Saturday, 5 May 2012

Ampeg Scrambler

Info from the manufacturer:

The AMPEG Scrambler was designed in response to requests for a distortion device that was flexible, easy to use, and most importantly, musical. Inherent performance limitations of all designs on the market precluded one or more of the aforementioned requisites. New concepts and methods were researched and tested by leading musicians until every requirement was surpassed. The end result was enthusiasm on the part of every one who tried the unit.

Basic understanding of the unit and its operation will result in the ability to use each of the sounds that the unit can produce. Don’t be afraid to experiment with all of the controls – a little time spent with the Scrambler will enable you to use the unit to its fullest capacity.






24 comments:

  1. Replies
    1. It links to Blend 2, instead of daisy chaining, it may be easiest to take the output wire from the 4th row, far right hand hole. In fact I'll add that to the layout to make it more obvious.

      Delete
  2. i just built this one today and it works perfectly. the only thin that i'm wondering about is the blend knob. when i move it toward the center, the clean tone drops quite a bit. the same goes for the fuzz effect. i then tried it with a stand alone split n blend and it blends normally (it blends perfectly), so i'm actually thinking about making & installing an internal split n blend circuit in it to replace the blend pot.

    ReplyDelete
    Replies
    1. I can't see anything in the schematic that would account for the level dropping off both sides in the middle of the pot. That shouldn't happen, as one gets quieter the other should get louder. That should simply pan between two outputs, one after the first buffer, and one at the end of the circuit. Very strange, has anyone else noticed similar?

      Delete
    2. yeah, i can't see anything either, but mine certainly does it. a drop in volume in the center of a blend pot is generally the result of the two signals being blended are out of phase, but since i ran it thru the split n blend to test that, that is not the case. maybe it could be a case of one signal 'loading down' the other, since in the split n blend it doesn't happen. i was also thinking of trying a stacked blend pot so in effect they have their own pot which is what i'm going to try next.

      Delete
    3. i just tried a stacked 100K pot and now the blend works perfect (no volume drop in the center) so that's what i'm going to go with, but i'd still like to hear from anyone else that has experienced this issue.

      Delete
    4. John can you explain how the wiring is done with the stacked 100K? I'd love to build this using your solution

      Delete
    5. http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/AmpegScrambler/ScramblerBlendandVolume.png

      Delete
    6. Fast! Thank you very much! I wonder if the sympton you are describing is the famous ampeg scrambler volume drop? Or is it still below unity?

      Delete
  3. BTW, i'm running 2N5306's in mine (Q1,Q3,Q4) with a 2N3904 for Q2. i tried a 2N5088 and a BC550 in the Q2 spot, but for me the 3904 sounds the best.

    ReplyDelete
  4. Try a small trim pot in place of the 1k resistor and adjust for unity volume.

    ReplyDelete
  5. Same problem here and i fixed it with a 15k trimpot, no volume drop now thanks Peeps Thecat. I still found that the octave up is quiet tho any suggestions?

    ReplyDelete
  6. Just built this with 2N5306's and a 2N5088, works perfectly!

    ReplyDelete
    Replies
    1. To fix the volume problem, use a 2-channel mixer instead. Blend 1 becomes your clean output. Add a jumper between Blend 2 and Blend 3 on the board. Outpout becomes your fuzz output. Add a LPB-1 daughterboard after the mixer, and Math's your uncle.

      Delete
  7. Having a problem with this one. Looking for suggestions. I've checked my build against the layout, checked for solder bridges etc... Everything seems to be where it's supposed to be. What could I be missing?
    Voltages are:
    Q1 E: .9 B: 1.47 C: 8.96
    Q2 E: .32 B: .93 C: 2.33
    Q3 E: 1.49 B: 2.07 C: 8.96
    Q4 E: 1.49 B: 2.07 C: 8.96

    ReplyDelete
    Replies
    1. Q4 shouldn't have full supply at its collector, are you sure the cut between Q3 and Q4 collectors is good?

      Delete
    2. Yeah, the cut is good. Everything is wired up right, etc... Any time I have something that doesn't work, it's usually a dumb mistake that's pretty easy to figure out. This one has me stumped for some reason.

      Delete
  8. what value should the volume pot be?

    ReplyDelete
  9. Hello, I do not understand how to add volume control. I have no sound. I connected "blend2" from the board to blend pot lug2 and from there to the volume lug 3. Vol2 to output (output from the footswitch) and Vol 1 to ground. Is this correct?

    ReplyDelete
  10. Correct. Lug 2 of the blend control should be connected to the board, to lug 3 of the volume pot. Lug 2 of the volume pot goes to the stomp switch, and lug 1 of the volume pot goes to ground. If that's how you have it you need to start debugging. Check the voltages at each of your transistors, and make sure one is not bad. Check for cold solder joints, and solder bridges between the tracks.

    ReplyDelete
    Replies
    1. I use 2n5306 but in to-92f case. and I ve found much maniers for pinouts. I have BC169c for Q2. I think the trouble must be there.

      Delete