HIFI AM radios - Videokarma.org TV - Video

darklife · #1 02-05-2012, 09:45 PM

I can't seem to find any radios that can reproduce decent high fidelity audio.
Most either roll off the top end or the bottom end, and sometimes both leaving a lot to be desired in the audio.
I would love to find a radio that could reproduce everything from 20hz to 10kHz with a mostly flat response.

I started to build a simple HIFI radio circuit and am stunned at the audio quality of some stations. They sound just as bright and clean as FM stations going through a simple AM detector.
Problem is I can't find any modern radios that do this.

Anyone know of some good books or websites with AM radio circuit designs?
If I could build a simple 5 or 6 transistor radio that would be great. Problem is I can't seem to find circuits that has AGC and other features in them.
The current circuit I whipped together came from the schematic at the bottom of this webpage..
http://sound.westhost.com/articles/am-radio.htm
Any other better designs would be greatly appreciated.

Thanks.

maxhifi · #2 02-06-2012, 10:34 AM

i would consider hi-fi tuners from the 50s, designed before AM was written off in terms of sound quality, if you'd be inclined to go that way. I know Heathkit AM tuners from the 50s were designed for high fidelity , and can't be worth a lot of money these days.

mstaton · #3 02-06-2012, 10:59 AM

Fisher 800 series receivers have very nice AM tuners.

bob91343 · #4 02-06-2012, 11:10 AM

I have a pretty good Sony tuner, as well as another Japanese job. They sound pretty good but you have to factor in my old ears, which roll off rather early in the frequency range.

Many years ago I built a tube type AM only tuner that worked well. I had a James Millen vernier dial on it.

Jeffhs · #5 02-06-2012, 11:59 AM

The need for wide frequency response on AM radio is debatable, considering that most of today's AM stations do not play music. There are still a few small-town stations that do program music during at least part of their broadcast day, but in big cities like New York and Philadelphia (to name but two) with stations operated by CBS Radio or Clear Channel, which, BTW, operate some 90 percent of the AM radio stations in this country, just about all anyone will find on AM is talk-based programming. No need for wide frequency response for just voice programming, so...there you are.

The same reasoning could have been applied years ago to stereo AM radio. Who wants to listen to Rush Limbaugh, for example, in stereo? Even sports radio wouldn't benefit much, if at all, IMHO, from being broadcast in AM stereo. And who wants or needs to listen to all-news radio in stereo? The news is bad enough over mono all-news radio; to broadcast it in stereo would be a waste of what could have been a step up for AM radio. If AM stations (the large network-operated ones in particular) programmed decent music (as was the norm until talk radio took over some time in the '80s or nineties) rather than loudmouth talk, AM stereo might still be a viable broadcasting mode today.

dieseljeep · #6 02-06-2012, 12:02 PM

Quote:

Originally Posted by maxhifi

i would consider hi-fi tuners from the 50s, designed before AM was written off in terms of sound quality, if you'd be inclined to go that way. I know Heathkit AM tuners from the 50s were designed for high fidelity , and can't be worth a lot of money these days.

I don't remember if they had a broad-sharp setting on them. Some of the old TRF sets had a better sound , because of no limitations of the bandwidth.

Dave A · #7 02-06-2012, 03:53 PM

How about the whole GE Super Radio series. Wide/narrow switch on mine.

jr_tech · #8 02-06-2012, 04:21 PM

Some decent info here:

http://www.fmtunerinfo.com/amtuners.html

jr

ChrisW6ATV · #9 02-07-2012, 01:36 AM

You could also look for a Sony SRF-42 Walkman. This was an AM/FM model with stereo AM reception ability as well as the "AMax" higher-fidelity tuner section. I hooked mine up to my home stereo years ago and it sounded pretty good indeed. Videokarma member "wa2ise" has a page about these units here:

http://pw2.netcom.com/~wa2ise/radios/amstmod.html

Ed in Tx · #10 02-07-2012, 09:43 AM

Quote:

Originally Posted by ChrisW6ATV

You could also look for a Sony SRF-42 Walkman. ...

Yep they sound pretty good. But my SRF-A100 has better bass compared to my SRF-A42 which sounds a little thin in comparison. Even though the SRF-A100 was years before the AMax standard. My '100 is still in use daily.

wa2ise · #11 02-17-2012, 10:39 AM

you could modify the AM IF of most modern SS AM/FM stereo receivers out there, to get better audio off AM:
http://pw2.netcom.com/~wa2ise/radios...tml#solidstate

details at the web link.

NowhereMan 1966 · #12 02-25-2012, 01:07 PM

Quote:

Originally Posted by Jeffhs

The need for wide frequency response on AM radio is debatable, considering that most of today's AM stations do not play music. There are still a few small-town stations that do program music during at least part of their broadcast day, but in big cities like New York and Philadelphia (to name but two) with stations operated by CBS Radio or Clear Channel, which, BTW, operate some 90 percent of the AM radio stations in this country, just about all anyone will find on AM is talk-based programming. No need for wide frequency response for just voice programming, so...there you are.

The same reasoning could have been applied years ago to stereo AM radio. Who wants to listen to Rush Limbaugh, for example, in stereo? Even sports radio wouldn't benefit much, if at all, IMHO, from being broadcast in AM stereo. And who wants or needs to listen to all-news radio in stereo? The news is bad enough over mono all-news radio; to broadcast it in stereo would be a waste of what could have been a step up for AM radio. If AM stations (the large network-operated ones in particular) programmed decent music (as was the norm until talk radio took over some time in the '80s or nineties) rather than loudmouth talk, AM stereo might still be a viable broadcasting mode today.

I like to listen to WKFB on 770 kc for music here in the Pittsburgh area. My 1994 Ford Explorer (sold) had an AM stereo capable radio but my new 1999 Blazer's Bose radio does not, at least so far as I know. I guess in the late 1980's and early 1990's, AM stereo was supposed to take off, I remember many cars of that era being able to tune AM stereo. IIRC, KDKA-AM was stereo for a while, I think it was one of the early station to do so around 1982/85. I admit I'm a talkshow junkie, but there are times I need to get away and music is the way to go. I like a lot of 1950's music too so I listen to AM stations that play that.

NJRoadfan · #13 02-27-2012, 06:19 PM

If you can find it, the AMax certified Denon TU-680NAB is a wideband AM stereo receiver. It can also be modified for true narrow band tuning too if needed (the wide/narrow switch is an audio filter, not RF).

The Sansui TU-D99AMX and TU-S77AMX tuners also seem to be wideband as well, but aren't that good for DXing due to their synchronous detector tuning. They do have the added bonus of being multi-system AM stereo too.