6C33C schematic

[contaxchen]

It uses 3 x 6C33C-B delivering 50 W RMS. Probably can be downsized to 2 6C33C-B's.

Well, in case that there is a need for output transformers. We take look at Lamm ML1.1
http://www.lammindustries.com/PICS/M...L11_inside.jpg
I just ordered two plitron 6c33c output transformers and pair of chassis for the amp. I can't change my plan for GraafGM20.
So, here is the circuit I tried to build which I don't where it comes from.
See the attachment.

[contaxchen]

Sorry

[Hesky]

I've heard of the new Plitron push-pull output transformer for the 6C33C tube, Plitron claim OTL-like frequency response and the ability to extract 100watts from a pair of 6C33C tubes!
contaxchen where did you get your pair fromm, cant seem to locate a source

Cheers

[fdegrove]

Hi,

It was a CROFT with ECC81 input and concertina splitter, ECC82 driver and 2x 6AS7 per channel. Not much power, but boy was I impressed by the live feeling i got. The best illusion so far! That's 10 years ago....

He,he...Glad you liked what you heard.
I'm the proud owner of a pair of CROFT OTL Series II. The exact same pair that was used for the Penta Show way back in 1987.
About 110W/8Ohm of muscle per channel using 10 6080s per side so no complaints there.
Have been an OTL afficionado ever since.

Nowadays, anno 2004, if I'd be asked to design an OTL I'd almost certainly go for the 6C33-C valves as I feel it's much easier to control a smaller number of output tubes.

The only OPT coupled amps that ever came close to mimicking the openness of the OTLs IME were the Megaherz designs.
Not surprisingly the HF response of their OPTs goes way up in the hundreds of KHz as well.

BTW, congratulations on your Graaf "clone".

I would very much appreciate it if you could give me some coordinates on your improvements.

Franco,

I'll try to find some time to look into it ASAP.
Unfortunately it may take a little while before I have a little spare time.
Since you want to use the PCBs Ernst designed I'd suggest you build the amp "as shown".
I'll base my suggestions for modifications respecting the PCB layouts so no major surgery will be needed.

Cheers,

[contaxchen]

where did you get your pair fromm, cant seem to locate a source

I got them from Ebay. Usually, you need to order directly from Plitron. The transformer is made like rock! of highest quality I have ever seen. They have posted the test data on their website. The bandwidth is amazing. Take a look.

The advantage of useing two 6c33cs' are obvious. Lesser matching problem and lesser transformer demand.

I am still looking proper toroidal power transformer for my project. I don't want to use two power transformers at the same time. I will use VTL's input and driver stage probably. David Manley use 12at7+12bh7 to push everything. I think I can do that too.
Lamm ML1.1 use 12bh7a for the driver stage. What you guys think? A little more power is better?

[fdegrove]

Hi,

David Manley use 12at7+12bh7 to push everything. I think I can do that too.

VTL has used about anything even remotely close to a 12BH7A since the war in former Yugoslavia_Ei being the only current producer of 12BH7As_ 6350s, 6463s etc.

Lamm ML1.1 use 12bh7a for the driver stage. What you guys think? A little more power is better?

If I read the schematic correctly it says 12B4A which is not the same as a 12BH7A at all.
The 12B4A is an exceptionally good sounding tube but its use depends on what the circuit requires.
It's certainly capable of kicking a pair of 6C33-Cs around, no worries there.

Cheers,

[contaxchen]

One more question:

I want to choke into for the B+, but we all know 6c33c draws a lot of current. For two 6c33cs is Push-Pull circuit, people gives like 1a at 250vac!
Lamm used a little hammond choke to solve the problem. This is really amazing to me.
Any idea?
Lhchen

[contaxchen]

hi,
I almost finish my 6c33c project, but the thing is that my design is poor. The power transformer is right under the output transformer and the power tubes are too close to power tanny too. I am thinking about aborting monoblock design and puting all power transformers inside one chassis. I think power-signal-seperation design is much better in this case.
Also, 6c33c runs too hot. I need to take care of safty.

[contaxchen]

inside the chassis

[gsmok]

Hi
Here you can find the description of VERY simple 6S33S SE amplifier (only two tubes per channel). Text is in polish but schematic diagrams and photos say everything:
6S33S SE amplifier