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Anish

6C3CC tube driven SET amplifiers

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Hi fellow members,

 

I'm looking for some information regarding the 6C3CC driven SET power amplifiers.

 

1. Are there any 6C3CC tube driven SET power amplifiers available in the Australian market today?

2. How do they compare to the more common 300B and 2A3 tube based SET amplifiers?

 

Thanks,

Anish

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Christian Feiffafe, master who re-does Quad57's and is one of Australia,s best at it, who taught Otto Major all he knew.

Also makes big paralleled 6C33C  single ended amps, even winds his own transformers

 They aren't  as euphonic (coloured) as 300b and 2a3, with far better control and bass impact. 

 

Send me a PM and I'll give you his ph. no. He's in Sydney (Roseville) 

 

Cheers George

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The Almarro  A 318 B is a fine example of the use of the Russian 6C33C power triode in a stereo SET amplifier. The price, availability and long working life of that valve is in its' favour ,especially in comparison to  the 300B valve  replicas. Knowing the output  power requirements of your speaker and your listening tastes play a large part of choosing an amplifier to meet your requirements.

 

                                     

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The Almarro  A 318 B is a fine example of the use of the Russian 6C33C power triode in a stereo SET amplifier. The price, availability and long working life of that valve is in its' favour ,especially in comparison to  the 300B valve  replicas. Knowing the output  power requirements of your speaker and your listening tastes play a large part of choosing an amplifier to meet your requirements.
 
                                     

Thanks VanArn. I saw that amp when I did a google search earlier, but passed it since it was an integrated amp, and I’m looking specifically for a power amp.

My speakers are made by Zu Audio with 97dB sensitivity and over 10 ohm impedance.

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Posted (edited)

Not sure what your price range is, but amplifiers using the 6C33C tube are quite rare and can be expensive.

 

The Almarro 318B from Japan is a very nice sounding valve amp, have heard it on a few occasions and it is very clear and explicit, but still has a nice tone to it. Not your typical mushy sounding valve amp and it punches quite well too. I owned a pair of Supratek Merlot SET monoblocs using the 6C33CB tube, super excellent and the best amplifier I have had in my system. Low power output of 10w/ch made them mainly usable with efficient speakers and reasonably expensive too at $9K, but you get a lot of construction for your money. Mick Maloney might still build the Merlot amps for you if you can twist his arm via email or in conversation at the Supratek website?

 

Other than that the only other 6C33C valve amps of repute that I am aware of, are Lamm and VAC in the USA, big bucks though starting at $20K+.

 

Btw, the sound of the 6C33C valve is worth pursuing, imho. It is a valve that seems to have high levels of accuracy and clarity aligned with the niceness that we have come to associate with the sound of valve circuits.

 

Cheers,

 

Steve.

Supratel Merlot S.E.T Amps3.jpg

Supratel Merlot S.E.T Amps2.jpg

Edited by Steve M

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I own a pair of these Ancient Audio Monoblocks.  A fantastic amplifier and generally  always prefer it to my 300B amps.

Image27.jpg

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That's a very nice pair of 6C33C valve amps you have there, Balk. :thumb:

 

Steve

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Weston Acoustics used to make 6C33C monoblocks called Tetons.  According to this FS ad from 2014,

 only one pair appear to have been sold and the Tetons are no longer available, but Earle might build you a pair if you were keen.

 

I understand the 6C33C valve is very ballsy and has excellent bass, but is hard to implement well and can fall out of bias regularly, which may account for the few amps that use it.

 

As far as a comparison between the 6C33C, 300B and 2A3 is concerned, I can offer an opinion on the latter two only.   I prefer the 2A3, as it is more neutral IMHO and has better bass, whereas I have always found the 300B to be a little syrupy and glamorous for my taste, although initially very impressive.  But of course the 2A3 has only half the output of the 300B.

 

Another valve you might want to consider is the 6AS7.  This was apparently the last triode developed in the West and puts out about 6 Watts.  There are a few amps using this as well.  I had an Icon Audio 6AS7 integrated that put out about 30Wpc using two 6AS7s a side in push-pull mode.  

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Posted (edited)
1 hour ago, balk2117 said:

 

Image27.jpg

 

1 hour ago, Steve M said:

 

Supratel Merlot S.E.T Amps3.jpg

Supratel Merlot S.E.T Amps2.jpg

Just look at all the valves being used in the Supratek Merlot SET amps ...you will never see anything like it, I reckon. The brainchild of Mick Maloney's eclectic and evolved mind.

 

From memory, there was one Russian 6C33C-B driving the other 6C33C-B valve, only one output valve used to maintain purity of sound. The other valves are drivers, Mullard GZ37 rectifer, a pair of OA-5 Regulator tubes that lit up the skyline bright as a nuclear reactor and reflected off the chrome transformer covers for visual effect and some interstage 6SN7+6SL7 valves. The amps worked flawlessly too in the 3-4yrs that I owned them. Sounded amazingly clear, transparent, tonally perfect ...liquid sounding. Should never have sold them, other than more than 10w/ch was needed at the time. :( 

 

Steve.

Edited by Steve M

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They look fantastic Steve and I'm sure they sound great.

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It’s interesting to see that everything I read about this tube talks greatly about its performance in a single ended amp, but there are very few amplifiers are out there using it.

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@VanArn I second your thoughts 

I suspect we might have listened to the same s people.

 

if ancient memory serves me the original Almaro amp used El84 valves

hsppy to be corrected here.

 

tbe highly inflated price of 300B valves makes "new" valve types essential 

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Posted (edited)

The 6C33C is perhaps a more accurate tube with the appropriate circuit and under ideal load conditions. Though perhaps less of the beautiful character that the 300B valve is famous for, or I could be completely wrong? The valve amp gurus will need to comment on this ...

Edited by Steve M

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Ok I dont come here too often, mostly because there are too many damn gurus here, but I can share what I do know about the 6C33C-B having used it for at least 20 years. 

Its a great tube, mostly because of its low plate resistance , much lower than a 300B , which means it needs a less complex output transformer and is capable of low output impedance, which gives it more oomph and results in a more linear frequency response into a speaker load. So it doesn't have the excessive midband accentuation common to non feedback 300B designs.

This results in a clean , reasonably accurate sound not typical of your usual SET design.  It can be undone by a less than capable driver stage as it does take a bit of power to drive it properly.

The 300B actually makes a great driver stage for it.  With a good driver stage it can put out a meaty 18 watts SE , quite a bit more than the 300B's 8 watts. 

Negatives- its hard to get matched pairs , they vary quite a bit from tube to tube, and consistency isn't great. They get bloody hot .

They're hard to keep in bias, however a mixture of fixed and auto bias seems to tame that problem.

I dont believe they're being made anymore, although I could be wrong.

Plitron made some awesome output and interstage transformers for them years ago that could be used to make  an extraordinary, and expensive SE amp, unfortunately no longer available , wish I still had some of them.

Sowter make a good set of push pull outputs - built a 6C33C-B amp using them that made a great amp, and room heater. 

 

All in all, a damn good tube that does require some dedication to get the best out of it. The 300B is a lot friendlier in use , although its "romantic" sound when used full range can be polarising, which is subjective of course. 

 

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I have DIY'd the Melquiades SET that uses the 6C33C as power and 6E5P as driver.  It has a complicated bias arrangement with a pair of gas voltage regulator tubes to eliminate the input coupling cap but as far as sound goes I've not heard anything better.  It is truely wonderful, and for me it has made most other amplifiers sound broken.  As @statmansays above the 6C33C has a low plate resistance and the amplifier can have a very low output impedance, which is important for driving commercial speakers.

 

You need speakers in excess of about 100dB sensitivity and with a benign impedance load to get the best out of SET amps.  Your speakers are close with 97dB/w/m but I do not know what the impedance graph looks like.

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This is the impedance graph the company provides in the spec sheet.

Zu Audio Impedance.png

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I've seen the Melquiades circuit, looks quite interesting. 

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There are 3 impedance peaks of 40-50R, so not exactly flat, but also the graph bottoms out at 8R or so which is way better than some speakers.  Of any single ended valve amp the 6c33c is probably technically the best you could get to drive those speakers because of the potential for low output impedance.  Higher amplifier output impedance will translate those speaker impedance peaks into extra SPL which is probably not what you want.  However, given the relatively high impedance load of the speaker you will probably get a good result with the 6c33c.

 

 

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9 minutes ago, statman said:

I've seen the Melquiades circuit, looks quite interesting. 

 

Yeah, it is different.  Apart from the unusual way the fixed bias is provided, it is against "convention" in that it uses big electrolytic caps in the power supplies.  The only film is at the interstate coupling cap.

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Yeah well the designer isnt exactly "conventional" either! 

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On 3/8/2018 at 1:54 PM, Anish said:

Hi fellow members,

 

I'm looking for some information regarding the 6C3CC driven SET power amplifiers.

 

1. Are there any 6C3CC tube driven SET power amplifiers available in the Australian market today?

2. How do they compare to the more common 300B and 2A3 tube based SET amplifiers?

 

Thanks,

Anish

On 3/8/2018 at 6:50 PM, Steve M said:

Not sure what your price range is, but amplifiers using the 6C33C tube are quite rare and can be expensive.

 

The Almarro 318B from Japan is a very nice sounding valve amp, have heard it on a few occasions and it is very clear and explicit, but still has a nice tone to it. Not your typical mushy sounding valve amp and it punches quite well too. I owned a pair of Supratek Merlot SET monoblocs using the 6C33CB tube, super excellent and the best amplifier I have had in my system. Low power output of 10w/ch made them mainly usable with efficient speakers and reasonably expensive too at $9K, but you get a lot of construction for your money. Mick Maloney might still build the Merlot amps for you if you can twist his arm via email or in conversation at the Supratek website?

 

Other than that the only other 6C33C valve amps of repute that I am aware of, are Lamm and VAC in the USA, big bucks though starting at $20K+.

 

Btw, the sound of the 6C33C valve is worth pursuing, imho. It is a valve that seems to have high levels of accuracy and clarity aligned with the niceness that we have come to associate with the sound of valve circuits.

 

Cheers,

 

Steve.

Those Merlot amps look sweet.

 

I recently had a pair of Lamm 2.1 monoblocks come through for service.  Built like trucks inside and out.  

 

WRT 6C33C - a great tube for SET..  and you can get some decent power without  requiring crazy HT voltages. 

I measured the Lamms at over 20  watts / channel.  They use an interesting arrangement where 1 of the 6C33C is used as a series regulator.

 

As already stated a/ they require a decent driver b/ they are all over the place WRT matching c/ The biasing can also be tricky     

 

However don't let any of that discourage you - go for it.     

 

T

Lamm ML21.jpg

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Does anyone know of a 6C33C SET amp kit available anywhere? Even that seems rare, compared to other tube based SET and push-pull amps.

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