AC/DC tape bias for beginners!
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- čas přidán 11. 09. 2024
- Old school vs. new school shoebox cassette recorders! And an introduction into tape bias.
Here are some new shoebox players to check out;
Tyler amzn.to/32oG0i2
Sony amzn.to/2GZ2i1B
RCA (brace yourself) amzn.to/2DY29KB
Coby amzn.to/3hucFa2
And here is our show on the Tyler;
• It’s cassette tape tim...
Thank you for watching and commenting!
Fun fact: It was the Germans during WWII that perfected the tape recorder. The preceding technology, the wire recorder, was problematic and clanky. The German scientists figured out that two things were needed to improve the magnetic recorder - BIAS, as you mentioned, and better media. They came up with the solution - a strip of acetate material with finely-ground iron oxide filings, instead of a steel wire.
The quality was so good that the device was used to deceive the allies, confounding their efforts to pinpoint Der Furher's location. When the Reich collapsed, US forces seized the equipment and sent it home to the US, where it was reverse-engineered and refined further.
Those early tape recorders had sound quality that would likely impress people even today. The technology was quickly adopted for radio broadcast and studio recordings by right around 1950.
That explains why are Hitler's speeches of so high audio quality, all things considered.
I used to tape the audio from movies quite a bit back when I was younger so I could listen to them on my Walkman while on the go!
Yes!
A lot of low end tape recorders back into the 80s (and maybe earlier, I'm not sure) used DC bias as well. I remember those cheap all-in-one bookshelf units of the late 80s/early 90s used DC bias recording.
Those RCA tapes had cheap cases and shells, true. But the tape inside was made in Korea, and is actually reasonable Type I (not "Type 0") quality.
“The Twilight Zone” makes for some really good audio tapes as well. I used to have “The Twilight Zone” playing when I went to bed and since I just had it on for background noise, I decided to just record some episodes to cassette.
Ahhhh yes, those great childhood memories of playing computer games in the 1980's. I had the Commodore 64 and those games on cassettes you loaded onto the computer through a shoebox cassette recorder similar to that white one. When I was a kid in the 80's we had something you could buy in shops called 'Story Teller'. They were magazines that were issued once a fortnight I think with children's stories in, and they came with cassette tapes so you could listen to the stories while reading along in the magazine. They were great fun. I think they made about 50 of them in total and you could even buy the special binders to store all the magazines in. They're quite collectable nowadays and I've seen complete sets of them on Ebay going for quite a lot of money. It's interesting when you played the Voltron cassette you mentioned about print through. I had a couple of music cassettes that had that issue with print through. I don't know for sure what causes it, but my theory is as a tape gets older in age and if stored for a long time and not played, some of the recorded sound on the next bit of magnetic tape to come off the reel gets imprinted onto the bit of tape around the outside of the reel and that's what causes the echo effect. I hope I explained that okay.
hahaha my school was still using those in the 90s up to the 2000s those audio books on tape where sometimes teachers would have a listening station set up with a shoebox cassette player or one of those cheap 3-in-one cd/cassette/radio boomboxes from walmart, and you had to turn the page when you hear the sound. I also recall in my ESL class using some thing that looked like a scope you look into or a TV that you put these filmstrips into and follow along in the
audio cassette tape that went with the filmstrip. They were still photos, but I cant find out what the player or format was called. Very similar to micromatic film slides, I know because years later my school gave me some of those. Have you ever used the language master? It looked like a shoebox recorder that you swiped a card through like a credit card but it had analog tape strips on it with audio kinda like talking flashcards
I now understand bias!
Thank you.
The AC bias frequency is a sine approximately 5X as high as the highest frequency the recorder is expected to record. Is is generally around 100kHZ. That signal is not erased and it stays with the tape but is filtered out by a low pass filter called a bias trap.If an AC biased signal is played back slowly enough (!/20th or so), the bias frequency can be heard. DC bias does not require a bias trap.
How much current applied to the bias frequency depends on the type of tape used. with Type I requiring the least current graduating up to type IV which requires the most.
Recording a Type II or IV tape with Type I Normal bias will make a recording that is very low in volume and with higher frequencies predominating.(Under bias) Recording a Type I tape with II or IV bias will produce a muddy tape because the bias current will partially erase the high frequencies.(Over bias).
Being in the recording business, I was often asked to try to salvage a tape made on a Shoebox or Boombox that had been recorded on Type II or Type IV tape. The client had gone into a store, usually Radio Shack and asked for "the best tape available" for a one time event such as a wedding or a recital. Not knowing what the tape was to be used on, the customer was sold high bias tape and the sound was terrible.
12:20 Adding dc to audio signal doesnt amplify it at all, it just shift/offset it according to the dc applied.
Interestingly, Philips' first (1963) cassette recorder was almost hifi: it had ac bias, a frequency response of 60 - 10,000 Hz and 0.35% wow and flutter. The microphone was dynamic but of reasonable quality (inexpensive electret condenser microphones arrived more than a decade later).. The first Japanese clones had only dc bias, no electronic speed stabilization and typically a frequency response of 200-6,000 Hz; more like the sound quality of a telephone, but played prerecorded cassettes reasonably well. It took about 10 years for anyone to produce anything better, when stereo heads were introduced, and chrome cassettes came out, which pushed the frequency response to about 15,000 Hz.
I was just listening to your explanation on AC bias which was OK. Did you realise the AC bias frequency is actually in the Long Wave frequencies? In UK and Europe, we have Long Wave and Medium Wave AM bands. What you call AM Band is MW to us. BBC Radio 4 is 198 kHz Long Wave. 148.5 to 283.5 kHz is used for AM broadcasting. AC bias often uses 150kHz not exactly an "Audio" frequency.
Shouldn't you be pressing stop between every button press? That may be why you broke the fast forward on the other video...
HEY it was broke out of the box lol!
@@Recordology still I would press stop between every function.
think you are right, at least thats how I was taught to operate one hahaha
I hope there's Black Sabbath tape bias, too. 😂
Vintage electronics are way better than new I have lots of cassette recoders RadioShack, General electric, Realistic, Califone, etc and I fix them too
Panasonic rq 2107A is the one my mom has
The question I still need answered--how can you tell if your cassette recorder is AC bias or DC bias?
I don't think there is a way to tell without looking at the specifications.
@@Recordology I appreciate your reply. Enjoyed the video!
The erase head should have some kind of type designation printed on it that should give you a hint.
@ Bobby Horton: If your tape player/deck has a 'normal' looking 'head' to the left of the main playback/record head - it may normally be black, but with a small etched area where the tape passes over it, and tape guides mounted to it, then it's an AC Bias erase head.
If it just looks like a smaller black 'lump' that's offset in relation to the main play/record head, and if it swings-up to meet the tape when recording - you can test this by pressing the record button whilst holding back the small tab at the back of the tape well (which detects whether the tape is record capable/protected), and you'll see this small lump move forward into the tape path.... this is a permanent magnet which just blindly erases whatever is on the tape in the crudest manner possible! It causes a lot of noise on the tape as it passes the play/record head, and so you get distorted, hissy recordings. This is a classic DC Bias head - it's just a small magnet!!
The proper AC Bias tape uses a varying electrical current to erase the tape determined by the type of tape being recorded: ie, a normal bias, or a chrome or metal tape.... This is why better cassette decks have either a switchable tape type selector, or they'll auto-detect the tape type.
The DC Bias 'magnet' is usually in cheap recording portables, shoebox recorders, and some inexpensive so-called 'boomboxes'...
Hope this helps. :-)
Usually you can tell by saying a sentence with many S and F sounds.
Example: testing The bias of this cassette player.
Be sure to really draw out the esses, that’s how I always do it. If the esses sound clear it’s likely an AC bias machine. If the esses sound slightly garbled or there seems to be some fuz in the recording whenever there are S and F noises it is likely a DC bias machine.
The really funny thing?
The new one isn't a rebranded GE, but the Radio Shack is. 8 )
Is it really??
@@Recordology Yes. It's a GE in a different case. Quite a few of RS' portables were GE at the time.
A few examples:t he SCR-8 is a GE "Blockbuster", the SCR-6 is a GE 3-5286A, the CTR-55 is a GE 3-5016C...
I saw AC/DC but it was not the AC/DC I was thinking about
lol sorry!
Very informative. Any recommendation for cassette recorders for music?
Thank you....so far I've had the best luck with 90's component decks.
Depends on what you're in for. 50 bucks and a bit of luck can get you an early-to-mid 90s working 2-head hi-fi cassette deck. If you want a refurbished higher-quality 3-head deck, you're in for 200+
Just got a few shoeboxes the other day:
A radioshack telephone cassette recorder that can be used for regular standalone tape recording aplications
and a GPX almost although not quite walkman size player with sholder strap
Both of them came in original box
Are these any good?
Belts are fine on both of them and they can run off wall adaptor or bateries
Believe both are of about the same vintage so to speak late 90s or 2000s maybe.
Mechanism is probably the same chewodenchy or tanachan mechanism? feels the same on both same layout of buttons, although feels more robust on the radioshack maybe its just the plastic or something but it just feels more legit on the radioshack lol and the radioshack is somewhat heavy compared to the gpx one
Awesome! Do you still have them?
Does anyone remember the language master using one in school? It looked like a shoebox recorder that you would swipe electronic talking flashcards through
Lol I remember overwriting those and pissing off the teacher hahaha.
10:10 "bias"
DC biasing is awful, even Nazi Germany had AC biasing on their later tape recorders because they knew that early how good AC biasing is. Its horrible that you can even still buy tape recorders with DC bias... like these junk Walkmans without rewind its like having less than nothing!