Friday, 11 November 2016

Bogner La Grange

Original Info:
The La Grange pedal is designed to emulate the famous British "Plexi" amplifiers from the mid 60's. The wide variety of controls and switches, give you decades of legendary plexi tones, all the way up to the era of the modded amps from the late 80's and throughout the 90's.
An independent boost function, with a level control, can be activated via it's own foot-switch to be either used as a stand alone boost, or together with the La Grange's main circuitry. Essentially two independent pedals, with the boost being in series after the La Grange!
Reinhold designed the La Grange pedal with an op-amp input, followed by five discrete Class A gain stages and incorporated Germanium diode clipping. This approach minimizes the input noise floor while retaining touch sensitivity and clarity throughout the entire gain range.
Original FSB thread and schematic available here.
The schematic should be correct but it hasn't being verified yet.
You can find the original manual PDF here.
I've used Mark's Dual Effect Offboard wiring.


22 comments:

  1. omg, this goes onto the build list for sure! :)

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    1. oh lookin at this, to me this is very similar to the Zvex box of rock / distortron, and as I see the boost is pretty much an SHO - just with more controls

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  2. Can I use 2, 12v diodes? I have a bunch but no 10's.

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  3. Hi, 2 question:

    - is the 7660s a voltage converter?

    - can i use this opa132ua?

    http://www.ebay.com/itm/BB-TI-OPA132UA-SOP-8-High-Speed-FET-INPUT-OPERATIONAL-/221575682186?hash=item3396f0988a:g:NfcAAOSwAHZUPQs1

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  4. Holy crap, great job, Alex!

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  5. Shouldn't the boost be at the end of the chain ? According to your layout the in is connected to the boost and the main circuit to the out

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    1. Probably but not according to the schematic.
      If it doesn't sound right it's just a question of swapping some wires.
      The Boost part would go to SW6-5 and Sw6-7.
      The main circuit would go to SW5-5 and Sw5-7.

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    2. Ok thanks it's a mistake in the layout then, but some might prefer it that way so...

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    3. Layout should be correct cause it matches the schematic (or at least I hope so).
      Either the guy has drawn the schematic wrong or the boost goes in front but (as we've said before) it's very simple to swap. You could even add a DPDT toggle switch to swap the boost position in front or at the end whenever you want. Should test it first.

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    4. Oups sorry I meant the schematic not the layout. It's said in the video that the boost comes after. I was also thinking of a toggle, both options are interesting whether you need more gain or more volume ;-)

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    5. If you build it (and it works) let me know if the boost sounds good in front (sometimes they don't). I'll add a toggle switch!

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  6. Looking at the layout, the footswitch LEDs only get power if the variac switch is flicked a certain way. Wouldn't you run them (or the clrs at least) straight off the 9v rail? Or am I missing something?

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    1. The LEDs are wired correctly.
      The 9V is always there.
      The Variac switch just changes the voltage that goes to the BS170s. The rest works at 9V.
      If you check the schematic it will be clearer.

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    2. Speaking of voltages Alex, which electro capacitors should be rated 25v+ ?
      Thanks

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    3. I would use 25V everywhere, just to be safe.

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  7. Thank you! I have been waiting for that one :)

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  8. hi
    great post alex.
    thanks for this one.
    built it but lacking of this OPA132
    i can tell the tone wires are reversed.
    i put opa275GP so all i got is a a big hiss (like distortion on with vol off on the guitar) and a reaction of the treble and the vol pots.
    is there any sub for this opa132 ?
    thanks

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  9. Hi Alex,
    maybe it is a dumb question. What do you mean with that you used Marks Dual Effect Offboard wiring? I checked Marks Post where he explained it. I understaood that you are going to use it when you have 2 veros, aren't you?

    Many thanks in advance!!
    Markus

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    1. Hi Markus.
      You use it when you have two independent separate circuits. Like in this case.
      The Boost in this pedal can be switched on on its own.

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    2. Hi Alex,

      thank you very much! I see, it is too difficult for me now :-) I am going to try a few easier one.

      Thanks

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  10. Hello,

    Interested for build it, but is there any opa132 replacement ?

    thanks ....

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