schematic - need expert advise

[sparchead]

Hi everybody!

looking at this schematic, aside from the missing isolation transformer, do you see something wrong?



Thank you

[Jack Hester]

Compare it with these:

http://www.el34world.com/charts/Sche...mony_h303b.pdf

http://www.el34world.com/charts/Sche...rmony_h400.pdf

Basically, the same configuration as yours.

Jack

[sparchead]

Compare it with these:

http://www.el34world.com/charts/Sche...mony_h303b.pdf

http://www.el34world.com/charts/Sche...rmony_h400.pdf

Basically, the same configuration as yours.

Jack

Hi Jack, thanks for the reply!

I know that all of those amps loaded with 50C5/35W4 tubes are very similar... I looked at some of those before drawing my schematic.

My concern is more about the "floating ground" Ive created, here is the original schematic I started with:



The new floating ground I did is highlighted in yellow, is it correctly wired?



I also replaced the 12AT6 tubes with 12AV6 (not 12AU6), is the pinout correct? plate/cathode resistors/capacitor are OK?

Finally, I moved the tone control before the volume pot and replace it with a 470K resistor (highlight in blue), is it correct like this?

Sorry for all those questions, this is my first amp project =)

[J M Fahey]

As is, it's wrong.
Please redraw including the isolation transformer and then we have something solid to talk about.
I see you are trying to modernize it , using typical Marshall/Fender values.
It won't work that way.
But for further discussion, please post the final version.
Thanks.

[Bruce / Mission Amps]

As is, it's wrong.
Please redraw including the isolation transformer and then we have something solid to talk about.
I see you are trying to modernize it , using typical Marshall/Fender values.
It won't work that way.
But for further discussion, please post the final version.
Thanks.

Other then the obvious, holding the whole driver and power amp up from ground by a 270,000 ohm resistor, a series 109vac filament string at 122vac or so, a 120vac to B+ rail, needs another filter node for the two 12AV6s... and no isolation tranny, what do you see that is: "as is, it's wrong" ?

[sparchead]

As is, it's wrong.
Please redraw including the isolation transformer and then we have something solid to talk about.
I see you are trying to modernize it , using typical Marshall/Fender values.
It won't work that way.
But for further discussion, please post the final version.
Thanks.

this amp is gonna be pluged into an external isolation transformer, like all my other AC/DC amps. If someday I wish to sell the amp, for sure im gonna put an internal one...

why you said "It won't work that way", can you explain more?

thanks

[sparchead]

Other then the obvious, holding the whole driver and power amp up from ground by a 270,000 ohm resistor, a series 109vac filament string at 122vac or so, a 120vac to B+ rail, needs another filter node for the two 12AV6s... and no isolation tranny, what do you see that is: "as is, it's wrong" ?

okay so the floating ground wiring is correct?

"needs another filter node for the two 12AV6s" can you explain more =)

[sparchead]

Here is the schematic Ive started with:



and here (Highlighted in yellow) is the new floating ground:



the blue highlights are the tone control I moved in front of the volume pot...

[J M Fahey]

Dear sparchead.
As is, besides parts value errors and connections, that amp is a killer machine, as was the original one.
Nobody will suggest you anything tonewise before you clearly show the separation transformer, properly connected, because doing so means taking responsability on what may happen, being part of your project.
And the isolation transformer *must* be internal, inseparable from the amp, period.
What you say,

If someday I wish to sell the amp, for sure im gonna put an internal one...

means you are *NOT* putting a fixed one inside now, which means the amp *CAN* be plugged straight into a wall plug, if somebody wishes to do so.
Well, that's a definite no no.
All this said with the best of intentions towards you.

[sparchead]

Dear sparchead.
As is, besides parts value errors and connections, that amp is a killer machine, as was the original one.
Nobody will suggest you anything tonewise before you clearly show the separation transformer, properly connected, because doing so means taking responsability on what may happen, being part of your project.
And the isolation transformer *must* be internal, inseparable from the amp, period.
What you say, means you are *NOT* putting a fixed one inside now, which means the amp *CAN* be plugged straight into a wall plug, if somebody wishes to do so.
Well, that's a definite no no.
All this said with the best of intentions towards you.

Hi Mr. Fahey =)

First, thanks for the best of intentions towards me, but nobody can plug my AC/DC amps directly in the wall, since I use, on all of them, a special plug that doen't fit in a standard 120V outlet, but only into my big 1000VA isolation transformer.

Now if you wanna talk about something other than iso transformer, Im gonna listen to you, otherwise I will ignore you. If you don't want to participate on this post, in worry of taking responsability, Im a little bit amazed, but I understand. You are a free man!

And please, don't put words in other people mouths, you have you opinion and don't pretend to know other people opinions, I think you are missing some point here, better letting other people express themselves.

I really appreciate that you care about other people security, but obviously, this is not the point here.

thank you

[J M Fahey]

Well, maybe safety *is* a point, after all.
Good luck with your project.

[sparchead]

Well, maybe safety *is* a point, after all.
Good luck with your project.

not yet a project, still in learning.. luck is not what Im looking for here on music-electronic forum =)

yes security is "a" point, and not the last.. I really care about it, but don't you think it is more dangerous if nobody answer to my questions

thanks anyway

[sparchead]

by the way, here's the schematic I was inspired from for drawing the new "line ground"

I actually own this amp, which has a killer sound =) an old 60's Canadian amp