Within reach And now an altogether more affordable tube amp from Croft Acoustics

by Paul Boak.

It is now almost twelve months since I had the good fortune to discover the excellent Croft valve amplifiers at the Wolverhampton hi-fi show. In their first year, Glen Croft and Pete Bruty have been hard at work developing their products (despite the setbacks of a pretty rotten sales period in the industry), and I am pleased to report that they are now ready to unveil an amplifier that is just about within reach of most dedicated music lovers.

The great drawback with their ingenious output transformer-less power amplifiers is cost, which meant that the cheapest Croft set-up came in at over 3000. Solution? Build a more conventional transformer-coupled stereo power amplifier to sell for around 600, which could then be used with the integrated valve preamp to give an all-in cost of 1000. This course of action has now been taken, and I have spent an evening listening to the final prototype which left me in no doubt that Messers Croft and Bruty are well on their way to producing a modern classic.

The basic design is very loosely based on an old Leak circuit, and is much more conventional than Croft's monobloc leviathan. Several points are worthy of note, however, especially the use of regulated supplies for the HT, bias and heater supplies. Regulation in the HT lines is rare to say the least; Glen tells me that the only other valve power amp so equipped is the staggeringly expensive Futterman OTL 1 (if you have to ask the price, you can't afford it). The constructional quality is also to the usual Croft standard, with bags of 1 percent resistors and film capacitors. The amp is hard-wired throughout with no PCBs and built with lots of the most important ingredient, care. The output valves may, be either 6L6, EL34 or KT77 and the power output is a conservative 50 watts into 8 ohms.

The integrated preamp has seen steady improvement since I was first acquainted with it. Various small detail improvements have been made, but the most impressive feature is the inclusion of a switchable moving coil input, suitable for all but the very lowest output ( eg some Ortofon and Audio Technica ) MC cartridges. Two pairs of phono sockets are provided on the disc input, one for MM and one for MC, with a switch to select which is connected.

As I was so impressed with the performance of the Croft Mega/ OTL system on the various locations and times that I have heard it, I had high hopes for the new `economy' version. It proved even better than I expected.

During the course of the evening my Audio Vois V21/210 transistor amp was given a well-deserved holiday, and the Crofts setup to drive my Q6 loudspeakers, fed from Rega/ Grado and Mentor/ Decca turntables.

Before I say anything about the sound quality of the Croft, I would like to state categorically that I am not against solid state amplifiers. In my previous Croft piece, about the Mega/OTL, I said something to the effect that most transistor amps sound awful and most valve amps are OK. Perhaps if I now qualify this by saying that there are thousands of transistor amps but very few good ones, while there are very few valve amps around but most of them are at least half-decent, my attitude should be clearer to the reader. I always think that if an amp delivers the goods, then who cares what type it is? I have the aforementioned solid state Audio Vois for my personal use, and love it.

Valve or not, then, the 1000 Croft outfit should stand on the merits of its sound quality alone. As I found, it sounded very good indeed. Using either turntable, the sound was very clear and focused right the way through the frequency spectrum. In my previous piece I remarked on the Mega/ OTL's ability to produce a lifelike range of tonal colours, which in my humble opinion was probably the best I have heard to date. The cheaper outfit was not up to the same standard, but good nonetheless and able to better even the V21/210, which I think is one' of the world's best transistor amps, regardless of price.

I usually find that the biggest moan about valve amps, apart from cost, is what most people would describes soggy bass or lack of impact. I respectfully suggest that these people might change their minds if they listened to an EAR or Croft design. The Croft was quite capable of exploiting the bass definition and clarity of my loudspeakers, and I felt it gave nothing away to transistor amps in that respect, which is some achievement when using transformer coupling.

Before I finish talking about the sound, I think I should make a special mention of the integrated preamp This is one of the quietest valve devices that I have ever used, via the MM disc input being roughly comparable, for subjective annoyance of hiss and hum, to most of its solid state equivalents. Naturally it has a higher noise level on the MC input, but show me a preamp that doesn't.

At 399 retail it makes me wonder just what one has to do to build a successful audio product, as the Croft is still a pretty rare sight in dealers' showrooms. I find this difficult to understand, as not only is the Croft a particularly good example of how to build a high quality valve preamp, with decent components and good old British craftsmanship, but it is also the cheapest available. Presumably if it cost twice as much, was shoddily built and imported from the USA it might be as well known as some of their esoterica.

I feel rather sorry for the manufacturers of British valve equipment, as they seem to be on a hiding to nothing now that imported tube amps are the vogue.

In the case of the Croft preamp, I think it quite easily outshines the competition until one reaches the heights of the more expensive British valve preamps while one has to spend very large amounts of money to find a better American product. The power amp will be in production by early 1985, so I think I should defer final judgement until such time as it appears in dealers' showrooms, but if the standards of the final prototype can be maintained, then some of today's expensive amplifiers could be in for a hard time indeed, whether they are transistor or valve.

Integrated Valve Stereo Preamplifier



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