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Blues Jr. Point to Point?

Discussion in 'Shock Brother's DIY Amps' started by JimmyJam, Apr 29, 2009.

  1. JimmyJam

    JimmyJam Tele-Afflicted

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    I know that PCB's save space/money in electronics.
    A handwired Blues Jr. circuit would probably require a larger cab than it's housed in.

    But,
    Are there any sections of a BJ that can be modified into PTP while maintaining space restrictions?

    Would there be any advantages to converting a PCB section to a PTP? Like better tone?

    I was thinking of actually changing the pots to ones that don't attach to the board. Although Billm mentions this on his website with regards to using different chicken head knobs; I am curious if there would be rational reasons to do this. I would think it would be easier to modify and replace failing components.
     
  2. PaisleyRocks

    PaisleyRocks Tele-Holic

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    I'm no expert, but if built to the same specs, there probably wouldn't be much difference in tone, but serviceability and reliability should improve.
     
  3. JohnnyCrash

    JohnnyCrash Doctor of Teleocity

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    The usual PTP stuff will likely get posted, so I'll try to cover some stuff briefly.

    PTP is point to point. Handwired amps are also turret or eyelet board constructed (this is likely what you're referring to).

    PTP, and/or handwired, sounds no different than PCB if all of the components are the same. Sometimes PCB can actually be less noisey (sometimes vice versa, depending on the PCB design). Depends on the AC noise and where stuff is wired/located.

    There is an advantage to replacing PCB mounted pots with chassis mounted. It should be easier to clean/lubricate as well as replace them. Pots often get scratchy over time and sometimes getting to the little hole in their casing to spray cleaner/lubricant into can be a pain with PCB mounted pots. Scratchy pots can be the first cause of irritation for amp owners.

    As far as maintenace, tubes and electrolytic capacitors will be the only stuff needing any "regular" replacing (every couple of years or 10-15 years). Electrolytics should be just as easy to replace on most PCB amps. Tubes and bias usually just as easy as well.

    As far as repair, it depends on what fails in the amp. Sometimes transformers are easier to replace in PCB since they use connectors (sometimes PCB is harder though). Shorted leads and other failures can be a pain with PCB. Sometimes figuring out where everything on a circuit is located can be hard, but generally PCB's are silkscreen labelled for ease of repair.

    Generally its sort of a case by case kind of thing as to what amp(s) would benefit from PTP conversion.
     
  4. Ben Harmless

    Ben Harmless Friend of Leo's

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    Crash pretty much covered it. I will point out, as I'll bet he intended to, that the other advantage of getting the pots (and jacks, and tube sockets) off the board is that the fewer surfaces of the chassis that the board is connected to, the less likely it is to crack when and if the amp takes a hard blow. In a BJ, whenever you smack the knobs really hard, that shock is at least in part transferred to the board. You can see why that might suck.

    I personally don't think there are very many amps that would benefit from a PTP/handwired conversion. The reason being that if you're already doing the work, you might as well build a better amp while you're at it. I don't mean to say that amps like the BJ aren't good - I happen to really like the BJ - but that there are always corners cut, and compromises made in modern large-scale manufacturing. If you're going to redo the amp, you could design in improvements, and make a whole new beast. Be bold!
     
  5. JimmyJam

    JimmyJam Tele-Afflicted

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    Wow. 2 of the TDPRI amp experts (in my book) just answered.
    Thanks for the quick response guys.

    You're right Ben. I guess if I was going handwired, be just as well to make a new/better amp.
    Sounds like the next project after the 4 other ones I got planned.
     
  6. celeste

    celeste Friend of Leo's

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    Thing is, component placement plays a roll in how a amp sounds because of the parasitic couplings between them. That said, it is possible to make a PTP amp that sounds worse then a PCB amp despite using identical parts. Wires and PCB traces are components. It is easier to go back and move a wire in a PTP then it is to move a trace on a PCB, so tweaking is easier with PTP.

    Get the board right and you are not going to be able to improve on it with PTP. Support the board right and you will not improve reliability ( think high performance aircraft). Lay the product out with serviceability in mind and you will not improve that.
     
  7. HBamps

    HBamps Tele-Meister

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    That would require alot of work to gut it and replace everything hand wired without much benifit. There are things that would help a BJ much more and be much easier to implement. Two of those would be 1) speaker and 2) output transformer. Swap those for something nice and your BJ will have new legs.

    FWIW I gutted a BJ and built AC15-esk (ef86 input) into it. The only parts I used from the BJ were the cab, chassis, and power transformer. It turned out great but wasn't cheap.

    [​IMG]

    [​IMG]

    [​IMG]
     
  8. pjholland

    pjholland Tele-Holic

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    I change my blues junior to PTP via s2amps (s2amps.com). Yeah, you can darn near purchase a second blues junior for the price of gutting/PTPing your current but I am very pleased with mine and I think it'll last forever. I later added a Weber ceramic silver bell and put it in a new cabinet (Weber also).
     

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