Adventures In Audio

Did that Dolby thing ever work?

I gave the width of cassette tape as an eighth of an inch, which is probably too much of an approximation. It should be 0.15 inches. Wikipedia states "The tape in a compact audio cassette is nominally ⅛ inch but actually slightly wider (3.81 millimetres (0.150 in))" DM

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Roger King:  This is a perfect illustration of how analogue recordings are vastly more dependent on the playback equipment (both quality and condition) than are digital recordings. I've been using cassettes since the 1970s and I have never felt that Dolby was less than excellent; but I've always had an interest in the technology so I wouldn't dream of using a dirty machine, crap tapes, wrong bias, or recording at the wrong level, etc. My current three head machine with Dolby S essentially makes recording that are indistinguishable to the ear from the source, be that vinyl, CD or whatever. However, one thing is certain - pre-recorded tapes almost always sound crap because it would have been too expensive to use decent tape stock or record them at only 1 7/8" speed (+ precise azimuth and probably loads of other factors).

Fire Angel:  Nakamichi used to make cassette decks that would adjust their Dolby levels for each brand of tape; you put the tape in and set it to calibrate and it would record a series of tones on the tape and set the Dolby level for recording on that exact tape type. It was a tedious process but was only needed when recording as the levels coming off the tape would be correct if you bothered to calibrate before using a new tape type. Of course if you only ever used one brand of tape then calibration only needed to be done a couple of times a year to get the best out of the machine.

Maybe there were other brands of cassette deck that did this but I never saw one.

landnnut:  The belt on my cira. 1982 Nakamichi BX-1 went bad so b type Dolby is moot.

Trev0r98:  The following is 100% true.

I sped up the tape transport of my 1971-vintage non-Dolby Sony TC-160 cassette deck by a factor of 3 (5.6 ips), rolled back the Equalization (the two outboard pots at the front of the MOSFET-based circuit board), and never looked back.

How did I speed up the tape transport? Simple: I put a couple of Revel car model tires over the drive motor spindle, where the belts went. Then I just wrapped the drive belt around the V-shaped groove where the model tires met. The tires were 3 times the diameter of the OEM spindle.

With this modification, I got around 72 db S/N ratio, and 20 - 22 KHz frequency response on good Maxell cassettes (oddly, not CrO2-based - even though the deck had a CrO2 selector switch) and less than 1% THD at 0 VU, 1 KHz, and .07% wow & flutter.

Of course, a 90 minute cassette was good for only 30 minutes at that recording speed, but damn if this Sony rig didn't sound as good as a Revox A77 reel to reel deck at 15 ips. Only problem was, I had to replace the F&F ("Ferrite and Ferrite") tape heads every 9 months or so, and they weren't cheap back in 1977, when I was 17 years old when I did this. They cost around $30 dollars back then, but were fairly easy to source.

I then boosted the dynamic range - S/N ratio of this deck up to around 105 dB using my SWTP expander/compressor that I put in the signal chain. Very similar to the dbx 119, but in kit form. Yes, I put the compander together myself and calibrated it.

Effectively, I had a 1971 Sony cassette deck making recordings better than any Revox 15" deck (forget about any Nakamichi 1000) and playing back at CD sound quality. Not bad for 1977 - 1978. Five years before CD technology came out.

Howard Skeivys:  Back in the day I had 2 premium cassette decks, one of which was a twin deck. Both units were equipped with Dolby B and C which I used extensively. That was multiple iterations ago of hifi components. Cassette decks no longer have a place in my hifi rig.

We need far more technical information from you. Especially if your technical assistant is going to present it.

MarkS 42:  Agree 100% Dolby B and C work, even my not quite real Dolby C on a Nakamichi 481Z sounded great, but it all needs to be clean and in A1 condition. But in my opinion Dolby B/C is better illustrated with a graph (a picture is worth a….), at school in the 70s, I could always explain it better to class mate’s with graph/diagram. I really love your articles, just good information no BS.👍😊

cheguitar:  Despite proper cleaning and demagnetizing, as an owner of multiple cassette decks, the main problem with HF roll off was due to azimuth head misalignment, exacerbated by Dolby encoded tapes.
Had I known this would be an issue at the outset, I would have recorded all my tapes without Dolby. Now the solution is to use decks with adjustable azimuth played back with Dolby.

Mr. X:  Great explanation... so I no doubt broke all logic but... I would record w Dolby B (also thinking my deck had C) and get the saturation as excellent as possible w/o distortion... then in my car the deck had Dolby B as well... but I de-selected the switch and presto the dynamics "seemed" perfect... yes in a pinch you could hear some noise... BUT because of the natural noise floor of the vehical and wind (as w would play Rock as I Rolled) the recorded tape noise was not present perhaps dither??? ... that was as good as it got in the car till CDs ... what are your thoughts?

Audio Masterclass replies to Mr. X: Switch Dolby out in a car, or anywhere, brings up low level high frequencies. So you'll hear more clearly above the engine and road noise. DM

JVRaines:  Leaving Dolby off, even when it works perfectly on playback, is better known as "High-Frequency Hearing Loss Compensation."

Audio Masterclass replies to JVRaines: Well technically you are wrong. But subjectively there is a certain amount of truth in what you say. DM

Kris M:  I've got 40 TDK and 5 BASF Chrome tapes all recorded with Dolby C and they still sound fine (not dull) today. I do clean the heads and drive parts now and then.

allan redford:  good video. imo, subjectively dolby b and s transparenz. the auto-tape calibration n my 90a Sony decks and good factory aignment, bettered mx 80s Nakamichi dcks.. dolby c was poor, audibly odd. few c-equipped production decks met dolby's strict alignment standardsm probably.. my Nakamixhi 700zxe auto.tuning dck+ NR100 v adapter was unsatisfacory. engaginc c on playback of a non-dolby tape is an effecive öpw-pass/high-cut filter for noisy source material, which fortunately, I have virtually none.
xour formidble-sounding lady assistant, looks like fun, if she loosened-up :-)I never experienced dbx I or II. read that it had issues......?

NackDSP:  No, it never worked. That tape deck rolled off the high end so the decoder never got the correct signal level to decode, so the high end roll off was exaggerated by the Dolby expander so the highs were wiped out. The expander had a delay relative to the compressor, so the high frequency transients were squashed. The system never had a chance of working. How could it. The signal used to drive the encoder was lost during encoding and the decode would always be late and wrong. Had Dolby found a way to bury the compressor commands as some sort of inaudible phase modulated tone to drive the expander decode logic it might have had some chance, but it traded dynamic range for a doubling of the frequency response errors and squashing high frequency transient response.

Tenn Vol:  The Dolby button was my least fav idea ever! Hated it! Muffled music button.

Dimitri Milewicz:  I clearly remember a friend saying "hey that sounds much better" when I switched the Dolby off, being a little perturbed as I am a techno geek and of course if the tape was recorded WITH Dolby so it MUST be played back WITH Dolby! Regardless of how it sounded I would stick to my "geek" guns. Then along came Dolby C and of course metal tapes and being an avid fan of head cleaning, de-magnetizing and correct azimuth & "variable bias" I would spend hours working out which sounded best. I spend so much time on this that I forgot to just sit back and enjoy the music. One day the same friend came over and suggested again I switch the Dolby off, so I did, and very quickly I heard an awkward "nah switch it back on it sounds better!" These days I just log into my TIDAL account, click my mouse and just sit back and enjoy the music - at 66 I no longer feel the need to labour for hours or days getting the right settings - I sit back and enjoy the music, which is what I should have been doing 50 years ago!

AndynAZ:  I thought Thomas Dolby invented Dolby NR when he was blinded by science in that missing submarine.

Lenny:  Sounds familiar. I always used Dolby B/C/S when appropriate, but I also know people who left Dolby B off to get a high frequency boost.

ns feliz:  you csn still dolbyize ur tapes today using software. use any daw or audio software that can perform level compression and set it close as possible to dolbay specs whae recording to tape.

David O'Banion:  Of course the manufacturers were nice enough to tell us exactly what tapes each machine was set up for....... NOT!
And then, what would happen when you couldn't get the "right" tape any more, provided you Did know what it was?
I didn't have the money to pay for a calibration.

With my TEAC A-170S, I nearly always recorded with Dolby on and played back with it off.
After I bought a Harman/Kardon TD392, if I recorded a tape with Dolby C I normally played it using B.

My Concord HPL-550 car stereo Sometimes gave pretty good results when I used the same
NR setting I had recorded with, but it really depended on the tape and the signal level.
Never got around to testing its dbx function because I didn't have a way to record with that NR.
I still have that unit, fortunately. It sounds amazingy good.

My tapes (I still have all of them) are labelled with the NR used.
A few have the same material on both sides, one with B and one with C.

John Mason:  When I was focussed on cassettes in the 80’s it became clear to me that Dolby killed the high frequencies along with the hiss, as a music purist it seemed idiotic unless you just hated hiss more than you loved the full sound. I would put up with the hiss in order to hear all the music.

Audio Masterclass replies to John Mason: I don't agree with this regarding Dolby, nevertheless it is a useful point. I'm not keen on single-ended noise reduction unless it is really, really necessary. A bit of hiss or a few clicks is often better than messed-about sound. DM

Ian L.:  Most commercially sold tapes are not encoded. The problem is if someone has heard an encoded program, it will sound brighter when playing back with Dolby off anyway. No one will think that the eq is now wrong because they have not heard the actual source. Brighter always sound better.

Same thing with FM de-emphasis. If it can be defeated, it will 'sound clearer' because of the boosted highs.

usaturnuranus:  I had a cassette deck with dBx encoding and decoding. With metal tape it was incredibly clean - but the only deck that I could ever play my encoded tapes on was that one deck. Never met anyone else who had the ability to play them, and they were unbearable without the function activated.

Michael DeLoatch:  You had me at your assistant's first utterance, and you won my heart with your hysterical expressions admiring her from your little bubble as she spoke! New subscribe here!

You missed discussing type C.

It's easy for me now - I have recorded one cassette in the past twenty years after getting my hands on a nice pioneer deck from the 80s, and I can't hear > 5KHz worth a beep anyway so hiss away tape, I recorded without it.

Forty years ago I did use it on prerecorded tapes with the logo and turned it off for those recorded without. For my own recordings, I found it better left off because as a kid I bought TDK or Maxell midprice tapes typically or whatever was on sale when I was running low on blanks, so I got inconsistent quality recordings and therefore dolby was imprecise on playback and annoying.

Audio Masterclass replies to Michael DeLoatch: Yes I did miss out Type C as I felt that would be overcomplicating this video, Type S too. HX Pro is a different thing entirely and I may comment in future. DM

blargg replies to Michael DeLoatch: There was also HX-Pro, which I believe was a bias modulation scheme that recognized that high-frequency content acted as a bias signal.

Michael DeLoatch replies to Michael DeLoatch: Oh yeah - another reason I forgot -- neither my early Walkman nor the cassette deck from radio shack I stuck in my parents' car had dolby available so it seemed logical to forgo it when recording back in the house on my deck.

Nicholas Sheffo:  The B-type of even C- type and S-type might not work as well later with tapes played a good few times, though some people just used a Chrome/Metal switch as substitute noise reduction and are happy with it, whether that is a good idea or not.

Polo:  In my cassette listening days i definitely left dolby nr off for the exact reason you say. Instead I would reduce the tone and Bob's yer uncle or in your case, Paul mc cartney 😂

Jesse Giles:  Interesting to hear a take on Dolby B I haven’t come across yet. Every audio engineer I’ve heard speak of it raves about it but as they describe it’s effect it’s hard not to wonder why no phasing effects are mentioned (I guess the curve is gentle so it’s ignored) and the lack of gain for portable decks.
The fact there was normally a switch means it’s no big deal in the real world. Sometimes it sounded better on, sometimes off. All depending on the system and context I was listening in.
I have had the pleasure of engineering and mixing a few recordings on 24 track 2” tape and applying Dolby B and S was a luxury you would be silly not to take advantage of. The quality of that sound isn’t something I’ll forget.
And home on the Nakamichi deck, all Dolby, all day. The Yammie amp took care of the make up gain and the dreaded hiss was gone.
On the school bus though it was worth flicking it off.
I still think the stereo image is a bit ‘altered’ to my ears and I can totally see how some people might seek out releases without it.
I used to love my tapes but hiss was enemy #1 behind a lot of problems. I’m loving the vinyl revival but feel no urge to drag out any old tapes, as cool as they may have been

Pölysormi:  Why is that AI so angry? 😄

Esteban Vega:  Or we could just use, idk, CD.

apmcd47:  Funny, really. I was told that "Dolby Noise Reduction" as found on cassette decks was for reducing tape hiss that I never really noticed unless I had the music so loud that the neighbours half a mile away were complaining about how loud I had it on! Seriously, though, I never could afford equipment with Type B and have never missed it. I had a sneaking suspicion that it was a con of some sort and would never have used it even if it was on a deck that I owned.

Terry Scanlan:  Who cares? I can't remember when I retired the last cassette deck. Isn't it 2000 something? Digital did not come soon enough.

Des Embrey:  Audio cassettes existed for one purpose only - convenience. They were a way to take the music of your choice with you, and you accepted the 'worse than AM radio' sound as a price you had to pay.

Benjamin Edwards:  My home deck is a harman-kardon hk400xm that does all 4 tape types with manual calibration facilities. Needless to say, it has Dolby Type B as well as HX Pro. I play these cassettes in my car because I drive a 1997. It sports a cassette player with Dolby and has been regularly cleaned and maintained by myself for 26 years. Friends and co-workers of mine get in my car, and they don't believe me when I tell them they're listening to a cassette. I have to eject the tape and prove it to them, and they are simply blown away by the sound quality. None of them knew cassettes could sound so good. This just goes to show that cassettes can sound absolutely amazing if you have proper equipment that has been maintained and that you know how to use correctly. Yes, Dolby absolutely does work. I've been proving it for decades.

Julio Cesar Pereira:  At first, I didn't know how to use Dolby B or C. But after I learned that you have to record with this feature to apply it on playback, it did work. And in fact improved the quality of high frequencies whenever I listened on some pocket stereo players. My last tape deck recorder had three heads and it meant I could monitor the recording in real time. And once, I bought a Sony Metal cassette tape. The first thing I noticed was that it allowed a much lounder recording. And as I listened to it in real time, I noticed the improvement such as much lower tape hiss. So in short, metal tapes allowed higher dynamic range and Doby C turned noise floor even lower, so tape his was dramatically attenuated. I was impressed when I found out that although the volume button of my pocket stereo was in "zero", the music was leaking to my headphones. The problem was that these tapes were very expensive and they shortened the lifespan of tape decks heads. So I returned to Chrome and Super Avilyn cassettes using Dolby B or not.

j7ndominica0:  On my Aiwa Creator's Stereo, the level reads back at about 3 dB less. The sound seems slightly muffled and "digitally processed," similar to fft noise reduction that people often overuse. Since there are no test tones on cassette tapes, I wouldn't know how to align it. If a type I the tape is overdriven, it loses high frequencies, so Dolby would see a radicaly different level. I find the best recording level to be where the VU is barely kissing 0. Holes in the tape also get emphasized by Dolby.

The one-sided Dolby-HX works better and allows to maintain high frequencies at higher levels by reducing the bias.

Tori:  Dolby B definitely helped. But you needed to tweak record and repro levels and bias for best results.

Audio Masterclass replies to Tori: Exactly so. DM

Grat Matassa:  i used dolby c mainly on normal tape & no dolby on chrome & metal worked well, hx pro helped as well

Brian F.:  If you had a good deck like a Nakamichi you could leave the Dolby button on during playback and still hear high frequencies and less hiss. That is because the Nak's can go to 20,000 Hz even with Type 1 tapes. If you had some inferior deck that only went to say 16,000 Hz you had to turn off Dolby to make the deck sound somewhat good.

Brian F. replies to Brian F.: @Audio Masterclass Studer/Revox was up there in quality with the Naks, if not even better than some of the lower level Naks. I have also seen some amazing Tandberg decks that were simply amazing sounding. I was talking more about cheap decks that struggle with high frequencies to start with. Those had many people record with Dolby on, then playback with Dolby off to squeeze a little more treble out of the decks. Even one of my high-end Pioneer Elite decks (15-23,000 Freq Resp) has Dolby B, C, S and HX Pro, but I still use just Dolby B on it (rec/play) and use the Pioneer Flex system to give it a little more sharpness. My other 3 head decks with manual Bias, Level and EQ fine adjustments for calibration allow me to get a little better response from cheap type 1 tapes with a push of more negative bias. It is amazing when you can get a cheap-o tape to sound exactly like the source. That is what makes this cassette hobby so fun. Cheers!

Audio Masterclass replies to Brian F.: I don't agree there. I've heard Nakamichi and their products were undoubtedly excellent, getting the very best out of the cassette medium. I've used Studer and Revox decks, basically the same with different badges. For myself, my first stereo deck was an Akai, then in the 1980s I had Pioneer, now I have a Denon in the loft in case I need it. In all cases, with the machine demagnetised, cleaned, and aligned properly, Dolby works fine and is far, far better than the noise there is otherwise. DM

Cars:  I was so obsessed with Dolby level and azimuth I purchased alignment tapes from Sony mainly because they were affordable and I had the proper equipment. My most foolish purchase was a Teac Dolby level tape and I had to sweet talk a Teac rep. to sell me one for $100.00 bucks. The only saving grace with Dolby is if you play back a tape made on a different deck and it sounds dull if you switch Dolby off it will usually sound much better.

Roger L -:  Looking back to the late 70s and early 80s I can't help think that there was a lot of hype about Dolby (I'm trying not to say "con"). Any deck which wanted to be taken seriously had to have it. It was pushed far more than the Philips rival DNL, for instance. Salesmen said we needed Dolby, but there was very little to no information about which tape a particular machine had been set up for, let alone any information about head cleaning and demagnetisation. If I had my time again I would have sought out a cheap machine with no Dolby and spent my money on good type II tapes instead. These days I use reel-reel.

Mike Fisher:  One thing that I'm not sure you specifically mentioned is that Dolby B was always intended to be something that did not spoil the music too much on non-Dolby playback - since very many portable or car players didn't have it. Since our hearing is less responsive to high and low frequencies at lower sound levels (hence 'loudness' buttons on some hifi amplifiers), then the Dolby encoding that has boosted lower level treble frequencies will sound fine anyway, especially in a noisy environment. But not on your hifi at good sound levels in a quiet room.

Thank you for what I think is a very good explanation of why it doesn't always work properly - I can remember frequently having to clean heads when the music didn't sound quite right.

Mike Fisher replies to Mike Fisher: @Audio Masterclass That's interesting, thank you.

Audio Masterclass replies to Mike Fisher: It was the same for Dolby Stereo in the cinema, which I first experienced with Star Wars in 1978 (we got it late in the UK). It was a real wow at the time compared to normal cinema sound. But the point was that the same print could be played in a non-Dolby cinema and it would still sound good. In fact, probably better due to more detail. DM

Jim Bendtsen:  I used dolby on my Pioneer CT-F1000 to record and playback. It worked just fine. Tapes I made with it still sound great.

Jim Bendtsen:  Your AI assistant has an extremely annoying voice.

robert lonergan:  Nice reverse clickbait with your fantasy sexbot. Can you make the breasts larger?

platterjockey:  I always used the Dolby switched on. You are 100% correct: if you get a dull sound from Dolby, it's the misalignment of the heads. Another reason is that the tape used was over biased when recorded, or just plain bad. I suspect most complaints came from commercially-duplicated tapes, which were mostly bad. They were duplicated at very high speeds on the cheapest tape possible to save costs.

Keith Wiebe:  Only had Dolby B on my early 80s Technics deck. Highs always sounded dead to me. Took it in and they supposedly adjusted it. Found out years ago that the bias needed to be adjusted. It was down 3db at 10khz adjusted from the factory-terrible. I readjusted and concluded if I could get it flat to 12khz I would be happy. Problem is by that time my head was worn out. Lows weren't as good as original material either.

Cheryl Ridone:  (From David) I always have Dolby switched in(on) & utilize Type C when the tape has been so encoded. There are some "noisey" environments, however, in which the sound "improvement" is perceived as limited.

Cassette Decks - Turntables Resurrection:  Dolby works best only in the cassette deck (assuming the deck is in perfect condition) that recorded the tape with Dolby...
I have many decks, alignment tapes, service skills etc ...
If I had to use NR in a cassette I would choose DBX any time...
But usually I record cassettes without NR... that's me ✌️

Digital Vinyls:  15 years ago I bought Pioneer CT-737 tape deck for 30€. It sounded awful. Wrong pitch, wrong azimuth, bad capstan roller. It was mis-calibrated also. It took me more than a year to do a complete overhaul. Then, it sounded EXCELLENT, it has 3 head with 15Hz-21kHz frequency response on ALL tapes. Dolby C was great in reducing noise with no noticeable degradation. I still do some mixtapes, 90 minutes it's best time to play best of the best from your 500 files playlist, sorted the way you like it. But, from time to time, I check pitch, calibration, I do demagnetizing and cleaning and this 35 years old workhorse still work amazing. I wouldn't sell it for 300€ now.

Digital Vinyls replies to Digital Vinyls: P.S. I also use to record and listen tapes in my old car that has tape with Dolby B and tapes sounded WAY better than radio. It was clean, quiet, dynamic. It even sounded better than my phone output.

Swinde:  I still have a Revox A77 and an external Dolby box made by Advent 100A. It works great. If you play a tape that was Dolby encoded with Dolby switched out, it plays with excessive treble. Some people equate this with "better".

Dow Fereday:  Dolby B seemed to work better with higher quality tapes chrome or metal...

Tomi:  Thank you, I'am Noise reduction user (B, C or dbx) Not like so much hiss...

Buster Piles:  Don't you mean DOBLY?

Buster Piles replies to Buster Piles: @Audio Masterclass spinal tap reference 😊

Audio Masterclass replies to Buster Piles: Yes, people did used to say that. DM

Len Imbery:  I remember experiencing the high end boost when the Dolby switch was off but thought that people were just hearing the boosted high end and preferred that as a psychological comparison, kind of like people prefer the sound of something that's a bit louder than what you're comparing it to. Thanks for clearing up the mystery.

Nico Ras:  I actually preferred dbx

poofygoof:  Dolby B was always a compromise, but worked well enough in good conditions. My experience with Dolby C is limited, but it worked significantly better than B, and I don't recall any issues transferring recordings with C from one unit to another. (I unfortunately never had a chance to interchange Dolby S.)

What gets me is that a lot of current cassette releases I am interested in don't even bother with Dolby B. I understand that currently manufactured cassette decks are sh*t and it's unclear if there are any current implementations of Dolby B decoding (which could not be called as such due to persistent trademark, but could be implemented due to patent expiration). At least let the format be the best it is capable of.

Marcel Hendrix:  About your question: I suspect most people used this like a tone-control.
My question: was/is Dolby-B really free from artefacts (on a perfectly aligned machine)?

Audio Masterclass replies to Marcel Hendrix: This is a good point. I've used Dolby types A, B, C and SR, missed out on S. On a properly maintained and aligned machine I was never aware of any problems though of course it would be possible to listen out for noise modulation and any effects on transients. I was so pleased however just to get rid of the noise that I would gladly have traded any small problems. DM

Simon Gills:  Please, give us an upload on how to align the typical cassette head.
And was there a head demagnetizer for cassette players available and who made them? How does magnetising work? The principles please.
I like cassette players which is why I ask. I know they are inferior but they are more than good enough for me and I have hundreds of cassettes (they were given to me by people chucking them out) in good condition. Grateful Dead bootlegs on metal type tapes, for example.
And no, I don't like the Grateful Dead but it's still worth the effort to make a cassette deck a better player, or less worse.
Thank you.
PS. Of course I prefer CD but I have these cassettes, like a lot of what's on them and want to make the best use of them.

Fernando Uribe:  Dolby works great. You can try recordong Dolby b anda play wirh Dolby c

MrAdopado:  Clean the heads and transport! Most people I knew never ever cleaned their tape heads and certainly didn't degauss. Some people always seemed to have tape problems, poor sound and tapes that ended up in knots. Funnily enough I never had those problems ... and I certainly didn't lend my tapes to anybody, and if I played someone's tape on my machines I cleaned the heads immediately afterwards. Yes that's over the top but I have 45 year old self recorded tapes that are still in playable condition and sound surprisingly good. Of course it also helps that as you age your high frequency discrimination reduces! (Pre-recorded tapes were always very poor and not worth the money in my experience.)

Emmanuel Gutierrez:  Dolby on my Pioneer no.
Dolby when recording yes, playback no. A little better on my three head Nakamichi deck.

Lathe Of Heaven:  Dolby C for the win!

Audio Masterclass replies to Lathe Of Heaven: I used to have a Fostex E16 1/2" multitrack with Dolby C. Maybe not quite a Studer but it sounded fine. DM

BATMAN DESTROYS:  It worked great!

Dale Boylen:  I sold high end audio for a bit. Our shop would run cassette deck clinics where customers would bring in their deck and we would clean the heads, pinch roller, capstan and demag them, align the heads properly, then measure them, give them a print out of those measurements. All for free. I seen every brand and model cassette deck under the sun come through that store. The brands that performed consistently better were Nakamichi, Harman Kardon and Tandberg. Most others had top end roll off's of between 12K and 14K. Dolby is a calibrated noise reduction. I believe the standard back then was 250 nanowebers per meter, which was zero vu. Sadly, many decks put the double dolby markers (Zero vu) at + 3 VU, so the dolby circuit didn't work properly. Dolby C was better (20 db noise reduction), HX pro better still. IF properly calibrated. Still, it's 1/8th inch tape with stereo front and back. Alignment, bias changed with each tape brand used.

Keith Wiebe replies to Dale Boylen: Problem is when my Technics was -3db down at 10khz from the factory. After adjusting it myself years later my deck was worn out and I had given up on cassettes. I concluded that if the freq. response was flat to 12khz or a little higher I would be fine with it. But 3db down at 10khz was a killer.

David Tennien:  It didn't work. The high frequency roll off killed the airyness.

Dad4:  Whatever…. In a professional sense Dolby Absolutely worked. There’s a ton of albums recorded on tape with either Dolby A or Dolby SR, that wouldn’t have sounded as good otherwise. The consumer version…. who cares…. Most consumers reflexively throw a smiley curve onto any consumer graphic EQ they find. In short, they can’t hear.

Jacek Schneider:  To make things worse, there were different dolby chips (licenced of course) Difference between new Sony chips and old Hitachi version i 've found on Akai cheap deck are huge. Hitachi version was clearly superior for unknown reason. And every maker (Sony, Pioneer) had different idea how to setup dolby level in their electronics. Most stupid idea was to skip dolby regulator and require to properly setup everything else to get a match...

Turrican 4D:  7:00 I cleaned our tapedeck once a week and demagnitized it once a month.

George Paxson:  I read about this as a middle aged adult recently and understood it. Would be interested to hear the difference with the proper tape and other conditions met. I won't be dealing with cassettes probably ever though.

Rich Sherman:  Thank You Sooooo much. Finally the missing tutorial on Dolby. Again, thank you!

Melanie Zette:  It worked for me with Dolby C on the same machine, when I could afford metal type cassettes nr was useless to my ears

CrueLoaf:  Yer…but…You don't do heavy metal in Dobly!

mixville2:  In the 80s the studio I worked in used had dbx noise reduction rack units for each track on both 2 track and multitrack machines - lots of rack units. We thought that worked very well. At home on my cassette deck, I never used Dolby B - even tapes recorded and played on that machine sounded dull to me. But the deck also had Dolby C, and I actually thought that worked well for my own recordings. I used it all the time. Not sure the difference between B and C. Will have to look it up. Thanks for the memories!!! No wonder we were so happy to get DAT! :) Love your videos!

cjay2:  I used my Nakamichi ZX7 with metal tapes, usually TDK, and the Dolby C switch in the 'on' position always, for about 20 years. I don't use the deck or the cassettes anymore, but it worked great through the 80s and 90s. Still have the vinyl records and the CDs I bought in the 90s and 2ks. The vinyl records are the best in the end.

CathodeRayTube99:  Good video. Agree with everything, and I think I understand. However, I only record cassettes for playback in my car and my car cassette player has no Dolby. (Yes, I play cassettes in my car in 2023!) So if the playback machine has no Dolby, am I right in saying there's no point in recording with Dolby?

Mark Philpot:  You can believe what you want. I could care less about this noise reduction as it took the life out of recording. I used to use it, but it took out more than it opened up. Most could care less about recording analog regardless which tape format they use. I choose not to use it anymore. More circuits used equals more chance of noise introduced into the signal path. You choose what suits your situation and needs. Your ears are the only ones that matter in this hobby.

Sparky 18:  I own some Nagra recorders including a IV-S. (2 in fact) Some time ago I found this Bryston 280B noise reduction unit with 2 Dolby SR cartridges in it. Its very hard to hear any difference in the recordings with or without. But I am almost 67 now. So it must be my hearing! The Nagra has always sounded good to me. Yes at 15 inch.

JayTemple:  I've known almost since "She Blinded Me with Science" that Thomas Dolby wasn't related to Ray. What I only learned a few years ago is that Dolby was a nickname that Thomas acquired because of his interest in recording technology, including the eponymous NR system.

BATMAN DESTROYS replies to JayTemple: Ray Dolby, did not want him to use their Dolby name! The matter went to Court! The Court decided Thomas Dolby, could use the Dolby name, but he could not release any electronic equipment using the Dolby name!

Audio Masterclass replies to JayTemple: I seem to remember that at one point Dolby Laboratories tried to stop him using it. DM

Nick Wallette:  IMO, who cares? Embrace tape for its deficits. :-) If you want noiseless recordings, there are other forms of media that are better suited. There's no need to archive on compact cassette anymore, so the use of tape these days is a conscious choice. Ergo, why worry about a few dB less hiss?

J.T. Cooper:  A CD recorded on High Bias or Metal tape and Dolby C made for the best sounding cassettes back in the mid 80's when I still had a use for them.

Cyto Wing:  When making my own recordings I don't use Dolby, I just don't have enough noise to justify it. On tapes encoded with Dolby I turn it on and if it is dull I turn it off . That doesn't happen often, usually on old wore out tapes. I used to be an electronics tech and I have the gear to keep my tape decks calibrated properly. Proper calibration is a must for Dolby to work.

Bill Mulvihill:  We played rock music and used dbx noise reduction.
No stinkin’ Dolby!

Andrew Hollis:  You don’t need Dolby on Type II or Type IV cassettes.

Steffen Mathiasen:  It depends on which tapes I use. I never use Dolby on type II cassettes. Never needed to. Some type I yes. SONY tapes as an example. Great tapes but noisy.

Merc Fredis:  I like your channel mate, I know you're getting started... but as soon as the AI digital assistant came on, all I wanted to do was punch my monitor. I didn't, only because I knew then I wouldn't know how to click off fast enough. Just explain it yourself mate, we like listening to you. ;-) Thanks for the video, though, seriously.

RR Channel:  Additionally the AIWA deck has CD/DAT direct inputs...

RR Channel:  Also the HX Pro & AMTS features really help along w/ metal tape. . I have found that to get the right record levels, it helps-- after recording a track-- to let it play back once all the way through before checking the level. The sound will embed itself onto the tape at a lower level than if one checks it directly after recording. Thanks for you channel..

RR Channel:  My decks are the Denon DRS- 810 & AIWA AD-F700. MO is that using Dolby C actually enhances the sound. See owners manual for DRS- 810 pg 10

Charles Hess:  I had a separate dolby unit for my reel-to-reel deck. My friend had an enormous record collection and I would borrow from him and make a dolbyB encoded reel-to-reel copy at 7 1/2"/s. They always sounded as good as the LP.

Charles Hess:  I used metal tapes. CrO2 didn't do it for me.

MacinMind Software:  If the music you listen to is already noise, dolby doesn't fix this. Seriously, I think of Dolby NR as something like the RIAA curve that goes way back with records. Even reel-to-reel decks without dolby have a curve I've discovered. I thought it would be brilliant to run my reels at double speed and digitally record them at 96 KHz sampling rate and simply change them to 48 KHz in software to save time. But I did a test first with white noise and frequency sweeps to discover that there was a frequency response difference and I assume a type of curve. So I've done all of my digitizing of reels at realtime speed.

John R replies to MacinMind Software: The reel to reel EQ curves are different for the various speeds. They're more agressive at the lower speeds. There were two slighly different standards around the world for many years although they didn't differ by a large amount. These were the CCIR and NAB curves. The cassette system also has pernament EQ curves which are always applied regardless of if the Dolby treatment is further applied or not.

dd0ck:  I have a Nakamichi RX-505 that was recently serviced. Both Dolby B and C work great. I feel like Dolby C doesn’t work as well between my deck and WM-D6C, and Dolby B on my WM-D6 sounds great! But I think the head on the WM-D6 is better. So I use Dolby B when recording for my Walkman for playback, and Dolby C when recording for my Nakamichi for playback.

Max Nielsen:  Great explanation. I really like your clear technical approach.

Pengochan:  I've never cleaned any cassette device in my lifetime, and i'd bet that applies to about 99% of people using the things. It's just not how the average consumer used these things. It's more likely they bought a new one. I had no idea about why different cassette types sounded different or which specific type i should buy for any specific device. I also have no idea how much of a difference it would have made for the consumer grade products i used. My experience with Dolby buttons was how it changed the sound when pushed during playback, regardless of how that tape was recorded (how would i remember if i fiddled around with the Dolby button when i recorded that thing?), which is, of course, not how it's supposed to be used.
So when evaluating statements of "the average joe" e.g. about the Dolby button, one should take into account how they used that stuff.

Pengochan replies to Pengochan: @Audio Masterclass I wonder if i would've bothered had i known better. I'm more a "listen to the music" type, and if it's too bad i switch it off. I'm passionate about other things. But i was happy to see cassettes and records replaced by digital. The audio was noticeably better (even for me), and it was much less hassle.

Audio Masterclass replies to Pengochan: This is mostly my point. Non-technical people used the Dolby the way it sounded best to them, regardless of whether it was correct or not. Cleaning the heads, both record/playback and erase, works wonders. DM

William Palminteri:  .....or switch to dbx and get rid of ALL of the noise.
Did I say that ?
Bill P.

Audio Masterclass replies to William Palminteri: Well you did say it. And my cordial response is DM

OrdinaryWorld:  I'm sure it works but there are so many variables that the average user can't be bothered with mitigating. If a friend offered to record something for me, I'd always say to them, "DO NOT USE DOLBY", because YES... I would always get a dull sounding cassette if they did. In addition, many of the "Walkmans" I had over the years didn't have a Dolby switch so it didn't make sense to record with Dolby. Right or wrong, I almost exclusively used BASF Chromdioxide and even Metal tapes and push the levels as high as I could to combat tape noise. No idea if it made that much difference but I'm sure I told myself it did. I recall having a few decks over the years with Dolby C and do remember experimenting with it. Unfortunately, so few decks had it that again, it didn't make sense to use it when recording in case the destination player didn't have Dolby C.

kirkp_nextguitar:  I recorded a bunch of vinyl records using Dolby-B and some using Dolby-S. I’d occasionally A-B a vinyl against the tape I had just recorded and to my critical ears they were quite good.

Mark Wheeler:  The best results I ever had recording Dolby B tapes was in 1980 using a quite expensive Aiwa AD6900 machine that had a pretty involved manual tape tuning facility which - if used properly each time before making the actual recording - made brilliant recordings that would also play faultlessly on other machines too. A couple of minutes well spent each time before making a recording.

Editing SECRETS revealed!:  I was hoping for the clip from Spinal Tap: They used too much Dob-lee on the recording...
I'm one of the ten people who used Dolby B as directed, whenever I recorded anything to cassette. For Walkman listening on the go, Dolby on if in a quiet environment, off if a noisy environment called for high frequency boost.

Douglas Watters:  When I was still using cassettes up to the early 2000s I just used maxell xl-ii with no noise reduction. It seemed to be the best at leaving good response on lows mids and highs. Sure there was some noise, but I could hardly hear it except for maybe the blank spots between songs.

Douglas Watters replies to Douglas Watters: @blargg metal type 4 tape wears the heads up to 3 times as fast as normal tape. Also type 4 tape is expensive, costing more than double the cost of type 2 tapes. The performance of type 4 is better than type 2, but not enough for me to pay so much for it plus wear my heads out.

platterjockey replies to Douglas Watters: @blargg They were always more expensive, not universally sold, and, frankly, the high-bias ferric oxides (Type II) tapes always sounded better on my Japanese-made decks. In the U.S., Japanese brands were the most commonly sold e.g. Kenwood, Pioneer, Sansui, Sony, Awia, Sharp, TEAC, Nakamichi, Kyocera....

blargg replies to Douglas Watters: Any reason to not use metal? I ended up using a number of those in my recording collection in the mid 1990s.

platterjockey replies to Douglas Watters: @chrisz78 Oh yeah, after 1985. But, before then, their cases were as good as Maxell. For me, Sony was the worst.

platterjockey replies to Douglas Watters: I always preferred TDK SA and SA-X. If the deck is in great condition, I can get away without using Dolby on record.

Ignacio Curiel:  I used to think that there was (is) a reason for Type-b to exist. High end tape recorders had it, and when I bought my first Walkman, it also had the option. So, I said, if there is this option, and not all recorders/players have it, then those that do have noise reduction have it for a reason and I should leave it on always. It was kind of a self-delusion because I thought that maybe I was losing something when I didn't use noise reduction both at the recording phase, and then when I played the music on my portables. I did hear the "muffled" sound of NR applied at playback, but then I thought that my ears weren't really trained enough to know if this effect made the music closer to reality or not. So... always on, and when someone told me that they did not like NR, I thought "they don't know what they're talking about" LOL

Kourosh Akef:  Dolby has always worked perfectly for me .

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Thursday April 20, 2023

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David Mellor

David Mellor

David Mellor is CEO and Course Director of Audio Masterclass. David has designed courses in audio education and training since 1986 and is the publisher and principal writer of Adventures In Audio.

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