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Great Mic Sound for your CB or Export Radio-part 4

CM-4441 said:
Very good info! I will be following your suggestions ASAP. Now...what about the mobiles!:whistle:

Terry
Click to expand...

Using pro mics in a mobile can be done. I just wouldn't do it myself. Too much ambient noise being amplified in a car! Better off using a decent mobile mic. The setup I've suggested is best suited for a base station with a quiet background.

I use a RF Limited CR-577 mic in my mobile. Works better than my D-104 Minuteman II. The RF Limited Xtreme 2018 mic is similar too. Verrry clean audio . . .
 
Robb said:
Using pro mics in a mobile can be done. I just wouldn't do it myself. Too much ambient noise being amplified in a car! Better off using a decent mobile mic. The setup I've suggested is best suited for a base station with a quiet background.

I use a RF Limited CR-577 mic in my mobile. Works better than my D-104 Minuteman II. The RF Limited Xtreme 2018 mic is similar too. Verrry clean audio . . .
Click to expand...
Hey Robb,

There's a guy, Al / Art in this area running a 577 on a new 2970DX and he does sound really good...
I've wondered if it's the same element & audio amplification circuit sans echo as the 2018.
I have to believe it's the condenser element that's giving it such a smooth 'studio sound' while it still retains some crispness in the highs for added clarity without sounding harsh.

Do you know if they spec & sound the same without effects?
 
Actually I just looked it up and the 577 is a ceramic element and I nelieve the 2018 Extreme is a condenser. I'n not certain about the 2018 having a condenser but I have an older version (with silly blue LEDs which illuminate when keyed, I had to cut one lead on each of them to shut them off) which looks identical except it's clear, and it has a condenser element and sounds rich on SSB.

A youtube video where the guy even takes it apart in his review mentions the boards are different between the 577 & the 2018.

I love the 2018 my friend Terry uses on his Cobra, when he turns off the damn echo it sounds quite a bit richer than Al's does with the 577.

The 2018 just seems to have that smooth, rich, crisp condenser sound.
 
tecnicoloco said:
You might need this too
viewblack.jpg
Click to expand...

LOL
 
I'll check out the RF Limited CR-577. Thanks for the suggestion. Right now I'm using a stock mic. Works, but not great. As for the base I have the MXL V67. I put everything together now all I have to do is get it hooked up the the base radio. I'm thinking of using a PTT switch mounted on the mic stand.

Terry
 
ok robb or any other audio geek out there i have a ranger 6900-25 10 meter 4 pin mic,i have a heil handy mic,with a 4 pin xlr pluging into the mic,so whats the wiring to the 4 pin from the heil 4 pin xlr by pin and color anyone know thanks jon..
 
skullman64 said:
ok robb or any other audio geek out there i have a ranger 6900-25 10 meter 4 pin mic,i have a heil handy mic,with a 4 pin xlr pluging into the mic,so whats the wiring to the 4 pin from the heil 4 pin xlr by pin and color anyone know thanks jon..
Click to expand...
Hey Jon/KW-35!
Well, that Ranger radio of yours uses the same wiring as a Cobra, Galaxy, Connex, Uniden, SuperStar, and Magnum. Dunno about the 4 pin Heil mic wiring. But I'll bet that there is a wiring diagram of it around somewhere on the internet. Never used a Heil in a mobile; but I can tell you that I prefer the CR-577 over every mobile mic I've had, heard, and used myself.

Brian/World Radio 264 uses a Heil 5(?) mic in his mobile.
Can't say that I was impressed with its performance.

I would give Bob Heil a call and see if he can email you the wiring diagram/schematic for that mic. Just need to know where the mic audio wire is, the ground wire, and the PTT. The mic's impedance should be OK too . . .
 
Captain Kilowatt said:
This is all you need for a preamp Robb.

http://www.rdlnet.com/pdf/Data_Sheets/stm-1.pdf

or this http://www.rdlnet.com/pdf/Data_Sheets/stm-2.pdf


Radio Design Labs has GREAT audio products but they come at a price. What kind of price? Well lets just say that the broadcast industry uses them so :eek:..................:D

I have a handfull of their STA-1 amps and a pair of STM-2 microphone preamps as well as a pair of older Altec Lansing mike preamps that I want to make use of in a future project. I want to build an interface box that will accept various mikes and feed various radios each of which is isolated from the other. That might get done this winter I don't know but hopefully it will get somewhat completed. Not really looking for HiFi audio but just decent quality audio.
BTW I don't know too much about the Jensen transformers you speak of. I use Hammond 800 series especially the 804, 812, 842, and the 850G series. Thier frequency responce is perfect and no ringing even when run up to their power limit, which nobody would ever want to do anyway in a microphone preamp application. They are meant to handle up to +30 dBm.
Click to expand...

The speech processor from CBCINTL has HI-Z and LO-Z inputs. Couldn't that take the place of the preamps you and ROBB suggested?
 
Lil'Yeshua said:
The speech processor from CBCINTL has HI-Z and LO-Z inputs. Couldn't that take the place of the preamps you and ROBB suggested?
Click to expand...

A 'speech processor' is just another way to rename a 'compressor'. A compressor takes any audio signal that runs through it and pushes the audio peaks downward to a specified level at a specified threshold point in amplitude. This is done to equalize the weaker audio signals closer to the peak signals.

This level is preset by the circuit design in the case of the CP-1. In the case of the SP1a, there is an adjustment control that affects the threshold level in which case it will aggressively begin compressing the signal.

All CB radios already have an AM Limiter in circuit already. 'Limiting' is another form of compression which accomplishes the same thing but at a specified level.

A preamp changes the gain of the incoming signal upward; so you can see that preamps and compressors are doing two different things to the audio chain.
 
I was relating to the HI-Z and LO-Z selectable inputs on the CBCINTL speech processor. The transformer you mentioned is a little too much $$$ than I want to spend. I thought I could use the speech processor board and plans from CBCINTL.
 
Lil'Yeshua said:
I was relating to the HI-Z and LO-Z selectable inputs on the CBCINTL speech processor. The transformer you mentioned is a little too much $$$ than I want to spend. I thought I could use the speech processor board and plans from CBCINTL.
Click to expand...

An isolation transformer is used to match the output of -say- your mic preamp to the input of the radio.

Choosing between either input impedances of your CBCINTL is not the same thing - BTW.
That just gives you the option to run a high or low impedance mic into it - is all.
Your Shure SM-58 or 48 is a low impedance mic.
 
Robb said:
An isolation transformer is used to match the output of -say- your mic preamp to the input of the radio.

Choosing between either input impedances of your CBCINTL is not the same thing - BTW.
That just gives you the option to run a high or low impedance mic into it - is all.
Your Shure SM-58 or 48 is a low impedance mic.
Click to expand...

Ok.
I'm wanting to run the Shure or Behringer mic through my Art Tube II MP preamp to my Galaxy DX-959. The Shure SM48 and the Behringer are close in price range. I haven't bought either mic yet. So,a isolation transformer you mentioned previously would make everything work right.

Thanks.
 

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