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.
16/12/2016 Layout Updated: Reversed Tone, Boost and Blend pots Swapped the position of the Boost circuit. Thanks to Thomas Roman for verifying it!


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

    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

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

  3. Hi, 2 question:

    - is the 7660s a voltage converter?

    - can i use this opa132ua?

  4. Holy crap, great job, Alex!

  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

    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.

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

    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.

    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 ;-)

    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!

  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?

    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.

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

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

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

  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 ?

    1. I use an OPA134PA and it works just fine

  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!!

    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.

    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.


  10. Hello,

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

    thanks ....

  11. You can tag this one as verified. Thank you for this great layout once again. A few problem with pots : blend, boost and tone work reversed. Just a few wire to swap, nothing hard. My build has whistle when I push gain or when I go to trebby setting but I test it with OPA134 and AD820 (less whistle) as I don't have yet OPA132. This problem is not from the layout I'm sure. Except this whisle the sound is awesome an it seems to be very versatile.
    I add a toggle to reverse boost position, but I didn't play enough to know my favorite order.

    Pics of the build :

    Thanks again for this layout

    1. have you tried some more common IC in it, like TL071 for example?

  12. Think too late, in waiting to find an OPA132, do you think that tweaking the 22P cap close to the IC will be able to reduce the whistle?

    Thank you

  13. I revert wire 1 & 3 on tone and blend and attach lug 2 & 3 on boost pot to make them work in the good way. Just now wait for a good OPA132.

  14. Finally, the whistle was because of my 7660S. I change them and it stop the whistle. There is 2 kinds of 7660S there is CPAZ and IPAZ, in that case the IPAZ work better in my build. I will play with it and keep you update for the boost position.

    Thanks again for the layout

    1. The 7660S tend to add high frequency whine when they are used as +/- voltage supply or voltage doublers. Sometimes the problem can be solved by putting them on a daughter board and placing this away from the main board or shield it with some foil. But I have found that the LT1054 works much better and rarely produces any noise. You can use the same socket, just make sure you don't connect PIN 1 (clip or bend out of the way).

  15. Can i use 9.1volt zener diodes for D3-D5? I also have 12volt zeners but no 10volt.Has anyone tried alternate diodes for D3-D5? If so do they make a big differance in the sound?

  16. So after test, I really think that the boost has to be in second position. It works very well as a volume boost and not very well at gain one. And the pedal has a lot of gain so boost the gain is not realyy usefull.
    In first place it works only well when the gain is low on the main board. That's why I think it has to be second. A toggle to change the position can be a good idea for some setting. Only needed if you want a 2 stage gain.
    In my case, I had to change the 5K1 resistor to correctly bias the BS170 of the boost. I use a 15K resistor to bias it to 6V.

    1. Thanks Thomas! Made those changes.

    2. I have built it and most of the circuit works fine. But the booster does not really seem to work. With 5k1 to ground and 5k1 to +18V it does not provide much boost. It is basically an SHO on the lowest Boost setting.
      Does the Boost pot really go from Source back to the Gate. Shouldn't it go to ground?

    3. Thomas, did you bias the Boost BS170 at 6V by ear, or is that documented somewhere?

    4. I finished mine up this afternoon and was not crazy about the Gain and Boost pots.

      They were acting more like switches than adjustable controls. Either nothing, or full on. Nothing in between.

      I replaced the Gain pot with a 50k log, much improved response and available gain.

      I also re-biased the boost BS170 as Thomas mentioned, but IMO it is still not functioning correctly.

      I think there may be a schematic error with the boost.

    5. The re-wiring of the boost control per the manfred schematic update here seems to be an improvement.

      I just noticed I'm getting a loud squeal with the gain switch in either outer position, in the center off position sounds fine. Squeal changes tone when in 18v mode, but gain, quiet in the center off position.

      Would someone mind posting the voltages you have on the the gain switch's BS170 DGS pins?

      In 9v mode, gain switch in center position, I have:
      D 7.63v
      G 3.70v
      S 1.65v

      Gain switch in high gain mode (1k resistor shunted to ground)
      D 5,69v
      G 2.82v
      S 0.59v

      Gain switch in max gain mode (100R shunted to ground)
      D 4.74v
      G 2.27v
      S 0.08v

  17. I have completed mien and I am finally satisfied. The following changes worked for me:
    Boost behind the main circuit
    Boost pot goes to ground, not back to the Gate
    Gain Pot should be 50K log (100K log with 40-60 K works too - experiment)
    Dispensed with 2M2 parallel to Gain pot
    Blend Pot is C1K instead of B1K
    LT1054 to make 18V
    100uF instead of 47uF to ground on the 18V side
    -9V and 18V circuits on separate daughter boards - as far as possible away from the main board
    Shielded wires for everything longer than an inch (there is a truckload of gain when you max everything)

  18. Excellent Han Solo,

    I'm also close...

    What did removing the 2M2 improve?

    Would you mind posting your voltages on the gain switch's BS170 so I can compare?

    Will try shieleded wires tonight to see if that tames the squeal I'm getting with the boost switch.

    1. No improvement with the shielded wires, still squeals like crazy with the gain switch.

      I did note that with the gain pot turned down to around 1k, the high gain switch setting stops squealing, the highest gain switch still squeals though.

      Maybe there is to much gain further upstream, due to a component error or something, not sure.

      Hopefully someone can post their voltage readings so I can compare. Maybe for the 2n5088 too?

    2. Here's a sound sample of the squealing:

    3. This comment has been removed by the author.

  19. Sorry I can't give you the voltage readings, I built the pedal for someone else and he has already picked it up.
    The squeal is not the typical whine you get from the 18V supply.
    Are you sure the Gain switch is wired correctly?
    I did not use Alex' Vero layout but build my own because I wanted the voltage converters off the board and also run a few components off board to make pot wiring easier and get a smaller Vero footprint. One of the things I changed is to run a wire from the source of the first BS170 to the center lug of the SPDT Gain Switch and then ran the 100R and the 1 K from the other two lugs directly, off board, to a ground rail. I did the same with the 470n and the 47u on the Blend knob and initially the 47R and the 2M2 from the gain knob, but I took these out again later as they do not serve much of a purpose.
    As a test: set the gain switch to the center position and then hook a croc clip to the S leg of the first BS170 (or the respective end of the 5K1), clip a 1K or 100R to the other end of the croc wire and touch the enclosure/ground. See if it is still squealing.
    In 9V Mode, my build was actually pretty quiet, even with gain switched to high gain.

    1. No luck as of yet, also tried the 22uf coupling cap as suggested by Manfred over at FSB.

      I know my layout matches the latest achematic, going to work through it with a meter and audio probe tonight to be sure my board matches my layout, and see exactly where the squealing enters the circuit.

  20. Hey Alex,
    Thank you so much for all your work on this. I'm going to get started on this build soon. Do you have any more information on how one would hook up an expression pedal for the gain. I see where the connection works go on the board, but would it just go to a jack? How would it be switched if so?
    Much thanks!!