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Tube circuit

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ELS122:
I've studied a bit of negative feedback loops and came up whit this circuit. also added 'presence' control

ELS122:
Is this a capacitor?? In the schematic this is labelled as a cap

001:

--- Quote from: ELS122 on September 07, 2019, 05:53:32 pm ---Russian logic sometimes can't be explained. for example, this radio has 2x8inch speakers and 1 2x4inch one but it has only 1 6p14p tube. I think they were really optimistic about the power output of this circuit!

--- End quote ---

Oh boy
It is not for power reason  :-DD
In my childhood it was a sort of "surrounding" for "premium" audio

ELS122:

--- Quote from: T3sl4co1l on September 07, 2019, 11:11:08 pm ---Short out the 150p, and there should be a, 470k or so from right grid to GND.  Otherwise yep, that's it. :)

Note that without feedback, it will have quite a bit of distortion at full output.  Gain may be pretty high as well.  Better perhaps for a guitar amp than general audio, but you'll figure things out as you use it I suppose.


--- Quote from: ELS122 on September 07, 2019, 05:53:32 pm ---Russian logic sometimes can't be explained. for example, this radio has 2x8inch speakers and 1 2x4inch one but it has only 1 6p14p tube. I think they were really optimistic about the power output of this circuit!

--- End quote ---



Yuo see Ivan, more speakers make moar sound, puny valve into make big!

Tim

--- End quote ---

Ummm. I think my mind wasn’t working right when I made that comment, now it’s obvious why there is loads of speakers...

floobydust:

--- Quote from: ELS122 on September 08, 2019, 01:02:09 pm ---Is this a capacitor?? In the schematic this is labelled as a cap

--- End quote ---

Yes, looks like 150pF +/-10% tubular capacitor

You can also add a potentiometer between the two 6N2 stages, if you want to overdrive the input tube for some crunch. That would look like a 250-500k pot where you have the 300k at pin 7, wiper goes to pin 7. Most amplifiers bypass the 2k cathode resistor on the input tube to keep gain high.

Older amps used several high efficiency, low power loudspeakers as an alternative to the cost of a higher power amplifier, to get the same SPL. If you play a gig in a big room, you will see it works just as well.

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