My first build from scratch, could use help. (Tube Screamer)

[joelap]

Hey all, I'm relatively new here.  I've built a few pedal kits and tweaked a Vox 847, but now I'd like to do my first build from scratch (well, aside from the circuit board).  I'm going to be building a tube screamer.  I've got a few ideas for mods, and I figure after I have the thing built and working I can tweak other mods, but based on the circuit board from www.buildyourownclone.com, I've planned to do the following as of now:
1) Switch between .47 cap and .22 to switch between the mid spike and a more smoothed out response
2) Switch between Symmetrical and Assymetrical Clipping
3) DPDT switch used to add an extra diode in series with the other diode, for more transparency and less distortion with more volume.

I made this in paint... maybe after my final exams finish I'll get adventurous and Pspice the circuit for my own good.  Is what I'm trying to do possible?  I'm almost possible 1 and 2 will work, but will 3 work?



Finally; whats some good quality components for caps and resistors?  I think I'll be going through Mouser, but whats a good company to buy caps from, and polyester vs. polypropelene?  I've built kits before but never ordered products from scratch.  And one more thing... any other suggestions for mods that you guys have tried or think might be worthwhile to consider?  I'm intending for this to be a pretty versatile beast, but with all switches off a TS808 clone.

Thanks.

Joe

[bioroids]

Hi!

What is exactly the difference between #2 and #3? I mean, with adding an extra series diode (so one side gets two diodes and the other one) you already have assimetric clipping.

Also, I think a SPDT is enough to add a series diode (#3).

Hope this helps!

Miguel

[RLBJR65]

Small Bear is a good place to buy stompbox stuff from. www.smallbearelec.com

[joelap]

Hi!

What is exactly the difference between #2 and #3? I mean, with adding an extra series diode (so one side gets two diodes and the other one) you already have assimetric clipping.

Also, I think a SPDT is enough to add a series diode (#3).

Hope this helps!

Miguel

I'm going off of information from this souce: http://www.buildyourownclone.com/screamermod.html
"If you want more
pronounced asymmetrical clipping just
keep adding extra diods in series to
one side of the clipping stage...that
is...solder them end to end. to make
one long diode.  This will also
increase your volume and decrease
distortion.  This is what is going on
with many of the boutique overdrives
that are know for their transparent
boost properties such as Klon.  You
can also use an LED instead of the
1N4001 because after all, an LED IS
just a diode.  This is the formula for the
clipping stage of a Langraff overdrive -
1N914 + yellow LED"

So basically, adding another diode in series will make it asymmetrical?  So then to get the more transparent effect of adding another diode in series, it would end up being asymmetrically clipped... I'm still new to this stuff, you'll have to forgive me.

[johngreene]

IMHO, I would recommend just trying different diodes yourself and draw your own conclusions. I few hours of experimentation and you will probably find out more about this than you could find in 20 hours of reading about it. As the Nike ad says, just do it. 

I would also try different values of capacitors rather than just go for a .22uF. I would also experiment with the .22uF caps that are after the clipping stage. I've found it's very difficult to find a particular value that works with every guitar and every kind of pickup. But that's what is cool about building it yourself. You can custom make your pedal to match the guitar(s) you play.

--john

[joelap]

IMHO, I would recommend just trying different diodes yourself and draw your own conclusions. I few hours of experimentation and you will probably find out more about this than you could find in 20 hours of reading about it. As the Nike ad says, just do it. 

I would also try different values of capacitors rather than just go for a .22uF. I would also experiment with the .22uF caps that are after the clipping stage. I've found it's very difficult to find a particular value that works with every guitar and every kind of pickup. But that's what is cool about building it yourself. You can custom make your pedal to match the guitar(s) you play.

--john

Good point.  I guess I'll just order the parts and see what I like for myself.  Thanks.

One final thing... on the Langraff, it has a Diode Lift option.  What does that sound like?

[johngreene]

I'm not familiar with 'Langraft' but if the diode lift option is just removing the diodes, then you are getting the effect of the opamp clipping. The effect will differ dramatically with different opamps. Try a bunch, most are less than $.50 each.

--john