Tube Screamer TS808 question

[jimitrader]

Tube Screamer TS808 question?
r17 and r18 show  as 510 k resistors ..i do not have these
I do have some 560 k and 470 k what do you guys think...would either be fine?
should i try to "make one" with series or parallel ?
what have other people done here? thanks a bunch in advance

[antonis]

Presuming R18 is the one marked as R12 on Q3 bias, you can use either 560k or 470k, with the later as first choise..
(ElectroSWmash schematics are full of typos ..  like 2 X R11 in Tone/Volume stage..)

[jimitrader]

r17 and r18 and r12 show  as 510 k resistors ..i do not have these

thanks for the response...i did not know that about electrosmash..thanks
so
antonis you are recommending 470k?

[antonis]

Yeapp..!! 

Depending on SC1815 variant (O, Y, GR or L), bias resistors may require to be of lower than 470k but this will lower Q1 & Q3 input impedances so proceed to 470k and cross fingers for SC1815O current gain of 100 or higher..

[willienillie]

Tube Screamers usually came with 2SC1815-BL.  2N5089 is an excellent substitute.

[Electron Tornado]

The 510k values for R2, R12, R17, and R18 seem to be consistent in a couple of schematics I checked. In this schematic, R17 and R18 are on either side of JFET Q4, which is part of the bypass switching system.

Try the 470k you have. If you want to get closer to the 510k, put a 33k resistor in series with each 470k resistor, and you'll be well within the tolerance range for resistors. Actually, 470k is already in range for 10% tolerance resistors, and fairly close for 5%. (Anyone want to venture a guess as to what tolerance Ibanez used?    )

[willienillie]

(Anyone want to venture a guess as to what tolerance Ibanez used?    )

Not a guess, 5%.

[antonis]

Not a guess, 5%.

You've measured them all or it's a logical assumption due to E24 series..?? 

[willienillie]

Not a guess, 5%.

You've measured them all or it's a logical assumption due to E24 series..?? 

Neither, they have gold tolerance bands.

[jimitrader]

thanks everyone! I did the series thing and created a couple 510k ..works good...thanks again.