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Beyer Blueprint A75

Stereo Amplifier By Paul White
Published April 1997

An amp is an amp is an amp... but Paul White finds himself vexed by such eternal verities.

Life is an odd assortment of very interesting things, slightly less interesting things, dull things, extremely dull things — and power amplifiers. If Arthur Pewty (Michael Palin's seriously dull Python accountant) were to score a nominal two out of ten on a scale of universal dullness, power amps would come out at about minus three, just above the A to Z of John Major's wardrobe and marginally below the Spice Girls' ten top tips for revitalising British politics. What's worse, power amps aren't even funny, although — unlike the Spice Girls or John Major's wardrobe — they are necessary items without which no recording studio could function. Beyer have obviously realised that there is a perception problem with power amplifiers because they've painted theirs blue, but I'm not convinced this is sufficient to elevate a power amplifier to the coveted status of 'mostly boring'.

Bored To Be Wild

Based on well‑proven bi‑polar circuitry, the Blueprint uses a complementary output stage based on the TIP3055 and its twin the TIP2955. The design provides 75W of clean power, per channel, into any well‑behaved 4Ω load; though, as most studio monitors seem to weigh in at 8Ω, the maximum power in this case will be 50W per side. The manual recommends 8Ω speakers for continuous high‑power use, and suggests that if several Blueprints are to be racked, there should be at least 1U of space left between them to allow cooling.

Studio power amps are required to be mechanically quiet and to take up as little space as possible, something the Blueprint achieves by packing itself into a 1U rack case with a generous heatsink protruding from the rear panel, enabling the amplifier to run without recourse to fan cooling. The inputs are electronically balanced on conventionally wired XLRs, though they may be used unbalanced if you join pins 1 and 3 together. Power goes in via an IEC socket, and the outputs are on Speakons only.

While Speakons are a good idea for high‑power amplifiers, I feel that their exclusive use in this case is pandering a little too much to the Euro over‑regulators who seem intent on choking our industry. I know that the Euro regs are based on guaranteeing immortality to a 90‑year‑old granny with a weak heart, soaked in sea water and earthed by the left leg to a copper water main, who's set on exploring every orifice of a piece of live studio equipment using a three‑inch stainless‑steel hat‑pin — but I'm more likely to die from stress at not being able to find a Speakon cable when I need one.

The front‑panel controls are frugal, to the extent that Beyer have put a knob on the rotary on/off switch, just to give you false hope that there might be something to twiddle with other than the channel 1 and 2 volume controls. However, any proclivity for twiddling will have to be satiated elsewhere. And apart from the matching blue power LED, there's not much to look at, either — not even clip LEDs.

In Use

Having gone to great lengths to underline the boring nature of power amplifiers, I have to admit that there is one area in which it is imperative that they remain boring — reliability. There's nothing worse than having an 'interesting' (in the Chinese sense of the word) power amplifier. All you really, really want is to plug the thing in, forget it, and have it last forever. Though I didn't have forever in which to put this to the test, the Blueprint runs reasonably cool, and shows no sign of misbehaving when used for extended periods into typical 8Ω studio monitors. Though I didn't have any 4Ω studio monitors around for test purposes, I wouldn't anticipate any thermal problems unless the amplifier were either very badly located, or subjected to maximum‑level, zero‑dynamics audio at all times.

On paper, the A75's specification is respectable without being anything out of the ordinary, but in practice the sound is powerful, smooth and apparently uncoloured. The bass end is particularly tight and solid — something bi‑polar amps seem to do well. There's also virtually no audible background noise from the speakers.

Summary

Though technically unremarkable, this is a very competent, sensibly priced power amplifier that runs quietly and doesn't hog too much rack space. Having just 50W per channel into 8Ω isn't over‑generous on the power front, but it is sufficient for many nearfield monitors, especially in a domestic situation where volume levels have to be kept under control. However, I do feel that leaving out clip LEDs on an amplifier with such a modest power rating is a bad move — it's very easy to drive a 50W amplifier into clipping on peaks if you're monitoring uncompressed material. I'm also less than convinced by the need to have Speakon outputs when spring terminals would have been easier to connect. All in all, though, in building the A75 Beyer have provided the right balance of cost and performance in a neat, quiet package — and when all's said and done, blue is slightly more interesting than black.

Pros

  • Tried and tested circuit topography.
  • Robust construction with adequate heatsinking.
  • Solid, well‑controlled sound.

Cons

  • No clip LEDS.
  • Speaker connection via Speakons only.

Summary

A practical and cost‑effective power amplifier for use with small nearfield speakers.