If you just plug all that rack gear into the stock mic jack and maybe change out a few caps to widen the tx bandwidth the results aren't that impressive. Not worth it unless you plumb it into the am regulator or balanced modulator
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smooth audio?
- Thread starter Bearcat
- Start date
If you just plug all that rack gear into the stock mic jack and maybe change out a few caps to widen the tx bandwidth the results aren't that impressive. Not worth it unless you plumb it into the am regulator or balanced modulator
I learned that the hard way...i did sound very clean and got flowers but I was hardly Bassmaster or 210 in the stone lol
RatsoW8
Supporting Member, W9WDX ARC Member - WD8T
Then one can find the other people who did the same bandwidth mod and bromance about each others audio like the hams do on 14.172. Unless your radio is all modded up to receive the wider bandwidth your not hearing it. And it's not good communications audio anyway.
Since my first hobby was studio and professional audio equipment, I'm all about sounding sounding smooth and clear in this hobby no matter what radio I'm broadcasting with.
You'll need a few tools besides a good main radio and good mic though to keep a check on things:
First off, a monitor radio and a good set of sealed studio headphones. I'm not a fan of wearing headphones all the time, but the "totally sealed around the ear" type will prevent any audio feed back when you are trying to listen to and adjust your broadcast. You can slip one earpiece over one ear and leave the other off to hear the main radio. I use a modern Cobra or Radio Shack 40 Channel HT with a simple rubber ducky antenna as the monitor radio. Nice small footprint. Both have decent enough audio quality when the studio headphones are attached for monitoring for any distortion on your broadcast. Adjust the main radio transmitter and mic for low distortion accordingly. Good sealed head phones run around $75 and the Cobra HT is around the same.
Take it to the next level; get an oscilloscope with an RF Sampler. Hook the RF sampler last in line with your coax after the radio (or amp if utilized). Hook the signal sensing wire to the input of one of the two channels on the O-scope. This will let you "see" if your flat topping (causing distortion) and if your getting the proper 1:4 carrier/ modulation ratio. Used scopes can be had for under $100. Just make sure it's rated no lower than 40 MHz.
Next a spectrum analyzer with a rubber ducky antenna. This will allow you to "see" the carrier and modulated signal within to make sure you are not creating extra harmonics or "spurs" off-frequency that rob your radio and amplifier of the power that supposed to be centered on a specific frequency (channel). Some digital Cable TV testers have good enough spectrum analyzers in them for under $300.
I have found that with a Turner desk +2 mic and a tiny smidgen of reverb, I can get almost any CB radio that can generate 100% modulation to sound "smooth" and clean when monitored with the system equipment listed above.
You'll need a few tools besides a good main radio and good mic though to keep a check on things:
First off, a monitor radio and a good set of sealed studio headphones. I'm not a fan of wearing headphones all the time, but the "totally sealed around the ear" type will prevent any audio feed back when you are trying to listen to and adjust your broadcast. You can slip one earpiece over one ear and leave the other off to hear the main radio. I use a modern Cobra or Radio Shack 40 Channel HT with a simple rubber ducky antenna as the monitor radio. Nice small footprint. Both have decent enough audio quality when the studio headphones are attached for monitoring for any distortion on your broadcast. Adjust the main radio transmitter and mic for low distortion accordingly. Good sealed head phones run around $75 and the Cobra HT is around the same.
Take it to the next level; get an oscilloscope with an RF Sampler. Hook the RF sampler last in line with your coax after the radio (or amp if utilized). Hook the signal sensing wire to the input of one of the two channels on the O-scope. This will let you "see" if your flat topping (causing distortion) and if your getting the proper 1:4 carrier/ modulation ratio. Used scopes can be had for under $100. Just make sure it's rated no lower than 40 MHz.
Next a spectrum analyzer with a rubber ducky antenna. This will allow you to "see" the carrier and modulated signal within to make sure you are not creating extra harmonics or "spurs" off-frequency that rob your radio and amplifier of the power that supposed to be centered on a specific frequency (channel). Some digital Cable TV testers have good enough spectrum analyzers in them for under $300.
I have found that with a Turner desk +2 mic and a tiny smidgen of reverb, I can get almost any CB radio that can generate 100% modulation to sound "smooth" and clean when monitored with the system equipment listed above.
That is ignorant bullshit. Anyone that has heard a decent wideband station on a stock receiver knows this. Crystal filters aren't brick walls. They roll off the highs but some are a steeper hill (shape factor) than others. Same goes for for caps that roll off the low end bass. You can make the best of the bandwidth you have to work with and sound better than average.
If communication grade audio is your style I don't have a problem with that. All that matters to me is that you enjoy the hobby.
Some people experimenting with wideband audio have left a bad taste in people's mouths because they take up excessive bandwidth, are constantly tweaking without using a dummy load and talking about their equipment...on 11 meters some constantly play music. I really do understand your frustration but don't be ignorant and put us all in the same group.
My favorite for AM was Johnson Messenger 250 50th anniversary edition with matching johnson power desk mike and limiter removed. Just deep smooth sound like plate mod and you could find these cheap at garage sales. I don't usually remove limiters but in this case the result was magic.
http://rover.ebay.com/rover/1/711-5...0001&campid=5336136228&icep_item=141811484645
http://rover.ebay.com/rover/1/711-5...0001&campid=5336136228&icep_item=141811484645
RatsoW8
Supporting Member, W9WDX ARC Member - WD8T
You're right, my apologies. I didn't bother to think before I posted from work. I do that occasionally here.
You can do a lot with a good mic and some rack gear if it's well thought out and not overdone. I have one of the old Radio Shack model 3303038 dynamic mics that I'm going to play with this weekend. I'll only be using a low end Behringer mixer and W2IHY iBox to interface it to the Yaesu.
You're right, my apologies. I didn't bother to think before I posted from work. I do that occasionally here.
You can do a lot with a good mic and some rack gear if it's well thought out and not overdone. I have one of the old Radio Shack model 3303038 dynamic mics that I'm going to play with this weekend. I'll only be using a low end Behringer mixer and W2IHY iBox to interface it to the Yaesu.
No worries. I do understand where you were coming from. People that start using rack gear can be annoying until the new wears off and they get everything set right. A dummy load and demodulator for AM would really solve a lot of the problem.
RatsoW8
Supporting Member, W9WDX ARC Member - WD8T
I'm not sure what 55 in Texas is running, but on Channel 38 LSB hands down some of the nicest audio I've heard in sometime. I'm in New Jersey by the way.
Most stock radios could sound good if unmodified and use a wideband audio section. Drive it to the peaks through a chain of mic>5kHz LPF (6 pole to roll off hard after 5kHz for least channel bleeding)>all pass brick wall limiter>diode peak clipper>high frequency limiter/filter to recude clipper audio harmonics>modulator stages of your rig.
This is almost exactly the same method used for broadcast AM stations except they include pre-emphasis stages and in modern times multi-band compression on the front end of the audio chain.
Doing this you peak up the audio using a tone generator and monitor the RF amplitude on a scope to make sure it is not clipping the waveform regardless of what crap is going in at the mic end, check for 100% modulation and no negative dropouts. All pass filters at the mic can help with asymmetrical audio which some peoples voice tend not to have (often going negative at peaks).
Do this and your signal will sound like the big boys, not just on CB but you can compare yourself to broadcasters on the professional end.
Best of all most of this can be done using software now, or basic circuitry if you have an understanding.
I recommend looking into broadcast audio processing manuals and documents, like those written by Orban and such.
When you get these basic things down and the scope (never lies) shows you modulating fully w/o distortion you will sound louder and more clear than almost everyone on the dial.
The issue is when people get to that point they start to question if they really want to sound that clear when they start talking smack
This is almost exactly the same method used for broadcast AM stations except they include pre-emphasis stages and in modern times multi-band compression on the front end of the audio chain.
Doing this you peak up the audio using a tone generator and monitor the RF amplitude on a scope to make sure it is not clipping the waveform regardless of what crap is going in at the mic end, check for 100% modulation and no negative dropouts. All pass filters at the mic can help with asymmetrical audio which some peoples voice tend not to have (often going negative at peaks).
Do this and your signal will sound like the big boys, not just on CB but you can compare yourself to broadcasters on the professional end.
Best of all most of this can be done using software now, or basic circuitry if you have an understanding.
I recommend looking into broadcast audio processing manuals and documents, like those written by Orban and such.
When you get these basic things down and the scope (never lies) shows you modulating fully w/o distortion you will sound louder and more clear than almost everyone on the dial.
The issue is when people get to that point they start to question if they really want to sound that clear when they start talking smack
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I also recommend skimming through this since it applies to more than just broadcast audio..
http://www.orban.com/support/orban/techtopics/optiair/
There are other documents online going into far more detail but that will give you an idea of where to start with a proper audio chain for HIFI transmission.
http://www.orban.com/support/orban/techtopics/optiair/
There are other documents online going into far more detail but that will give you an idea of where to start with a proper audio chain for HIFI transmission.