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Author Topic: want to change amp from 6v6 to el84, having to simplify  (Read 4433 times)

sgmypod

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want to change amp from 6v6 to el84, having to simplify
« on: May 09, 2012, 11:07:45 PM »
aimed at amp blokes, would like valve, bases etc everything to do, is it possible obviously will have 6v6  or el84 in but have the two valve bases permanently connected. have provided schematic and drawing
« Last Edit: June 03, 2012, 12:03:12 PM by sgmypod »
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jpfamps

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We built a single ended amp with switchable EL84/ 6V6.

I think we used a DPDT switch to simultaneously lift the cathode on the unused valve and switch the filament supply off. This was with both valves connected to the OT.

By doing this we avoided having the unused valve on and wearing out, and avoided any switching of high voltages.

I could probably generate a schematic.

sgmypod

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cool how much schematic and parts
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jpfamps

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I've composed a schematic and will try to remember to bring it into the workshop where I have internet access.


HTH AMPS

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It'd be cheaper to buy an Epi Valve Junior, strip out the guts and wire it PTP.

The Harley Benton ones are the same, but slightly cheaper.


sgmypod

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Would have thought that would be more, would'nt I need to buy new trannies for them
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jpfamps

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Here's the schematic.

The resistors marked in blue probably aren't needed, and I wouldn't include them.

I've not included the screen grid circuit and guestimated the cathode resistor values etc.


sgmypod

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Thanks frank, could you supply bits
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sgmypod

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frank i have run out of, space and skill. so am going to just swap out 6v6 for the el84 (obviously swapping pins)
so with bits you sent  need swapping on the original schematic 
6v6 C9 22uf 25v  (el84 100uf)
6v6 R9 470R 2w  (el84 150ohm)
6v6 R8 10k           (el84 1k)
6v6 R10 470r       (el84 10k)

am i correct or miles out (as say will connect pins correctly on top of this)
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sgmypod

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Re: want to change amp from 6v6 to el84, having to simplify
« Reply #9 on: June 06, 2012, 12:14:04 PM »
Was slightly out, thanks frank
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