Sans Amp GT2 Lion's Roar

[Athin]

Well @ least the topic will be interesting. This probably will turn out 2 B a silly question but whatnot be it. I've built a SinAmp as on tonepad.com got all the parts allmost right (instead of the BC413B i've got a BC413C and I'm also using TL072CP's) rest the same. Anywayz, when I turn it on all I get is a sound that can be compared to... a lion's roar and the overdriven guitar somewhere in the far background. I don't think this is b-cause I didn't put the bugger into an iron box. I've chceked the board, but since I don't have 2 much time on my hands I was wondering if someone has already experienced a problem like this and knows @ least part of the solution to hthe great puzzle of SOUND.

TIA.

[bwanasonic]

My Tech 21 GT2 used to make some really strange growling and UFO/synth noises originating from a dirty drive pot. I even wrote Tech 21 to see if there was a way to reliably reproduce some of these sounds. I'm not sure what part of the circuitry was making the sounds ( they went away when I sprayed some DeOxit in the drive pot), but I'm not suprised you have lions in yours! Good luck - there's a reason tonepad calls the difficulty level of that build INSANE.

Kerry M

[Athin]

I know why the roar kicks in :oops: . Discovered it just 5 mins ago. When the batt goes weaker the "roar" kicks in. That's all. Basically. But the fun part is that I can control the tone of the roar with the switches on the stompbox and on the guitar !!. Any suggestions as for what to look for first?

[Arno van der Heijden]

Check the pinout of your transistor against the layout. I believe the pinout on the layout is reversed from the bc413.

[Mobster]

Actually...yes and no. If you make yor own board, then, dont
forget to "mirror" the layout before etching. Okay, i guess, its
too late now   , in such a case you either place the transistor
and the ops ON the "copper-side"- but remember, in this case
soldering will become more dirty and less reliable - or place
the elements on the other side - in that case, you need to rota-
te the transistor and..."invert" all op-pins....;-), thats fun........

If unsure, look at Sans Amp GT-2 pics at tonepad.

Nice day to you all !