I have been tinkering with radios and recording since I was a kid and those devices were new, have a full amateur radio license and have a degree in high frequency electronic engineering AND I NEVER KNEW UNTIL TODAY WHERE THAT SWITCH WAS FOR! Thank you for explaining this unusual but very useful feature. 😅
I think it’s interesting that over the years they didn’t come out with a marketing term that would explain its function better for people who had no idea. Something like “Radio Noise Reduction” akin to Dolby.
@@GaryKeepItSimple And the technically correct term for what Dolby Noise Reduction does is compansion, but they sure as hell didn't market it as a compander to the general public.
Why would they. It's like "2000W PMPO" found on boom boxes in the late '90's, early 2000's. No one actually knew what that meant, either - except maybe for people like me. Another fictitious marketing measurement of perceived output power. It's interesting that they can get 2000 watts from an amplifier that was running on 12V maximum producing under 3 watts.
When recording from FM radio it's actually the opposite: The 19kHz pilot tone of the stereo multiplex interferes with the bias frequency or the frequency of the erase head, causing a beat frequency resulting in an audible whine. That's what the MPX filter is for: It's just a notch filter that removes the 19kHz pilot tone and the 38kHz subcarrier.
The 19kHz can also interfere with Dolby noise reduction when recording tapes. I also discovered another use for the MPX filter, some CD's and even LP's were very hard to record, they'd produce distortion on cymbals when recording. Changing the bias and recording levels reduced but would not eliminate the problem. Other cassette decks and even reel to reel would also have the problem. I finally realized frequencies in the cymbal sound were mixing with the tape bias in a nonlinear way and producing an unpleasant sound. I don't know if this was intentional analog copy protection or just an artifact. MPX filter would almost completely solve the problem even though the recording was from CD or LP and not FM stereo.
@@davidg4288 Did this happen mainly with rock music recordings? I guess the reason is because the drum sounds and cymbals are always very compressed on that genre of music making them consistently loud at a relatively high level. That would do it.
@@circattle This was a long time ago, I recall it happening in progressive rock and fusion jazz which was NOT very compressed but did have all the highs they could record. Recording at a lower level did not fix it, it was more frequency than loudness related. I no longer have working tape machines to test with.
For anyone who doesn't know, "beat" in this sense can refer to the observable difference between *any* two frequencies, not just audio (although audio is where the term is encountered most often, which no doubt adds to the confusion with the musical homonym.) But for example, if the turn signals on two cars seem to be flashing in sync, but the signal on car A is just a little bit slower and starts flashing more and more behind that of car B, you're seeing the signals' beat frequency
Pilots of multi engined bombers during ww2 used to synchronise their engines to prevent the loud "pulsing" of the beat frequencies between the engines. Allegedly the Germans didn't bother so much and people could tell the difference between formations of German and allied planes because the German aircraft had a distinctive drone caused by the beats.
100%. If it's of interest: before the days of digital tuning meters this is exactly how pipe-organ tuners used to "lay down" the middle octave of a set of pipes, playing fifths and fourths - each interval between 2 notes should have a specific number of "beats" (different for each two notes) in the same way as you describe. Once you've laid the bearings of that reference octave, you then simply tune the rest to exact octaves of each note with no beat audible.
Irc another example is when you see wheels or propellers in films, slow right down or even reverse as the vehicle is moving. This happens because the "frame speed" or frequency of the camera is interacting with the frequency of rotation of the wheel or propellor. When the frequencies get close to each other, you start to see the beat frequency or difference between them. This is what gives the odd looking effects and can often be seen best in old movies with stage coaches or steam trains with spoked wheels.
@@crabby7668 not true. Germans used tiny propelers on their wings that would create siren-like sounds during high speed dives so they can psychologically dominate over people by frightening them further more. Look it up
MPX is FM stereo. It works with a nearly inaudible 19kHz carrier tone which could beat with the recorder's bias oscillator. The MPX filter removes this high frequency so this doesn't happen.
MPX is short for "multiplex". An FM signal can have up to 6 signals mixed together - L+R, 19kHz pilot, L-R, 57kHz RDS (scrolling text) plus 2 hidden subcarriers at 67kHz & 92kHz. I've never seen an MPX filter button but it would work on the same principle. I have seen MPX line-out sockets on vintage Sonys (mid-70's). This was when FM was new and allowed outboard equipment to decode the stereo or subcarriers.
@@Anon-fv9ee wow, that’s very cool. As fascinating as the Beat Cut issue although I never saw an MPX marking on the many radio recorders I had growing up, unlike Beat Cut which was a constant mystery. I’d love to know what the optional FM subcarriers were used for - audio? Surely not? Do the illuminati have their own commercial free versions of popular radio stations? Military use?
OK!.... "It's Official" - You are NOW my New Hero! - They NEVER taught is this stuff back at Berklee in Boston in the 80s! - So GLAD I found your channel!!! 🙂
Great explanation! While living in the UK, I had a 1980 mono radio-cassette recorder manufactured by PYE. The beat switch was labeled RIF. Later on, here in NJ I received a crappy Soundesign boombox (1988). It had a beat-cut switch.
A long time ago back when I was a kid I didn't know what that button did, so I tried it and smoke came out! It was obviously faulty but for a long time after that I stayed away from ever using that on anything else that had it.
I figured it out a few years in to my adulthood and experimentation with radio receivers (building them and such) that they were referring to "beat frequency". But, when I was 10, I was just as perplexed as to what is this "beat" switch for as switching it on or off did nothing.
Before the internet you just had to ask around. Any book at the public library which might have helped was already stolen and that was that. Nowadays no one on You Tube even knows what a library is any more.
This video was so nice to watch, I love both cassettes and AM/FM Radio, I used to record music from the air broadcasts of my city on my tapes back when I was a kid, and oh boy, I miss those days with my little and cheap Lennox all-in-one.
I grew up in the 80s and 90s. I think I owned (or more likely my parents owned) at least two of the exact stereos shown in this video. I used to record music from the radio all the time. I had no idea what that "beat"/"iss" button did. It only took like 40 years but now I finally understand it!
I remember I found what that switch is for, when I read the manual for my favorite soviet boombox - the VEF 260. That thing is an excellent AM receiver, with the regular medium wave band split in two for better selectivity, so the engineers who designed it put some care in explaining what the bias switch does. The switch has three positions, but what was NOT explained was that it would shift the bias frequency enough to allow recording on chrome tapes.
Many ham radios and high-end shortwave radios have a "beat shift" or "clock shift" as well. The interference is from the local oscillators and CPU clocks. With CPUs, IFs, and internal buses now in the tens to hundreds of MHz, it can affect VHF/FM radio, and similarly, the feature changes oscillator frequency slightly to place the "birdies" off the frequency you're listening to. Most modern radios have firmware that automatically activates this when you punch in a problematic frequency, so you'd never know it's being used.
Nice clear explanation. I did always wonder about it back in the 80s but I never recorded AM. Still, it’s nice to get an explanation decades later. Thanks!
An excellent video. Despite being big into recording I never knew this, but then pretty much all my radio recordings were from FM and like many others I obviously didn't read manuals as fully as I could have. Thinking about it, I feel the switch should really be called AM Whine Cut.
@Vaquero357 But that is superheterodyne beating caused by two stations in close proximity, rather than that caused by the tape bias oscillator. I think the marketing departments of these products wouldn't want to claim they are solving that problem which is actually most of the whistling sounds on AM.
I truly learned something today. And just because you have spoken about them the under appreciated cheap end stereo systems of the 80s might get the respect they deserve. There were some great systems produced round then, like the Aria FX series, even the cheapest FX 20 came with a neat linear tracking turntable. No kidding.
Holy Crow; that was a good explanation! Just based on the term "Beat Cut", I would have thought that it had something to do with adding blank sound, before the start of a recording, which wasn't even close.
"...I know this topic may be of diminishing relevance..." It certainly isn't. This is an excellent representation of the phase shift in frequencies that college physics students learn about that you can hear. When you are doing the calculations, it's hard to visualize what they mean. This is a great tutorial.
Thanks, VWestlife, for your in-depth video about the beat cut switch. I recall seeing that switch on some of my previous boomboxes from the mid-1980's to the 90's (Prosonic, Samsung, Fisher, etc.) and never understood what it was for. Now I know and knowing is half the battle. G.I. Joe! All the best. :)
Wow, never knew that, also think there could be a reason to do a video on bias too, maybe comparing different methods and frequencies, could also record in Audacity and pitch shift so we can hear different AC bias signals, cool!
I had always wondered what that was. I had played around with it thinking beat cut literally meant it cut the drum beat out of a song. Of course it didn't. Thanks for sharing this!
Great video, I never knew what this switch did either! Since you mentioned long wave, the Irish station on 252 kHz (RTÉ Radio 1) is closing it's LW transmitter on Friday 14th April, less than two weeks away. Not much left although BBC Radio 4 on 198 kHz is still clinging on for now.
I've owned several stereos with a beat cut switch, when the time I was about 9 or 10 I discovered that if I was recording on AM radio and played with the switch, I'd hear that whistling noise, I have a recording of a radio program on a tape and I was playing with the beat cut switch while recording, so you hear lots of whistling noises. I remember Mum had a Sanyo portable stereo with a beat cut switch, and I remember recording on it in around 1991 and the switch was set in the wrong place, so all through that recording, you hear that bloody howling noise. I was only 7, so I didn't understand that I needed to change the switch setting. My own tape recorders were DC Bias, so didn't need a beat cut switch. This video makes me wish UA-cam had been around in the 90s. BTW, I love your collection of radios and tape recorders, I wish I had more like that. I have a Sony CFD-S28L that has, I believe, 5 ISS settings, and I never knew what that did. Mind you I've never used that unit to record AM radio, only FM.
Very well explained. I would imagine that the 'correct' setting moves the beat frequency above the audible range. I suppose it would even have been possible to automate this - with a modern radio tuner having a digital display, there's enough information available to pick a bias frequency that won't beat in the audible range without requiring user input, not that this would have ever been cost-effective in the sort of devices that actually needed it.
I have always wondered what the purpose of those switches were on radios from decades ago. I never did record anything from AM onto cassette tapes so I never figured this out. Excellent explanation and demonstrations too!
Thank you so much for addressing this! It’s an unsolved mystery from a crappy boom box I had as a child. The completely unnecessary, meaningless “beat cancel” switch. It was only to fill space.
😂Wow I don't remember this at all, probably because I would never have used it. But as soon as you mentioned AM radio I knew exactly what it was for 😊I could hear the AM beat in my head, my mom used to listen to a lot of am radio, she was older and AM played music from the 40s and 50s etc. Great video 🖖
I learned now that "beat" or "beat frequency" is what is called in German "Schwebung" - the amplitude changing signal resulting in two frequencies next to each other. The amplitude changing frequency is then approximately the difference of the two involved frequencies (in first order). Was an effect very used by musicians on their analog synthesizers ;-)
Great explanation, thanks! I have not recorded off AM in 40+ years but good to know exactly what that little beat cut button did, not to mention its the same as OSC, ISS, etc. 😊
Very interesting. I’ve seen those buttons years ago in the 80’s and 90’s on my old boom box radios but as never recorded off mw radio I didn’t need it not that I knew what it did back then anyway!
This is the most useful video on UA-cam I have ever watched, I have a GPX AM FM & tape player, I bought way back in the 80s, "still works LOL", it has a Beat switch on the end by the power input cord, never in my life, could I figure out what it did, thanks to you video, I now can get a good night sleep, without the perplexed worry I always felt from that Beat unsolved mystery
The "beat" is basically beating two signals together. It's the "B" in BFO, the Beat Frequency Oscillator, which mixes a second signal with a received single sideband (SSB) one to allow it to be heard normally.
Great job explaining that. I myself have always wondered what that was all about. Very cool you had some real life samples and could duplicate the issue. Thanks for the new wrinkle in my brain!
Assuming you could find the manual, Sanyo actually did a pretty good job of explaining what the switch would do. I was quite young when I first saw a boom box with a beat cancel switch, and while I didn't understand the "why" back then, it didn't take long to figure out that toggling it would suppress the whistling that popped up while recording certain AM stations. I picked up one of those Sony boomboxes a while back and was quite surprised they actually included that feature.
Very interesting, I never knew what it was, and I'm 49 years old. I mainly recorded from the FM band, so it wouldn't have been really an issue for me back in the day. AM still going strong here in Australia. They have mainly voice for AM and FM for music with exceptions. I live in Country Victoria and they have a music radio station on AM (531 khz). Nothing beats the range of those low frequency AM broadcast stations.
I can imagine a country the size of Australia needs something better than line of sight for transmission. I once picked up a faint signal from radio Ceylon in Mumbai on a pocket handheld, I remember it was during a power cut back in the 80s so local interference was probably low enough to let it through. still, that signal travelled over a 1000 miles with a few mountains in between!
I have not had this problem (Radio stations here in Norway typically used FM, and those were the ones I recorded off of) but I am still thrilled that I now know more about recording and radio and such. So thank you for that, mr. Westlife.
Thank you for making this. Always wondered what it was supposed to do. In UK, in the mid eighties when I was recording from the radio, pretty much all music stations had gone to FM, or VHF as we liked to call it, so no wonder couldn't work out what it did
I used this for the first time on Friday to make a posterity recording of RTE 1 on 252kHz longwave using a Siemens RK770. As soon as I pressed record I got a loud whine, but having watched this video just a few days before I knew what to do! Perfect! Thank you! (The SWLing Post brought me here).
It becomes more confusing when, as on a couple of units in the video, the same switch has multiple functions, ie: tape playback eq, ISS mode, and FM stereo mode.
In a previous job, I worked as an applications engineer, serving customers from around the world. I observed that having to translate technical jargon or describe phenomena was quite challenging for our customers who were not native English speakers. Thus, I can appreciate that these stereos were designed overseas, and the engineers recognized that some cost-effective means of eliminating the bias oscillator interference was needed. Very likely, somebody else was tasked with designing the control labels for these products. This person or persons likely looked in some Japanese-to-English dictionary, and "beat" came up as a synonym for the Japanese word. While the translation was correct, the big picture was missed in that in English vernacular, "beat" is associated with musical rhythms.
Seen this on various products growing up and never knew what it was for! My father said 'its mainly for LW and we dont really listen to those frequencies' so thank you for that! Very informative!!
Wow! I used to have that very GE boombox at 9:14. that was a good little unit. I had it in my art studio and it was painted with extra paint and a little splattered as well.
It's interesting to me that that one switch for beat cut on the bigger stereo system is also used for the stereo mode when in FM, and the tape type when in playback mode. I think it would be a pain in the butt to have to keep switching that forth and back depending on what you're doing with and using in what mode, even when you don't have to, just because you had to switch it for something in a different mode.
It saddens this 52 year old that AM will be extinct in the US in my lifetime. I too, used to record AM broadcasts when I was a kid, most notable the Mighty 690 in San Diego whose antenna was located across the border in Tijuana, MX. Truthfully, I have such fond memories of listening to AM on my Realistic hand-held transistor radio while sitting in my bean bag chair reading the latest issue of Daredevil.
Consider that DAB can offer FM-or-better quality within the same bandwidth as an AM signal. The MW band offers better range than FM/VHF/UHF ones; wouldn’t it be handy to be able to put some DAB stations on the MW band?
Awesome video, as always, my friend! I'm astounded at how much WORK/TIME/EFFORT you put into your fantastic demonstrations! You are to be COMMENDED! :)
Crazy to see my little AIWA stereo/radio cassette deck AND my Casio SK-1 looking in such great condition. Mine look like they've been through a partially successful raid on the Death Star
I still have the only two "boom boxes" I have ever owned, and neither of them have the switch. But, being the nostalgia hound I am, I'm certain I will own one at some point.
Really nice video. I also wondered what this setting was. And wow, you still have a Casio SK-1? That's amazing. One of the very few sampling keyboards and one of the best.
Great video 👍 thank you! At last...an answer to the mystery 😅 I have the same stereo system for 30 years...and I NEVER dared to touch that Beat-cut button!!! thank you for this insight 🙏❤
I always assumed the whistle was caused by interference introduced by the tape deck's motor and chalked it up to poor quality components; never did I know that THIS was the reason behind it. For years this has been one of those curiosities I've never been invested enough in to get to the bottom of, but always wondered about--not anymore thanks to this video!
I cant tell ya how weird it is getting an answer to a 30yr old question involving all the music equipment, esp cassettes and recording (the hunting task of scanning radios stations for that song you absolutely love & trying to hit record at just the right moment), that brought me so much joy as a teenager from UA-cam.
I knew what it was for back in the day but had totally forgotten so thanks for the throwback. We couldn't get a decent AM signal where I live anyway so recording off it was never an issue. I'm actually looking to purchase a vintage boombox to complement my growing collection of Compact Cassette tapes which are having a bit of a revival.
i love how your videos are like, this wonderful trip to the fever dreams of trying to figure out ham radios growing up in mercer county with the random ass stations you test with
Thank you for another interesting and informative video! I use those exact same AM loop antennas that you briefly showed in the video. I was wondering if you’d ever do a video on those types of antennas and the FM ones too, as I have always gotten mixed results using them. It feels like they’re super finicky trying to find the best position for them.
Loop antennas are indeed directional. That's not so good if you're trying to receive stations from different directions, but the advantage is that it also lets you position the antenna to null out interference or an unwanted signal.
I never had such a switch on any of my sets. Parenthetically, there's also nothing I would ever record off the A.M. side. But the explanation answers a lot of questions. A lot more confusing is how Pause key works on VHS. You have to fathom the time shift to get clean edits.
Very interesting. I never bothered to record anything on AM (I was a kid when AM was still relevant and I couldn't have cared less (and still can't) about Rush Limbaugh, Baptist revivals, or most country music) so I would've never noticed the BEAT CUT function effects. It sounds like something you'd turn on as a bass reducer, honestly. A better name would probably be AM OSC MODE (AM oscillator mode) or REC INT CANCEL (record interference cancel). At least these suggest what the function is a little more clearly than BEAT CUT.
Where were you in 1968 to 1973, when I made all my AM radio recordings? Well, back then, there were all kinds of problems, but that beat interference did plague a lot of my recordings, but I don't think my recorders had any kind of "beat cut" feature. The biggest problem I found back then was if I was in my room trying to record from 93 KHJ in Los Angeles, and someone had the big (25 inches!) color TV on in the living room, that would really mess up my recordings. It took me a while to figure out it was the TV! So, another piece of advice for recording AM radio is to make sure no one is watching a late 1960s tube color TV nearby! And also make sure you don't pick a DJ who really likes to talk over music. (I'm looking at you, ghost of The Real Don Steele!)
I have the last Sony Boombox you showed got at Goodwill super cheap, and it worked fine for a few weeks, but now when I plug it in, it will say on for like 30sec to a minute max before just dying, and I dread doing a teardown on it. 😤
Make sure the power cord is plugged in firmly, and that you're using the original power cord that came with it. Mine does the same thing if I try to use it with another power cord besides the original Sony one.
@@vwestlife I've got the original Sony cord, and I tried a few others, all do the same thing, so yeah it's got to be internal to the power supply. Also I have a elder neighbor who bought one off Walmart's website new back in 2021 after I showed her what to get, and the first one had the same power supply issues, so she took it back to the store, ordered a 2nd one, and some of the buttons just did not work unless you pressed them really hard, or just right, she took that one back to the store, then ordered another one, and the 3rd one works correctly, and she can finally play all her old tapes from church, so i'm seeing this as a sign of Sony having some bad QC issues with these, and it's sad to see from one of the last big well known companies(a company your average Joe 6 pack, or mother Jane could name without much thought) still making Cassette/CD boomboxes.
Thanks for answering something that puzzled me 40 years ago. I never knew as there was no internet to look it up. As most of us would never dream of recording from AM, I don't suppose it was a big deal.
Thanks for this, as I rarely listened to (or recorded) AM i always wondered what the Beat Cut switch did. Never seemed to do anything. Now I know why lol
I forgot I used to see those switches. Back then, reading the owner’s manual was kinda required for a lot of things if you wanted to get the full functionality from your device.
WAIT A GODDAMN SECOND, the beat from the keyboard at 2:25 is the very beginning from a German Song from EAV called "Burli"! Whaaaaaaaaat... did they really sample THAT keyboard???
Obviously they couldn't use "Beat Off" as the nomenclature for that switch.
😂 nice!
It's like on a fishing boat. They never call the person in charged of the bait the "Master Baiter"
They should have called it "Whistle Out"
"Sometimes you just gotta 'choke the chicken' when recording AM radio" ~ every AM radio recording enthusiast ever.
Kinky
I have been tinkering with radios and recording since I was a kid and those devices were new, have a full amateur radio license and have a degree in high frequency electronic engineering AND I NEVER KNEW UNTIL TODAY WHERE THAT SWITCH WAS FOR! Thank you for explaining this unusual but very useful feature. 😅
I think it’s interesting that over the years they didn’t come out with a marketing term that would explain its function better for people who had no idea. Something like “Radio Noise Reduction” akin to Dolby.
Sony got close: ISS "interference suppression switch"
@@rijjhb9467 The term Beat is technically correct it is a beat frequency.
@@GaryKeepItSimple And the technically correct term for what Dolby Noise Reduction does is compansion, but they sure as hell didn't market it as a compander to the general public.
The all new (beat) function allows you to cut the whining noise when recording AM stations lol
Marketing timing 50 years too late lol
Why would they. It's like "2000W PMPO" found on boom boxes in the late '90's, early 2000's. No one actually knew what that meant, either - except maybe for people like me. Another fictitious marketing measurement of perceived output power. It's interesting that they can get 2000 watts from an amplifier that was running on 12V maximum producing under 3 watts.
Having parts of your narration play from cassettes was a really cool touch in this!
When recording from FM radio it's actually the opposite: The 19kHz pilot tone of the stereo multiplex interferes with the bias frequency or the frequency of the erase head, causing a beat frequency resulting in an audible whine. That's what the MPX filter is for: It's just a notch filter that removes the 19kHz pilot tone and the 38kHz subcarrier.
The 19kHz can also interfere with Dolby noise reduction when recording tapes.
I also discovered another use for the MPX filter, some CD's and even LP's were very hard to record, they'd produce distortion on cymbals when recording. Changing the bias and recording levels reduced but would not eliminate the problem. Other cassette decks and even reel to reel would also have the problem. I finally realized frequencies in the cymbal sound were mixing with the tape bias in a nonlinear way and producing an unpleasant sound. I don't know if this was intentional analog copy protection or just an artifact. MPX filter would almost completely solve the problem even though the recording was from CD or LP and not FM stereo.
@@davidg4288 Did this happen mainly with rock music recordings? I guess the reason is because the drum sounds and cymbals are always very compressed on that genre of music making them consistently loud at a relatively high level. That would do it.
@@circattle This was a long time ago, I recall it happening in progressive rock and fusion jazz which was NOT very compressed but did have all the highs they could record. Recording at a lower level did not fix it, it was more frequency than loudness related. I no longer have working tape machines to test with.
BNMRR .. Beat Noise Mitigation for Radio Recording!😉
For anyone who doesn't know, "beat" in this sense can refer to the observable difference between *any* two frequencies, not just audio (although audio is where the term is encountered most often, which no doubt adds to the confusion with the musical homonym.) But for example, if the turn signals on two cars seem to be flashing in sync, but the signal on car A is just a little bit slower and starts flashing more and more behind that of car B, you're seeing the signals' beat frequency
Pilots of multi engined bombers during ww2 used to synchronise their engines to prevent the loud "pulsing" of the beat frequencies between the engines. Allegedly the Germans didn't bother so much and people could tell the difference between formations of German and allied planes because the German aircraft had a distinctive drone caused by the beats.
100%. If it's of interest: before the days of digital tuning meters this is exactly how pipe-organ tuners used to "lay down" the middle octave of a set of pipes, playing fifths and fourths - each interval between 2 notes should have a specific number of "beats" (different for each two notes) in the same way as you describe. Once you've laid the bearings of that reference octave, you then simply tune the rest to exact octaves of each note with no beat audible.
Irc another example is when you see wheels or propellers in films, slow right down or even reverse as the vehicle is moving. This happens because the "frame speed" or frequency of the camera is interacting with the frequency of rotation of the wheel or propellor. When the frequencies get close to each other, you start to see the beat frequency or difference between them. This is what gives the odd looking effects and can often be seen best in old movies with stage coaches or steam trains with spoked wheels.
In music I have heard it referred to as "beating" which can be a clearer term
@@crabby7668 not true. Germans used tiny propelers on their wings that would create siren-like sounds during high speed dives so they can psychologically dominate over people by frightening them further more. Look it up
This was very well done and explained so you can easily understand. Next, you should do a video on the "MPX' filter button on cassette decks.
Yes, sort of a related topic but different.
Yes please, if anybody can make me understand MPX it is Mr VW 👌
MPX is FM stereo. It works with a nearly inaudible 19kHz carrier tone which could beat with the recorder's bias oscillator. The MPX filter removes this high frequency so this doesn't happen.
MPX is short for "multiplex". An FM signal can have up to 6 signals mixed together - L+R, 19kHz pilot, L-R, 57kHz RDS (scrolling text) plus 2 hidden subcarriers at 67kHz & 92kHz. I've never seen an MPX filter button but it would work on the same principle. I have seen MPX line-out sockets on vintage Sonys (mid-70's). This was when FM was new and allowed outboard equipment to decode the stereo or subcarriers.
@@Anon-fv9ee wow, that’s very cool. As fascinating as the Beat Cut issue although I never saw an MPX marking on the many radio recorders I had growing up, unlike Beat Cut which was a constant mystery. I’d love to know what the optional FM subcarriers were used for - audio? Surely not? Do the illuminati have their own commercial free versions of popular radio stations? Military use?
More than 30 years I have been waiting for this explanation. Thank you so much.
This video fixed my childhood! And I am pretty sure not just my childhood. Thanks for the explanation!
OK!.... "It's Official" - You are NOW my New Hero! - They NEVER taught is this stuff back at Berklee in Boston in the 80s! - So GLAD I found your channel!!! 🙂
Great explanation! While living in the UK, I had a 1980 mono radio-cassette recorder manufactured by PYE. The beat switch was labeled RIF. Later on, here in NJ I received a crappy Soundesign boombox (1988). It had a beat-cut switch.
A long time ago back when I was a kid I didn't know what that button did, so I tried it and smoke came out! It was obviously faulty but for a long time after that I stayed away from ever using that on anything else that had it.
So it did what it said, it "cut your beats".
😂
I think you had a Mission Impossible tape recorder
Dude. You took the time to demonstrate for the world a puzzling mystery for me and my generation of radio geeks. Thank you!
Agreed. I would’ve paid to know what the beat cancel button meant on my boom box on 1980!
Lol, would have been helpful three decades ago! 😂
I figured it out a few years in to my adulthood and experimentation with radio receivers (building them and such) that they were referring to "beat frequency". But, when I was 10, I was just as perplexed as to what is this "beat" switch for as switching it on or off did nothing.
Before the internet you just had to ask around. Any book at the public library which might have helped was already stolen and that was that. Nowadays no one on You Tube even knows what a library is any more.
Exactly!
Thank you for the explanation, my younger self back in the 80's always wonder what the beat cut switch did.
This video was so nice to watch, I love both cassettes and AM/FM Radio, I used to record music from the air broadcasts of my city on my tapes back when I was a kid, and oh boy, I miss those days with my little and cheap Lennox all-in-one.
I grew up in the 80s and 90s. I think I owned (or more likely my parents owned) at least two of the exact stereos shown in this video. I used to record music from the radio all the time. I had no idea what that "beat"/"iss" button did. It only took like 40 years but now I finally understand it!
yeah... well... who in the 80 and 90's recorded from AM, regardless?
I remember I found what that switch is for, when I read the manual for my favorite soviet boombox - the VEF 260. That thing is an excellent AM receiver, with the regular medium wave band split in two for better selectivity, so the engineers who designed it put some care in explaining what the bias switch does. The switch has three positions, but what was NOT explained was that it would shift the bias frequency enough to allow recording on chrome tapes.
Many ham radios and high-end shortwave radios have a "beat shift" or "clock shift" as well. The interference is from the local oscillators and CPU clocks. With CPUs, IFs, and internal buses now in the tens to hundreds of MHz, it can affect VHF/FM radio, and similarly, the feature changes oscillator frequency slightly to place the "birdies" off the frequency you're listening to. Most modern radios have firmware that automatically activates this when you punch in a problematic frequency, so you'd never know it's being used.
Nice clear explanation. I did always wonder about it back in the 80s but I never recorded AM. Still, it’s nice to get an explanation decades later. Thanks!
An excellent video. Despite being big into recording I never knew this, but then pretty much all my radio recordings were from FM and like many others I obviously didn't read manuals as fully as I could have. Thinking about it, I feel the switch should really be called AM Whine Cut.
@Vaquero357 But that is superheterodyne beating caused by two stations in close proximity, rather than that caused by the tape bias oscillator. I think the marketing departments of these products wouldn't want to claim they are solving that problem which is actually most of the whistling sounds on AM.
I truly learned something today. And just because you have spoken about them the under appreciated cheap end stereo systems of the 80s might get the respect they deserve. There were some great systems produced round then, like the Aria FX series, even the cheapest FX 20 came with a neat linear tracking turntable. No kidding.
Holy Crow; that was a good explanation! Just based on the term "Beat Cut", I would have thought that it had something to do with adding blank sound, before the start of a recording, which wasn't even close.
Thank you for solving a 40 year old question for me. That switch has mystified me since my first boombox.
"...I know this topic may be of diminishing relevance..." It certainly isn't. This is an excellent representation of the phase shift in frequencies that college physics students learn about that you can hear. When you are doing the calculations, it's hard to visualize what they mean. This is a great tutorial.
Thanks, VWestlife, for your in-depth video about the beat cut switch. I recall seeing that switch on some of my previous boomboxes from the mid-1980's to the 90's (Prosonic, Samsung, Fisher, etc.) and never understood what it was for.
Now I know and knowing is half the battle. G.I. Joe!
All the best. :)
Wow, never knew that, also think there could be a reason to do a video on bias too, maybe comparing different methods and frequencies, could also record in Audacity and pitch shift so we can hear different AC bias signals, cool!
"Beat Cut" is why Edward Scissorhands never looked at naughty magazines
lol
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Hahahaha
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I had always wondered what that was. I had played around with it thinking beat cut literally meant it cut the drum beat out of a song. Of course it didn't. Thanks for sharing this!
Great video, I never knew what this switch did either! Since you mentioned long wave, the Irish station on 252 kHz (RTÉ Radio 1) is closing it's LW transmitter on Friday 14th April, less than two weeks away. Not much left although BBC Radio 4 on 198 kHz is still clinging on for now.
I've owned several stereos with a beat cut switch, when the time I was about 9 or 10 I discovered that if I was recording on AM radio and played with the switch, I'd hear that whistling noise, I have a recording of a radio program on a tape and I was playing with the beat cut switch while recording, so you hear lots of whistling noises. I remember Mum had a Sanyo portable stereo with a beat cut switch, and I remember recording on it in around 1991 and the switch was set in the wrong place, so all through that recording, you hear that bloody howling noise. I was only 7, so I didn't understand that I needed to change the switch setting. My own tape recorders were DC Bias, so didn't need a beat cut switch. This video makes me wish UA-cam had been around in the 90s. BTW, I love your collection of radios and tape recorders, I wish I had more like that. I have a Sony CFD-S28L that has, I believe, 5 ISS settings, and I never knew what that did. Mind you I've never used that unit to record AM radio, only FM.
What a fascinating video - today I finally learned what the mysterious "beat cut" was all about! Thanks! 🙂
Very well explained. I would imagine that the 'correct' setting moves the beat frequency above the audible range. I suppose it would even have been possible to automate this - with a modern radio tuner having a digital display, there's enough information available to pick a bias frequency that won't beat in the audible range without requiring user input, not that this would have ever been cost-effective in the sort of devices that actually needed it.
I have always wondered what the purpose of those switches were on radios from decades ago. I never did record anything from AM onto cassette tapes so I never figured this out. Excellent explanation and demonstrations too!
Thank you so much for addressing this! It’s an unsolved mystery from a crappy boom box I had as a child. The completely unnecessary, meaningless “beat cancel” switch. It was only to fill space.
😂Wow I don't remember this at all, probably because I would never have used it. But as soon as you mentioned AM radio I knew exactly what it was for 😊I could hear the AM beat in my head, my mom used to listen to a lot of am radio, she was older and AM played music from the 40s and 50s etc. Great video 🖖
As an amateur radio operator I immediately recognized the function.
I learned now that "beat" or "beat frequency" is what is called in German "Schwebung" - the amplitude changing signal resulting in two frequencies next to each other. The amplitude changing frequency is then approximately the difference of the two involved frequencies (in first order).
Was an effect very used by musicians on their analog synthesizers ;-)
The English technical term is “heterodyne”. Also used as the basis for higher-frequency radio receivers (e.g. FM).
Great explanation, thanks! I have not recorded off AM in 40+ years but good to know exactly what that little beat cut button did, not to mention its the same as OSC, ISS, etc. 😊
Very interesting. I’ve seen those buttons years ago in the 80’s and 90’s on my old boom box radios but as never recorded off mw radio I didn’t need it not that I knew what it did back then anyway!
This is the most useful video on UA-cam I have ever watched, I have a GPX AM FM & tape player, I bought way back in the 80s, "still works LOL", it has a Beat switch on the end by the power input cord, never in my life, could I figure out what it did, thanks to you video, I now can get a good night sleep, without the perplexed worry I always felt from that Beat unsolved mystery
The "beat" is basically beating two signals together. It's the "B" in BFO, the Beat Frequency Oscillator, which mixes a second signal with a received single sideband (SSB) one to allow it to be heard normally.
Getting that frequency wrong produces some entertaining effects ...
We use those in ADF
Great job explaining that. I myself have always wondered what that was all about. Very cool you had some real life samples and could duplicate the issue. Thanks for the new wrinkle in my brain!
Assuming you could find the manual, Sanyo actually did a pretty good job of explaining what the switch would do.
I was quite young when I first saw a boom box with a beat cancel switch, and while I didn't understand the "why" back then, it didn't take long to figure out that toggling it would suppress the whistling that popped up while recording certain AM stations. I picked up one of those Sony boomboxes a while back and was quite surprised they actually included that feature.
Very interesting, I never knew what it was, and I'm 49 years old. I mainly recorded from the FM band, so it wouldn't have been really an issue for me back in the day.
AM still going strong here in Australia. They have mainly voice for AM and FM for music with exceptions. I live in Country Victoria and they have a music radio station on AM (531 khz). Nothing beats the range of those low frequency AM broadcast stations.
I can imagine a country the size of Australia needs something better than line of sight for transmission. I once picked up a faint signal from radio Ceylon in Mumbai on a pocket handheld, I remember it was during a power cut back in the 80s so local interference was probably low enough to let it through. still, that signal travelled over a 1000 miles with a few mountains in between!
I have not had this problem (Radio stations here in Norway typically used FM, and those were the ones I recorded off of) but I am still thrilled that I now know more about recording and radio and such. So thank you for that, mr. Westlife.
I have it on my RCA boombox. Never knew what it was until now.
Thank you for making this. Always wondered what it was supposed to do. In UK, in the mid eighties when I was recording from the radio, pretty much all music stations had gone to FM, or VHF as we liked to call it, so no wonder couldn't work out what it did
I used this for the first time on Friday to make a posterity recording of RTE 1 on 252kHz longwave using a Siemens RK770. As soon as I pressed record I got a loud whine, but having watched this video just a few days before I knew what to do! Perfect! Thank you! (The SWLing Post brought me here).
This is the clearest and cleanest explanation about this mysterious button. Thank you very much.
I had a 1994 Sanyo boombox back in the day with this switch in the back. Thank you for answering this question after 29 years of head scratching.
I have been a electronics hobbyist over 50 YEARS and I Learn something, thanks! 👍
It becomes more confusing when, as on a couple of units in the video, the same switch has multiple functions, ie: tape playback eq, ISS mode, and FM stereo mode.
In a previous job, I worked as an applications engineer, serving customers from around the world. I observed that having to translate technical jargon or describe phenomena was quite challenging for our customers who were not native English speakers. Thus, I can appreciate that these stereos were designed overseas, and the engineers recognized that some cost-effective means of eliminating the bias oscillator interference was needed. Very likely, somebody else was tasked with designing the control labels for these products. This person or persons likely looked in some Japanese-to-English dictionary, and "beat" came up as a synonym for the Japanese word. While the translation was correct, the big picture was missed in that in English vernacular, "beat" is associated with musical rhythms.
40 years later, I finally find out what that means. I can rest easy now. Thank you!
Seen this on various products growing up and never knew what it was for! My father said 'its mainly for LW and we dont really listen to those frequencies' so thank you for that! Very informative!!
Wow! I used to have that very GE boombox at 9:14. that was a good little unit. I had it in my art studio and it was painted with extra paint and a little splattered as well.
It's interesting to me that that one switch for beat cut on the bigger stereo system is also used for the stereo mode when in FM, and the tape type when in playback mode. I think it would be a pain in the butt to have to keep switching that forth and back depending on what you're doing with and using in what mode, even when you don't have to, just because you had to switch it for something in a different mode.
It saddens this 52 year old that AM will be extinct in the US in my lifetime. I too, used to record AM broadcasts when I was a kid, most notable the Mighty 690 in San Diego whose antenna was located across the border in Tijuana, MX. Truthfully, I have such fond memories of listening to AM on my Realistic hand-held transistor radio while sitting in my bean bag chair reading the latest issue of Daredevil.
Consider that DAB can offer FM-or-better quality within the same bandwidth as an AM signal. The MW band offers better range than FM/VHF/UHF ones; wouldn’t it be handy to be able to put some DAB stations on the MW band?
@@lawrencedoliveiro9104 Google for digital radio mondiale
Awesome video, as always, my friend! I'm astounded at how much WORK/TIME/EFFORT you put into your fantastic demonstrations! You are to be COMMENDED! :)
Thanks so much for that very thorough explanation. I knew about the Beat switch and knew it had something to do with AM radio, but that's about it.
You ought to archive these tapes! How fascinating!
Thanks for solving this mystery, I've always wondered about that.
The tapes *are* my archive. They've lasted longer than any computer or CD-R I could've transferred them onto.
Crazy to see my little AIWA stereo/radio cassette deck AND my Casio SK-1 looking in such great condition.
Mine look like they've been through a partially successful raid on the Death Star
I forgot how confused I was with this back in the day! Thanks!
I still have the only two "boom boxes" I have ever owned, and neither of them have the switch. But, being the nostalgia hound I am, I'm certain I will own one at some point.
Really nice video. I also wondered what this setting was. And wow, you still have a Casio SK-1? That's amazing. One of the very few sampling keyboards and one of the best.
I love how much style old electronics had, really pretty stuff
Great video 👍 thank you! At last...an answer to the mystery 😅
I have the same stereo system for 30 years...and I NEVER dared to touch that Beat-cut button!!!
thank you for this insight 🙏❤
I always assumed the whistle was caused by interference introduced by the tape deck's motor and chalked it up to poor quality components; never did I know that THIS was the reason behind it. For years this has been one of those curiosities I've never been invested enough in to get to the bottom of, but always wondered about--not anymore thanks to this video!
I've never heard bias compared to msg before. That had me in tears. 🤣🤣
I've never recorded an AM broadcast to experience the oscillation issue but now I know what the cryptic B.P. switch on my boombox means.
I cant tell ya how weird it is getting an answer to a 30yr old question involving all the music equipment, esp cassettes and recording (the hunting task of scanning radios stations for that song you absolutely love & trying to hit record at just the right moment), that brought me so much joy as a teenager from UA-cam.
Thanks for taking the time to share this with us!
I knew what it was for back in the day but had totally forgotten so thanks for the throwback. We couldn't get a decent AM signal where I live anyway so recording off it was never an issue. I'm actually looking to purchase a vintage boombox to complement my growing collection of Compact Cassette tapes which are having a bit of a revival.
i love how your videos are like, this wonderful trip to the fever dreams of trying to figure out ham radios growing up in mercer county with the random ass stations you test with
Thank you VWestlife for making these well done videos on topics few know about.
Thank you for another interesting and informative video! I use those exact same AM loop antennas that you briefly showed in the video. I was wondering if you’d ever do a video on those types of antennas and the FM ones too, as I have always gotten mixed results using them. It feels like they’re super finicky trying to find the best position for them.
Loop antennas are indeed directional. That's not so good if you're trying to receive stations from different directions, but the advantage is that it also lets you position the antenna to null out interference or an unwanted signal.
Even reading the instructions back in the day I didn't understand what problem it was trying to solve until seeing this video. Thank you!
Now I want to hear what it sounds like with either too much or too little 'bias' on a tape recording.
me too!
Too much bias makes the recording sound muffled and too little bias makes it sound tinny.
@@vwestlife make a video example, you are very clear in your videos!
Great job! As soon as you mentioned it in the venue of shortwave, I knew exactly what beats you meant.
Always wondered why I heard that noise while recording AM radio!!! Thanks for this entertaining expose.
This is why I love the internet. Answers to questions we all have or had but never really thought much about.
I just want to tell you how much I enjoy this UA-cam channel. (A lot.) ✌️❤️
I never had such a switch on any of my sets. Parenthetically, there's also nothing I would ever record off the A.M. side. But the explanation answers a lot of questions. A lot more confusing is how Pause key works on VHS. You have to fathom the time shift to get clean edits.
Very interesting. I never bothered to record anything on AM (I was a kid when AM was still relevant and I couldn't have cared less (and still can't) about Rush Limbaugh, Baptist revivals, or most country music) so I would've never noticed the BEAT CUT function effects. It sounds like something you'd turn on as a bass reducer, honestly. A better name would probably be AM OSC MODE (AM oscillator mode) or REC INT CANCEL (record interference cancel). At least these suggest what the function is a little more clearly than BEAT CUT.
Excellent video. Thanks for taking the time to explain this. I never knew either!
Thank you so much for improving my knowledge! I humbly thank you for your efforts!
Where were you in 1968 to 1973, when I made all my AM radio recordings? Well, back then, there were all kinds of problems, but that beat interference did plague a lot of my recordings, but I don't think my recorders had any kind of "beat cut" feature. The biggest problem I found back then was if I was in my room trying to record from 93 KHJ in Los Angeles, and someone had the big (25 inches!) color TV on in the living room, that would really mess up my recordings. It took me a while to figure out it was the TV! So, another piece of advice for recording AM radio is to make sure no one is watching a late 1960s tube color TV nearby! And also make sure you don't pick a DJ who really likes to talk over music. (I'm looking at you, ghost of The Real Don Steele!)
it took almost 40 years. now i am complete. thank you.
I have the last Sony Boombox you showed got at Goodwill super cheap, and it worked fine for a few weeks, but now when I plug it in, it will say on for like 30sec to a minute max before just dying, and I dread doing a teardown on it. 😤
Make sure the power cord is plugged in firmly, and that you're using the original power cord that came with it. Mine does the same thing if I try to use it with another power cord besides the original Sony one.
@@vwestlife I've got the original Sony cord, and I tried a few others, all do the same thing, so yeah it's got to be internal to the power supply.
Also I have a elder neighbor who bought one off Walmart's website new back in 2021 after I showed her what to get, and the first one had the same power supply issues, so she took it back to the store, ordered a 2nd one, and some of the buttons just did not work unless you pressed them really hard, or just right, she took that one back to the store, then ordered another one, and the 3rd one works correctly, and she can finally play all her old tapes from church, so i'm seeing this as a sign of Sony having some bad QC issues with these, and it's sad to see from one of the last big well known companies(a company your average Joe 6 pack, or mother Jane could name without much thought) still making Cassette/CD boomboxes.
Thanks for answering something that puzzled me 40 years ago. I never knew as there was no internet to look it up. As most of us would never dream of recording from AM, I don't suppose it was a big deal.
The beat cut switch was used to remove the high pitched whistle that you could sometimes hear on AM radio stations. It was only active when recording.
Always a good day when a video drops ❤️
Astonishing. Thank you for producing and sharing.
Excellent explanation starting with a funny twist, therefore it's only appropriate to cut the beat before noon 🤣😂.
FANTASTIC video! I learned so much!
Thanks for this, as I rarely listened to (or recorded) AM i always wondered what the Beat Cut switch did. Never seemed to do anything. Now I know why lol
I forgot I used to see those switches. Back then, reading the owner’s manual was kinda required for a lot of things if you wanted to get the full functionality from your device.
Wow, my dad had that Sanyo music centre - I now have it as a retro relic - always wondered what that button was for 😂
WAIT A GODDAMN SECOND, the beat from the keyboard at 2:25 is the very beginning from a German Song from EAV called "Burli"! Whaaaaaaaaat... did they really sample THAT keyboard???
Probably the best explanation of this obscure switch. The only thing I still don't understand is why they thought *Beat cut* was a good term to use..?