A racy amp that misses nothing

REVIEWS

Stereoplay 07/92 - Avantgarde A1

Haute Fidelste 02/93 - Avantgarde A1

Stereoplay 11/94 - Avantgarde A1

Stereoplay 09/95 - Avantgarde C1

Sound 07/96 - Avantgarde Kombi

Video & Son 12/96 - Avantgarde Kombi

Beyond the wall of sound

A steel case with a wide black front panel in opaque Plexiglas: the C-1 from AvantGarde has all the charm of a transformer block. A quick look inside confirms this impression, given the presence a 1000 V/A transformer and two blocks of capacitors. The A-1, masterpiece of Fred Gassmann (34,000 marks, rated by Stereoplay in its 7/92 edition as "absolute Spitzenklasse 1" [top class] and considered at that time as an unequalled reference model), gets the best part of its inexhaustible power supply from enormous lead batteries. To achieve comparable conditions in the new C-1 integrated amplifier, Fred Gassmann uses no few than 32 capacitors (16 per stereo channel) each rated at 4,700 mF.

However, this energy flow is slowed down by a small resistance of 0.01 ohms in the power supply. In theory, this reduces the decay time in the bass frequencies. At the same time, the resistance brings the decay time of the bass frequencies closer to that of the treble ones, taking advantage of the lower inductivity of the cables. Does the C-1 benefit from this forced equalisation? One would like to think so.
At any rate, the accelerated reaction of the amp has the effect of minimising distortion. Therefore, Fred Gassmann hits the accelerator everywhere he can. If only at circuit board level, which is small and has very short, rounded conductor tracks. Ultra-rapid regulators keep the voltage to the preamplifiers permanently on maximum. Also, the capacitors which slow down the signal and harden the sound are banished from the signal path. Finally, when this Swiss gentleman insists he selects transistors manually to get the best possible match, Stereoplay has no difficulty in believing this.

At first, just an affirmation from Fred Gassmann left the experts sceptical: according to him, all you need is fuses to protect the unit. This is why, after having carried out all the measurements in the laboratory, the engineers used fuses for short circuit testing. Once they had been replaced, the unit started working again as if nothing had happened.
This is fortunate for the ears of the experts, because it would have been a shame to miss the phenomenal demonstration of the C-1's talents. By comparison, the PA-1500 from T+A just didn't have the guts, right from the first round of tests, despite its well-known qualities. There is no comparison, the C-1 really lets the music take flight.
Even the fantastic Accuphase E 210 and the charming Electrocompaniet ECI 2 are not in the same league. Using the C-1, a piano has more colour. Each note is noticeably detailed and the emotion flows at every turn. Nothing could better translate the hammers striking the strings and the airy resonance of the chords than this racy Swiss amplifier.

Adapted from the article "Der Rasende" which appeared in Stereoplay 9/95

Back to the mains

Fred Gassmann, king of the rechargeable battery is going back to the mains: unlike their predecessors, the latest amps from AvantGarde no longer have a battery power supply. What does this mean in sound quality terms?

Since becoming a vegetarian, hi-fi master Fred Gassmann has levelled out at 58 kilos without his clothes on. On the other hand, his amps are stuffed full of vitamins - in other words big lead batteries supplying almost unlimited power. Fred Gassmann has applied this principle without compromise to his last amplifier, the A-1, awarded the title of "Champion, All Categories" by Stereoplay (7/92).

But not everybody wants to shell out 34,000 marks to satisfy their taste for perfection! "I can also create something for a more moderate price category," says Fred Gassmann, who did make a few concessions in the A-1. Not only has he done away with the 8 enormous Sonnenschein batteries and all the charging electronics, but all the regulators for the output stage. The input stage has a discrete regulator which maintains a constant supply. On the new basic A-1, the A-1 1000, connected to the mains, 16 big capacitors per channel keep the voltage stable no matter what type of playback or load. Happily, the total capacitance of 16 x 4,700 mF is much greater than that of comparable power amps. The 1 kW transformer should easily be able to supply the necessary power, especially as this is a transformer that is heavier than normal, and capable of storing magnetic energy.

"We carried out listening tests for each component, making systematic comparisons with the battery amp," Fred Gassmann assured us. According to him, the basis design is not decisive. In the case of the A-1 1000, Gassmann is satisfied with a standard high quality layout (for the engineers out there: an ultra-rapid input stage with transistors in series and four Toshiba bipolar transistors per channel).
No false modesty! The measures effected by Stereoplay show there is no signal degradation, even using loudspeakers that are hard to control. And AVantGarde is also offering us a genuine innovation in amplifier history: absolutely equivalent decay times in the high and low frequencies.

Even if the A-1 1000 will not let you forget its luxurious big brother, it does not deliver a less than extraordinary sound quality. It suffices to make a comparison with the Chord SPM-1200, brand new reference model which has just entered the "absolute Spitzenklasse II" category of Stereoplay. " has the Swiss model been doped or is the SPM-1200 on tranquillisers?" the critics gush.

More depth and consistency in the bass frequencies: without doubt a contribution from the A-1; but also lighter, purer, better distributed trebles - its competitors are already biting the dust.

In other words, here is an amp for 6,800 marks which really deserves to be in "absolute Spitzenklasse I"!

The tests also involved another product fresh from Fred Gassmann's "kitchen": a new preamplifier, the B-1, with a big power supply. A few discrete transistors and a slightly larger number of regulators are positioned in a smaller circuit. The price of the new B-1, say about 12,000 marks, has remained relatively moderate in comparison with the old one. And when it comes to the amplification of a CD signal, the B-1 is top notch.
At last, the B-1 is a remarkable match for the striking A-1. Never before has a marriage of components in this price range offered such a clean or such a rich sound. In conclusion, then, excellent news for hi-fi gourmets : even if the culinary preferences of Fred Gassmann, audio bigwig, leave them cold, they will not fail to appreciate the currently more digestible prices for his extraordinary amps!

Adapted from the article "Netz-Spannung" which appeared in Stereoplay 11/1994

Revolution in amplification

Battery powered

It's a long time since Fred Gassmann of Switzerland started experimenting with power supplies for power amplifiers. At that time, he exclusively swore by a block of enormous lead rechargeable batteries, capable of maintaining the respectability of any kind of amp or loudspeaker (see Stereoplay 9/91).

Since then, the power amps of Fred Gassmann have been powered exclusively by battery. And after this initial revelation, the Swiss electronic engineer has not stopped innovating. After 4 years' work, the "Gassmann Akustik" team have come up with an incredible amplifier, the A-1, which Fred Gassmann presented to Stereoplay at the time with a simple, "There you have it, now I'm completely satisfied by the sound of our A-1."
To power his "baby" he opted for no less than 8 very high quality lead batteries. You only had to recharge them after 6 hours' listening. It takes one hour with a high performance charger to re-establish an output of 200 amperes/hour. These rechargeable batteries have a capacity that is much greater than that of large capacitors. Also, the supply voltages of the A-1 remain in the order of 52 volts (4 x 13 volts), even after long orgies of bass. However, the loss of voltage arising after several hours of listening, although inoffensive and limited to a few volts, remained a point of dissatisfaction for the Bienne team. This is why 21 transistors permanently ensure a voltage of 45 volts to the 8 output transistors of each stereo channel.

The printed circuit board is itself exemplary: the amplifier, totally symmetrical, works in the AB class. It is made up of two monoblocs, each of which has 14 Toshiba bipolar transistors, which were chosen because they allow very detailed sound reproduction. The input and output stages have ultra-fast regulation and it is a fact that the A-1 amp is the fastest in the world. It can supply over 100 amperes per nanosecond. As for the decay time, it has proved incredibly high, even for the high frequencies, so that even loudspeakers with dreadful impedance variations were unable to move the output signal curve one iota.

Even before measurement, the Swiss phenomenon triumphed over its competitors in listening tests. The two monoblocs, DMA X2 Stax and Mark Levinson 20.6 (both classified as references in "absolute Spitzenklasse I"), gave up the ghost with the T 230 loudspeakers of T+A, but only just. "Amazing," murmured the experts, who could not get over it. Each time the LED meter hit the red, the music filled out.

The French magazine "Haute Fidélité" confirmed this: "(...) the AvantGarde A-1 amplifier stands out because of its exceptional sound qualities. It is endowed with a richness in the midrange/treble areas which puts it amongst the best amplifiers you can listen to. (...) An end to poor or disembodied sound. [This amplifier] seems to have decided to use the full palette of colours necessary to offer a gentle yet analytical musicality (...) The dynamics are also a success. For example, be it a solo piano or full orchestra, everything happens quickly. No dragging, no weight. The imaging of such instruments as timbales, bass drum, double bass and cello has remarkable clarity. The stereo image does not have to worry about the competition either, being simultaneously wide, yet distinctive as regards the various sound levels."

And the Editor in Chief of Stereoplay confirms this, "I can't believe my ears. With the A-1 from AVantGarde, the sound is infinitely more pure."