACB I own several sets of these, under both names, and often use them as auxiliary speakers to my larger ones. I've even deployed them as P.A. speakers when only a small amount of reinforcement was called for. I sometimes use one as a cart speaker when I need cart playback. They'll run off of either AC or DC. Quote Link to comment Share on other sites More sharing options...
Colin Heath Posted May 17, 2011 Author Report Share Posted May 17, 2011 Thanks everyone! This all has been helpful to me. Now i just have to land the gig. Crosses fingers. Quote Link to comment Share on other sites More sharing options...
Tony Johnson Posted May 17, 2011 Report Share Posted May 17, 2011 http://twistedwave.com/mobile Hi for those interested here is a very cool app for iPad for playback , very similar to Audacity and it works very well . Tony Quote Link to comment Share on other sites More sharing options...
TomBoisseau Posted June 17, 2011 Report Share Posted June 17, 2011 If you use a 100' of small gauge wire for the induction loop, it would probably be difficult to get a 4 ohm load on the amp output. I've done it with many different amp types, high-end and not so high-end, and always had good results and there was never any damage. Regarding what playback equipment to use, in inexpensive Mac or PC notebook with Audacity (free download) will take care of most anything that doesn't need complex on-the-fly editing, for which you would want to hire a protools playback specialist who has their own gear. I've done tons of playback with Audacity and a computer, including special needs such as pull-up, 2x and 1/2x speed, etc, etc. Glen Trew How many conductors should there be in this "inductive loop" cable? Tom Quote Link to comment Share on other sites More sharing options...
Glen Trew Posted June 17, 2011 Report Share Posted June 17, 2011 How many conductors should there be in this "inductive loop" cable? Tom You could do it with just one conductor. One end is connected to the + and the other end comes back and connects to the -. gt Quote Link to comment Share on other sites More sharing options...
studiomprd Posted June 17, 2011 Report Share Posted June 17, 2011 How many conductors should there be in this "inductive loop" cable? Tom while it maybe possible to use only one conductor in an inductive loop, many amplifiers will not be happy, as even 100' would seem almost like a short-circuit to the amplifier output... most amplifiers need at least a 2 Ohm load... Quote Link to comment Share on other sites More sharing options...
Jeff Wexler Posted June 17, 2011 Report Share Posted June 17, 2011 This is a little confusing but the last time I made an induction loop I made it based on what was once described as a snake chasing it's tail. Take a 100' multi-conductor (lets say 4 conductor) cable and strip the conductors on both ends. We'll call it end no. 1 and end no. 2. Take the red conductor on end no. 1 and connect it to the blue conductor on end no. 2. Then go back to end no. 1 and connect that blue conductor to the yellow conductor on end no. 2. Back to end no. 1, connect the yellow conductor to the green conductor on end no. 2. Once you have made all the connection in this "loop" you take the free conductors, the two of them (whatever color they are!) and connect them to the amp. What you have done is effectively taken 100 feet of cable and made a 400 foot loop of wire with it. This presents a reasonable load to the amp. Quote Link to comment Share on other sites More sharing options...
John Blankenship Posted June 17, 2011 Report Share Posted June 17, 2011 This is a little confusing but the last time I made an induction loop I made it based on what was once described as a snake chasing it's tail. Take a 100' multi-conductor (lets say 4 conductor) cable and strip the conductors on both ends. We'll call it end no. 1 and end no. 2. Take the red conductor on end no. 1 and connect it to the blue conductor on end no. 2. Then go back to end no. 1 and connect that blue conductor to the yellow conductor on end no. 2. Back to end no. 1, connect the yellow conductor to the green conductor on end no. 2. Once you have made all the connection in this "loop" you take the free conductors, the two of them (whatever color they are!) and connect them to the amp. What you have done is effectively taken 100 feet of cable and made a 400 foot loop of wire with it. This presents a reasonable load to the amp. That sounds like a winning way to do it. You've created a coil with four loops -- nice technique. I imagine unshielded cable would be called for. Of course, as you know, that depends upon the gauge of the conductors. For instance, if the conductors were 24 gauge, with 400 feet you'd have a load of about 10 ohms which should work fine with about any power amp. If you used 20 gauge conductors, you'd have about a 4 ohm load which, with most professional amps, would work well, too. I'd try to stay within that range. Quote Link to comment Share on other sites More sharing options...
TomBoisseau Posted June 19, 2011 Report Share Posted June 19, 2011 This is a little confusing but the last time I made an induction loop I made it based on what was once described as a snake chasing it's tail. Take a 100' multi-conductor (lets say 4 conductor) cable and strip the conductors on both ends. We'll call it end no. 1 and end no. 2. Take the red conductor on end no. 1 and connect it to the blue conductor on end no. 2. Then go back to end no. 1 and connect that blue conductor to the yellow conductor on end no. 2. Back to end no. 1, connect the yellow conductor to the green conductor on end no. 2. Once you have made all the connection in this "loop" you take the free conductors, the two of them (whatever color they are!) and connect them to the amp. What you have done is effectively taken 100 feet of cable and made a 400 foot loop of wire with it. This presents a reasonable load to the amp. Thanks for the clairification Jeff. I certainly understand the need for an adequate load to make the amplifier happy however, I was wondering if by having "more" conductors would yield a stronger induction field? Additionally, can someone give me some hints on how to build my own induction neck loop? I have a couple of the Phonak induction ear pieces, but am short one neck loop. Of course they can be purchased for $90, but that just seems like to much for what they are. Thanks, Tom Quote Link to comment Share on other sites More sharing options...
John Blankenship Posted June 19, 2011 Report Share Posted June 19, 2011 Thanks for the clairification Jeff. I certainly understand the need for an adequate load to make the amplifier happy however, I was wondering if by having "more" conductors would yield a stronger induction field? Additionally, can someone give me some hints on how to build my own induction neck loop? I have a couple of the Phonak induction ear pieces, but am short one neck loop. Of course they can be purchased for $90, but that just seems like to much for what they are. More loops might work better, but you'd need to go with smaller gauge conductors so's not to put too much of a load (too low an impedance) on the amp. You can often find the neck loops used for much less than that -- check the used items at the "usual suspects" (Coffey, Trew, Location, Professional, Gotham, etc.) Quote Link to comment Share on other sites More sharing options...
Philip Perkins Posted June 19, 2011 Report Share Posted June 19, 2011 Thanks for the clairification Jeff. I certainly understand the need for an adequate load to make the amplifier happy however, I was wondering if by having "more" conductors would yield a stronger induction field? Additionally, can someone give me some hints on how to build my own induction neck loop? I have a couple of the Phonak induction ear pieces, but am short one neck loop. Of course they can be purchased for $90, but that just seems like to much for what they are. Thanks, Tom I've done it both ways and didn't notice any difference in the strength of the field or any damage to the amp, so I made it easy on us and just used a single strand for the loop. It worked great with the old Phonak and PSC bugs. YMMV. Do some tests before your gig! phil p Quote Link to comment Share on other sites More sharing options...
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