Thanks Phatt and Fahey for your reply and great explanations..

I have some experience in etching PCB...

So the summery of the above discussion is too much thin tracks will cause terrible problem for home etching board.

Too wide tracks are not necessary either meaninglessly. The difference between tracks are also an important parameter must be in consideration.

I think ironing image on the copper board weaken the copper layer to stay attached to the board and too slim tracks often wore off..

Now my question is -
Is it bad to have ground plane (not closed:)) ??

please see my attachment of p27 pcb 100% sized image and rate it overall for spacing and widening only..(1 to 10).

Thanks

Hello

I have just completed drawing p27 pcb (preamp board) on 1.75"*2.5" board area.
please check my attachments...(pre2.pdf)
I have used trimmer instead of real pot for checking purpose.

couple of questions to ask..
when drawing PCBs i sometimes find free spaces so that i can thicken certain tracks..Is it good to widen tracks unnecessarily (without wasting any extra board area of course! ). Cause wide tracks are stronger..Which is beneficial for home PCB etching and soldering
For example I am uploading a PCB image from General_guitar_gadget_com. The tracks can be broken any time.. 

Dear Fahey

Great explanation...Yes c14's negative should be connected to emitter..Similar to input buffer in microamp....

Thanks

Thanks enzo for your reply...I am from the other part of the world, India...where i have to rely on my local market. Sad but true...here larger value non polar capacitors are available in very higher voltage values like 300v,400v...which are not only costly but also huge to fit in boards...that's why i have asked here to substitute with polar electrolytic..

So can you please verify whether the polarity of those capacitor are correct or not??(please look at the second picture)....

HELLO,

I am currently drawing pcb for rod's project 27mk2. there are few capacitors in the diagram greater than 1uf in non polar which are hard to find in small voltage. so i would like to replace them with electrolytic capacitors. i have edited that image in paint...please verify if their polarity are ok.
Thanks in advance...
Subha

ok! Best of Luck!

Hello Stormbringer,

I am currently building my amp too. recently finished power amp module and cabinet speaker assembly. Stuck on preamp. My requirement is quite same as yours. can you please elaborate your plans on adding several components. since you have already completed tonestack+cabsim. is it common for all the channels(tone stack).? Or each individual channel will have a separate but same tone stack? what is your plan on different channel. Mr Fahey recommends 1.Elliot project 27/27b 2. Marshall Lead 12 preamp.

dont know but curious: why dont you use higher voltages like +-15v for opamp biasing which is very common in commercial amps?

you can check my thread recently started:
http://www.ssguitar.com/index.php?topic=2759.0

thanks 

Ok Mr Fahey, Let me try firstly Rod Elliot project 27. But please clear certain facts--

some quotes from rod's site

1.
"A photo of the Revision-A preamp is shown below. You'll see that there are two dual opamps, but the schematic only shows one. This is the main part of the Rev-A update - the output section now has gain (which is easily selected), and a better buffered low output impedance. The remainder of the circuit is unchanged. Full details of the new version are available on the secure site for those who purchase the PCBs."

2.
"The diode network at the output is designed to allow the preamp to generate a "soft" clipping characteristic when the volume is turned up. Because of the diode clipping, the power amp needs to have an input sensitivity of about 750mV for full output, otherwise it will not be possible to get full power even with the Master gain control at the maximum setting. "

now my questions...

1. The power amp mentioned there is transistor based. so can i directly use preamp out to lm1875/lm3875 etc?
or any interface is required?
2. same thing about if i add fx loop, fx loop in will directly goes to power amp in?
3. I see every commercial amp use +-15v supply for preamp compared to 9v for pedals. What is the benefit of using bipolar supply?
4.many people suggests ROG projects. Now are they meant to be used as a preamp? though they use 9 v supply.
5. i have earlier checked with my friends amp that adding dist pedal infront of clean channel sound thin.

Quote from: J M Fahey on November 06, 2012, 08:40:00 AM
Start by building the Marshall Lead 12 preamp , coupled to any power amp you like , from 10W to 100W.
Killer sound.

Have a good reading of this thread:
http://www.ssguitar.com/index.php?topic=2749.0

To show that I do what I preach, in the end there's a small demo of an amp I built long ago, using such combination.
And, no tubes needed, of course, to get excellent sound.

Hello Mr Fahey,
Thanks for your reply.. Yea I have checked your post. Is that you playing the guitar??Very Cool

By the way this is the youtube link for 8020:
http://www.youtube.com/watch?v=eQyvi8iVT2w
Sound good to me. Though a bit complex than lead 12. Whats your thought? If you please verify 8020 to see if at all the schematic is promising or if there any flaws. after confirmation I will redraw the circuit in circuit maker and again will post here.

another thing to ask. 8020 schematic contains 1875power amp . practically what I was looking for.

Hello,

I am new to this site. actually I am trying to build a solid state guitar amp of marshall type. do marshall valvestate 8020,8040 worth trying? 8040 even have a tube. i never worked with tube. so 8040 is bit harder for me.

basically i need this: Guitar to amp(clean and distortion channel) --fx loop-- power amp. so i need to drop the reverb circuit.

http://www.drtube.com/schematics/marshall/8020.pdf
http://www.drtube.com/schematics/marshall/8040-iss8.pdf

Thanks