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Hoffman Amps Forum image Author Topic: 12AX7's enhance cap question  (Read 3285 times)

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Offline bluesbear

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12AX7's enhance cap question
« on: January 07, 2012, 03:25:46 pm »
I want to make sure I'm getting this correctly. I've drawn what I think it is onto a 5E3 layout. Is this what you had in mind?
Thanks,
Dave

Offline tubenit

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Re: 12AX7's enhance cap question
« Reply #1 on: January 07, 2012, 03:38:26 pm »
As I understand that version of the enhance cap, it is after the coupling caps and prior to the 220k resistors to ground.

With respect, Tubenit

Offline 12AX7

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Re: 12AX7's enhance cap question
« Reply #2 on: January 07, 2012, 03:52:14 pm »
Yep. Basically the difference between this and a cap across the PI plates is this is across the power tube grids, or in other words AFTER the coupling caps coming off the PI plates. Or in the simplest of explanations, it's the typical vox cut without the pot and with a smaller cap than typically used for a cut control.

Offline bluesbear

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Re: 12AX7's enhance cap question
« Reply #3 on: January 07, 2012, 08:56:33 pm »
tubenit,
Isn't what I've drawn exactly what you've drawn? It looks like it to me.
Thanks,
Dave

Offline tubenit

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Re: 12AX7's enhance cap question
« Reply #4 on: January 07, 2012, 09:31:45 pm »
Quote
Isn't what I've drawn exactly what you've drawn? It looks like it to me.

Yes, that is correct. I was simply putting into a schematic format as a reference for the other forum guys looking at your layout.

With respect, Tubenit

Offline bluesbear

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Re: 12AX7's enhance cap question
« Reply #5 on: January 07, 2012, 10:30:03 pm »
Great; I just wanted to be sure. This looks like one I want to try out. I just bought and cut the wood for the cabinet yesterday and I'll start putting it all together tomorrow. It's easier for me to mark and drill the chassis mounting holes in the cabinet with the chassis bare. So... my cathode biased Deluxe power with SF voltages to the PI and preamp, a power tube only VVR and a footswitched relay operated hot switch will be forthcoming. This is all my different design experiments I've liked rolled into one. Should be fun!
Thanks,
Dave

Offline tubenit

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Re: 12AX7's enhance cap question
« Reply #6 on: January 08, 2012, 09:08:41 am »
IF you have not already added the 166pf cap there,  you can experiment with clip wires (carefully) and try it across the 56k phase invertor plate resistor also to see which position you like the tone of best?

PLEASE share the results of your final amp build.  I am very interested in hearing how this turns out.

With respect, Tubenit

 


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