tube screamer- affects of diodes

[christobean]

hi, i have searched around on here to try to find the answer to this, but i dont think the other posts are talking about the same problem as me

i built a tube screamer 808 with the tonepad layout, and it works and everything, except there is a volume drop even when the volume is maxed.  i used the asymmetrical clipping diodes, is that the problem? should i remove the 3rd diode and use symmetrical clipping instead?

[blustrat]

Hi, what type of diodes in the pedal? Using 2 diodes instead of 3 (even for asym clip mixing different types) volume drop will be more consistent. Look for some wrong resistors values, the colors on the res are not so clear sometimes.

[markm]

I'm no electronics wiz but,
Maybe the diodes are reversed or there is a problem with a transistor...incorrect pin out maybe?
Take this with a grain of salt 'cause....I don't always know what I'm talking about.
At least, that's what my wife says
  MarkM

[christobean]

haha, i will check the diodes, but it isnt a volume drop like you can hardly hear it(that is what usually happens when i reverse a diode or transistor) its just that even when maxed, the volume isnt as loud as when it is bypassed. ill also check the resistor values, cuz  this was my first project, i am just now going back to tweak it

[petemoore]

  Volume drop = problem with TS, there should be lots of boost in that circuit.

[MartyMart]

Check the "what to do when it doesn't work" stickie and come back
with some voltage readings from the opamp etc, it's "fixable" but we
need details

MM.

[Mark Hammer]

  Volume drop = problem with TS, there should be lots of boost in that circuit.

It's not the loudest pedal in the world, but yes there should be a noticeable volume boost.  Moreover, the addition of the 3rd diode will increase volume not decrease it, by raising the ceiling on clipping.  The difference won't be huge but it will be quite noticeable.

There is a build problem somewhere.  Possible you read a component value wrong?  Or that there is a solder bridge somewhere?  Possible a buffer transistor is installed wrong?

[christobean]

dont have time now but i will double check the traces and get some voltages sometime this weekend
thanks!

[Gus]

Many years ago I built a TS like effect with a rotary switch(6) to change diode clipping types and even comp caps.

This is a good way to teach your ear/brain the different "sounds" of diodes and other parts

Make before break

[petemoore]

Many years ago I built a TS like effect with a rotary switch(6) to change diode clipping types and even comp caps.

This is a good way to teach your ear/brain the different "sounds" of diodes and other parts

Make before break

TS is a great taste testing circuit for diodes, a wide range of diodes can be used to clip the threshold voltages available, quite the likable circtuit [IMO] it lends itself well to getting alot of use, and the circuit [unlike the DIST+] can get a clip from even LED's with 'less opamp distortion to dilute the discernable differences the diodes make.
  I took another route, socketing diodes w/8pin IC sockets on clippers.
  To make a TS sound different, Diodes replacements are a great place to start, same is true with all diode clippers.
  Make before Break"...I assume you refer to the theory it is easier sometimes to create a second as it is to take apart and put together the first [assuming it goes back together...]?

[petemoore]

  TS Diode socket....
  not made that I know of, but a 4 pin, 2 connector socket, with 6 wiper socketlugs on top, a direct fit to a TS board, ie remove the sockets from their 4 holes and mount the specially [not]made socket right there...
  Daft...silly idea...would come in handy once or twice per customer...
  "Dude just bought a TS9, says it sounds almost exactly like his TS808, and they sound alot like his Blues Driver...lol...I told him I could build him one up with the sockets here...there...for checking out TS tones...not that I believe in all that past the point of a couple diode changes...[they Have Tone And Gain adj.] after that, one might as well move to a derivitave design I figure...no matter...plenty of TS types for all, to go around...and around.

[Gus]

make before break switch

the switch makes the  contact at the new position then breaks the contact

This helps to reduce clicks and pops

there is also break before make

[dano12]

I'm in the middle of building a frankenscreamer. I couldn't make the choice between diodes, I wanted them all. So the final design was to add a bus for each of the clipping diodes with DPDT switches and various diodes that could be run in series--all switchable from the front panel. By making each side of the bus independent, I'm hoping for lots of variations in symmetrical and assymmetrical clipping.

[christobean]

finally had some extra time to get back to this pedal, and i found that i had inserted a 100k resistor where it called for a 100 ohm resistor.  problem solved.
thanks to all!