You may recall that we've reviewed a product from this French company before: the Phono-1 phono stage (UHF No. 46). We thought it was terrific, but perhaps you shrugged that off, because after all a phono stage is just an accessory, right? And isn't designing one a lightweight assignment?
Not really, no. A phono stage must deal with an impossibly small signal, a mere fraction of a millivolt, and it has to amplify it to perhaps 600 times that, far more than a power amplifier does. Its noise level must be near the theoretical limits, and to make things even tougher it must apply a frighteningly steep equalization curve that is nearly impossible to execute without disastrous side effects. A designer who can do magic with a phono stage can do anything.
Of course, this amplifier is also something of a challenge. It is a class A tube design, with remote control. Because it is expensive, it needs to justify its price by turning in performances that seem to be worth the price. Not easy.
First, a note about class A amplifiers. Like most amps, this one uses a push-pull design, with one tube amplifying the positive half of the wave and the other the negative half. Push-pull amplifiers have a potential problem, however: distortion near the crossover point, when one tube "hands off" to the other. This is negligible at full power, but it gets much worse as signal level drops. For that reason most amplifiers are designed so that the two output devices overlap, to avoid the worst of the distortion. A class A amplifier throws efficiency away and overlaps the two completely. Unneeded power is discarded in the form of heat. And even though this amplifier's rating is a mere 40 watts per channel, it dissipates as much heat as an amp with ten times the power.
Actually, if you dig further into the specs, you discover that it operates in class A only up to 33 watts, after which it slips into conventional class AB. To translate that, it means that from zero to 33 watts it draws constant current from its power supply. From 33 watts up it increases its demand on the power supply. Is Audiomat cheating? No, because any class A amplifier will do this at some point. In this case, the company has chosen to rate the maximum power above that of maximum class A power. Think of it as a 33 watt per channel amplifier (just 0.83 dB less), and it's class A all the way.
This is a remote-controlled amplifier, with not many buttons on its remote. You can turn it on (providing it's in standby position, not completely off), and its volume control will rotate all the way down while it goes through the warm-up cycle. Volume can then be controlled by two sets of buttons, one for moving quickly to the desired volume, the other for fine-tuning. There is also a mute button. Inputs (marked line 1 through line 6) are selected from the front panel.
The rear (see above) includes the input jacks plus "line out" jacks, which are actually "tape out" jacks. There is no matching tape input, nor of course a tape-source switch. There are two sets of output jacks, allowing easy biwiring, and of course with separate posts for 4 ohm and 8 ohm speakers. The posts are rather slim, and because they are not hexagonal we couldn't use our Postman wrench to tighten them.
Inside is an all-tube circuit, with half an ECC83 (12AX7) input buffer and an ECC82 (12AU7) phase inverter feeding a pair of Russian Svetlana 6550 output tubes. And unusual detail: the circuit operates without the usual feedback loop. The power supply has muscle, as it must. Its 10,000 mF filter capacitors are bridged by 1000 mF capacitors to give better performance at low frequencies. The machined aluminum case uses a special paint with a high damping factor developed by Siemens.
Because the Reference 3a Suprema speakers in our Omega system have a 4 ohm impedance, and because we anticipated that the Solfège would need every watt it could get its hands on to drive them, we connected to the 4 ohm posts. However we should add that this is controversial, and some audiophiles prefer to use the 8 ohm taps. That's because the 8 ohm winding on the output transformer has only half as much wire as the 4 ohm tap, and it might potentially sound better for that reason. There will be a loss of power, however.
We began our test with the HDCD gold version of the famous Antiphone Blues disc of saxophone and pipe organ recorded in a vast church (FIM CD003). Reproducing it is difficult for an amplifier, which must draw lots of detail from the saxophone without making it sound edgy, and must be able to handle the low organ notes and the considerable reverberation.
Model: Audiomat Solfège Référence
Price: C$6890, US$4790
Warranty: Two years, transferable, except six months on tubes
Dimensions: 44.5 x 19 x 40 cm
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