LM308 in the UK

ReaGeorge · Post by **ReaGeorge** » 01 Apr 2015, 11:25

Hi,

I'm new to the forum and pedal building.

I'm in the process of getting a RAT clone kit working the main board and wiring is assembled but it's not functioning as should. I've done allot of checking and rechecking swapped out some of the more sensitive components but nothing has made a difference.

So now I'm gonna replace the IC and really hope that works. Problem is I can't seems to find a supplier in the UK, does anyone know of one, or do I just need to order of ebay?

I know doctortweek used to stock them but his site has been down since the beginning of the year it looks like.

Nocentelli · Post by **Nocentelli** » 01 Apr 2015, 11:41

You could try eBay, but beware they seem to be charging stupid money. Any single opamp with the same pinout should *work* in the Rat, i used a 301 and it sounded great, so make sure the rest of the board is good before you dismiss the fault as the lack of original chip. Is it actually working but not sounding exactly like an original Rat, or not working properly?

ReaGeorge · Post by **ReaGeorge** » 01 Apr 2015, 15:32

So the volume and filter seeem to work, the distortion pot acts rather strange with no signal when all the way down, it increases until a certain point when it makes the the whole pedal react completely different, there will be signal if you play loud but sustain is completely lost. And the pedal is also decreasing the overall volume from guitar to amp rather than amplifying it.

You can check out this recording I made of it showing first the dist at the point just before it changes then turned all the way up.
https://www.dropbox.com/s/4nzk5oqnbb2v2 ... t.aif?dl=0

Yeah it looks difficult to get a good price, but I don't feel like I have much choice. Might try the 301 if its a considerable price difference, does it not differ in sound from the 308?

Nocentelli · Post by **Nocentelli** » 01 Apr 2015, 20:05

What IC have you tried? And what layout are you using (link)? I haven't tried a an authentic LM308, but the 301 has similar specs, i think I messed with the compensation cap value and also tried out a few other single and dual opamps, most of which worked. I must have got the 301 from tayda, because my usual UK cheap postage sources (bitsbox, spiratronics, Dr tweek) don't stock it.