6L6 Circuit

[JJH0906]

Yes, you pointed out if you things that you believe were incorrect. You made it sound if those were edited correctly, possibly the circuit would be viable?

If there's a better solution, I'm completely open to learning about it. This was just another reference source I was trying to use, which seems to steer me in the wrong direction each time I do that!

[sluckey]

Put that book under the bed and look at some real schematics.

These use a fixed biased cathodyne PI...
https://el34world.com/charts/Schematics ... eg_g15.pdf
https://el34world.com/charts/Schematics ... eg_g20.pdf

These use a bootstrapped biased cathodyne PI...
https://el34world.com/charts/Schematics ... d_5f10.pdf
https://el34world.com/charts/Schematics ... _schem.pdf
https://el34world.com/charts/Schematics ... ne1482.pdf

These use a direct coupled cathodyne PI...
https://el34world.com/charts/Schematics ... _200s2.pdf
http://sluckeyamps.com/rocky/rocky.pdf

There are 1000s of amps that use these versions of cathodyne PIs. But not a single one that uses EJs circuit because it is wrong.

[JJH0906]

Ha ha ha! Tha ks! I haven't been that impressed with the book so yeah, it may end up as shim for my wobbly table.

Thanks for all the info, I will be digesting that for awhile.

[bepone]

There are 1000s of amps that use these versions of cathodyne PIs. But not a single one that uses EJs circuit because it is wrong.

there are mistakes in the books. so just omit first coupling cap, and schematic will be direct coupled (resistor to the gnd let say is 1Mohm) and schematic will be ok

[Stevem]

This is not a schematic for a class AB amp that would need a phase splitter / gain stage to drive each tube, this is a parallel signal ended output stage so that one section of the 12AX7 before the output tubes is just there to drive them.
With this 6L6GC type parallel output stage the most RMS wattage your going to have is about 22.

Also if you look at the output voltage noted on the schematic, it’s 7.9 volts A/C across a 8 ohm load. That’s 7.8 watts RMS. Not very efficient.

The wattage I posted is the max that could be made while still in class A with two outputs, not what that amp he is referencing would make.

[sluckey]

there are mistakes in the books. so just omit first coupling cap, and schematic will be direct coupled (resistor to the gnd let say is 1Mohm) and schematic will be ok

While that may sound OK, in practice I have never seen a direct coupled cathodyne or cathode follower that used a grid to ground resistor. What would be the point? IMO better to just omit the cap AND the grid resistor. But, in this particular schematic, the input comes from a reverb circuit that we can't see, so direct coupling may not be an option.

[bepone]

there are mistakes in the books. so just omit first coupling cap, and schematic will be direct coupled (resistor to the gnd let say is 1Mohm) and schematic will be ok

While that may sound OK, in practice I have never seen a direct coupled cathodyne or cathode follower that used a grid to ground resistor. What would be the point? IMO better to just omit the cap AND the grid resistor. But, in this particular schematic, the input comes from a reverb circuit that we can't see, so direct coupling may not be an option.

actually i was using that, direct coupled cathodyne with some load in front. before was srpp circuit and with some feedback to the first stage i was getting oscillations after the cathodyne, and loading srpp with 1 Mohm, was the cure.

[JJH0906]

Merlin's website actually has a push pull configuration.

Perhaps this would be more pleasing to the members of the forum?

http://www.valvewizard.co.uk/pp.html

[JJH0906]

Thanks to several suggestions provided by members, attached are some updated power supply/output stage schematics.

Just a few notes:

* The nodal RC circuit on the power supply isn't complete, still trying to figure out necessary voltages and the needed RC network to achieve those results.
* The Output State drawing has a few references to other drawings not included. In particular there is a reference FROM LINE OUT stage, which is referenced to a drawing for an intended Line
Out but the signal is actually from the Reverb Section, it just happens to be on the Line Out page.
* The Output Transformer is still being worked on, I believe it will be rated at 50W with a 3k-4k input impedance.

Any thoughts or input would be appreciated!

[bepone]

what is the goal here? trying to redraw schematic from the books? redraw still not ok

[JJH0906]

You might recall from my earlier post that I'm not trying to build a kit, or necessarily go grab a Marshall JCM circuit off the internet and just rebuild that. The intent is to build my own amplifier, voicd The way that I would like. It is a compilation of multiple circuits from different sources that I think fit what I'm trying to look for.

So the intent of redrawing circuits is to be able to put it all into a single drawing, eventually, of the entire circuit of this amp build.

[Colossal]

The two phase inverter output coupling caps in your schematic marked C? and 10pF...they should not be picofarad. Should be 10nF, nanofarad.

[bepone]

@JJH
to me it looks that you are jumping the steps which can lead to loosing time, dissapointment in tube circuits (instead of very amusing thing).
you need at least 5-10 builds to understand some circuit basics and interaction, about the layout, positioning the parts..grounding..overdrive which is very sensitive.

if you are novice, it is better to build some standard PP amplifier like fender priceton , to run it (allready a lot of skills needed for this) learn from it, and go on the modification, learn again, modify again etc. this proces mentioned is allready one year in average. take another amplifier, do the same. another half year. you are spending 1-2 years to gain skills needed. ok. but you will have some results..

if you go by own flow.. then you will waste your resources without good results.. and you'll ask a lot of questions and you will depend of the other people's will and free time to pull you from it, usually nobody will do this on long term. thats why step by step, part by part, build fast 5 amps.. and you will get it, pass the basics and then you can start with the own designs.

[JJH0906]

Thanks for correcting that error, probably a copy and paste thing.

[JJH0906]

@JJH
to me it looks that you are jumping the steps which can lead to loosing time, dissapointment in tube circuits (instead of very amusing thing).
you need at least 5-10 builds to understand some circuit basics and interaction, about the layout, positioning the parts..grounding..overdrive which is very sensitive.

if you are novice, it is better to build some standard PP amplifier like fender priceton , to run it (allready a lot of skills needed for this) learn from it, and go on the modification, learn again, modify again etc. this proces mentioned is allready one year in average. take another amplifier, do the same. another half year. you are spending 1-2 years to gain skills needed. ok. but you will have some results..

if you go by own flow.. then you will waste your resources without good results.. and you'll ask a lot of questions and you will depend of the other people's will and free time to pull you from it, usually nobody will do this on long term. thats why step by step, part by part, build fast 5 amps.. and you will get it, pass the basics and then you can start with the own designs.

Thanks for this advice in talking me off the ledge a bit. I do realize I have bitten off quite a bit. Despite my background and electricity and electronics, this is all very new to me and I'm certainly running into a lot of roadblocks.

The good news is I have tons of parts that I have already ordered, so I can go ahead and build something simple with that, haha!