Technics RS-B11W Cassette Deck Thoughts & Repairs

This, the RS-B11W from Technics, is one of the best double cassette decks ever made. It’s also one of the most basic in function and appearance. It has Dolby B, high-speed dubbing and a manual tape counter with manual recording level adjustment – and two tape transports, only one of which can record. What’s so special about that?

Front

It’s the mechanisms. Dual well tape decks have a bit of a reputation for being low-end rubbish, and it’s not undeserved. Most dual decks were sold at similar prices to their single equivalents. Obviously to hit those lower prices with room for retail margins and profit, there has to be some compromise. The most expensive component of any cassette player is the mechanical element; the tape mechanism itself, a complex blend of electromechanical motors, switches, levers, sliders, wheels and gears. To make a twin tape deck, you need two mechanisms and hence double material cost. And so the mechanisms are the obvious compromise, with most dual decks outfitted with cheap mechanisms, usually off-the-shelf items bought in at volume for further price reduction, or parts built for compact systems sold en masse.

It doesn’t help that most dual tape decks were feature laden. Autoreverse was almost a prerequisite, as were high-speed dubbing to halve the time required to copy a tape between the two decks. An autoreverse mechanism needs two capstans and flywheels and two pinchrollers, plus the added mechanics to switch between them and rotate the heads accordingly. High-speed dubbing necessitates that those components be of sufficient quality that they can run at double the normal tape speed and still maintain acceptable levels of mechanical stability. You can see how simple features can quickly add significant additional cost. 

Matsushita, better known to you and I as Panasonic, were the world’s largest consumer electronics manufacturer in the 1980s. I doubt even they know how many cassette decks they made in that time, but the numbers were enough to make developing their own components worthwhile. Matsushita made everything from the mechanisms to the motors and from the chips to the capacitors. And it was typical for them to improve or simplify their mechanism designs for successive product generations, rather than reinventing the wheel each time. A sensible move, and one that allowed them to bring the best quality mechanics to their most cut-price machines. The RS-B11W was no exception.

The mechanisms in an RS-B11W are virtually identical to the mechanism you find in the vast majority of Technics’ machines from late 1979 to early 1987, with the exception of the microprocessor controlled models. They are big, bulky and bombproof, most still running to spec without a service over 40 years after they left the factory. There were several variants of the mechanism, some with a row of piano-key buttons beneath the door and some with the buttons mounted to the side, but they all share the same DNA and many of the same components.

Back Of Deck A Closeup

The mechanisms have impeccable speed stability, giving equivalent numbers to Technics’ direct-drive tape transports of which there were several variants. Massive flywheels and a quality motor were a contributing factor. They are dependable and reliable too, with gear-driven reels, standard belt sizes that are readily available, durable heads and a quality of construction that belied the price of some of the machines they’re found in.

Back Of Deck B Closeup

The RS-B11W cost £220 in 1984, equivalent to £679 today. For an extra £60 (185.19 in today’s money) would buy you the RS-B33W, one of the few twin tape decks to come with DBX noise reduction but otherwise very similar. The equivalent single mechanism model was the RS-B12, £130 in 1984 or £401.25 today. The B12 was virtually identical besides the addition of a fixed-level headphone jack and a couple of additional controls and no automatic tape type selection which the B11W has. YouTuber VWestlife did an excellent video covering the RS-B12 which you can watch below.

The inside is messy with cable clutter but the deck is well constructed with a steel chassis and moulded plastic front. Most of the electronics are confined to the main board, with a switch board and the vacuum fluorescent display on the front. The display is another carry over from previous models and was a selling point for Technics tape decks at the time. You get a mechanical tape counter for the recording deck, high-speed dubbing, a mic/line input switch with twin microphone jacks, a record level slider and a Dolby switch.

The mechanism controls are all soft touch, actuated both by a solenoid and the rotation of the flywheel which operates a large cam. There’s no clunking and grinding though, only a slight whir when the heads rise. That sound is one I remember fondly from my childhood, putting miles of tape through my father’s RS-D200 with the same mechanism.

You don’t get autoreverse, but that’s not a disadvantage in my book. Most autoreverse mechanisms work by electro-mechanically flipping the head and using a second pinchroller and flywheel to spin the tape in the opposite direction. Better mechanisms used a four-track tape head and simply reversed the motor, but they are few and far between in the consumer space. I think only a couple of Nakamichi decks did that, and perhaps a JVC though don’t quote me on that.

You due get a cueing function though. No automatic music scan, but holding the forward or rewind buttons in playback will drop the head slightly and wind the tape at high speed, allowing you to precisely cue up part of a tape. This was commonly used for recorded books or magazines, where low-frequency tones would be recorded onto the tape that would be heard as high-pitched ‘beeps’ when the tape was reviewed at high speed. Dropping the head fractionally reduced wear on the tape and the head itself, though frequent use of the review feature would eventually diminish the quality of a tape. The same goes for the music scan or track skipping functions on most later cassette machines.

The belts were still fine in this particular example, which was sold as broken stating that “the tape doesn’t play”. Indeed it didn’t, though the issue was much simpler than it appeared. There are a number of small leaf switches in the mechanisms which indicate their mechanical state to the electronics. One of those is closed by a slider when the play mode is activated and controls power to the motor. The leaves of the switch had deformed sufficiently to break the electrical contact, and thus while the heads would rise, the motor wouldn’t spin, and neither therefore would the reels or the capstan. The fix was as simple as bending the leaves of the switches, located on the rear of each mechanism near the bottom, until they made contact when the actuating slider was pushed against them.

If you are experiencing this symptom, you can determine if the switches are at fault by holding the play button. Applying a slight additional pressure to the play button moves the slider forwards, applying more pressure to the switches which is usually enough for them to make contact. If you have a deck that uses this mechanism, and won’t run unless you hold the play button, that switch is most likely the cause.

I decided to change the belts anyway, as they were 40 years old and had lost their elasticity. I used DeckTech belts, naturally, who can supply the correct size belts to fit these mechanisms and meet or exceed the factory specifications for wow & flutter and speed deviation. Each mechanism takes a square belt to drive the reels and a flat belt to drive the capstan flywheel, and there is an additional counter belt driven by the take up reel – the right-most reel of the recording deck.

Overall Inside

The mechanisms are held in by 2 screws through the rear into the front panel, and a number of countersunk screws through the front panel in the bottom of the machine. Cut most of the cable ties and unplug the cables for each mechanism, noting their locations as you go. Note spring-steel white behind the recording mechanism, linking it to the record/play switch on the main board. When you activate record that switch engages the erase and recording heads, switches the meters to show the recording level and mutes playback. If you’re having issues with channels dropping in playback, no sound on playback, tapes being erased on playback, excessive humming in one or both channels or a high-frequency feedback, it is likely the contacts in this switch have become oxidised and cleaning it should be your first port of call. I’d do it anyway as part of a general service.

When you have them free, a few screws remove the rear motor plates of the mechanisms to expose the flywheel and drive gearing. You’ll note the two-section pulley on the motor and the reel drive pulley, and assume rightly that reinstalling the belts requires more pairs of hands than the average human possesses. You can do it though, a couple of bent paperclips to use as makeshift belt pullers will help you immensely.

Flywheel 1

But first, lift out the flywheel being careful not to lose any spacing washers that may be fitted around the capstan. Clean the capstan shaft thoroughly with isopropyl alcohol and apply a lightweight oil to the shaft, avoiding the final 20 mm or so. Then reinstall the flywheel, and clean its surface and the rear of the capstan shaft with IPA. Drop a dab of silicone grease on the rear of the shaft, ready to make contact with the thrust bearing when you replace the plate.

Mech Open 1

Add a drop of lightweight oil to the motor and spin it to work the oil in. Clean the pulley thoroughly with alcohol. Clean the reel drive pulley too, and the various leaf switches on the front and rear of the mechanism. Check for any hardened grease, clean and replace as necessary. Dry grease is the only failure point of these mechanisms in my experience.

Flywheel 2

Then you can replace the belts. Start by hooking the flat belt over the motor pulley, and position the square belt on the pulley above it. Then begin the delicate ballet of hooking the square belt over the reel drive pulley, the flat belt over the flywheel, and dropping the plate into place.

Mech Open 2

Reinstall the mechanisms and connect the cables. You’ll need a 3kHz test tape to set the speed, the controls for which are on the rear of the motor. Begin by setting the ‘normal’ speed, before progressing to the high-speed dubbing adjustment. Using a clip lead, Ground the resistor R120 to the chassis or the rear mechanism plate, which will put the deck in high-speed mode for playback. Then adjust the high-speed pot on each tape mechanism until your 3kHz tape plays at 6000Hz. Remove the ground and double-check the normal speed value, balancing the two as necessary to achieve correct figures for both. You should be able to get within 5Hz (0.16% deviation) easily.

Main Board 1

Incidentally this is one of the few tape decks in my opinion where high-speed dubbing is actually viable. The mass of the flywheels and the larger, more powerful motors means the mechanisms can actually cope with running the cassette at double its normal speed, so you don’t get so much of the speed variance that you usually do when you copy a tape at speed. Copying tapes at normal speed is still the best way if you want the best quality in the copy, but tapes dubbed at high speed on these machines are better than most.

The sound on these decks is excellent, up there with single decks of the time and later single decks that cost a lot more. It’s crisp and clean with good imaging and low noise. Detail is very good and the character is generally very neutral, or at least as neutral as cassettes ever got. You always get that slight warmth of the analogue tape, especially compared agains the obvious contrast of modern digital recordings. But aside from being a bit light on bass perhaps, the character of most Technics tape decks was rather like their better turntables. That is to say what you hear is what’s on the tape.

Heads B
Heads of deck B

I often find with Technics cassette decks that the low-end models sound a lot like the high-end models do. Obviously you get better electronics as you move up the range, so you get more headroom for playback and recording, less preamp noise, better heads and better head amps and better implementation of the Dolby noise reduction. And you get a lot of additional features too, including three-head realtime monitoring, better metering, remote facilities (wired in the early days), better source monitoring and so on.

So while I’m not saying that a bottom of the line Technics deck is sonically identical to a top of the line model of the equivalent generation, it is usually obvious that the two machines are from the same lineage, and the benefit of the component sharing is to the advantage of the lesser model. They give you a good taste of what you can expect if you move up the ladder, but are always satisfactory. You don’t feel like you’re listening to a budget tape deck.

Not all twin cassette decks were cheaply made. Technics proved that doubling the decks didn’t mean halving the performance and the results speak for themselves. It helped that Matsushita were the world’s largest manufacturer of consumer electronics at the time, and Technics and its products were centred in the line of sight of the general consumer at a time when owing a hi-fi was not only accepted, but practically a given. And you can have the performance for little money too, as the RS-B11W typically tops out at £50, even for a serviced example. Expect to pay a lot less if it hasn’t been serviced, maybe £20 for one in tip-top condition. Probably one of the best bargains in cassette decks at the moment.

By Ashley

I founded Audio Appraisal a few years ago and continue to regularly update it with fresh content. An avid vinyl collector and coffee addict, I can often be found at a workbench tinkering with a faulty electronic device, tweaking a turntable to extract the last bit of detail from those tiny grooves in the plastic stuff, or relaxing in front of the hi-fi with a good album. A musician, occasional producer and sound engineer, other hobbies include software programming, web development, long walks and occasional DIY. Follow @ashleycox2

Share Your Thoughts