Help with a vibe amp design

[mhajish]

Hello, I've been looking for some help in designing an instrument amplifier. Due to my limited experience with tubes (not with solid state circuits) I figured it would be best to get some second opinoins. I have done the math for the cascode and phase splitter and would like someone with experience to tell me if I'm going to blow up some perfectly good tubes if I power this succer up. Also I would like some help with power stage design. I'll post pics of the schematic in the morning.

 

[mhajish]

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

The schematic

The tubes are two x 6dj8 and four x 6c33c

I do not know much about power stages so if someone could link me to
Information on how to calculate the bias resistors that would be immensley helpful.

An externally hosted image should be here but it was not working when we last tested it.

 

[boobtube]

Do you have any data on the 6c33c tube? I can't find it in the RCA tube manual or at Duncan Amps Tube data base which is one of the most complete that I know of.

 

[mhajish]

Data

http://www.jogis-roehrenbude.de/Rus...myZpKQ&usg=AFQjCNErk7JeE67GtpUen4U92-wkltqvaw This is the one i've ben using, but there are others if you're willing to scroll through tons of Google pages.

 

[boobtube]

Sorry, I just get the dreaded "404 page not found" at that link.

 

[mhajish]

I'll convert and the pdf to jpeg and post later. In other news im considering using two 6c33c's as ac coupled cathode followers. Thoughts?

 

[boobtube]

Also, your schematic and layout won't load. I'm afraid without that I can not help.
I found several threads about this tube elsewhere on this site. Go to the homepage and in the upper right corner is the search link. Just type in "6c33c tube". You should get several hits. Good luck!

 

[mhajish]

I'm giving up on mobile
here is the schemo and the tube data

 

[okcrum]

I'm giving up on mobile
here is the schemo and the tube data

Yes, it's still hard to get actual work done that way. 🙁

 

[okcrum]

The topology looks OK, but the schematic is hard to read. You should get LTSpice; there's an excellent sticky here - someone likely already has a model for the 6c33c. Some of the plate resistors look 10x too small but if you are within the cathode current limits on the tubes, it is not necessarily bad. AFAICS the 6c33c is functionally similar to a 6080, in a more interesting shape.

 

[boobtube]

Here's a link to a LTP phase inverter design using a 12ay7 which is somewhat similar to the ECC88/6DJ8. This guy really knows his stuff. I have his book on preamp design which I HIGHLY recommend. I agree with okcrum on the values of the resistors. I have never seen a design with these small values for all resistors for a long tailed pair.
The Valve Wizard -Long Tail Pair

 

[mhajish]

I've been using his site, it has been increadibly helpful. Since they are estimations I made on a bus ride I don't doubt I left off a decimal somewhere. I've also shanged the output stage around a little with using two of the 6c33c's as dc cathode followers going into the push pull stage with pots for distortion control.