#75 lighter but I owned a Radford STA25 Mk III. It was 1978 and I was desperate to transcend the limitations of an ailing Rogers Cadet. Not that the Goodmans Eleganzas were all that hungry; I just knew that I had to run something with greater dynamics, better bass control and a sweeter midband. The Radford was the amplifier with all the street cred and a friend was willing to part with his. Little did I know that over a decade later I'd be reviewing its great-great-grandson. But had you told me this, I wouldn't have been surprised.
I still own that STA25, which served as the heart of my system for five years. What I learned from it has only been made apparent during the past few years, since Arthur Radford allowed
Woodside Electronics to undertake the upgrading and manufacture of his classic. The STA25 Mk IV was a natural starting point, a modernised version of its ancestor. So, too, were the mono versions, dubbed the MA75s. These in turn led to the replacements for the STA25 Mk IV, the new STA35. And all of these begat the amplifier under review, the Class-A 50W monoblock MA50 Renaissance. And they confirmed the lessons imparted by the old
Mk III: that the basic circuit was so 'good' and so 'right' that it could evolve along with the rest of the electronics industry – right into the Digital Age.
Back when Arthur was at the helm, items like trick cables and tweak resistors weren't even part of science fiction lore. Gold-plated sockets, ultra-low-impedance speakers, sophisticated
solid-state components for mere pence – John Widgery, the 'heir' to the legacy, has addressed or exploited all of these and more in the time he's been entrusted with the Radford's development. He's now graced the amplifier with Class A operation and greater security with nasty loads by reworking the power supply to include solid-state regulation feeding the phase splitters. Other changes include a move to cathode bias, creating both the Class A operation and removing the need for manual bias controls, as well as a return to EL34 valves. Martin Colloms deals with these changes in full elsewhere in this review; I cite them only to reinforce the relationship to the venerable circuit of the grey-painted predecessors.
The empirical differences connect the MA50s to its current siblings while one key change actually links this to a long-departed ancestor. If my memory serves me well, this is the first amplifier in the STA series since the sought-after STA15 to do away with manual bias facility. It may be a minor point, but I know from discussions with dozens of valve amplifier manufacturers that this is the sole remaining cause of techno-fear in would-be tube converts. As non-technical as I am – my skills are limited to soldering good enough for kit-building duties – manual biasing never worried me, especially as most modern valve amplifiers provide meters (eg Raymond Lumley) or tell-tale LEDs (Beard, Radford) which make rebiasing no more of a challenge than setting record levels on a cassette deck. Still, if someone leery of tubes can be assured that an amplifier is virtually maintenance-free, then it's one less obstacle for the nervous one to overcome.
That aside, the ergonomics and operation of the MA50 differ hardly at all from most solid-state products. Radfords run warm even in low-powered, Class AB or B form; the MA50s give off
enough heat from each bank of four EL34s to make the mesh cage uncomfortable to the touch, hotter than the 150W Raymond Lumleys and almost as scalding as the 12-valved Beard P1000. These need breathing space, so allow room for two 17x16in radiators (including switches and terminals) if you're considering the MA50s.
As with other current Radfords, the MA50 is finished in black with gold trim, the cage covering all of the valves in the interests of safety. (If you want romance in the form of exposed valves, consider the presence of pets, children or maladroits before removing the protective cage.) The front sports only an on/off switch and a green 'on' indicator, while the back offers three-pin IEC mains input, fuse holder, a gold-plated phono socket and five-way binding posts for speaker connections. Switch-on is accompanied by a 'sproin-n-ng' sound, but the amp
settles down immediately. A half-hour is ample for pre-listening warm-up.
One curious aspect of the MA50s which had me worried when I tried them with the 3 ohm Apogee Divas was a smell of melting plastic or paint. Had I cooked the Radfords? Was a light show soon to follow? Naaah...it was the actual burn-in procedure, described in the literature as 'quite normal'. It disappeared after a couple of days, but did bring back horrible memories of faulty anachrophilia.
Although the Radfords will handle devilish impedances when the transformer is rewired to suit such loads, I opted for something a bit more in line with the capabilities of a 50W valve amplifier. The Radfords were auditioned with Celestion SL700s, the rest of the system including the Marantz CD-12 CD player, Oracle Delphi turntable, SME Series V arm, Audio-Technica ART-1 moving-coil cartridge, Audio Research SP-9 and Air Tight ATC-1 preamplifiers. Cables included Lieder speaker wire and Mandrake, Lieder and masTER LINK interconnects.
This was no blast from the past, as I learned through a side-by-side comparison with an STA25 Mk IV. Readers with experience of Radford products will recognise the mid-band, with
its rich, rounded sound and ample detail, but the extremities may cause some shock. Partly this is due to the extra headroom and greater dynamic capability provided by the extra power. You'd expect the bass to have greater impact, just as you'd expect a gain in maximum level and whatever else an extra 3dB can provide. But you cannot prepare for what the Class A operation and those extra decibels do for the edges of the frequency spectrum.
I've never had any complaints about the way Radford amplifiers handled the bottom octaves. I've tended to use Radford amplifiers with small monitors and I'm not all that bothered about life below 70Hz. But for those of you who don't believe that there's any bass to match the bass which damages bladders and induces nausea, YO! The Radford works with 'eavy metal!!!
Continue on to Page 2 for more about the MA50.
Uh, sorry about that, but I just did not expect the Radfords to rise
to the drum/bass barrage opening of Helloween's Live In The UK or the
darker moments of This Is Spinal Tap. (This also speaks volumes for the
SL 700s, which continue to confound those without the requisite amount
of respect for British skills with small enclosures.) Don't think I'm
referring only to extension. I'm talking about weight, control, power
– hell, I'm talking about MASS. I cranked that sucker up to 11, no –
13, and was hit with a wall of sound of Spectorian bulk. It was, to
drift into the vernacular, awesome by any 19in rack-mounted,
heat-sinked standards. Yes, kiddies, the Radfords have the stones to
deal with hard rock, deep rap/funk and – dare I mention it in this
company? – large scale orchestral works. No, I don't mean in tandem
with 3 ohm loads but with a half-dozen ohms or more. But remember: the
SL 700s ain't exactly Jamos when it comes to sensitivity. Yes, the
Radfords have bottle both literally and figuratively.
At the other extreme, we're almost talking solid-state. Say 'Bye,
bye' to 'the classic valve sound', the cuddles and whispers of ageing
tubes and Ortofon SPU cartridges and slow-cones. The MA50, when
required, can cut like a knife, with all the sharp notes having edges
defined with absolute precision and no fatigue-inducing grit or grain.
It's lean to the STA25's plump, and the synergy with the SL700 produces
such an absolutely enticing treble region that you can easily forget
that the SL700 is a descendant of the dull-as-Clayderman SL6. The
downside is that the MA50s can seem a bit dry, as evidenced by the
portrayal of space.
As with all monoblock amplifiers, interchannel grief is a byproduct
of the sources and preamplifier, so you can always assume that
left/right integrity is above reproach from the amps' inputs onward.
The stage recreated by the MA50s – again referenced to the SL700s –
is simply massive in all three dimensions; stage height rivals anything
I've used in recent
memory. Width extended beyond the edges of the speakers, but it fades
off abruptly enough to warrant the use of a tape measure. A most
staggering illustration of this phenomenon occurs in 'Troubles' on
Champion Jack Dupree and His Blues Band, with Dupree in conversation
with Mickey Baker, one voice dead-centre and the other stage-right,
past the right-hand speaker. The precision with which the voice is
positioned is the among most emphatic proof I've heard for silencing
those who refuse to accept such a condition. By the time the recording
– a 1967 Mike Vernon production and a testimony to his brilliance –
moves on to 'Caledonia', the guitar is so far to the right that you'd
think Maggie Thatcher had discovered the blues. But this is a
choice of between superlative image placement and three-dimensionality
over a sense of 'air' and atmosphere. A minor complaint, but one you
should relate to your personal preferences.
The Radford MA50 power amplifier is one of very few British
amplifiers which I would enter into the global high-end battlefield. At
#2127.50 per pair, inc VAT, the Radfords retail for a lot less than
equivalent-quality imports. (John Widgery points out, sadly, that a
trip westward across the Atlantic puts this into direct competition
with amplifiers which sell for #3000-plus in the UK.) Now I know that a
couple of kiloquid is far from sensible money when the man on the
street considers #500 for an entire system to be nothing short of
criminal, but I have to describe the MA50 as a bargain in relative
terms. What I see here is another indication that British valve
amplifier manufacturers are – finally – aiming for greater glories
than 30W/channel affordables can provide. The natural competitor for
this amplifier is the pending Beard P1000, while EAR, Croft, Raymond
Lumley, Grant, Cadence and a few others join to make up a field of
valve-driven powerhouses which can satisfy the home market with aplomb.
I'm just glad that one of the best of the current crop wears the same
badge as the first amplifier which made me valve-mad a decade ago.