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D104M6 vs D104M6

2NC995

DAN
Feb 23, 2008
2,219
4,005
273
Coastal NC
Ok, got around to testing the modified D104M6 vs the factory stock one.

Must say...differences are way more subtle than I expected.

Not exactly high speed testing here, just recorded with an iPhone.

Transmitter is my Lincoln Ii+, and receiver is a Washington. The modified mic has a 1.5M resistor in place of the 270k, and the stock D104 is straight out of the bubble pack, with proper plug attached. Volume on both is set to 3, talking about 1” from grill.

 

Pull the resistor , let the cartridge see a high impedance load from the gate of the FET. The cartridges tone will sound closer to its normal state.

I ran it without the resistor before, and found it sounded very much like the stock mic on the Lincoln..maybe ever slightly more clear.

I ended up putting the higher value in because of some reports that the clipped resistor might cause the transistor to shut down. I never ran into the problem, however.

I’m not exactly disappointed in how it sounds...just thought the difference would be more substantial. Need to compare it with a 575, and see how it stacks up the to unobtanium.
 
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To make it sound like a 575 you need to put something around the cartridge to seal it against the case front,
later 104 uses the 575 cartridge in the old style case leaving a big gap around the cartridge causing a hollow boxy colouration to your audio.
 
Thanks Bob and Shade.

I do think the second mic sounds better - slightly less nasaly, but not as much as I anticipated.

I’m going to stack it up against a 575 this week (I bit the big bullet), and then maybe try some more variations as suggested here.
 
i compared the tone modded 104 against my 575's, it sounded very much like the newer 575 with the same silver front cartridge,

my old style 575 with black front cartridge sounded a bit mellower/warmer but i only compared it against those two,

stock new style 104's sound like a hollow 575 with the tone turned up to my ears.
 
I ran it without the resistor before, and found it sounded very much like the stock mic on the Lincoln..maybe ever slightly more clear.

I ended up putting the higher value in because of some reports that the clipped resistor might cause the transistor to shut down. I never ran into the problem, however.

Yes, I found that without a resistor, the transistor did shut down with prolonged modulation.
Unkeying mic and letting it rest for a spell brought the transistor back online.
I have had this happen on 3 separate mics on 3 separate radios.
So, I installed a 1.5 Mohm in all three. All was good again for awhile.
One of the mics will start acting up again with prolonged modulation, but haven't had the issue with the other two as of yet.
 
Thanks Bob and Shade.

I do think the second mic sounds better - slightly less nasaly, but not as much as I anticipated.

I’m going to stack it up against a 575 this week (I bit the big bullet), and then maybe try some more variations as suggested here.
What did it run you?
 
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