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Easiest way to achieve hi fi?
- Thread starter Bearcat
- Start date
I had to go outside of the forum for someone to show me in person a audio rack and how it works ect ect...you gotta play the guessing game around here
This is one of those things where a person has to learn or buy something turnkey like the motor mouth maul board or one of those asymod radios on ebay. That or buying an apache labs sdr is the only easy way. Even then some people will have he'll with RFI and rack gear.
Then you have to run the equipment under its rated limits or your good sound will go to he'll. The info is out there. I don't mind helping anyone but if you hold their hand the whole way they never learn and end up blowing something up. Frustration and confusion is the price of admission we all pay sooner or later. You can do it now or make payments the for the rest of your life.
Then you have to run the equipment under its rated limits or your good sound will go to he'll. The info is out there. I don't mind helping anyone but if you hold their hand the whole way they never learn and end up blowing something up. Frustration and confusion is the price of admission we all pay sooner or later. You can do it now or make payments the for the rest of your life.
RatsoW8
Supporting Member, W9WDX ARC Member - WD8T
Lol I don't know if what I have is what people would call "hi-fidelity".... but it's certainly not normal bandwidth... it has slightly enhanced low end, and enhanced high end..... but it still has to pass thru the filters, and one of the ways to get better "hi-fi" audio is to install different filters that roll off the lows and highs in different areas than the stock filters.
Also, the radio that receives this "hi-fi" signal has to be modified to fully reproduce the signal properly. You can mod your TX for 5K width or even 20K bandwidth, but the average Joe Blow CB'er won't hear a big difference on his end unless his radio is modified on the RX to reproduce that extra audio width. It can be done, but it's just not the easiest of things to do.... and in most cases, it's not practical, either.
That's why I didn't go nutty on making my CB "hi-fi". I changed out a few capacitors and did a re-alignment. That was it. Anything beyond that wouldn't be very practical. It did make a modest difference, however.
"Results may vary, and are not guaranteed."
~Cheers~
Also, the radio that receives this "hi-fi" signal has to be modified to fully reproduce the signal properly. You can mod your TX for 5K width or even 20K bandwidth, but the average Joe Blow CB'er won't hear a big difference on his end unless his radio is modified on the RX to reproduce that extra audio width. It can be done, but it's just not the easiest of things to do.... and in most cases, it's not practical, either.
That's why I didn't go nutty on making my CB "hi-fi". I changed out a few capacitors and did a re-alignment. That was it. Anything beyond that wouldn't be very practical. It did make a modest difference, however.
"Results may vary, and are not guaranteed."
~Cheers~
I know on a normal stock radio like a cobra 25 you can definitely tell a difference when let's say 131 mustang is on the air...do you have any audio samples of your station or videos?Lol I don't know if what I have is what people would call "hi-fidelity".... but it's certainly not normal bandwidth... it has slightly enhanced low end, and enhanced high end..... but it still has to pass thru the filters, and one of the ways to get better "hi-fi" audio is to install different filters that roll off the lows and highs in different areas than the stock filters.
Also, the radio that receives this "hi-fi" signal has to be modified to fully reproduce the signal properly. You can mod your TX for 5K width or even 20K bandwidth, but the average Joe Blow CB'er won't hear a big difference on his end unless his radio is modified on the RX to reproduce that extra audio width. It can be done, but it's just not the easiest of things to do.... and in most cases, it's not practical, either.
That's why I didn't go nutty on making my CB "hi-fi". I changed out a few capacitors and did a re-alignment. That was it. Anything beyond that wouldn't be very practical. It did make a modest difference, however.
"Results may vary, and are not guaranteed."
~Cheers~
You can hear some of the bandwidth on a stock CB, enough to notice a difference if the equipment is used right. You can hear a little more if you modify the receiver. It gets even better if you use a a better receiver.
Something like an SDR Play with some quality PC speakers will get you a lot of bang for your buck. You can tap one of the IFs in your radio or build a T/R relay to disconnect and ground the input on the receiver on transmit.
If you do the cap changes in the 29 you might replace the 455 filter with a 6k to pass more high frequency tones. It's not a dramatic difference.
Bearcat and Leapfrog,
The Cobra 25's and 29's will probably receive "hi-fi" better than most SSB radios, because the RX conversion circuitry/design is a done a little different than on an SSB radio. Technically, that's not a fair comparison... apples to oranges there. I made my observation based on my Cobra 2000GTL, which has the double conversion AM RX MB8719 board in it. That being said, most guys who run SSB radios won't see as much of a difference on a stock radio. I haven't ran an AM only radio in over 20+ years, so I can't make any kind of observations there. But it would not surprise me if there's more of a noticeable difference when using a straight AM only radio.
~Cheers~
The Cobra 25's and 29's will probably receive "hi-fi" better than most SSB radios, because the RX conversion circuitry/design is a done a little different than on an SSB radio. Technically, that's not a fair comparison... apples to oranges there. I made my observation based on my Cobra 2000GTL, which has the double conversion AM RX MB8719 board in it. That being said, most guys who run SSB radios won't see as much of a difference on a stock radio. I haven't ran an AM only radio in over 20+ years, so I can't make any kind of observations there. But it would not surprise me if there's more of a noticeable difference when using a straight AM only radio.
~Cheers~
543 Dallas Thank you for the idea of the sdr play and relay that's really neat, I will jot that down in the sketch book.
About the ceramic filter:
I have seen a guy swap the filter in a to-be-hifi modded export on youtube but I forget what he mentioned was used.
6 kilohertz wide would be nice, here is one I found on ebay 8 Khz Murata!
http://www.ebay.com/itm/MURATA-CFM4...455K-IF-FOR-HI-FI-SHORTWAVE-ETC-/222252515336
$40 is more than I have in the rig, but you got to pay to play!!
Thank You
Exit13 I think you are 100% correct about the a.m. only radios, the 25/29 have double conversion and outperform my 142 GTL (SSB & single conversion as you know) on RX.
-Leap
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Correct me if I'm wrong but on an AM radio a 6khz filter would give 3khz of audio and the 8khz filter would give 4khz audio bandwidth, so based on that I would think that an 8 would be the way to go. But I've also heard that most Murata filters pass more than their spec and for all practical purposes a 6khz Murata is actually closer to 8khz, if the 8khz Murata shows the same difference in spec it would almost put you into the adjacent channel. If this is true you would have to take into account what brand/type filter you're using when choosing a filter. Anyone have a link to a good reference on filters?
Now as far as SSB radios are concerned would there be any advantage to cap change type modifications for AM audio? I've been tossing around the idea of having a 2950dx done with something like Goldfingers mod and possibly a 455khz filter change, I know that the SSB filter would significantly limit any change in audio on SSB but is there anything else that would need to be considered for AM use? Also would there be some reduced benefit on SSB or no benefit at all?
I would like to put together a simple ''better than stock CB fi" station but I'm still at the stage of figuring out just what the options are, so definitely take anything I type here with a grain of salt.
PS: anyone know a good tech who is familiar with hi-fi mods and good with SMT stuff?
Now as far as SSB radios are concerned would there be any advantage to cap change type modifications for AM audio? I've been tossing around the idea of having a 2950dx done with something like Goldfingers mod and possibly a 455khz filter change, I know that the SSB filter would significantly limit any change in audio on SSB but is there anything else that would need to be considered for AM use? Also would there be some reduced benefit on SSB or no benefit at all?
I would like to put together a simple ''better than stock CB fi" station but I'm still at the stage of figuring out just what the options are, so definitely take anything I type here with a grain of salt.
PS: anyone know a good tech who is familiar with hi-fi mods and good with SMT stuff?
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I've considered this myself, would a better quality crystal 455khz IF filter help to mitigate the problem?
I think it comes down to bandwidth and how the channels are spaced apart, after one starts to transmit wide-beyond-wide they will splatter... I don't know from memory how wide a CB channel is.. So i'm just spittin' in the wind here!
But some of the locals here can be heard 1 channel above & 1 channel below the target frequency, they sound loud as h3ll though!
Also I'd expect adjacent channels to be heard in the RX if I used an 8 Khz Murata but nothing in my experience can verify this, it's all conjecture on my part.
StrangeBrew:
I know of a guy who eats SMD repair for breakfast, lunch, & dinner but he repairs Apple products mainly and doesn't touch radios as far as I know. [Louis Rossmann of Rossmann Repair Group N.Y.]
Also Mike of Mike's Radio Repair does SMD repair, but I don't know if he messes with Hi-Fi mods he is more of a restore-it kind of guy I think.
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