Need help for a shaka tube!!!

j.frad · April 23, 2005, 05:51:16 PM

well i'm gonna swap opamps inthe coming week see what that does.
I'll try to find a good multimeter too because mine is making things a little difficult...
just a question, in this layout is it possible to have a negative bias?i'm not too good a this yet(1st year of college and this is my third build, i'm new to troubleshooting)
thanks!

Paul Marossy · April 23, 2005, 08:52:42 PM

I believe that the bias circuit is designed to be either more positive or negative from a midpoint bias setting. I don't think you can make it fully negative, though...

Someone correct me if I'm wrong!

j.frad · April 26, 2005, 03:58:22 AM

ok so I read about this audio probe device on another thread (i had never heard of it) and i made one out of a jack and this shitty 2Watt amp i have and it allowed me to check if the opamp worked or not...
actually the opamp works fine (i tried another type too and it didn't change anything) the output of it give a good amplified signal, so I guess it must be the tube then...
the guy a my local electronics shop keeps telling me it's the tube that is not polarised enough, maybe he's right!
the tube i'm using is very old so i'm gonna have to try another and that will have to wait until next weekend (thats the problem with linving at two different places)...
if this doesn't work I'm thinking of putting this circuit aside for a while because it's kind of getting on my nerves!!!

j.frad

Paul Marossy · April 26, 2005, 10:22:26 AM

Well, you've made some progress at least. Sometimes leaving it alone for a few days does the trick - you come back to it and say "doh!" when something jumps out at you that you couldn't see before. It may well be that your tube is worn out, so it's not working as it should be in this circuit...

j.frad · May 04, 2005, 12:59:48 PM

well i've tried it with a recent EH tube and still no result, maybe I should use 13V AC instead of 12... anyway I'm stopping this build. It took me too much time and money compared to what I wanted to invest and I've got other builds waiting!
Thanks to you Paul and the others for your time and advice, I still have made a lot of progress with biasing issues and troubleshooting it'll sure be usefull!!!
I'll see you around the forum for other stuff, as soon as I'm done with Yngwie malmsteen overdrive , tube reamer, modded green ringer and stuff i'll make build reports!!!
bye!
jules

Paul Marossy · May 04, 2005, 01:04:58 PM

Sorry to hear that. All I can say is that I built mine from that same layout and it works just fine. :?

Happy building!

j.frad · May 04, 2005, 01:51:01 PM

Yeah I don't know what I did wrong, I might try again another time because well, this pedal is the reason that got me into DIY so I can't give up can I? But not in the coming months at least. I'm pretty happy with the sound I get out of my recently built YJM 308 and a microamp and I still have an orange squeezer to build...

Paul Marossy · May 04, 2005, 02:03:19 PM

Well, put it aside for a while and come back to it later. The first Shaka Tube I built didn't work right. I put it on the shelf for several months and revisited it, reworked it, etc. And then it worked great!

Paul Marossy · May 07, 2005, 10:34:19 PM

Just thought I'd mention something that might be worth trying. Another individual building a Shaka Tube from my layout has had problems getting it to work and has alerted me to an error on my layout which might possibly be the cause of your problem - that cap between Pin 1 & 7, I show it as a 0.01uF - it should be 0.1uF. I don't know if that can freak out the whole circuit, but it might be worth a try switching out that cap and seeing what happens.

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Need help for a shaka tube!!!