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Creek CAS3140

Tuner

Surprise

 

creek_cas3140

 

One of the best kept secrets in the budget tuner world was Creek’s CAS3140, which offered genuinely high end performance at an extremely affordable price. Who better then to tell its story, than designer Michael Creek himself...?

 

“I have had a genetic interest in radio, since my father got into consumer electronics when he was a boy, and then joined the RAF as a wireless operator and technician during World War 2. I made my first tuner while working my apprenticeship with him at the Wyndsor Recording Company in 1973, which used a modular front end, RCA CA3089 IF and Motorola MC1310 decoder. It also had a Sanyo AM circuit and used a compact air-spaced tuning capacitor.

 

When Creek first started in 1982, my customers requested a tuner to match our first product, the CAS4040 amplifier, and thus was born the 3040 tuner in 1983. The 3140 replaced this, also a conventional non-synthesised tuner. It was analogue because, at the time, it was far more complicated to make a synthesised tuner. The simple chipsets that make it easy now were not available then and required several chips and lots of interference, due to the complication with mixed frequency oscillators. There was also a lot of digital prejudice in 1983. Even if I had made it with a Phase Locked Loop ‘digital’ front end, consumers were warned against it by the press and trade alike...

 

The 3140 used a Philips three chip family solution. This enabled the 3140 to be built more easily than if I had used a combination of discrete circuitry for the front end and RCA and Motorola chips for the IF and decoder, which was quite common at the time. I have a long held trust and respect for Philips radio ICs which were developed in Germany in the Valvo factory. Unlike many other UK companies, Creek made the wideband front end itself. It was then, and is now, more common to buy in a module...

 

The great advantage of the TDA1574 was its buffered double balanced mixer and buffered oscillator output, which could be used with a conventional frequency counter to display the wavelength and frequency. It also had keyed automatic gain control by use of a field strength output driving a pin diode to attenuate the RF input. In later models Creek also used its regulated output voltage to improve the frequency stability. The 3140 used a discrete IF gain stage with three multi-pole 10.7 MHz ceramic filters to provide a very sharp wide band IF response. One of the filters was 180kHz which could be switched in and out as required for Dx operation, and the other two were 280kHz types for good stereo separation.

 

The TDA 1576 IF was particularly good as it produced very little distortion with a single quadrature discriminator coil, although the 3140 used two, to fine-tune the pass band. It also produced DC reference voltages to connect to the stereo decoder to smoothly blend the left and right channels when the signal to noise was poor. The TDA1578A decoder was probably the best available at the time. It used a pilot cancelling system of rejecting 19 and 38kHz tones, which meant that it had excellent pilot rejection and could therefore work easily with a first filter frequency at 26kHz, which meant it could reach 19kHz before rolling off, which was a significant sonic benefit.

 

The 3140 was designed to be as simple as possible to use, so it included some hidden features such as variable display brightness to indicate maximum signal strength and a ten-turn potentiometer to tune the four stage vari-cap diode tuning circuitry.

 

In 1986, Creek changed the colour of its front panel printing to green on black and the logo style was also changed to the type used today. At the same time, the 3140 was updated to the T40. We changed the position of the tuning knob slightly to line up with the volume control on the matching 4040 amplifier; otherwise there was little or no electrical difference, just cosmetic. Later on, the T40 was modified to improve the tuning stability, by using the in-built band-gap reference diode in the front-end together with a better AFC circuit that was temperature compensated differently for one each end of the dial.

 

Sales performance of the Creek tuners was never as strong as the amplifiers; the rule of thumb then was four amplifiers to one tuner sale. If memory serves me correctly, the total 3140 sales, together with the earlier 3040 and later T40 combined was about 10,000. In 1984 we were regularly making 500 per month. I think the one tuner I have the most affection for was the 3140, but would have to say that the later Creek T43, which also used a newer Philips chipset but had a built in PLL, and was operated by a microcontroller sounds better and of course doesn’t drift. It is the daddy of the current T50 and Classic Tuner we now make.

 

I’m not an expert on other makes, but I know there were many Japanese and American tuners that produced excellent performance, especially if they used open vane capacitors with up to six tuned circuits for good selectivity. Valve tuners are especially good when it comes to overload margin in the mixer. I always dreamed of making a six tuned circuit FM tuner using a valve RF and IF and semiconductor decoder. Unfortunately, I never found the time and now the demand for FM is so small it would be a commercial flop, more’s the pity!”


BUYING

If you’re after serious radio sound for peanuts, then Creek’s 3140 is peerless. Unlike the Leak Troughline, it’s modern enough to work straight out of the box, with no need for new decoders or huge aerials, but it still gives a taste of that classic tuner sound. It’s very warm, smooth, open and dimensional, but detailed and defined too. The downside is noise – you’ll need to be reasonably near a transmitter if you’re to get away with a ‘piece of wet string’ for an antenna, otherwise there will be some hiss intrusion. Either way, a decent four element roof or loft aerial will work wonders. The 3140 is an amazing bargain secondhand – excellent boxed examples can be had for under £100, which is a lot of sound per pound. DP

 

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