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Post subject: Re: Packard Bell Model SA-5 Question
Posted: Wed Nov 20, 2013 12:28 pm
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http://www.thevintagesound.com/ffg/schem/champ_aa764_layout.gif

would that be out from pin 1 back in to pin 7?

thanks!!!!


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Post subject: Re: Packard Bell Model SA-5 Question
Posted: Wed Nov 20, 2013 2:59 pm
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Jimitrader,

Yes, signal goes out from pin 1 and into pin 7 of the 12AU7 (whose pinout is the same as the 12AX7). Tone stack placed in between. You may need to remove an existing coupling cap (in the 5F1 circuit Champ --- the 0.02mfd/600VDC cap) & replace it with the stack. See the 5F1 circuit versus the AA764.

http://www.webphix.com/schematic%20heav ... _schem.pdf

http://www.webphix.com/schematic%20heav ... _schem.pdf

Logically, it's easier to trace the signal path and power supply from the schematic. The signal usually flows from left to right. And the power from bottom to upper right side (output tranny). Then, relate this to the physical layout of the circuitry --- which most of the time is nothing like the schematic layout.


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Post subject: Re: Packard Bell Model SA-5 Question
Posted: Wed Nov 20, 2013 3:01 pm
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You can download the Tone Stack calculator from here:

http://www.duncanamps.com/tsc/


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Post subject: Re: Packard Bell Model SA-5 Question
Posted: Wed Nov 20, 2013 10:13 pm
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I TRIED THIS ONE

http://amps.zugster.net/articles/tone-stacks#18Watt

AND IT SEEMS TO WORK AS A VOLUME CONTROL BUT I AM NOT NOTICING ANY TONE CONTROL..IT DOES SOUND A LITTLE LOUDER AND MORE BOTTOM END THOUGH? DO YOU SEE ANY TONE STACKS IN THIS ARTICLE THAT WOULD BE A BETTER FIT? I TRIED the calculator but wasn't sure what to do..


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Post subject: Re: Packard Bell Model SA-5 Question
Posted: Fri Nov 22, 2013 4:35 am
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The Fender Pro 6G5-A tone stack seems pretty close to the Champ (AA764) stack. I need to get home and look at both schemos.

You can use the tone stack calculator to fine-tune the range of tone control. At least, get an idea what changing each coupling cap does to the frequency response.


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Post subject: Re: Packard Bell Model SA-5 Question
Posted: Fri Nov 22, 2013 6:51 am
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Looks like the Pro 6G5-A tone stack is the same as the Champ (AA764). I'd start here and experiment with range of tones.


http://amps.zugster.net/images/articles ... /6G5-A.gif


http://www.webphix.com/schematic%20heav ... _schem.pdf


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