«New» vintage Hiwatt Custom 100 «Jimmy Page» build

Discussion in 'Building the Classics' started by shakti, Feb 9, 2020.

  1. shakti

    shakti Active Member

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    Hi Neil, that would be terrific! I really just need enough to fill in that gap between the two boards. In a perfect world I would have an entire board spanning the whole length, but I also like the idea of using as much of the original amps as possible.
     
  2. shakti

    shakti Active Member

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    Tragichero, many thanks for your offer though! I appreciate it.

    I am still looking for 25k Plessey pots. I got a reply from the Ebay seller but he’s unable to sell any at the moment. There is a single one on Ebay, but I need another for the other amp. Also, the original Page amp used a 25 (22) k presence pot as seen in the photos. I’ve seen a mid 69 DR201 with a 22k presence pot, but typically Hiwatts had a 100k presence pot. Many different variations around though.
     
  3. pleximaster

    pleximaster Well-Known Member

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    I am trying to organise my parts (that came out strange ) but I find any 25ks they are yours for free my friend!

    plexi
     
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  4. shakti

    shakti Active Member

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    C9B65938-9554-47B8-977B-49B5F2347D3A.jpeg Cheers to that! My parts bin is your parts bin...or something like that. ;-)

    A little progress tonight. Not much left now. I’ll probably toss in a different 25k just to get it up and running, but need to decide how to fix the «hole» in the preamp board. The missing turret is a junction in the ground buss running underneath the board (the two thin black wires you see poking out from each end will be joined at that turret. At the other side it is a connection node for a small filter cap. I suppose I could just solder the filter cap + end to the turret right next to it and have it suspended in the air, and also have the two ground wires soldered together and suspended in the air, but it will feel a bit too wobbly for comfort, so I think I want to add some turret board material and turrets, and epoxy it between the existing boards to get it nice and solid.
     
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  5. BanditPanda

    BanditPanda Well-Known Member

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  6. MickeyJ

    MickeyJ Well-Known Member

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    Hacking up a slave unit to make something like this is not desecration, it's called upgrading.
    This is gonna be a hell of an amp.
    -Respect.
     
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  7. shakti

    shakti Active Member

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    I realized I forgot to put in a 100k resistor on the layout drawing. I'll explain later when I get to the two different types of phase inverter. I think I'll start with type 1 (i.e. standard Hiwatt 60s/70s) phase inverter and then try type 2.
     
  8. neikeel

    neikeel Well-Known Member

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    Looking really good, what wire are you using?
     
  9. shakti

    shakti Active Member

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    It’s solid core wire that I got in a trade, I think it’s various pieces of vintage solid core. I haven’t found any modern equivalent of the right thickness, it’s usually too skinny.
     
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  10. shakti

    shakti Active Member

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    Amp is alive!! Photos are coming, and sound clips (eventually). I had to do put in some makeshift solutions for the time being, basically hovering the filter cap in the middle of the preamp board in the air above the board, but until I can get some board material in there it’ll have to make do for the moment. Also I only had a 16uF which is too high, should be between 3-8uF. Furthermore, I used a 2k2 cathode resistor for V3. That is stock value for a DR103, and might have been the original value in Page’s amp, but in the photos it has a 1k5 with a 47n(?) bypass cap. I’ll be trying out different values in the phase inverter with alligator clips, and also try the two different phase inverter types.
    I also wired it up without a presence control, and I don’t have a switch for the balance control yet, so it’s always at full (no gain cut/balance control inactive).

    Lastly, I don’t have an appropriate choke yet, so I am using the regular DR103 100 ohm resistor instead. A choke will dirty it up a little bit.

    All that out of the way - it sounded absolutely great even with just a set of test tubes (Sovteks and some Chinese stuff). Fat, fast, clear and ballsy. DR103 on steroids.
     
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  11. neikeel

    neikeel Well-Known Member

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    Excellent. Makes me want you o bring mine forwards in the project list.
    What caps are you after? Cans or axials. I have a bundle of 8uFs
     
  12. shakti

    shakti Active Member

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    Thanks for the offer Neil. It needs an axial 8uF 350-450V. I have a bid on a pair on Ebay at the moment.
     

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