Newbie wants to build SET 6C33C

[azazello]

I'd like advise You use mixed bias - 100 ohm resistor plus -Ufixed, and current about 260-270 ma per tube.

 

[FullRangeMan]

Iam not expert but hi bias value seems unnecessary IMO, as he just want 12W per channel.

I wonder if this low power(10 to 12W) may be achieved with self-adjusting Bias??
Thanks

 

[tubetvr]

A classical operating point is 200V at 220mA with 600 ohm load, this gives 13 W. Same operating point was used by Dakesue who was the first who discovered this tube in Japan and imported it as EC33C. See here for one of his circuit diagrams http://www.tubetvr.com/se.html

 

[azazello]

I tried mode 170-180v - plate-cathode, with currents from 200 to 270 ma and sound start from dry to sensitivity better and deep with giant bass, with load 1,2 kohm, 25 sq. cm iron.
200v and small current gave me little burned and pressed sound....IMO.

 

[FullRangeMan]

A classical operating point is 200V at 220mA with 600 ohm load, this gives 13 W. Same operating point was used by Dakesue who was the first who discovered this tube in Japan and imported it as EC33C. See here for one of his circuit diagrams Single ended amp with 6C33C

Thanks pal, very interesting project with 12AX7 gain

 

[jfbaquero]

Thanks everybody for the great feedback, I have learned a lot of things in just a few days. Today I read a triode tutorial for dummies by Lampizator and finally understand a lot of stuff that wasn't clear. I learned of the existence of ARG amps from Ukraine, etc...

ErikdeBest and FullRangeMan thx for the all the information, it has been of great value.

I think I will go for a driver with 6N6P tube (6N1P not discarded yet, the 6N1P is form the family of the ECC 88CC or 6DJ8). Question, can I get a 6N6P swing 100 V PP? I have read a lot of criticism about using auto bias with the 6C88C but it seems safer than using fix one, I have no decision yet about this issue.

Thanks Tubetvr for the drawing used by Dakesue, 200V @ 220 mA with 600 ohm load this operating point seems great. No answer yet from SAC Thailand.

 

[esltransformer]

I used my 6c33 for many years to drive my homemade esl.
I preferred fixed bias (NOT a regulated fixed bias!) and I used a E55L in triode for driving the 6c33. I use a interstage for the E55L.

Because I used a electrostatic speaker I made a transformer with a direct output for my esl.
Now I have plans to use my old 6c33 to drive a normal speaker and like to design a new transformer for it.
I think a 800 Ohm would be a little better then 600 Ohm. If people are interested I can build some more opt.

 

[FullRangeMan]

I used my 6c33 for many years to drive my homemade esl.
I preferred fixed bias (NOT a regulated fixed bias!) and I used a E55L in triode for driving the 6c33. I use a interstage for the E55L.

Because I used a electrostatic speaker I made a transformer with a direct output for my esl.
Now I have plans to use my old 6c33 to drive a normal speaker and like to design a new transformer for it.
I think a 800 Ohm would be a little better then 600 Ohm. If people are interested I can build some more opt.

Nice, one more option.
Do you has any link to we seeing info or photos??

 

[esltransformer]

If it's ready i will post

Nice, one more option.
Do you has any link to we seeing info or photos??

 

[FullRangeMan]

No answer yet from SAC Thailand.

SAC-Thailand seems to be in vacancy: We will close from April 13 to June 3, 2013
SACThailand

 

[jfbaquero]

Oh S*** FullrangeMan, I miss the vacation information from SAC. For now I spotted the Lundahl LL1627 for OPT at 260 USD each, this transformers might fit the bill. The Lundahl LL1651 might work as a PT, this one is 205 USD all from K&K audio in the US. I am not sure if the LL1651 is right for the job, any insights about this are welcome.

I have been toying with Tube CAD and SECAD Amp CAD but the tubes I want to use (6N6P, 6N1P and 6N2P) are not included in the list. Does anyone have list of specs that must be enter in Tube CAD for this tubes (mu, gm, rp, Imax, Vmax, Ggp)?

Same goes for the LL1627 transformer, I have the data sheet, but I am not really sure what is what. I want to get 13 watts @ 8 ohms from the amp. (Impendance, Turns Ratio, Inductance, Eficency, Wattage, Max I, Prim DCR, Sec DCR)?

Is RUTubes.com a good resource to buy russian tubes?

 

[FullRangeMan]

You may collect data on some datasheets:
electron Tube Data sheets - Search

Iam neewbe in Lundahl OPTs, but its informative site seems agree:
Lundahl Transformers - Tube Amplification Output Transformers
But I would prefer secondary 6 ohms, not 4 or 8.

Never bought at RUtubes, GS-Tubes service is very good.

 

[FullRangeMan]

If it help, the SAC-Thailand price informed on the site are:
9500 Bats = us$ 321 for the 20W S-6-6C33F model (low inductance and 150kHz response)

14,500 Bats= us$490 for the 30W S-1000A model

According the today dolar rate.

 

[jfbaquero]

Hi FullRangeMan, thanks for the information! The prices for the transformers from SAC are OK, not cheap, but they might fit the bill. The problem is how much would shipping to Bogota, Colombia will cost. You told me you live in Brazil and that you where asked like 600 USD just for the shipping, that would simply be to much. I have no rush with this project, I can wait till june (when SAC is back from vacation) in the mean while I will keep learning, reading M. Jones and trying to get a design out of SE Amp CAD and Tube CAD.

 

[FullRangeMan]

It was around $600 for two big GM70 OPTs, that are heavier than this your S-6-6C33F 20W model, which I feel is better than the 30W model S-1000A IMO.

This price are Fedex, the regular air mail is much more cheaper.

 

[jfbaquero]

Hi FRM, 600 USD is a lot of money for just the shipment, but if they do ship by regular mail there might be a great difference, I am not in a rush, but I am tempted to start the project with the Lundahls. This weekend I try to start working on the circuits.