TS 808 hiss

[Gledison]

Hello Everyone!
Jus finish a TS808 following the tonepad layout.
Im having an issue with a hiss. It seems die to the untegulated power supply, because the problem is gone with batery. The thing is that if i move the drive all the way up, the hiss is gone! Its there only when the drive is between 10 to 90% what do you think? Cheers

[Govmnt_Lacky]

Can you try the 808 with a battery? If it is still hissing with the battery, you can eliminate it from being a V+ supply problem and move on to looking at the actual circuit.

Also.. what op amp are you using?

[Gledison]

Can you try the 808 with a battery? If it is still hissing with the battery, you can eliminate it from being a V+ supply problem and move on to looking at the actual circuit.

Also.. what op amp are you using?

hey Govmnt Lacky.
With the battery no problem at all! im using  a 4558 IC.
cheers

[Govmnt_Lacky]

More than likely the hiss is being induced by the unregulated PS. I have lost count of how many pedals I have that get some kind of noise with unreg PS.

My advice is to look for a 1Spot or another filtered PS. Since I got my 1Spot (which can often be found for a good price) I have had no problems 

[Gledison]

Hmmm, im using 1spot! I thought that 1spot is not regulated is'nt?

[Govmnt_Lacky]

I have never had a problem with my 1Spot. 

The only other suggestion I could make is to try a quiter opamp (NE5532, OPA2134, etc)

-OR- try a different REGULATED power supply.

[Gledison]

hmmm, this will be difficult at the moment..
The wierd thing is that the hiss started at 10% drive untill 90%, from there up, no hiss at all...
if was an unregulated PS issue, it should keep all at full drive right?
i have noooooooo bloody clue!

[Govmnt_Lacky]

hmmm, this will be difficult at the moment..
The wierd thing is that the hiss started at 10% drive untill 90%, from there up, no hiss at all...
if was an unregulated PS issue, it should keep all at full drive right?
i have noooooooo bloody clue!

SO, are you saying that there is NO hiss from 0-10% and from 90-100%?

You might want to do some basic checks to rule some things out:

1) Did you use the right size and taper pot? (500K Log or Audio)
2) Is your wiring to the Drive pot correct?
3) What kind of diode clipping are you using?
4) Did you use the called for 51pF cap?

[Gledison]

hmmm, this will be difficult at the moment..
The wierd thing is that the hiss started at 10% drive untill 90%, from there up, no hiss at all...
if was an unregulated PS issue, it should keep all at full drive right?
i have noooooooo bloody clue!

SO, are you saying that there is NO hiss from 0-10% and from 90-100%?

You might want to do some basic checks to rule some things out:

1) Did you use the right size and taper pot? (500K Log or Audio)
2) Is your wiring to the Drive pot correct?
3) What kind of diode clipping are you using?
4) Did you use the called for 51pF cap?

Hey mate!
im sorry, actually the hiss is when the "level" is from 10=90%, not the drive.
the pot is correct , 100k linear. I've re-checked the wiring and it is correct.
im using the symmetrical clipping diodes 1N4001 (on the layout should be 1N914)
Instead of the 51pF I've used a 56 pF
the other substitution was a 0,033 uF instead of a 0,027 uF suggested.
I've seen you know quite well this layout don't you
ah, I etched my own PCB
Cheersa

[Govmnt_Lacky]

OK...

Well, this is an AMPLIFYING circuit so, it will amplify any impurities in the incoming signal.

Next recommendation is to use shielded wiring from the Input and Output jacks to the 3PDT.

If that does not work, then you might try adding shielded wiring from the 3PDT to the In and Out of the PCB.

Since it is quiet with the battery, it must be caused by the PS (1Spot)

You could also try a larger decoupling cap (100uF instead of the 47uF)