Muy Caliente VOX Pathfinder 15/15r Modification

Discussion in 'Amp Central Station' started by SnorkelMonkey, Jun 11, 2010.

  1. Guran

    Guran Friend of Leo's

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    No, it doesn't have an OT.
     
  2. Lostinthe50s

    Lostinthe50s Tele-Afflicted

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    Nobody's modded a Pathfinder to 30W because Vox already made one. It's called the Cambridge 30. There aren't 600 mods for the Pathfinder because it doesn't need any.
     
  3. glpease

    glpease TDPRI Member

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    I had a Cambridge 30, and currently own a Cambridge 15. The Cambridge has a 12AX7 in the preamp section, whilst the Pathfinder is 100% solid state.

    I didn't like the 30. There was noticeable crosstalk between the channels, so it was impossible to get a really sparkling clean tone on the clean channel if the OD channel was turned up at all. The 15, on the other hand, is a delight, though it lacks reverb. I prefer it to the Pathfinder, overall, but the Pathfinder has the benefit of reverb, and of actually being available...

    And, true, the Pathfinder doesn't need mods, nor does it really benefit from most of them. It's an affordable, amazingly competent little amp. To my ears, it's the best sounding of all the lower-end SS amps by a dramatic margin. But, that still doesn't stop us from wanting to change them. ;)
     
  4. strat_tone

    strat_tone Banned

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    Thanks for the replies all. I was aware of how the wattage to dB deal goes. I was intending on replacing the speaker anyway. Anyone know the stock speaker sensitivity? I think the vox forum was estimating low 90s. I was thinking a eminence ragin Cajun. 10 inch, 100 dB sensitivity, 1.5 inch voice coil, 75 watt rating. Quite the beast.

    I was hoping the new PT & chiP would result in more clean head room, ie I can dime the volume and keep the gain knob down lower. Anyone know what type of specs I would look for in a PT? I think the combination of the 3 things could make it a truly gig worthy amp, I know some already think that. Maybe I cans find a Hammond PT that will do for around $50 or so. I can Pickup a ragin for about the same used. How much do chips run?
     
  5. strat_tone

    strat_tone Banned

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    And glplease, how much can I bump up the wattage without having to remodel the power supply? I was trying to be realistic at 30, but 50 would be even better as long as I'm going through the trouble.

    Im studying to be an engineer, so this is more entertaining and worthwhile to me then wasting a weekend playing Xbox. The amp is so dirt cheap to start with I'm not afraid of throwing a little extra $ into it. Plus it sounds nice enough that I don't really feel like I'm trying to polish a turd.

    I just want to say the led mod is epic win. Goodbye mush mud, hello clarity and articulation. I'm not really bent on 'the tube' sound. I have this thing called a tube amp for that ;).
     
  6. glpease

    glpease TDPRI Member

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    You're at the wall with the power supply. You can replace the chip with one with more grunt, but it'll want more volts, as well. As I recall, you've got about ±18v, enough for the TDA2030 that's in there. If you replace it with a TDA2050, you'd need ±22 or so to get a full 32WRMS into 8Ω; at ±18, you'll still get 15W according to the spec sheets. Obviously, the bigger the chip, the higher the needed supply voltage. You'll also need to pay attention to increased current load. Not hard stuff, but if you forget something, you may get smoke.

    You also need ±15 and ±9 for the opamps in the rest of the circuit. You could change the PT to get your ±22 without changing things, but beyond that, you might have to make some downstream adjustments. (I don't have the schematic in front of me, but I recall a very simple PS.) A 100W chip amp wants 60V, which will sauté the opamps if not dropped sufficiently.And, you'll have to worry about increased heat dissipation...

    So, 30WRMS is probably about as far as you can go easily without doing more significant changes. You could just build a separate chipamp with its own PS, and run it from a preamp out. Just thinking out loud, there.
     
  7. FenderGuy53

    FenderGuy53 Poster Extraordinaire

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    The Pathfinder 15R is what it is: a simple-circuited, 15-watt, solid state amp, with some personality.

    If you want or need to do any modding, then go ahead. Move it to a larger cabinet or pull the LED's out (aka "LED Mod") to enhance the low end and open up the tone. That said, plenty of folks seems happy with their P15R's, just the way they sit.

    IMHO, if a 15-watt, solid state guitar amp wasn't enough for me, then I'd be looking for another amp, not spending time, energy and money, and hoping that I end up with something that I actually want.

    My $.02. ;)
     
  8. glpease

    glpease TDPRI Member

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    Some people just love to tinker. I'm one of them. And, since everything I REALLY want is out of my budget, I just convert amps I can afford into amps I love. So far, it's been a good working strategy. ;)

    I completely agree about the P15. It's amazingly good at what it does, but it's kind of like a small engined car that you can make go a little faster with some effort. It's just plain fun, and if the results are good? Great! I built a 50W Fender Champ, once, just 'cause I could. I sold it to a guy who fell in love with it for $1200...

    To date, the ONLY amp I've ever owned that I have NOT hot rodded in some way is the AC15VR. For some reason, that thing rings my bells just the way it is, weak reverb and all.

    It's all good. It's all fun. The P15 is the best bang for the buck out there, I think, and I think there may be some hidden potential locked away inside that box. I may have to get one myself, just to play with it.
     
  9. FenderGuy53

    FenderGuy53 Poster Extraordinaire

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    Just wanted to make sure that nobody was drinking out of the jug labeled ELECTRIC Kool-Aid... ;)
     
  10. Poppatwang

    Poppatwang Friend of Leo's

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    For some (uninformed) reason I thought the Pathfinder had the tube preamp too. I bought a second hand Cambridge 15 some years ago. It's my go to for grab & go rehearsals and occasional coffee shop gigs.
     
  11. glpease

    glpease TDPRI Member

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    Is this the Acid Test, then? ;)
     
  12. strat_tone

    strat_tone Banned

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    Alright thanks again. So I'm okay with getting a bigger power transformer than I need, as the chip will only draw as much power as it is spec'd for eh? If anyone has a schematic of the pathfinder 15 r, I know someone posted it earlier but as they mentioned it is hard to read. It would be good. Otherwise Im going to email vox for the specs of the PT and go from there. What else should I keep in mind? Upgrading a few caps and resistors for the extra power, or will they do as is? The opamps will be okay around 30 watts?
     
    Last edited: Mar 12, 2012
  13. Scott57

    Scott57 Tele-Meister

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    I don't have a Vox PF yet and I'm a total electronics noob but if all you have to do is snip off the two LEDS, aren't you actually creating an open circuit? Wouldn't you have to "jumper" the lugs where the two terminal legs were?
     
  14. strat_tone

    strat_tone Banned

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    Not if they were wired in parallel. That could be true if they were in series.
     
  15. strat_tone

    strat_tone Banned

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    Well the chips are very cheap, a couple bucks each. If I can measure the specs on the stock PT I can start to look for something bigger. Hammond transformers seem to cheap enough and are made in canada, so anything from them will be a welcomed suggestion.
     
  16. Manolete

    Manolete Friend of Leo's

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    Sorry to bump this thread. I picked up a Pathfinder 15 R yesterday 2nd hand. I had a shot of it in the shop and really enjoyed the warm tones at lower gain settings but made a mental note there and then to never wind it up to far.

    My dislike of the higher gain levels game from that really trashy fizz that was gradually entering the signal as you push the gain higher.... so I took a risk and desoldered the red LEDs.

    I knew wiggling them off the board would open up all sorts of problems. I also found it quite hard to get the PCB off the chassis without bending the pots on their legs slightly. Still, after a wrought half hour of going at it I was able to desolder both LEDs.

    Now the hour is late, so I have no idea what effect this has on volume. It does mean that without the boost on, even at high gain levels the signal is much cleaner. Kicking in the boost button seems to add a lot of volume. An amazing level of volume for such a small amp. The 'good' distortion remains, the sort of cheeky British crunch I was loving to begin with. However the budget fuzz-pedal filth has gone.

    A big concern of mine was that I would somehow lose gain. Yes, I've lost the fizzy dynamic-chomping fuzz from before, but I still have a lot of inherent crunch left. This amp has already made me appreciate my overdrive pedal for the first time in 5 years, so I imagine results will only improve when I get my pedals hooked back up to it tomorrow.
     
  17. lareplus

    lareplus Tele-Afflicted

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    I would like Vox to make a 50W and 100W Pathfinder. In other words, solid state non-modeling amp. It would give the Bandit a run for it's money and maybe even the higher end JC series. .
     
  18. Big Steve

    Big Steve Tele-Holic

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    Thanks guys, for the info. I love my little Pathfinders. I have two. I will try the LED mod.
     
  19. norumba

    norumba Tele-Meister

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    Well i finally got mine working again, lol, and picked up a second one, did the LED mod to the second one. These are great little amps for the money, though I dont think theyre gig worthy if you need cleans. That said, I use them in our rehearsal space and theyre perfect for that -- at that level, i love them!
     
  20. dqami

    dqami Tele-Holic

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    What did you end up having to do to fix your amp?
     
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