Saturday, 7 July 2012

Guild Brian May Box

This is a bit of an unusual one because I'm not even sure what it is.  It's based on a schematic done by Analogguru and is obviously a Cornish buffer in front of a booster, so what I am assuming is that the Guild Brian May is the treble booster, and the whole circuit amounts to the modifications done by Pete Cornish when putting the effect in one of his boards for Brian.

Some or all of that may be wrong as it is just my assumption, so please correct me if anyone knows more, but the thought of a Cornish buffer into a Brian May treble booster seemed too good an opportunity to miss so I thought I'd have to do the layout! :o)

The input socket should be taken directly to the board input and so only a SPDT stomp is needed for the switching because the buffer remains in circuit during bypass (the stomp is the "Sw#" connections shown in the layout).  You will of course need a DPDT stomp if you want to include an LED.  For those wanting true bypass instead of the Cornish buffer .... shame on you! :o)


  1. While waiting for more info on English channel, i put this together. I don't know anything 'bout no MPS8098s, but their datasheet suggests that the hfes are around 300. So i sticked BC109Bs in for some extra mojo. Other substitutions were 1µF monolithic instead of electrolytic. Yes, poor me. At the moment i'm out of 1µ electrolytics:(, and i i'm also out of A250K pots, so i used B250K. That works ok, although the sweetspot just above unity feels a bit short - so if possible, use A250K. :)

    Really nice treble booster. IMO, it's better/meaner/insert_your_adjective_here than screaming bird, and it's wrestling in the same league with the Rangemaster. Heck, i think i like this over RM... Buffer is also good, but doesn't get any wows out of me :) Booster is really mean. I had to say it again :)

    Definitely worth a build!

    Wonder what caps make it a treble booster.. I guess i would like to hear how it would sound with more frequencies boosted...

  2. Cool, another verification to wake up to! :o) I'd much prefer to use monolythics instead of electrolytics, they'll live longer, less leakage and the ones I've got are more accurate. I just got some 1u and 2u2 and they measure pretty much bang on the money. If you want to experiment with frequencies look at the 10n, 47n and 4n7 to ground.

  3. If you were to box this with an overdrive as the boost section would it be better to go first because of the buffer? Thanks

  4. I'd love to have this, but I am lousy at this sort of thing. What will it cost to have one of you guys populate a Vero board for me?

  5. I'd like to give this a try, but how would I wire it with a DPDT stomp to add an LED, per above?

    1. The switch configuration would look like this:


      1-3 would be used for the main bypass wiring shown in the layout, connect 5 to ground, 4 to the LED cathode, and the LED anode to 9V via a current limiting resistor of your choice. I use 2K2 a lot for LEDs but it depends how bright you want it.

    2. Just noticed the resistor is already included in the layout so just connect the LED anode to LED+ on the board.

  6. Ah, ok, so the LED CLR is already accounted for. Thanks!

  7. So, the 6k8 resistor is the LED CLR in this case? If so, I can alter that to change the brightness, and the higher the value, the less bright it is. Is that correct? Sorry, I'm a n00b.

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  9. I built this boost and put it into an enclosure with a G2-SS2 that I built. I used the wiring schematic for the G2 with the cornish buffer and then went to the 2nd and 3rd pedal (ss2-->Boost) and for the ss2 and boost used the regular offboard wiring. My goal was to make it so the buffer would be inline for all 3 pedals. If I hit the G2 it sounds really good as well as the SS2. When I use the boost it sucks all of the volume and tone. It works but sounds hollow. My question is am I wiring it correctly and how do I use the boost inline with the G2 and SS2 and keep good tone. I did try changing the 250k LOG to a 500k LOG whch did not help. Would changing to a bigger cap help? Please review my wiring and setup at the following link. I really appreciate any feedback.


    is it just me or does this guild brian may treble booster have far less components then this layout