NEW Acuhorn amplifiers 6C33C tube output transformerless

Matej Isak · Jul 19, 2014

This seems like much worthy of sharing. This seems like something completely different and new. Acuhorn OTL amplifiers with an intriguing approach...

A new solution for tube amplifiers output transformerless. It is a very interesting idea to apply 6C33C tubes operating at the utmost level of Amperes in the world. The high level setup class A per tube is up 8 times greater. For example, in the S1 amplifier one tube per chanel works like traditional 8 tubes. Monoblock M4 is the equivalent of incredible 32 tubes. Acuhorn in its new amplifier series fused the newest technology with vintage audiophile tubes' qualities. The latest power supply technology breakthroughs. The Vicor power modules as 10 times more excellently supporting splendid performance in audio. We have a powerful amplifier in pure class A, the beauty of the single ended triode in the audiophile way. Each tube operates independently with self-regulation. Input voltage mains autoranging 90-264Vac 47-440H ready for worldwide work. The amplifiers include 21 Stepped Attenuator volume control - it is possible to connect without preamplifier. Easy to use - just insert the big tubes in their socket and start the music.

http://www.monoandstereo.com/2014/07/acuhorn-amplifiers-6c33c-tube-output.html

Reinhard · Jul 20, 2014

hello,

they set the tubes at 0,6 A at idle so they must use a low supply voltage under 100 Volt.

No word about THD, Hum and Output power in different impedances, strange to me.

Can anyone tell a little bit more about the used technology? Tube/Resistor? Tube/CCS or the like?

Reinhard

Matej Isak · Jul 20, 2014

Hello Reinhard,

I'm trying to get more detailed info. Will reply as soon as I'll have more.

Matej

Tom B. · Jul 20, 2014

A better overview of the circuit topology would be interesting. 6C33C SE OTL, looks like SRPP. Those big Russian bottles are tough on sockets, from past projects I recall trying to stay well under 60~70% plate dissipation as even the NOS sockets would quickly degrade, along with increased temperature of the plate structure. Never tried to push the power on this one.

Tom

LL21 · Jul 20, 2014

Matej Isak said:
Hello Reinhard,

I'm trying to get more detailed info. Will reply as soon as I'll have more.

Matej

Thanks, Matej. Also interested in reading more.

Reinhard · Jul 20, 2014

Tom,

in the smallest amp they use one tube per channel. SRPP not possible,

Reinhard

Tom B. · Jul 20, 2014

Reinhard said:
Tom,

in the smallest amp they use one tube per channel. SRPP not possible,

Reinhard

Yes, you are correct. 6C33C is two triodes in one envelope, although the plates and cathodes exit in parallel.

Tom

Reinhard · Jul 22, 2014

tomelex said:
Probably cathode follower with coupling cap output

That means a gain of 1,

Reinhard

DonH50 · Jul 22, 2014

I'd assume one tube with two (internal) sections, thus a gain stage followed by cathode follower buffer.

Tom B. · Jul 22, 2014

Which means a driver stage with substantial voltage swing, but I don't see that in such a small package. Could this simply be a class D amp with tube buffered output stage?

Tom

Reinhard · Jul 22, 2014

Matej Isak said:
Hello Reinhard,

I'm trying to get more detailed info. Will reply as soon as I'll have more.

Matej

Think we have to wait for this,
Reinhard

JackD201 · Jul 22, 2014

I lived with 6c33s for a long time (BAT and Lamm). HOT!

It's got to be a hybrid of sorts.

Tom B. · Jul 23, 2014

DonH50 said:
I'd assume one tube with two (internal) sections, thus a gain stage followed by cathode follower buffer.

Unlike other twin triodes in the same glass envelope, the 6C33C internal structures are connected in parallel, except for the filaments.

Reinhard · Jul 23, 2014

http://www.jogis-roehrenbude.de/Russian/6C33C/6C33C-B-6S33S-VExtendedDatasheetMB.pdf

DonH50 · Jul 23, 2014

Well, that's an interesting design choice. I suppose it makes sense given the tube's stated purpose as a voltage regulator pass device. However, I am still confused; is the 6C33C the "pencil tube" referred to in this thread, or is the pencil tube a second tube (buffer/driver) plus the 6C33C output tube? I guess I was thinking the pencil tube was a small thin ("pencil") tube inside the chassis and the 6C33C was the output tube. My apologies, I misunderstood the context.

Tom B. · Jul 23, 2014

If you look at the photos from the link in post #1, the 'pencil tube' is the tiny glass tube located on the board near the RCA jacks, lying horizontal. Best guess is that it is the driver for the 6C33C, but that's just my assumption. As mentioned they're often used as tube buffers in solid state output stages.

Tom

Matej Isak · Jul 25, 2014

Acuhorn S2 tube power amplifier just arrived few minutes ago. I'm super excited to hear what this OTL contemporary amp will show in terms of performance, but sadly cuirier service did they mighty signature job and left me with the two broken power tubes. Replacement should arrive quickly in meantime few pictures...

http://www.monoandstereo.com/2014/07/acuhorn-s2-tube-power-amplifier-arrived.html

acuhorn_s2_tube_amplifier_new_test_review_matej_isak_mono_and_sterere_14.jpg

acuhorn_s2_tube_amplifier_new_test_review_matej_isak_mono_and_sterere_16.jpg

acuhorn_s2_tube_amplifier_new_test_review_matej_isak_mono_and_sterere_12.jpg

acuhorn_s2_tube_amplifier_new_test_review_matej_isak_mono_and_sterere_08.jpg

Reinhard · Jul 25, 2014

Accuhorn told me that the Output stage tube is working on a resistor.

Reinhard

JackD201 · Jul 25, 2014

Matej, please solve that pencil tube mystery for us

Reinhard · Jul 25, 2014

Acuhorn S2
stereo audiophile power amplifier
tube 6c33, single ended, class A
absolute spitzenklasse röhren klang
Black finish

ready to shipping immediately
shipping worldwide
bank transfer accepted

technical specifications:
input voltage mains autoranging 90-264Vac 47-440Hz
maximum input power 460 W
hi-tech architecture amplifier
output transformerless type
power tubes 6C33C
driver tube Philips JAN 6111WA
recommended connect without preamplifier
21 Stepped Attenuator volume control
output power tube 10W
weight 3,5 kg piece
dimensions W 320 x D 460 x H 26 mm

parts of the structure
power tubes 6C33C one per channel
driver tube Philips JAN 6111WA
Vicor modules DC-DC converters
Murata Y2 capacitors
Nippon chemi-com LXZ KY KMQ 105c
WIMA MKP 4 polypropylene capacitors
Potentiometer 21 resistors
power film resistors Caddock MP930 Kool-Pak®
metal film resistors Dale RN
input and output connectors Rhodium
Arcolectric rocker switches copper-silver
Schurter 10A/250V AC mains input
audio path solid core PCOCC copper

Positive feedback:
Acuhorn S1 Simply superb product…mind-blowing, music is as clear as a crystal…Thanks
Acuhorn S2 fast delivery, very nice amp, perfect

Award Statement High Fidelity Best Amplifier 2010
mono3.5 That is an ingenious gear that ought to be in every recording studio, in every audio dealer listening room.

NEW Acuhorn amplifiers 6C33C tube output transformerless

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