The new Symasym V5-2 was designed by Michael Bittner to function as the cost-effective centerpiece of a quality component system. It may be offered as a kit to the people who would like to build it.
I was asked to help with beta testing and evaluation of the amp. I described my experience with building this amp on another webpage. I made several small changes to accommodate Toshiba 2SC5200/2SA1943 output transistors, IMHO the best devices on the market. I will speak about my version of this amp.
The amp is constructed in Fischer SKE 3400 19" rack box with heatsinks. Front panel is made from clear anodized alluminium of 4 mm thickness.
On the rear panel are 2 pcs of Neutrik XLR inputs, two sets of doubled speaker outs, a socket for AC power cord, and a power switch.
The PSU consists of 300VA toroidal transformer, 2 rectifier bridges (1 for each channel), 2 capacitor banks. Total PSU filtration capacitance is 40.000 uF.
System, Setup, Space
I did my auditioning of the Symasym in my 4.8 x 3.8 x 2.5 m standard listening room. The current audio system consists of SONY CDP-XA2ES player, enhanced by PMA - audio buffer at the output, AU/RA D7A passive 22k preamp or PMA - Dispre discrete active preamplifier, PM-AB1 power amplifier with output error correction, New Monster Clear Jacket Speaker Cable, VOBA Acoustic Sforzato 2-way closed boxes (400 x 250 x 330 mm) modified to 3-way with added midrange box (155 x 155 x 130 mm, with Seas MCA11FC speaker), the speakers are on stands, standing inside the room. There are minor acoustic adjustments made by carpet on the wall behind the speakers.
Listening
First of all I quickly decided not to
use the AU/RA passive preamp at all. As every solid state amp, Symasym
sounded much better with the active preamp. The sound with passive preamp
was a bit boring, less controlled and less detailed, with worse soundstage,
compared to active preamp.
The first thing I noticed was that Symasym sounded dynamic, emphatic, with no harsh, no grain and no colorization. Very good start.
To burn-in, I played several relaxing CDs, like Diana Krall Love Scenes, Patricia Barber Modern Cool, Joao/Astrud Gilberto/Stan Getz Back to Brazil .... Symasym plays very lively, with very good and articulated bass, smooth and detailed midrange and highs. No harsh, no grain, and it is not dry. Patricia Barber's Constantinopole is a must experience!
Now let's go serious.
J.S.Bach, Die Sonaten fur Viola da
gamba und Cembalo. Jordi Savall - Ton Koopman. Alia Vox AV9812.
I like this CD very much. Played on historical
instruments, Clavecin Christian Zell, Hamburg 1737 and 3 different viola
da gambas, dated 1550, 1697 and 1757. Not only nice music, but excellent
test, harpsichord tends to "melt" on worse amplifiers. Nothing like this
here, symasym plays it well defined and distinguished, retaining wonderful
sound of both instruments.
Leonard Bernstein, West Side Story.
Conducted by Leonard Bernstein. Deutsche Grammophon, 415 963-2.
Excellent recording of a very nice music.
Natural dynamic and clarity preserved. Symasym plays it dynamic and clear
- perfect.
Ludwig van Beethoven, Piano Concertos
Nos. 1-5. Chamber Orchestra of Europe conducted by Nikolaus Harnoncourt,
on piano Pierre Laurent Aimard. Teldec 0927 47334-2.
I have special relation to this 3CD.
It was recorded in Austria, Graz, Stefaniensaal. 2 years later I visited
the same concert hall, with same orchestra and conductor, same pianist
and the same piano! So I can compare ;). In this CDs the Aimard's piano
is very well recorded. I am playing Concerto No. 2 through symasym - and
it is as it should be! I can hear the real Aimard's piano, the sound color
is correct. And the orchestra sounds well, good job!
To prove behaviour during dynamic peaks, I tried Hector Berlioz Symphonie fantastique, mov. iV - March to the Scaffold (Telarc), and Antonín Dvorák From The New World, mov. I Adagio (Telarc). There are large peaks from great drum and tympani, often compressed or scrapped by poor amplifiers. Symasym plays it poweful, dynamic and undistorted.
Sidebar 1: Specifications
Description: all BJT transistor
2-channel power amplifier with one line-level input, pseudo-symmetrical
floating (resistor 10R between input GND and power GND) with XLR connecors,
pin 2 live input, pin 3 input GND, pin 1 Shield. Output power: 33W rms
power into 8 ohms, 60W rms power into 4 ohms, for power supply 2 x 27.5Vdc.
THD: 0.003% into 8 ohms 1kHz small signal, 0.04% 10W/4 ohms/6kHz. Intput
impedance: 22 kohms.
Dimensions: 440 x 140 x 440 mm.
Weight: 14 kg.
Serial number of unit reviewed: 001
Price: not estimated, not intended
for production. Approximate number of dealers: unknown
Manufacturer: Pavel Macura, Prague,
Czech Republic. Web: web.telecom.cz/macura/audiopage.html
Sidebar 2: Measurements
The chassis of the symasym did not show almost any temperature change after the usual one-hour preconditioning period at 1/3 power into 8 ohms. The heatsinks are oversized, so no output power of any duration is a problem. The amplifier didn't invert signal polarity, and the maximum voltage gain was a high 32dB. Input impedance was 22k ohms and the damping factor is high, much above 100, as the output coil is not used.
The frequency response is nothing to speak about, it is flat over the whole audio band.
The step response has very slight overshoot, about 2%. Slew rate of the symasym is symmetrical and its value is +SR = 24V/us and -SR = -24V/us.
The symasym's total distortion was low in level but changed a bit with frequency, flat to 1 kHz, and starting to rise above 2kHz.
Fig.1 symasym, THD spectrum vs frequency at 1kHz, 16W into 4 ohms
Fig.2 symasym, THD spectrum vs frequency at 1kHz, 44W into 4 ohms
Fig.3 symasym, THD spectrum vs frequency at 200Hz, 16W into 4 ohms
Fig.4 symasym, THD spectrum vs frequency at 5kHz, 16W into 4 ohms
From the distortion spectra, one can see there are only low order even harmonics (2nd, 4th, 6th) for moderate output levels, these harmonics are nicely decaying and are quite low in magnitude. They rise a bit with frequency, but remaining same in ratio.
Only when pushed hard, the amp starts to produce odd harmonics, that are lower in level than those even ones.
The measurements taken of the symasym indicate very good operation of the amplifier. Certain rise of distortion at high frequencies might be reduced by PCB modification (just presumption), this is a question for designer of the amplifier. Anyway this rise is not harming at all.
The symasym verified to be a very good amplifier. I can recommend it to potential users.—Pavel Macura