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-   -   microphones (https://www.dvinfo.net/forum/canon-xl1s-xl1-watchdog/317-microphones.html)

bovongsak November 11th, 2001 04:25 AM

microphones
 
Anyone know of any decent microphones that utilize the RCA jacks on the XL1 or do I have to by the MA 100/Shoulder pad? I know professional mikes have XLR jacks but can I avoid this big cost?

Paul Robinson November 11th, 2001 04:33 AM

I'm trying to get around this problem by making my own Balanced XLR connector to unbalance RCA connector. It just consists of an opamp with a split power supply. I'll tell you how it goes. I'm following one of the circuits you can find here.... http://www.tagmclarenaudio.com/members/news/news28.asp

bovongsak November 11th, 2001 04:38 AM

keep me updated.

Don Palomaki November 11th, 2001 07:48 AM

For about $20 you can buy an balanced to unbalanced matching transformer, about the size of a large cigar. They usually provide XLR to 1/4" phone or RCA conections. You can run a RCA cable from it to the XL1. Best place to find one is at a store that caters to musicians or professional audio. MARS Music is a nation wide chain that has them. So do many electronics parts outlets. Be sure to get one that does 600-to-600 ohms (or close to that ratio). Warning: The units I've seen at Radio Shack are mainly 600-to-50k ohm and may not give satisfactory results. Some brands I've seen have a switch and will do both 50k-to-600 and 600-to-600.

You can buy an adapter for about $7 that connects an XLR balanced to unbalanced, but then you loose much of the noise cancelling property of the XLR connection.

Note that the MA-100 gives an additonal 6 dB of gain, no gain is provided by the $20 adapters.

Paul Robinson November 11th, 2001 09:55 PM

Yeah, I considered a transformer arrangement, but unfortunately you tend to get quality degredation. My op-amp arrangement shouldn't cost more than 20$ for the circuit, though on top of that is the XLR connectors and the like.
By just changing a few resistor values 6db will be easy enough to achieve.... we're talking about extrememly small signals here.

Don Palomaki November 12th, 2001 11:31 AM

Paul. FWIW, that is what the guts of the MA-100 are, an electronic implementation executed with op amps, probably 4 per channel. At a street price well under $200, in a package designed to work with the XL1. Hard to justify a do-it-yourself approach if time has real value other than for the fun of building one.

Profesional quality matching transformers should give good results - more than adequate for all but the most critical music recording.

Paul Robinson November 12th, 2001 10:08 PM

Well double the price and thats what you buy them for here in New Zealand, our curency isn't that strong against the US at the moment, so a device that costs 20$us to make compaired to 180$us I think is pretty good savings, especially when the support you get with the MA100 isn't very good to begin with, might as well make a sholder support as well.
Theres no reason they'd have 4 op-amps per channel, you'd just use 2 TL072's which are low noise dual amps, and theres your 4 channels. They cost around $1.00 each.
If you can make something of satisfactory quality yourself, that costs a lot less and does exactly the same job, I think you're a bit nutty not to give it a go.
But having said that, I agree that there are soem things that are better just bought, for instance a wireless mic setup :). To make a proper diversity UHF setup would cost more than buying a nice professionally made one methinks.

Don Palomaki November 13th, 2001 09:31 PM

Actually there is reason to use multipel op amps per channel but that goes into circuit design.
Again, if one's time is worth money - better to buy. For talkingpurposes, assume takes on the order of 8 hours to build a decent substitute for the MA-100, counting design, hunting down parts, making the circuit board, assembling it in a decent looking package, testing, mountng it somewhere, and so on. If time is worth US$20 per hour, and US$20 for the parts (that sounds cheap), we are at the price of an MA-100. But as a recreational/hobby exercise or to occupy otherwise available time it is a money saver.


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