Re: [Harp-L] Question on impedance and Z matching



Simply put, Low-Z is useful for long cable runs and PA systems because it's less noisy. Hi-Z is for amps and harmonica mics, where your cable is only 15 or 20 feet long. If you want to get a low-z mic to work in a tube amp, you'll have to get an impedance-matching transformer. They're available at MusiciansFriend.com., any music store, or even Radio Shack, starting at about 15 bucks.

Good luck,

Tim Dougherty
www.HarpMicGaskets.com


At 04:13 PM 2/7/2005, you wrote:


Hi, I've been lurking here for over a year just absorbing info, for which I am quite appreciative having learned a lot. I have been playing amplifed at home through my home theater system using a mixing board to get everything I want to go smoothly through that system. However, now I have acquired some tube amps and have a selection of mics and need a little info if possible. Since I'm just getting into the variations on amplified playing, could anyone set me straight on the ins and outs of impedance matching, what are considered Hi and low Z ranges, etc. Specifically, I have a tube amp that does not say what the input impedance is. The schematic shows a 63K resistor between the input jack and the amplifier circuits. Would this be the input impedance rating? If not, how do you determine this value? There is also a 1M resistor between the input jack and a ground. Next question is, if I have a high impedance mic, say 1 M ohm, what kind of impedance is needed at the amp to properly match to that? If someone can give me some advice on what is good-better-best in terms of Z matching or what is inadvisable with respect to Z matching I would be grateful. If you could also tune me in to the Z matching devices and how they should be set up that would also be helpful. I don't really understand the pros and cons of it so any info would be of benefit.

Cheers. Jon


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