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Robb · #9 01-30-2012, 05:49 PM

Quote:

Originally Posted by Whiplash-265

Quick question for you Robb if i might?

600ohm stock handheld mic (as per stats on the FT-950)

replacement mic Audio-Technica ATM61HE (i see entry level Heil mics are 1000ohm)
ELEMENT Neodymium Dynamic
POLAR PATTERN Hypercardioid
FREQUENCY RESPONSE 50-18,000 Hz
OPEN CIRCUIT SENSITIVITY -51 dB (2.8 mV) re 1V at 1 Pa
IMPEDANCE 600 ohms
OUTPUT CONNECTOR Integral 3-pin XLRM-type

will be using the new Heil CC1-XLR-Y-BAL cable (to eliminate a history of rf)

600=600 so should be no issues correct?
i'll be using the radios internal dsp for now

No problemmo with 600 ohm mic impedance, Marty.

Whiplash-265 · #10 01-30-2012, 06:19 PM

thanks tons Robb!!!! appreciate the sharing of your knowledge and experience

The Bruce · #11 08-19-2012, 10:59 PM

Question... and this is assuming you're not bypassing the radio's preamp:

Wouldn't the current coming out of either a preamp or mixer need to be reduced in order to be plugged directly into the radio's microphone connection (mic level vs. line level)?

I'm worried that I might fry a radio.

Robb · #12 08-20-2012, 01:41 AM

Quote:

Originally Posted by The Bruce

Question... and this is assuming you're not bypassing the radio's preamp:

Wouldn't the current coming out of either a preamp or mixer need to be reduced in order to be plugged directly into the radio's microphone connection (mic level vs. line level)?

I'm worried that I might fry a radio.

Sure it can fry the radio's mic preamp if you have it too high to start with. Start by turning the mic gain on the radio down all of the way - first. Then, turn up the external preamp to the 10 or 11 o'clock position. Then slowly turn the mic gain on the radio up ever so slightly until you see the radio's meter moving when TXing. Be aware that moving it just a little bit will go a long way and too high may fry the radio's mic preamp.

One can also use an isolation transformer between the external preamp and the radio's mic input. This will also eliminate hum and isolate the signal between the radio and the preamp.

The whole idea is to get clean gain from a clean amp and mic; not to get the sound distorted/over-driven. Otherwise, the whole game is lost.

The Bruce · #13 08-20-2012, 07:30 AM

Quote:

Originally Posted by Robb

Sure it can fry the radio's mic preamp if you have it too high to start with. Start by turning the mic gain on the radio down all of the way - first. Then, turn up the external preamp to the 10 or 11 o'clock position. Then slowly turn the mic gain on the radio up ever so slightly until you see the radio's meter moving when TXing. Be aware that moving it just a little bit will go a long way and too high may fry the radio's mic preamp.

One can also use an isolation transformer between the external preamp and the radio's mic input. This will also eliminate hum and isolate the signal between the radio and the preamp.

The whole idea is to get clean gain from a clean amp and mic; not to get the sound distorted/over-driven. Otherwise, the whole game is lost.

By isolation transformer, would you be talking about something like W2IHY iBox?

Supposedly, it takes the line-level current and attenuates it back down to mic-level (along with eliminating hum/noise).

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