Checking circuit continuity in a switch; bad capacitor?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by ALittleMore, Mar 13, 2018.


  1. ALittleMore

    ALittleMore Member

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    Got it! Did you draw this up with the pads in mind by chance? Does it matter which wire goes to which side of the pads? For example, C67 has a ground pad, which wire on that diagram is supposed to go to that ground pad?

    Also @Jeff Gehring what watt resistor or does it matter? I’m not too familiar so I picked up a couple different wattages of 1M resistors. I picked up a 1/4w and 1/2w
     
    Last edited: Mar 13, 2018
  2. Jeff Gehring

    Jeff Gehring Silver Supporting Member

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    No, it doesn't matter which of the two C67 side wires go to which of the two C67 pads, ditto for C8. I'd use a 1/2W resistor there.
     
  3. ALittleMore

    ALittleMore Member

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    We did it!! Thank you so much Jeff! What a successful thread and a learning experience! Everything checks out as it should with everything soldered up! Used a 1/2w 1M resistor too! Was a bit of a struggle to get them tight and together on the switches small lugs but worth it! Can I buy you a six pack of beer? :beer

    I did turn the switch upside down, I wanted it to be akin to a Mod on/off vs Cap on/off. So the down position turns the caps back on or “stock/not modded”
    And a video, to show the effect of the BC mod for the Vox

    Takes off a lot of that top end fizz. The other switch is the tonestack mod, so don’t mind that.


    UPDATE: So it indeed does work but the amp appears to not behave the same as it did. Previously, turning the mod off yielding significantly more brightness. Now it seems to just add more fizz. It’s almost as if the mod is only working for C67, which is to smooth off the high end (fizz) when the bright cap is on. I reckon the bright cap might always be in the circuit now. I wonder why that is? I did follow your diagram to the T.

    UPDATE UPDATE
    So turns out my original wiring was just flat out WRONG. For curiosity sake I wired the new caps up the same way I had it previously. Turns out, I forgot that previously, for whatever godforsaken reason, I wired up only ONE leg of the C8 cap. So essentially, there was no bright cap, but the bright caps curcuit pads were joined by the switch. This made the amp astronomically bright, like amazingly bright, even a slight volume boost. I’m not sure why this happens but, for now, I’m gonna leave it like this. I actually prefer the contrast and use that stark brightness for sparkly ambient cleans.

    I’ll be archiving this thread and your helpful diagram, should I want to go through the process of wiring up my amp the correct way with the bright cap mod switch diagram that you provided. Because it DID work, it was just so foreign to me. Because I’m used to this weird other modification lol.
     
    Last edited: Mar 13, 2018
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  4. VaughnC

    VaughnC Supporting Member

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    It's your amp...but I wouldn't leave that sloppy wiring like that. Looks like an accident waiting to happen even if it does work for now. Good luck!
     
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  5. ALittleMore

    ALittleMore Member

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    I’m not sure what you mean by this. My amp is behaving properly; sounds great too, I even A/B tested it with a stock amp at the store once. With the bright caps switched out it has the same behaviors as a stock amp just without the fizz.

    I’m gonna do more experimenting but I’m curious why there is more perceived volume when wiring up the switch as Jeff suggested and switching the caps out vs not having a switch and leaving the bright caps out. Normally people suggest just clipping your caps out of the circuit, but when switching them out as per Jeff suggested it gave more volume, yet the same effect. It’s curious but I think I’m gonna wire up another DPDT switch exactly like Jeff suggested and do some further A/B testing. I might prefer it that way especially if you suggest this current wiring could be an issue. Though the intense brightness comes in handy with clean tones...
     

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