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.






34 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.

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  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.

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    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?

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    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.

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    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.

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

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

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    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?

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  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.

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

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  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?

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

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    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.

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  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

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

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    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.

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  8. what value should the volume pot be?

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  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?

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  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.

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    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.

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  11. Is the 100p and the 4M7 from input to ground to help kill RFI?

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    1. I think the 100pf cap is to roll off some high end, and I think the 4M7 is for pop reduction. Not actually sure tho.

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  12. Hi, mine waiting for the box. Thanks John for the volume control. I used 3904 (thanks again John). I tried with 2n5088, but it was too low sustain. For q1, 3, 4 I used BC517 (for me the best, total massacre :). I tried with the 3906, but it was too farty. Another thing I did, was to remove the diodes D4 and D5, maybe I'll add them to the switch. Now that's a fucking monster :) works great with my precisionbass and also Stratocaster.
    IvIark thanks, and maybe you can tag it as a ampeg :)
    Sorry for my english.

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    1. This comment has been removed by the author.

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  14. In the case of the blend pot doing something else apart from blending 2 signals, I dont find any use for it since I just want an all the way fuzz. Is there any way of disregard of it¿, (the volume control seems interesting though),

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    1. Hmm I think just take Blend 3 to the 3rd lug of a 100K pot, 1st lug to ground, and 2nd lug is your output.

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  15. You mean that blend 3 would be the fuzzy signal that goes to a regular 100k volume pot, which lug 2 would go straight to the footswitch, right¿

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    1. Yeah totally, lug 2 of your new volume pot goes to your footswitch (you can consider this 'effect out').

      It's blending between full fuzz volume on the 3rd lug and nothing (ground) on the 1st lug.

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