Mach3 – Breaking through the clouds – DPA 6C33C mono power amplifier
One nice day of September in 1976 a Russian jet figter landed at airport Hakodate in Japan.
Media didn’t spread disinformation about complicated weather conditions or navigation error – it was a pure desertion – news were totally blocked.in the Soviet occupied area. Please note that Cold War was going on.
The pilot got political asylum; never-seen-before jet was examined/disassembled by NATO; then re-assembled and trailed home. There was a hard NATO inquisitiveness about jets coming from beyond the Iron Curtain; especially this world-fastest jet. MIG25 originally created to destroy NATO bombers that had never got to be built.
There were several interesting stories and urban legends spreading in Hungary on the technical solutions were found inside of MIG – a strange geometry of engine’s compressor-stages or the suspension of the 3D giroscopes – we must remember that at that time giroscopes had a weight of kgs – nowadays Ipads and small helicopter models have giros in one cubic mm only.
Another feature was the special steel-alloy that could stand deformatoions caused by 3Mach, which MIG25 could easily reach – in this respect the fighter was not simply ’supersonic’; as it was capable of three times of the speed of sound with the cover in flames while escorting space-ships into the stratosphere – that’s why everybody thought that the jet was made of titanium and other unknown materials. CIA in the background may have known the truth and let media make up fantastic theories; it was a clever hoovering system for more money to Cold War use. What’s more interesting for us: there were special PSUs and operation amplifiers containing tubed electronic blocks. It was an out-dated technologie at that time too but the Russians had an ideology for using tubes: they were supposed to be more nuclear-weapon-resistent. Luckily, this project was never tested in real life. In the PSU of radio/weapon line there was a strange, never-seen-before triode in sight.
A real monster; absurdly thick glass; robust building; big cathode-heater; relatively small voltage and enormously big current. Power-station-like dissipation and very, very low internal resistance. Name was the same as today, 6S33S; spelling with Cirill letters 6C33C.
The story continued in quite a strange way. Some 6C33C tubes appeared in Japan at the tubeamp-maker community; they built several 6C33C amps; the sound was very good. So far is the legendary. After many years 6C33C became well-known; Japan imported hundreds for audio application. Some makers built them here, in Hungary too; high bias was always a big problem and nobody could get rid of the diode-based rectifying. Then new kings arrived; 2a3 and 300B had easier settings; 6C33C almost sank into oblivion but appeared again on the hifi horizont through interesting coincidences.
While 300B was in a real dump, Peter Dénes developed the full-tubed 6C33C. I assume that finding out the new rectifying system was an enormously complicated brain-work and it took several years – I picture him as Poirot sitting there with the guests around and drinking coffee and making hot air – while his mind is full of the thousand-lined matrix of the murders/alibies/motivations/times/dates.
This way the ’new’ 6C33C block was born.
What type of monster?
Well, it’t quite a big one, sitting in the same cabinet as 300B does; and there are several elegant technical solutions inside: giga-form 500W PSU; high quality pre-tubes; very short signal path; 3cm lenght between connector and the first tube; output connectors fixed on the OPT secunder. Rectifying is real-tubed: two big rectifier tubes control the high power tube’s current; a separated stage controls the low currents somewhere inside. 6C33C has extremely low impedance which means the output transformer has low excitation; going down to 17 Hz easily. Coulping is performed via interstage transformators – I think it’s a great invention. In the 300B blocks it caused two things: first, there was an enormous sound improvement; (the question appeares ’why we had to wait for it so long); second, that no more changing of coulping-condensators which is similar to cable-madness because you always find the most recent oil-fat-belladonna-miracle coulping cap and each one has its own character. Of course interstage trafos can also be changed similarly to caps and each one sounds differently but in Hungary it’t not that usual; unlike in Japan
At my place a simmetric-input version landed; I ordered this type because it is really grey and has got really simmetric coulping to a standard 600 Ohm.
6C33C is 19W measured, Naim 135 was 75W; 300B was 7.5W – but theese are only numbers, which; may be important; but we shouldn’t misjudge this parameter.
Turn it on. Nothing happens. Is something wrong? No, the iron bastard is aweking gently; 6C33C needs 2 minutes literally – in reality 25 sec and it’s ready. No hum, no crackling, no any initial madness. Naim 135 started much harder, almost jumped off the stand while 6C33C departure is similar to that of an automatic-geared car. No brumm, no noise, no stratchy sound of tubes, everything is absolutely silent. Then I start to check the speaker cables because of the missing idle-noise listening to tweeters really close – ear-furs almost reach the dom – finally I can realize an ultra-silent sssss – I imagine cosmic background-radiation exactly like this. I’ve never-ever owned such a silent amplifier. Then warming up takes 5 minutes only while currents get stabilised – no more time is needed as its real character shows itself in cool conditions; just to the opposit of how coffé works. Please do not believe in long-time burning period.
What is the sound like?
Delicious, great and spacious.
It is like when you enter a big room with a beautifully laid table.
It is like when your frozen body sinks into a Turkish bath.
It is like when you realize in the shop that croissant is still warm.
It is like when you have a good coffe and feel your body beeing saturated with the nice poison.
Do you know that caffein becomes traceable in all your tissues in 180 sec?
When a November morning after 3 weeks of total fog, with all insects and moles already suffering from heavy depression, you take off and ascend with bad iceing on all surfaces, concentrating on a red-light gadget that is your only connection to the outside world, at 900m it’s a gradually getting brighter; and you suddenly catapult over the ceiling of clouds where there is dark-blue sky and enormous brighteness. Your tears flow and you blink and the clouds are like whipped cream with a visibility of 150+ kilometers – well, it’s that kind of feeling…
There is no similarity to any 300B amps previously listened to. It has no special character; music just flows: no loosy bass; no tight bass; just a ‘bass’; fine and very alive. There are absolutely perfect overtones on piano sound. Several good sets present right-hand very well; but now all keys are OK. On low volume…well,….it is gently dinamical and so fast that speed can’t be realized; it’s a paradoxon but you understand what I mean. Timbres and high section are real suprizes; previously the big Naim set performed this area extremely well but 6C33C is a completely different galaxy; another empire; astoundingly living. I never thought before that an oldish ScanSpeak D2008 can do this sound or a tube amp can ever produce this.
‘Complicated sopranos’ – now there rather wonderful sopranos; and I realize that CD sound generally is OK.
6C33C doesn’t focus on mids as many 300Bs do; it performs in another way – I think in a much better way – as bandwidth is so wide that music is full of small noises: there is a strange scabridity on the female voice and a light accent on the male voice and an ultra-light squeak on plucked string. The most interesting is a tone of echoes and finishes, something like an instrument-shadow or aura that compasses the sound when the last note leaves a signature or reminessence this can be heard in under-skin-mode only. I say bandwidth but I suspect it’s a kind of sub-micro-dinamics. Calm, wonderful and ‘big’ sound – each moment is a pleasure and I have to force myself to remove discs.
We definitely have to examine it as a system of wires, Cd player, room and mistakes and in addition my strong prejudices; please do not expect an unbiased report from me; you will find it in the official papers; but the fact is that at present you don’t need a high-sensitivity speaker as 300B/2a3 always do, but a normal one is OK. Not-really-good (bad) impedance is also OK, as a Naim SBL has that too. This SBL lost loyality to Naim; although it was originally invented for Naim electronics. And another fact is that 6C33C serves well a ten time more expensive front too.
I feel like being on a good Early Music concert: the player doesn’t push himself into your face with artificial ultrasonic sounds and never-existing bass, rather he lets harmonies live and work. The character here may not be a special character; it lets front to sing which enjoys my highest respect now – though I never liked full ML sets at all. This maybe the first tube amp I’ve ever listened to that can make you forget about all tube/not tube/SE/PSE/PP/OTL questions and all technical blabla and also about what process is there producing the music in the room.
Of course, you can’t get rid of the sight of the tubes: in darkness 6C33C has the view of an oil-refinery-station, which tube lovers know exactly. Each occaison when you turn it on is a ceremony: you have to kneel down in front of the blocks because the only switch is on the back side.
But the most important thing is that ‘listening to music’ with 6C33C is a real celebrating of music. Highly recommended.
ML512 SACD player
DPA 6C33C mono power amplifiers, 2 stücks
2×1.3m XLR interconnect; a secret unidentifiable wire from the ‘60s
2×7m NACA5 speakercable