unusual tubes to drive a JAN 829B
Now rather than make my first tube amp easy and use someone elses schematic I want to make my life more difficult and design my own. What I want to design is a Single-ended 829B amp by tying the two grids together into one grid and the two anodes into one anode. Making one beam tetrode out of dual.
I have a few questions though.
With the 829B set up like this would Ultra-Linear be an option?
I'd like to drive it with an equally strange looking tube like an acorn or one of those tubes that look like they have horns. I don't know very many tubes off the top of my head so what are some suggestions for odd looking but not ridiculously expensive tubes that I could drive this with?
What are the advantages/disadvantages of parafeed (i was thinking of using it in the design)? I read a few articles and post where people hate it and others where they love it.
Now rather than make my first tube amp easy and use someone elses schematic I want to make my life more difficult and design my own. What I want to design is a Single-ended 829B amp by tying the two grids together into one grid and the two anodes into one anode. Making one beam tetrode out of dual.
I have a few questions though.
With the 829B set up like this would Ultra-Linear be an option?
I'd like to drive it with an equally strange looking tube like an acorn or one of those tubes that look like they have horns. I don't know very many tubes off the top of my head so what are some suggestions for odd looking but not ridiculously expensive tubes that I could drive this with?
What are the advantages/disadvantages of parafeed (i was thinking of using it in the design)? I read a few articles and post where people hate it and others where they love it.
You can do UL with a parallel connected 829B. There is an internal cap between screen and cathode but it doesn't seem to have any effect at audio. Safest to keep the plate voltage under 300 or so, though many (myself included) have gone as high as 400V without problems.
Dual-plate-cap tubes that come to mind are the RK34/2C34/DET20 dual triode, and the 2C22/7193 single triode (basically 1/2 6SN7 with P and G on caps). Also RK60/1641 rectifier, more or less 5R4 with two plate caps.
Pete
Dual-plate-cap tubes that come to mind are the RK34/2C34/DET20 dual triode, and the 2C22/7193 single triode (basically 1/2 6SN7 with P and G on caps). Also RK60/1641 rectifier, more or less 5R4 with two plate caps.
Pete
larc99 said:
Parafeed (parallel feed) connection requires a DC blocking cap between the tube and the transformer. In single-end topology, there is only one connection from the plate to the transformer, thus one cap.
In single-ended ultra-linear topology, the plate and the grid of the tube conect to the transformer; thus, what you're proposing would be a "single-ended, ultra-linear, parafeed topology" with two caps, one at the plate and one at the UL connection.
Here is a link to a SE parafeed 829B amp:
http://829b.com/829B_1.aspx
To connect it as a UL parafeed, remove R9, and place another cap between the grid the the UL tap of the transformer.
I hope this helps,
-- josé k.
Well heres the ultra-rough-probably-screwed-something-up schematic. Yes I know there are no values on anything but I want to know if I set the schematic up properly and I'd like to know what would be suggested as the value of the output transformer. I'm looking for a Hammond one as they seem to be the most bang for the buck.
Also TinyCad doesn't have a dual beam tetrode available for schematics so I used two single beam tetrodes.
Also TinyCad doesn't have a dual beam tetrode available for schematics so I used two single beam tetrodes.
An externally hosted image should be here but it was not working when we last tested it.
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