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Post by Raccoon on Feb 22, 2021 13:13:01 GMT -5
I have a couple of vintage tube CB radio's here that I've talked about here on the forum before . They both have their stock mics , but I was wondering what mics would be the best to wire up , and use with them ? One is my Lafayette Comstat 23 , and the other one is my Kris 23 + . I know they both use the same wiring code , I was just wondering what mics are the best match up for these 2 radios .  |
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Sandbagger
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Post by Sandbagger on Feb 22, 2021 19:12:42 GMT -5
I have a couple of vintage tube CB radio's here that I've talked about here on the forum before . They both have their stock mics , but I was wondering what mics would be the best to wire up , and use with them ? One is my Lafayette Comstat 23 , and the other one is my Kris 23 + . I know they both use the same wiring code , I was just wondering what mics are the best match up for these 2 radios . Tube radios usually mate up well with unamplified D104's. If you want a little more kick, and you don't have a Demco modulator lying around, you can also use an amplified D104. |
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Post by Raccoon on Feb 23, 2021 10:27:28 GMT -5
That's what I thought too ... but when I put my amplified Gray Base on my tube radios , I was told that it sounded "Tinny". I mean "Maybe" the mic element in the mic is bad , but it sounded ok to me when it was on my Pearce Simpson Bengal.
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Sandbagger
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Post by Sandbagger on Feb 23, 2021 17:15:05 GMT -5
That's what I thought too ... but when I put my amplified Gray Base on my tube radios , I was told that it sounded "Tinny". I mean "Maybe" the mic element in the mic is bad , but it sounded ok to me when it was on my Pearce Simpson Bengal. I used an amplified D104 on my Lafayette Comstat 25 and it never sounded tinny. I would suspect that there may be cathode bypass or coupling electrolytic capacitors in the audio stage that may have opened up, or changed value, if the response is "tinny". Try a couple of other mic's and see if they are all tinny. If so, I'd look for bad caps. |
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Post by Polycomm on Apr 23, 2021 16:37:05 GMT -5
The original D104 mic is a high impedance element that wants to see 5meg to 10meg on the grid input of the first audio stage. If the grid resistor is lower the mic looses lows and results in a tinny sound.
The original amplified D104 gray base (TUG8, TUG9) have a little amp inside that the mic element sees as low impedance. So by design the amplified D104 does not have the deepest low response that the element is capable of providing. Now 50 years later there are replacement amps for the amplified D104 mics that are high impedance input so that the mic element performs well. From there its a matter of what your radio can pass through it.
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Sandbagger
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Post by Sandbagger on Apr 23, 2021 21:18:20 GMT -5
The original D104 mic is a high impedance element that wants to see 5meg to 10meg on the grid input of the first audio stage. If the grid resistor is lower the mic looses lows and results in a tinny sound. The original amplified D104 gray base (TUG8, TUG9) have a little amp inside that the mic element sees as low impedance. So by design the amplified D104 does not have the deepest low response that the element is capable of providing. Now 50 years later there are replacement amps for the amplified D104 mics that are high impedance input so that the mic element performs well. From there its a matter of what your radio can pass through it. You can always buffer the D104 element with an FET preamp which has a high impedance input. That would work wonders toward flattening the frequency response. |
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Post by narfedwards2 on Apr 25, 2021 15:45:35 GMT -5
good idea to replace the oil filled caps and electros now before POP....
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