Series Pass Modulator for D.I.Y. Hi-Fi & Asymmetry

[543_Dallas]

How come on the spectrum analyzer it looks like he is on 3 channels?

More audio bandwidth takes up more space. If the transmitter will pass a 10k tone the AM signal has the potential to be 20k wide. You would have to limit the high frequencies with your audio gear or use a filter to prevent this.

This video kind of explains that after 3:45.

 

[Rick Hicks]

Wow; a little over the top - ya think?!?
But yeah, it better rock!
Beau coup expensive - too

Hi Robb!
that was my feeble attempt at humor Robb. I don't have a Neumman Uxx, a 1073, 1176, Demeter DI, or a Cobra 19. Although I have used all extensively in recording sessions (minus the 19)

I just have those same feelings about this so called "hi-fi" shite on a CB. It's over the top.

If someone wants to come up with something really useful for a CB radio then build a device to interface between the speaker and audio output that filters out curse words. You could sell a million of them.

Hi-Fi Fo-Fum exclamation point!

 

[543_Dallas]

Hi Robb!
that was my feeble attempt at humor Robb. I don't have a Neumman Uxx, a 1073, 1176, Demeter DI, or a Cobra 19. Although I have used all extensively in recording sessions (minus the 19)

I just have those same feelings about this so called "hi-fi" shite on a CB. It's over the top.

If someone wants to come up with something really useful for a CB radio then build a device to interface between the speaker and audio output that filters out curse words. You could sell a million of them.

Hi-Fi Fo-Fum exclamation point!

Try changing the channel or turning the volume knob fully counterclockwise until it clicks.

 

[Robb]

Hi Robb!
that was my feeble attempt at humor Robb. I don't have a Neumman Uxx, a 1073, 1176, Demeter DI, or a Cobra 19. Although I have used all extensively in recording sessions (minus the 19)

I just have those same feelings about this so called "hi-fi" shite on a CB. It's over the top.

If someone wants to come up with something really useful for a CB radio then build a device to interface between the speaker and audio output that filters out curse words. You could sell a million of them.

Hi-Fi Fo-Fum exclamation point!

One of the cool things about radio, is that people experiment with them. Having a hi-fi CB is relatively new concept, and has been explored for at least over the last ten years. Perhaps you should look into it and find out yourself. Some guys do use top gear, but it really isn't necessary to go that far.

It isn't real 'hi-fi' per se; but it is clearly better than the over-modulated and distorted radio transmitters of the past. Last solar/skip cycle, there were a bunch of operators using improved fidelity systems; about 4-5kc wide. when using a a real mic, the difference was far better. With a few component changes in the radio and incorporating an isolation xformer cinched the deal. Not that hard to do at all. More emphasis on a clean radio output has also helped overall - too.

I use a MXL tube condenser mic with protools with results that are pretty awesome. There are some YouTube viddys on it that you can check out if interested.

 

[Rick Hicks]

Thanks Robb!

Rule of Thumb: If it sounds good - it is good.

I would be interested in doing an A/B comparison someday for sure.

Hey 543_Dallas did I say something you didn't like?

 

[543_Dallas]

Thanks Robb!

Rule of Thumb: If it sounds good - it is good.

I would be interested in doing an A/B comparison someday for sure.

Hey 543_Dallas did I say something you didn't like?

No. I was just sharing my method of filtering out curse words.

 

[Shadetree Mechanic]

Bump for people looking to get away from the transformer in their 29.

 

[LeapFrog]

More than one way to lower your carrier,
I.m.o. this is the best "carrier suppression technique" floating around right now for high level modulated radios.
{Granted a form of limiting must used!}

"Why Punch is more important than power in a CB"

"Punch through Loud and Clear; with a Cobra!"

I will post an update for this thread, eventually!
The "open asymmetry project" isn't dead yet!

 

[Rick Hicks]

The more active devices put into the audio path raises the noise floor. The noise floor will never be less than the noisiest device in the audio signal chain.
Same applies to the overall dynamic range. Your dynamic range will never be greater than that of the device with the least amount of dynamic range in the audio signal chain.

I see a lot of noise in the unmodulated carrier shown on scope in your video.
I not saying you're wrong. Because if it sounds good > it is good!

Most people cant hear 20KHz let alone 20Hz.
Maybe they can feel those 2nd and 3rd order harmonics. ; )
Depends on if you run 44.1k or maybe 96k res
16, 20 or 24 bit?

Im not trying to argue just trying to understand why a CBer would go to such great lengths and costs for such a small payoff.

I liken it to a handheld condenser microphone for your mobile rig. Yeah it might punch thru but there is a cost trade off in unwanted artifacts.

Im just not sold yet.

 

[groundwire]

Very cool, but where do you find a CB receiver with any frequency response?

All those highs and lows are wasted if the receiver at the other end filters them all out.

73

Exactly, cb radios just dont have even close to the bandwidth to pass those audio frequencies, plus 90% of the cb'ers dont even care if they hear hifi or not. also it sounds nice for rag chewing locally but for dx, 300hz - 2900hz audio bandwidth will take you out. its all about "power spectral density". Very important if you wanna bust thru those pileups, the hifi guy will be in the background barely heard

 

[Shadetree Mechanic]

Listen to some DX, you can hear the difference even on a stock radio.

 

[dave457]

You can have "power spectral density" with hifi am

 

[DoctorAudio]

"it sounds nice for rag chewing locally but for dx, 300hz - 2900hz audio bandwidth will take you out."
This is only true if the receiving end has narrow/stock receive. When you are receiving full bandwidth, the guy with the heavy low end cuts through the high pitched transmissions almost more than the reciprocal.

 

[groundwire]

"it sounds nice for rag chewing locally but for dx, 300hz - 2900hz audio bandwidth will take you out."
This is only true if the receiving end has narrow/stock receive. When you are receiving full bandwidth, the guy with the heavy low end cuts through the high pitched transmissions almost more than the reciprocal.

thats the point, its just cb radio. nobody has 10k+ receive bandwidths to hear it. and the comment on how "heavy low end" will cut thru the highs makes no sense and is absolutely false. your excessive 50hz - 100hz rumble carries 0 intelligibility and adds nothing to the signal, its just wasted energy. i run the whole full range audio thing too, but on bands where it can be appreciated and enjoyed.

 

[DoctorAudio]

Like "HAM" bands?
OK, since you are the authority on the subject matter, I'll just quit listening to my lying ears and concede that it's completely false because you said so. Thanks for being the arbitrator of all things audio. I'm not sure the world could exist without you, thanks.