The wireless cassette deck - Grundig CF-IR

[cmjones01]

Whilst half-heartedly searching for a suitable cassette deck to put in our living room, I came across this oddity at a price I couldn't refuse. It's a Grundig CF-IR. Though it looks like a fairly normal hi-fi component, albeit with drawer loading that's pretty unusual for a cassette deck, it has no wires other than the (short) mains lead!

It's quite a high-spec machine: 3 heads, Dolby B, C and HX Pro, digital counter, automatic music search, remote control and so on. But how does the music get in and out?

[cmjones01]

Here's the spoiler: it's all done by infra-red. There are IR transmitters and receivers on the front corners of the deck which communicate with compatible hi-fi components (of which there exists only an amplifier, tuner and CD player from the same Grundig range). The IR beams send the audio digitally as well as remote control information. Believe it or not, this analogue cassette deck contains A/D and D/A converters because its only connection with the outside world (other than the headphone socket) is via digital data streams.

The deck basically works, though needs a service and some proper setting up. The display flashes every couple of seconds, I think because it's unhappy that it can't see its infra-red friends.

The circuit diagrams are available on line, and it's clear that conventional analogue audio is present, so bringing it out to connectors shouldn't be hard. The digital IR interface seems to be based around a Crystal Semiconductor CS8425 chip which is designed to create "audio networks". It's as if someone at Grundig saw the chip's data sheet and, to coin a phrase, were so preoccupied with whether they could, they didn't stop to think if they should.

Has anyone here ever encountered this, presumably short-lived, range of hi-fi components?

Chris

[paulsherwin]

Very unusual. I must say it all seems rather pointless though. Did you buy it in the UK?

I vaguely remember that the 'Fine Arts' branding was used by some iteration of Grundig in the 1990s for 'lifestyle' audio gear.

Normally you'd need to watch out for odd calibration with a Grundig cassette deck, but that is late enough to be set up for Japanese tape formulations. It won't really matter if you don't plan to record on it though.

[cmjones01]

Originally Posted by paulsherwin

Very unusual. I must say it all seems rather pointless though. Did you buy it in the UK?

No, I bought it in Poland. There seems to be a few of these things around in Germany, which makes sense given the brand.

Pointless is, I think, a good description. Using advanced digital technology to make a simple device more expensive and less convenient. What if I want my hi-fi components on shelves, or mixed with other brands?

Chris

[DMcMahon]

Yes very unusual, have never come across it before.

How does the audio sound on headphones ?

David

[paulsherwin]

I suspect these were mostly sold as parts of complete systems, presumably with all the usual interconnects replaced by IR. It must have been fairly high end stuff. I've never seen the Fine Arts branding used on expensive separates in the UK, only on things like micro systems in Dixons.

They seem to have gone to some effort to make a cassette deck look and function like a CD player.

[cmjones01]

Originally Posted by DMcMahon

YHow does the audio sound on headphones ?

It sounds absolutely fine, given the crackly headphone volume control and need for tape head cleaning/alignment. It's running about a semitone slow but the wow and flutter seems inaudibly low and sound quality good, with decently low noise. Looking at the circuit diagram it's clearly built with good quality, "european" parts - the tape head preamplifier is made of BC550C transistors, for example, and I've seen LM833 op-amps used in some of the components. The transport seems quite slick - it seems to have a separate motor for fast wind functions. It behaves like I'd expect a good quality hi-fi deck in need of a bit of TLC to behave.

Chris

[paulsherwin]

I think they were still building stuff in the Braga plant in Portugal when this was made.

[cmjones01]

Yes, this deck was built in Portugal.

[cmjones01]

I've just managed to get hold of an original service manual for the Grundig Fine Arts "IR" range of hi-fi separates. It's quite a piece of work, with a huge amount of detail on how everything works.

It explains how the IR communication works, and it's either terribly clever or a horrible bodge depending on how you look at it. The IR is really just normal AES/EBU/SPDIF digital audio, the same as you'd get on the optical digital input or output of a CD player or PC sound card. The odd part comes in how the components discover each other and communicate remote control commands. Though the CS8425 chip which handles the digital audio also has a data channel available for exactly this purpose, the Grundig components don't use it. They amplitude modulate the digital audio stream with a slightly modified Philips RC5 remote control code in order to pass commands from component to component.

There's also some clever trickery done to get the IR beam sent and received from the right one of each of the four available ports on each component, and to pass audio data through any component that's not currently playing.

The service manual hints at the existence of an IR DCC recorder in the range. Now that I have to see.

Given all this information, it's very tempting to try adapting an existing hi-fi component - like a Minidisc recorder, for example - to the IR system, thus achieving the expandability that was never possible when all this was new back in the mid-90s. That's one for the long winter evenings.

Chris

[Radio Wrangler]

I think it would also suffer from confusing its market. Given the product name printed on the panel, there would have been people out looking for "infra-red cassettes" to use with it.

David

[knobtwiddler]

were so preoccupied with whether they could, they didn't stop to think if they should.

A solution looking for a problem -)

What exactly did it achieve by making them as separates? How far apart can the units be? Does it have a buffer in case someone walks in front of the beam?

I recall seeing a demo of a Schneider audio system in the 80s, whereby each face of each enclosure had an interface, enabling the owner to configure the system in any physical configuration / shape that they wanted, without leads.

You are obligated to find the rest of the separates now. You can't leave us hanging like this. Were the speakers wireless as well? What other delights are there in the range?

Ooh! A quick search of Ebay reveals a matching tuner that's unused! The seller has punted 3 of them and has 1 left so you'd better get your skates on!

edit - I am disappointed to see that they sold out and fitted RCAs on the rear of the amp.

[paulsherwin]

It does seem to be a completely mad use of technology. I wish I'd been present at some of the early project meetings.

There was certainly a period in the 90s when both politicians and marketing people seemed to become obsessed with 'digital' as a concept, without any understanding of what it meant or whether it was appropriate. Didn't Dixons rebrand its shops as 'Currys Digital' for a time?

[cmjones01]

Originally Posted by knobtwiddler

A solution looking for a problem -)

I have a theory that some time in the early 90s the management of Philips and B&O got fed up with the "too clever by half" innovations coming from their R&D departments and sent their engineers on a field trip to the Oktoberfest where they couldn't cause any more trouble. There, they bumped into Grundig's R&D engineers who were drowning their sorrows as they bemoaned their employer's decline as a major player in the consumer electronics market. Much of the local brew was imbibed and, as the rest of the beer hall danced on the tables, the disgruntled Philips and B&O staff finally found someone who was willing to listen to their latest idea.

The following morning, as their heads cleared, the Grundig team had a feeling they'd got hold of a plan which would propel their formerly staid and sensible company in to the 21st century, leapfrogging the competition. They sat down with a collection of the latest data books and set to work. The rest is, sadly, history.

Chris

[knobtwiddler]

Either someone spiked the water fountain at Grundig HQ or they had a lot of IR AD / DA chipsets to find a use for.

[agardiner]

I wonder if Techmoan knows about this technology? Would make a good video for him.

[Martin Bush]

I think this is excellent. A mad idea in many ways, but very interesting all the same.

As to the use of "digital" as a marketing ruse, I once bought a vacuum which I was proudly told had a "digital motor". I asked what a digital motor was and the salesperson had no answer, even after asking someone else at the shop.

I don't know what a digital motor is in the context of a vacuum. Probably way off topic, but if anyone can explain PM me a link.

[Nickthedentist]

It's a bit bonkers, but we do now have wireless bluetooth turntables, "speakers" and headphones, so why not a cassette deck?

[paulsherwin]

Originally Posted by Martin Bush

I don't know what a digital motor is in the context of a vacuum.

It's just marketing speak for a brushless DC motor controlled by electronics. The motor itself isn't 'digital'. They are now widely used in domestic appliances as they are light and easier to run at high speeds.

Back on topic please.

[knobtwiddler]

I'm still struggling to work out exactly what was in this concept for Grundig...(aside from using up a skip full of IR chipsets...).

Whereas Bluetooth is relatively omnidirectional to a few feet, the IR concept here would require a direct line of sight to work.

I would assume that the matching CD and DCC players would have no DAC internally, simply sending out raw binary to a master DAC in the amp. Is that correct or simply too rational for what was going on here?

Was the transmission 16-bit? 14-bit?