Ok I've redone the schematic again. If I didn't have you guys I would of seriously gotten nowhere 

That was just the value i got from my equation, i will obviously put a std resistor in there i just couldnt think of what value at the time. I shall take a look later if i have time, got band practice first. Thanks guys for all your input on this.

Right I found a website to help me design the second stage of the Pre Amp, only part I'm not sure about is the 5K Pot as I'm supposed to use a 3K Resistor on the base......

Hmm could i do that with a JFET though? Or would i have to add a bjt stage?

Yer i think i saw a schematic where they mentioned using 2 diodes one way and 1 diode the other to get the extra harmonics.

Site came back up, I've attached an updated schematic. I picked the 1N4148 as a few circuits I looked at used those.

Right I see, I think I know how to achieve the soft clipping now, however the online schematic website I use is currently down so I can't publish a schematic to show you how I think I can do it 

Ok on my amp would that be between the negative input of the TDA2050 and the 22k resistor coming off the output of the chip?

I'll probably try both the diodes and the extra gain stage, get an idea of the different sounds both methods make. I quite like the fact that a lot of people slag off the diode method when actually companies such as Marshall were using that method in their valve amps

Thanks, I'll see what the amp sounds like once I've built it and go from there. I don't actually like very much overdrive, but then I don't like clean either . If I can't hear my open chords ring out, theres too much overdrive!

I've updated my schematics so they are much easier to read now. I've added the dots in and also removed the 1M Pot between the two Pre Amp Transistors as I believe when I had this in the circuit before it simply acted as a volume control.

I've not got round to building the circuit just yet as I've been a bit busy, but tonight I have taken off all the components off the PCB from the old Power Amp so I'm ready to start laying out my circuit.

Now once I've built this, if I want to increase overdrive/distortion within the pre amp, how would I go about it?

You made a very good point Roly, so I've edited my schematics. I shall remember to use these symbols in future.

I have now ordered a couple of TDA2050s, so once they arrive I shall dig out the rest of the parts and work out how I'm going to lay out my PCB. I will also change that tone control capacitor to try and improve things, just for the moment anyway, might change it altogether as suggested by yourself.

Alright I didn't mean to upset anyone by picking the wrong symbol, I just used that symbol as it was there in front of me and I understood what it meant. If I was publishing this schematic online (which I most definitely will not) then I may of put a bit more thought into it. I'm not a young whippersnapper trying to reshape the world, I'm just trying to learn about electronics.

It wasn't on the schematic you're right, I just forgot to add it in, that capacitor is currently in the circuit. I'm not saying you're wrong in anyway, I was just pointing out the circuit currently works with the 470uF in it (well barring the power amp obv), sorry I forgot to point out my mistake.

I will add that trim pot modification onto the PSU, just need to work out how due to space etc. It may be below the maximum for the chip but it won't do my Pre Amp much good as those Transistors can only take up to 25volts. Not sure how the guy who originally designed the amp had 33volts going on it as those Transistors should of blown surely.

It does work quite well at the moment though? A little too well to be honest it can make the sound so bassy that you can barely hear the high notes!

This amp won't use more than 2amps will it?

I've amended the schematics and attached them to this post. The PSU I may leave as is as it is already built and working, however I will add the 4.7K Resistor in parallel with the Trim Pot to give a maximum of 24volts. I've also left that 100K resistor on the PSU in case I want to test the PSU without the amp connected.

With regards to the AMP the capacitors you specified are on the schematic as non polarized, they just use the same symbol as the polarized capacitors except for the missing positive sign. I will add an 100uF capacitor by Q2's Drain if need be but it does work ok with that 470uF on Q1's Drain at the moment.

O god i'm sorry i forgot to connect them, apologies it was late last night i drew these up. Ok i'll make amendments tonight. The trim pot modification on the PSU may be a bit difficult as its already built and bit tight on space in that area but i'll see what i can do.