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Possible to control the Boost level on a Vox Pathfinder?

Started by Little Ricky, August 23, 2012, 12:42:34 PM

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Little Ricky

I've done the led mod on 4 PFs . The first I lifted one side on each led, insulated with hot glue and left it that way thinking it would be easier to put back to stock if I wanted. The second I lifted 1 leg each , tied the legs together and connected a mini-switch. The other 2 I just removed the leds.

The switched PF helped see exactly what the difference is.  Basically you lose the "cheap distortion pedal" sound and get more of a tubish breakup. It is a little noticeable at home volumes when played fairly clean. It's also a bit louder with the leds removed.

It seems the louder the amp and more gain run the bigger the volume hit with leds installed. At home I typically run the volume at 9, boost on and use the gain as a volume control. Late 60s Stones is about as dirty as I ever play.  Running the PF like that it gets very loud for home with the tone I like, never gets really nasty. Switching the leds back in the volume drop is noticeable and gets  "buzzy".

As a test I turned the gain up high with the leds switched, instant "blizzard of nails" flip the led switch to off and there was a huge volume increase and the sound cleaned up. I think this is why there are conflicting reports on the volume increase as attributed to the led removal, if you play with more gain you get a bigger volume increase with led removal.

Another mod I've done is add a "Raw control". I used a pot as in place of the set midrange resistor, turn it enough and the tonestack is lifted from the circuit. Increase in volume and added gain.

danmahoney

#31
Quote from: Little Ricky on November 06, 2012, 04:18:18 PM
Late 60s Stones is about as dirty as I ever play.

Thanks for a great answer to my question Ricky! The late `60s Stones is a great point of reference. My rhythm sound is very Keith Richard and for solos I don`t really get crazier than Mick Taylor`s very natural sounding, bottleneck through tube amp (no pedals) tone.
I`m just getting to know my PF in rehearsals right now, but will be out Thurs (in a small bar) to test the amp at the small room levels that I will be using it at.
I`m still waiting for the 1M pot to arrive in the mail and when it gets here I`ll definitely mod the boost level.
I`ve found at low levels that I can get lots of great tone out of the amp, but I get the sense from turning it up here that it might get a little too 'hairy' for me if I use much gain at higher volumes. At low levels I would be fine with the LEDs still in there but I get the feeling (from your experience) that I`ll be happier with them out at gigging levels.
I`ll know more after Thurs but I`m sure I`ll try lifting them when I`ve got the amp open for the boost mod.
Thanks again for such a great, detailed answer. One quick question: does it matter which leg of the LEDs I lift (I plan on doing it that way in case I want to put them back at some point)?
Dan

danmahoney

Hey Ricky, I`ve had a chance to play through the PF at louder volumes and I don`t hate the hotter settings (volume at 3:00 or more, gain at around 12:00) for soloing. That`s with no boost engaged (I really need to get the pot in there to really see what change that makes first hand).

So what I`m thinking of doing, since I have to open the amp up and drill a hole in the bottom of the chasis for the pot anyway, is to drill another hole for a mini switch and wire that to the LEDs (like you did with one of your PFs). That way I can switch the LEDs in/out as I like and control boost levels with the pot, all from the outside of the amp.
Be a nice little hot rodded PF with both those options tweakable right on the underside of the chasis.

So I was hoping you could walk me through exactly which legs of the LEDs you lifted, where you wired them to the mini switch, and then where you went to ground from the mini switch. Any chance you remember?

Once again, really appreciate your input on all of this. Thanks!
Dan

Little Ricky

Sorry just getting back into things. As far as legs on the led's it really doesn't matter, they just connect to ground. Looking at the board I used the top 2 as they were accessible. I bridged the 2 together and connected that wire to one side of the switch. The other side of the switch gets soldered into one if the two holes in the board that the led legs were lifted from, you are just continuing the circuit.

If you want versatility add the "Raw" control

danmahoney

Thanks Ricky, appreciate you getting back to me!
My mini switches are DPDT so I`m thnking that (in theory) I should be able to wire leads from each side of my switch to the solder points for each of the LEDs on the underside of the PCB (without even lifting an end of the LEDs).
Does that make sense?
Dan

Little Ricky

No that wouldn't do it. What you're looking to do is interrupt the signal from going to ground. Sounds like you're trying to ground the  signal?

I would really just remove them. You should be able to do it without even removing the chassis (which is time consuming) .

danmahoney

Thanks Ricky, I see where I`m going wrong with my logic on that one...
Hopefully I`ll have time over the next few days to do the work on the PF. I`ll let you know how it goes.
Thanks again for all the great input, all the best!
Dan