Why does my Ampeg Scambler build sound like poo?

[Jebus0000]

It's a project from www.tonepad.com.

It sat on the shelf for about a year cause i couldn't ever get it to work.  i pulled it out today and after discovering all my stupid errors I got it working...kind of.  It effects my guitar signal but it's obvious that it's not right.  There's no sustain...the notes just kind of cutoff.  sounds nothing like the clips I've heard.  it really sounds like crap.  I wondering if it was my choice in transistors cause there are a few options for each.  Also, there are some diodes that were apparently on the original factory schematic but not in the pedals.  I put them in.  If I want to take them out do I replace them with jumpers or just leave them blank?

[Samuel]

I personally could hear no difference with the additional diodes. I don't think they get jumpered if you leave them out but I can't be 100% sure I remember correctly...IIRC the pinouts for the transistors in that circuit can be a little.....weird. Are you 100% sure you know the pinout of your transistors? That would be my first suspicion...

[Jebus0000]

I looked up those transistors on this site: http://www.nteinc.com
as recommended by the FAQs on this website.  So unless they're different then the NTE versions I should be good there.  Would I even get any sound if I screwed that up?

[petemoore]

Yupp, and that's a big. complex looking build, audio probe it?

[phillip]

The 2N5306 darlington transistor that the Scrambler uses has the B-C-E pinout, as opposed to the more common C-B-E pinout that were used to seeing.

The BC169B in the T0-92 package also had the B-C-E pinout.

There's a pinout diagram of the 2N5306 on my Scrambler page at Fuzz Central, which also applies to the BC169B:

http://fuzzcentral.tripod.com/scrambler.html

Phillip

[shawn]

The additional clipping diodes serve no purpose. I gave them a try and noticed no difference with or without them. I say save those two diodes and built a second one! That's what I did.

[Jebus0000]

The 2N5306 darlington transistor that the Scrambler uses has the B-C-E pinout, as opposed to the more common C-B-E pinout that were used to seeing.

The BC169B in the T0-92 package also had the B-C-E pinout.

There's a pinout diagram of the 2N5306 on my Scrambler page at Fuzz Central, which also applies to the BC169B:

http://fuzzcentral.tripod.com/scrambler.html

Phillip

That's how I have them layed out.  and I used those transistors.  I tried the pedal again but with a distortion pedal infront of it to crank the signal.  The sound was a lot better.  It gave a pretty cool octave sound but was very thin sounding and is a lot quieter then the signal going in.  Any ideas?

[Jebus0000]

Yupp, and that's a big. complex looking build, audio probe it?

I made an audio probe but have no idea how to use.  The only information I can find on Geofx is on how to make the thing but not how to use it.  Are there instructions on how to use the darn thing?  Sorry, I'm new at this.

[Travis]

Audio probe:  have the schematic and layout in front of you.  Use the audio probe as a tap out to your amp.  After you have attached the ground lead, use the probe to see where you get signal, starting from the beginning of the circuit.  Follow the signal path through the circuit.

I built the scrambler two days ago, and the audio probe helped me fix it.  I had miswired the 1/4"out socket.  I'm an idiot.  It seems that the more builds I do, the less complicated my mistakes become.

The Tonepad guys did take the time to label your pinout options, make sure that you used the correct pads for your transistors.

Oh, and don't jumper the diodes.

[Jebus0000]

Success!!!!!! I'm so happy.

after learning how to audio probe I audio probed the circuit.  Tracked down to the Q2 and WAIT A MINUTE!  it gets all fuzzy just before Q2 even though the joint just before that point is fine.  There was a break in the..uh..whatchama call it...circuit.  So I fixed it up good and now it works perfectly.  

edit: whoops...this was supposed to be posted in my OD-1 thread.  I was talking about my OD-1...my scrambler still sounds like shit.

[trescat]

I have checked four different ampeg Scrambler schematics which are available on the internet, and two of them are different than the other two, one of them is the original schematic, which shows the 1uF electrolytic cap which comes off Q1 as having the negative polarity connected to Q1's emitter Here is a couple of links to that particular schematic --
http://members.aol.com/portaflex/schems/scrambler.gif //http://members.optusnet.com.au/trescat/pictures/scrambler%20original%20Sch.gif
The schematic at tonepad shows the same arrangement --
http://www.tonepad.com/getFile.asp?id=31 //But%20the%20schematics%20at%20General%20Guitar%20Gadgets%20---%20http://www.generalguitargadgets.com/diagrams/scrambler_sc.gif
and the one at Fuzz Central ---
http://fuzzcentral.tripod.com/scrambler.html [url]
Well they both have this particular Capacitor with the polarity reversed from the original schematic, so which one would be correct, I am assuming that the original would be the way its meant to be , but then why would they change the arrangement at those other two sites, any light on the matter would be appreciated.

Cheers
Trevor

[Paul Perry (Frostwave)]

Well they both have this particular Capacitor with the polarity reversed from the original schematic, so which one would be correct,

maybe someone has built one, and can pop a multimeter across the cap while it is running & see what the voltage is & whihc way it is! Sometimes my brain hurts and this is what i have to do... but i diont have a scrambler.
EDIT: just looked at ckt, my bet is + to the emitter.
Incidentally, so long as it doesnt SMELL like poo, you are ahead!

[phillip]

But the schematics at General Guitar Gadgets ---
http://www.generalguitargadgets.com/diagrams/scrambler_sc.gif [/url]
and the one at Fuzz Central ---
http://fuzzcentral.tripod.com/scrambler.html [url]
Well they both have this particular Capacitor with the polarity reversed from the original schematic, so which one would be correct, I am assuming that the original would be the way its meant to be , but then why would they change the arrangement at those other two sites, any light on the matter would be appreciated.

The original Ampeg schematic had that 1uF capacitor reversed...the positive lead of the capacitor should be facing toward the emitter of Q1.  If it's installed with the positive side facing away from the emitter you'll get a horrendous "POP!" because the capacitor is reversed and will be dumping about 0.5V or so on the output and onto the switch.

Phillip

[sovtek50]

Scrambler from Tonepad? You might haven't wired the Blend pot correctly. Wiper goes to output. Is that the mistake? Then poo should turn into mayhem.

[Jebus0000]

no it was my stupidity.  One of the caps is valued at 10nf on the parts list.  Me being new at this (even newer when I first started the project over a year ago)I thought that nf was the same as pf so I ordered a 10 pf cap for the project.  All I had to do is put the right cap in there and it works perfectly.  In case anyone's interested in experimenting with theirs, if you change the value of the 10nf cap it really changes the sound.

One thing I don't like about it is that there's no volume boost...I'd like it better if I could have the same scrambler tone but then crank it louder.

[Elektrojänis]

One thing I don't like about it is that there's no volume boost...I'd like it better if I could have the same scrambler tone but then crank it louder.

Stick a some kind of a booster after it. I did that to my unit.