microphone cable
I have a desk microphone without the cable. I need to put on a cable that is just a center conductor and shield. It will be about 3 to 4 feet long. This is a crystal mic going into a tube amplifier. As this is high impedance, is there a special mic cable ,or can I just use some rg58 or rg 8x cable without degrading the audio. It is only for communications quality speech. I know all about RF type cable, but have not ventured into the audio. |
microphone cable
In article ,
Ralph Mowery wrote: I have a desk microphone without the cable. I need to put on a cable that is just a center conductor and shield. It will be about 3 to 4 feet long. This is a crystal mic going into a tube amplifier. As this is high impedance, is there a special mic cable ,or can I just use some rg58 or rg 8x cable without degrading the audio. It is only for communications quality speech. I know all about RF type cable, but have not ventured into the audio. Ralph- I think RG cable is more than adequate for audio use, maybe "too good"! It may not be as flexible as you would like. Fred |
microphone cable
In article ,
Fred McKenzie wrote: I have a desk microphone without the cable. I need to put on a cable that is just a center conductor and shield. It will be about 3 to 4 feet long. This is a crystal mic going into a tube amplifier. As this is high impedance, is there a special mic cable ,or can I just use some rg58 or rg 8x cable without degrading the audio. It is only for communications quality speech. I know all about RF type cable, but have not ventured into the audio. Ralph- I think RG cable is more than adequate for audio use, maybe "too good"! It may not be as flexible as you would like. For that short a distance, and for speech-quality audio, I agree on both points. The flexibility of the cable may be an issue, although since it's a desk microphone that may be less of a problem. If you do want to optimize... professional microphone cables are often designed with low capacitance per foot (to minimize the degree to which the cable's shunt capacitance loads down the mic element and affects the frequency response) and low amounts of triboelectric effect (so that bending the cable doesn't generated voltages inside the insulation which are then transferred to the conductors - this can cause crackling or other noises in the audio). Most of the big cable manufacturers (Belden, Mogami, etc.) make cable of this sort. Markertek sells it, but only in bulk quantities :-( Ralph, if you want to experiment... I have a whole bunch of fancy mil-spec cable sitting in my garage from a previous project / sideline business... it's stuff like Belden 83318E. I've got some fairly thin one- and two-conductor (plus braided shield) that might work for you... it's not as flexible as rubber- or PFC-insulated of the same diameter but is definitely more flexible than RG-58 or RG-8x. I've used it for line-level audio wiring in my stereo setup, among other things. Email me directly, send me a mailing address, and I'll post you a long enough piece to try with your microphone. |
microphone cable
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microphone cable
On 8/22/18 4:00 PM, Ralph Mowery wrote:
This is for a D104 Crystal mic that is going nto an old Johnson Viking 2 transmitter . The audio quality on them is not all that great from what I understand. Only if you've been listening to the "broadcast quality" AM guys. The D104 tends to accentuate the highs. That transmitter is set up for just a center conductor and outer shield. An audio plug similar to a pl259 with the center pin just flush with the connector. Forgot what they are called. They are called an Amphenol connectors. By the way, if you want to do the PTT upgrade, that Mic connector is mounted in a 3/8" hole, so a standard 1/4" TRS jack will fit. I did not think it would matter in this case what kind of cable I used. Actually, it makes a lot of difference. The audio input on the Viking is a vacuum tube grid. And the D104 is a high impedance. As such you want to use low capacitance cable. RG-- is not low capacitance. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
microphone cable
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microphone cable
On Wed, 22 Aug 2018 12:54:50 -0400, Ralph Mowery
wrote: I have a desk microphone without the cable. I need to put on a cable that is just a center conductor and shield. It will be about 3 to 4 feet long. This is a crystal mic going into a tube amplifier. As this is high impedance, is there a special mic cable ,or can I just use some rg58 or rg 8x cable without degrading the audio. It is only for communications quality speech. I know all about RF type cable, but have not ventured into the audio. You can buy a cheap 6 foot guitar cable on ebay for under $5. Cut off the 1/4" jacks and install your own connectors. A local music store may even have an old used guitar cord and sell it real cheap. |
microphone cable
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microphone cable
In article ,
Fox's Mercantile wrote: On 8/22/18 4:00 PM, Ralph Mowery wrote: This is for a D104 Crystal mic that is going nto an old Johnson Viking 2 transmitter . The audio quality on them is not all that great from what I understand. Only if you've been listening to the "broadcast quality" AM guys. The D104 tends to accentuate the highs. That transmitter is set up for just a center conductor and outer shield. An audio plug similar to a pl259 with the center pin just flush with the connector. Forgot what they are called. They are called an Amphenol connectors. By the way, if you want to do the PTT upgrade, that Mic connector is mounted in a 3/8" hole, so a standard 1/4" TRS jack will fit. I did not think it would matter in this case what kind of cable I used. Actually, it makes a lot of difference. The audio input on the Viking is a vacuum tube grid. And the D104 is a high impedance. As such you want to use low capacitance cable. RG-- is not low capacitance. You have a point, but is the higher capacitance enough to matter for a relatively short cable? Also, has the D104 crystal element held up over time? My recollection of microphones back in the 50s, was that a crystal element eventually "dissolves" in normal humidity. The D104C ceramic version was supposed to overcome that problem. Fred |
microphone cable
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microphone cable
On 8/23/18 12:06 PM, Ralph Mowery wrote:
Again this is not hifi and 20 or 50 feet of cable whereI am sure it would make a difference. As in everything in life, you can make an attempt to do things the right way, or you can just say "**** it, close enough." You asked if there was a difference and I said that there was and why. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
microphone cable
Ralph Mowery wrote:
I have a desk microphone without the cable. I need to put on a cable that is just a center conductor and shield. It will be about 3 to 4 feet long. This is a crystal mic going into a tube amplifier. As this is high impedance, is there a special mic cable ,or can I just use some rg58 or rg 8x cable without degrading the audio. It is only for communications quality speech. I know all about RF type cable, but have not ventured into the audio. 75 ohm type would have less capacitance. Ideally you want 3 wire line. Ground common and hot. The D104 has rising peak 2-3 kHz and they sounded very intelligible to me, in fact others try to duplicate, either with electronics or other mikes with similar response. Guitar cable should also do fine. Greg |
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