tube screamer trouble

[ben moore]

i am having with a tubescreamer build off the tonepad site.

the unit does boost the volume slightly (over the uneffected volume) but there is no overdrive there at all , and i would have expected a larger volume boost.

i could not locate a 51pF cap for near to the diodes - so had to use 56pF instead. could this be the source of my grief??? or where else should i look for something wrong?

any help is appreciated.
thank you

[zeppenwolf]

Hey dude; sweat not.  Someone who knows way more than me will be along sometime...  I guess they all have a "social life" or something--  bunch of lame-o's.  But I can get you started, I think...

i could not locate a 51pF cap for near to the diodes - so had to use 56pF instead. could this be the source of my grief???

No way.  Those are probably 20% tolerance caps anyway, right?  This electronics stuff doesn't sweat the small stuff-- if some value were mucho critical, you'd have a trimpot in there to get it just right...  Your 56pF is totally close enough.

or where else should i look for something wrong?

Well, do you have a VOM?  Start with your Power connections-- they're the easiest thing to Assert/Fault.  Do you have an "Audio Probe"?  Basically just a loose cord into your amp w/ a blocking cap-- look on R.G. Keene's site for a little picture, I think.  Plug yer guitar into the TS, let the output stay empty, plug your Probe into yer amp, then poke the business end around in your TS, starting at the beginning of your signal chain and working towards the end, and... ?

That should keep ya busy for a few minutes.  

Eden

[ben moore]

so any ideas why the unit might not be distorting??

[Paul Marossy]

What kind of opamp are you using - a JRC4558D? The opamp doesn't really matter all that much, any dual opamp ought to work OK, some will be noiser than others, but they should all work.

Double check every component against the layout and make sure that you didn't unintentionally switch two resistors or something like that...

The other thing that comes to mind is maybe there is a problem with the clipping diodes in the feedback loop. Check that out, too.

Hopefully, you will find out what the problem is quickly. Using an audio probe really helps to troubleshoot something like this. Here's one that I made:

http://home.att.net/~u2p0j0m4/DIY-AudioTester.pdf

Hope that helps, and let us know what it was when you figure it out.  

[timrand]

Have you got the Pot wired correctly from my memory you on only wire two pins on the pot not all three. So make sure you solder one wire to the middle one and one to the outside. I reckon you have wired the two outside pins on the Pot.

Check the diodes as well.
56pf Is fine.

[ben moore]

thanks for the suggestions. i am using a 4558 from jaycar.
i will double check all my components and have a go with the audio probe when i get home.

i assume that you are talking about the drive pot having only 2 pins wired...  i'll give this a look as well.

will post my results later.....

thank you guys heaps

[timrand]

yep thats the one let me know what it is

cheers.

Also check for a solder blob between the pins of the opamp. Especially on the opamp that drives the drive section you could have shorted the input to the output

Cheers Mate

[ben moore]

thanks man you were right on the money. i had all 3 pins connected on the drive pot! i am now tube screaming away........... sounds nice

thanks a lot

[jason h]

ben-
    At what point on your level control is the output of the effect signal and the bypass signal the same? And how do you like the tone control?

jason h

[timrand]

Happy to help give me a credit on your Number 1 album !!

[ben moore]

jason

been a bit busy to check that out for you but i'll have a play tonight an let you know.
from memory, the volume is level about 12 o'clock ish, but depends on teh drive position

[ben moore]

yeah i was right. unity is at about 12 o'clock. and i found the tone control to be fine.

[Brian Marshall]

if everything works but the gain pot, then the problem has to be the feedback loop.

[ben moore]

thanks guys my tube screamer is working great now.....

[Paul Marossy]

What version did you build? The TS808?
Did you use tantalum caps for the .22uF caps or?
I'm building the TS808 circuit right now, looking for opinions on the tone caps and stuff.  

[brett]

Hi.  Although my TS9-ish pedal has tantalum caps in it, I don't believe they make too much difference.  Some say they add a little "grittiness", but there's probably more difference to be had from other things in your 808.  The "body" cap mod is an example that is worth pursuing (ie increase the grounding cap from 0.047uF in the gain stage).

Have fun

[ben moore]

yeah i did build the 808.
i just used ceramics actually.

[Paul Marossy]

I actually have used ceramics in a lot of my projects, and they sound fine to me. I usually use the HV type, which exhibit less hysteresis than the low voltage ones do. Which means they respond to frequencies a little better than the low voltage ones do. I also like to use them because they seem to make things a little slightly more crunchy. Some people claim that they can hear the difference between ceramic caps and other types. The differences between them, IMO, are so subtle that only DIY'ers and their kin can hear such things. I seriously doubt anyone on the street who would do a "taste test" could really hear any difference. But that's just my opinion. People can get into arguments about caps!  :?

[Paul Marossy]

Well, since were on the subject of the Tube Screamer...
I just finished up mine tonight. I must say, that is a nice sounding circuit. I measured all of my resistors with my DMM to get them as close as possible to the values spec'd on the schematic and used precision resistors where I could. I used film type caps for the 0.22uF caps and ceramic for the rest. I also used 2N5089's for the input and output buffers, JRC4558D for the opamp. It's nice and quiet and has a good amount of distortion. It really does sound good - really smooth and tube-y sounding.
Thanks for the help.  :wink:

[ben moore]

can someone direct me towards a representative sound sample of a ts 808. as after hearing the ts9 sample on tonefrenzy i realise minbuild has nowhere near that kinda of distortion at all.
how distorted should it get? or is it jsut a sort of boost to slightly overdriven sound?