Easiest way to achieve hi fi?

[Mustang 131]

Just leave the frequency door wide open, as long as you don't pinch the carrier. 160% + 99% - is the limit before you need goofy things to sound good on average radios.
The real magic is in the processing. Less is more.

 

[Robb]

Neat trick, but not very efficient, especially in a mobile.

Hifi and mobile really do not play well together. Going hifi is primarily a base station thing, since it is far easier to control the background noises in a home vs a mobile where it is nearly impossible due to ambient noise (tires, rushing air, bumps, rattles, squeaks, and other vehicle noises). As well as other cars/trucks on the road you share. Even if you are driving a Mercedes or a Cadillac, the noise level in db's still leak into a D104; let alone a studio-grade mic that is far more sensitive to that.

If you can pass 50-4000hz using a noise-cancelling mic and your radio can do likewise; then I'd say that you are already 'stepping in high cotton' and any further audio improvements would not be realized.

 

[dave457]

MMM runs hifi In his mobile, I'm sure most people on the east coast heard him at one time or another

 

[Robb]

MMM runs hifi In his mobile, I'm sure most people on the east coast heard him at one time or another

Tough trick to do.

EDIT:
I'm sure his radio can; but that isn't what compromises the radio. The mic. High end noise-cancelling mics are not really that high end. As you know studio/hifi mics have very flat response with a huge dynamic range carefully that will need to be matched to the input impedance. These mics won't even miss the smallest room sound; car sounds will all be heard. Not to mention the cost for a ElectroVoice RE-20 or Shure SM7 could make it too costly. Curious; what he is using? A hypercardiod mic?

Like to know how he manages mobile hifi. Sound processing? Mic mount and decoupling (important things to be done there), preamp, noise gate, EQ/parametric, compression, spacial effects, as well as putting ferrites on every cable all inside a car - could be a bit cumbersome. Or perhaps he is using ProTools audio software on a small Windows laptop?

But I don't doubt if its possible or not if you said he's doing it already.
Interesting.

 

[StrangeBrew]

....

If you can pass 50-4000hz using a noise-cancelling mic and your radio can do likewise; then I'd say that you are already 'stepping in high cotton' and any further audio improvements would not be realized.

This is what I would like to do, a real HiFi setup would be nice but would not be practical for me from an operating standpoint.

Any idea of cap changes/values that would achieve this? I've seen the goldfinger mods but they generaly don't tell you the frequency they will pass, they just say "more".

MMM runs hifi In his mobile, I'm sure most people on the east coast heard him at one time or another

I don't think the fact that MMM pulls it off means that it's easy.

 

[dave457]

This is what I would like to do, a real HiFi setup would be nice but would not be practical for me from an operating standpoint.

Any idea of cap changes/values that would achieve this? I've seen the goldfinger mods but they generaly don't tell you the frequency they will pass, they just say "more".




I don't think the fact that MMM pulls it off means that it's easy.

I didn't say it would be easy, I just stated MMM does it.
The only problem I would see in a mobile setup is RFI and background noise

 

[Onelasttime]

You can replace cheap audio transformers in radio's with much better audio transformers. That POS in a Cobra 29 would be laughed out of a recording studio. You audio is only as good as the transformer it passes through. You can gain up to 25db with just an audio transformer. Depending on what the transformer in the Cobra 29 is starting at and it's response curve you could have a lot to gain.

Add in a flat condensor mic, shift the 6db down point of the audio to fit your voice, lower the noise floor of the add a bit more modulation and a faster agc little bit of delay a bit if compression and watch the sparks fly....LOL You can cook the books more than one way and come out with better than average audio.

 

[Onelasttime]

That is nice to know. I respect your input because you are in the trenches doing this daily. I am just a amateur getting back into radio a bit more each day and doing a bit more work myself each day.

What is your take on my old school routine of using a condenser mic ------> clean low noise pre-amp with notch filter into a phase rotator then into the first stage audio chain? I am thinking about putting WIMA cap or Pannasonic Stacked film in the audio decoupling caps in the first stage of the audio chain. This is high level modulation.


On another radio I run a condenser mic into a Ten-Tec Audio Processor than into the radio in stock trim. I thought about doing the Wima or Film Cap mod to it as well. It is low level modulation President Lincoln. I recapped it recently with Nichicon, Panisonic, United Chemicon caps. Every place that space permitted I used 105°C 5000 hour caps. Where i could not fit these type caps due to size restraints I used audio grade Nihicon 85°+ 1000-2000 hr caps and and all of them caps I used I tried to get the best in ripple and low esr. I upgraded voltage as much as sapce would permit. Other than power filter caps I kept to OEM capacitance rating, There where a few cases where they no longer make a cap in the proper voltage with such a low capacitance rating that forced and up grade.

I would love to moestly improve it not butcher it. WOuld a modest increase to the main lytics inthe audio chain from 50V .22uf lytics to .63V .68uf Wima or 50V 1uf Pannasonic Stacked Film make a noticable on air difference?

 

[JoeDirt]

The easiest HiFi setup is, get a Galaxy (or equivalent), Direct inject, buy a Lexicon Alpha, Buy cheap dynamic XLR mic, Buy a couple patch cords and last download free VST plugins and host!

Someone was asking about trapezoid scope pics of the Mauldulator, trapezoid is not only for testing the linearity of an amp it can test the linearity of any radio.

DISCLAIMER: Motormouth Maul "NEVER" said that his Mauldulator doesn't produce distortion, fact is it does. The higher percentage of modulation the higher the distortion will be, that's just the nature of the beast. These scope pictures were done using my "birds nest" Cobra 2000. The Mauldulator modulates the finals in a high level configuration, the Cobra 2000 is factory aligned. Factory aligned also means in AM the finals operate in class C. So there should be some distortion regardless.

 

[Robb]

Used/owned some expensive Lexicon gear in the recording studio. This Alpha is something I'd never seen before, so it must be relatively new. But they make some fine gear, and this Alpha looks like a high-end/low cost CB audio solution. i'll have to look into one of these in the near future. Thanks for that tip, JoeD.

 

[LeapFrog]

The Mauldulator modulates the finals in a high level configuration, the Cobra 2000 is factory aligned. Factory aligned also means in AM the finals operate in class C. So there should be some distortion regardless.

Are you saying that the Cobra 2000 runs class C in AM mode, unless adjusted to outside of the factory specs? Or that the factory alignment was not performed "up to snuff"?
Cool tip on the Lexicon, and d.i. Galaxy.


Thanks
-LeapFrog

 

[Onelasttime]

I would never spend good money on a Galaxy Radio. If I am not going to have Dual VFO's, rock steady SSB and the ability to continuously tune 10-12m than I am not going to and would not buy a export radio. I would consider an RCI2950DX since I did own and loved my RCI2950 I owned in 1991-1998 before Fred Balantine of Hinseville Ga. failed to return it to me after I shipped to him while in College for repair and alignment. He went out of Business and prior to that he gave my Mom and Dad the run around when they went to his shop to check on it for me. They had a rental property in Hinesville long after Dad retired and moved to Michigan. I think their might have been a combination of money issues and family issues but I was 1200 miles away so not sure.

I do not see DI or ASYMETRIC Modulation as being the end all be all. Both are a bit too extreme to me. Their is a ton of ground one can play around in between factory stock and the extreme's of MMM and DI. To me it is like someone asking about a better way to get their charcoal lite for their grill and you recomend a WWII Flame Thrower or Thermite. It is like using a anti-tank missle to take down the tree in your back yard.

Hifi should not equal greater than 100% modulation. I think that it is rather limited view on the subject even if that is how 99.9% of those in the hobby see it.

I was not aware that the Cobra 2000 ran in class C bias in am or that it was set up to change bias with mode selection. I know the Crea 8900 and I think Anytones do that they automaticly change bias for mode selected C for AM, AB1 for SSB etc....

 

[Robb]

I would never spend good money on a Galaxy Radio. If I am not going to have Dual VFO's, rock steady SSB and the ability to continuously tune 10-12m than I am not going to and would not buy a export radio. I would consider an RCI2950DX since I did own and loved my RCI2950 I owned in 1991-1998 before Fred Balantine of Hinseville Ga. failed to return it to me after I shipped to him while in College for repair and alignment. He went out of Business and prior to that he gave my Mom and Dad the run around when they went to his shop to check on it for me. They had a rental property in Hinesville long after Dad retired and moved to Michigan. I think their might have been a combination of money issues and family issues but I was 1200 miles away so not sure.

I do not see DI or ASYMETRIC Modulation as being the end all be all. Both are a bit too extreme to me. Their is a ton of ground one can play around in between factory stock and the extreme's of MMM and DI. To me it is like someone asking about a better way to get their charcoal lite for their grill and you recomend a WWII Flame Thrower or Thermite. It is like using a anti-tank missle to take down the tree in your back yard.

Hifi should not equal greater than 100% modulation. I think that it is rather limited view on the subject even if that is how 99.9% of those in the hobby see it.

I was not aware that the Cobra 2000 ran in class C bias in am or that it was set up to change bias with mode selection. I know the Crea 8900 and I think Anytones do that they automaticly change bias for mode selected C for AM, AB1 for SSB etc....

Present day AM commercial broadcast stations run 137% modulation - IIRC - and have for decades. Getting a radio to get that much modulation/over 100% modulation is done by negative peak compression/reduced carrier modifications.

Direct injection allows direct access to the input of the balanced modulator. So long as you get a proper impedance match by running a cool piece of dedicated hardware, like a Lexicon Alpha mic preamp, isolation xformer, and a good mic to test with first. Then you should sound more natural, have better freq response, better gain, and a lower noise floor/distortion before equalizing. Many have been doing this on AM and SSB.

 

[Captain Kilowatt]

Are you saying that the Cobra 2000 runs class C in AM mode, unless adjusted to outside of the factory specs? Or that the factory alignment was not performed "up to snuff"?
Cool tip on the Lexicon, and d.i. Galaxy.


Thanks
-LeapFrog

Pretty much all CB radios do that. That is what is called high level modulation. Basically the solid state equivalent of tube plate modulation. It is done for simplicity and efficiency.

 

[Captain Kilowatt]

Present day AM commercial broadcast stations run 137% modulation - IIRC - and have for decades.

FCC regulations allow positive peaks to reach a maximum level of 125%.