Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Hello friends,

I want to modify tone stack from preamp, and need output impedance value from marked point to simulate new one (tone stack) through LTSpice.. How to do that?

Thanks in advance!

To a first approximation it's zero.

It's actually about 200 ohms, but it's so low compared to the values in your tonestack as to make no never mind.

On the datasheet the equiv cct shows two 64 ohm emitter resistors into a 128 ohm series resistor to the output, so it's at least 128 and more like 200-odd.

In LTSpice you are going to use an op-amp model, and this will have the internal source resistance accounted for.  You can find a TL07x model at Yahoo LTSpice group, a great resource.

Or you could measure it.   8|

An op-amp provides almost perfect voltage source drive from very low impedance which is just what this tonestack wants.  It's the load on the tonestack output that is quite important, generally the higher impedance the better.

Thank you! Now it is much clearer.

My intentions is to add origin Fender tone stack, with mid pot, like that on first attachment and from TSC... Current tone stack have similar frequency response like Fender TS, i am aware of that situation after simulated it via LTSpice, but i want control of middle frequencies.. And what confusing me... Zsrc of Fender TS is 38K... Do I have to achieve this value, as with, let say 200ohm of Zsrc, i get a totally different frequency graph in LTSpice?

I was comparing in LTSpice this two tone stack, but with Zsrc of 38K, and were very similar, almost identical graphs ..

The 38K in TSC is a rough approximation of the output impedance of a 12AX7 with a 100K plate resistor.

I understand that, but what the impact will be on the response curves when I add a Fender tone stack instead of the existing one, when i have only a few hundred ohms of output impendance after inbut buffer, but before tone stack.. I ask this, because simulation of that situation drasticaly changes response curves..

In fact it does not drastically change *shape*  which is what's real important, what gives it "flavour".

What it changes basically is attenuation, but in a more or less even way.

I don't use LTSpice but simulate with excellent Duncan's TSC and which has memory of different curves, so simulate the same with different generator impedance, say 200r , 1k , 4k7 , 22k and 38k .

You'll see they are roughly parallel.

As of the effect of the mid control, all it does is set the depth of the filter notch, so yes, in a way, it "controls mids" .

Don't expect much from a simple resistive, non frequency selective control.

Hi mladenu ,,
Um  unless I'm mistaken the drawing is from a Rockette amp which was discussed here not long ago.
So might help if you mention What amplifier are we talking about? :tu:

This is not easy to explain but I'll give it my best shot;
As has been said already forget the output Z of the opamp, the response curves set by the components wrapped around (and in series with) the first stage will alter the result far more than output Z.

Many of those famous Valve amps have identical tone stacks yet sound very different. :o
In other words, just inserting the perfect tone stack inside an existing circuit will not magically make mojo. :-[

In fact with 2 identical circuits just changing one Cap value before or after the preamp and tone circuit can reap 2 very different results. 8)

Tone circuits are just there for tone trim by the user they Do Not (on there own) dictate the Tone, as That is the sum of the whole circuit not just knobs on the panel.

Now as to the circuit snippet you have given;
There is a Cap with no value? So that will alter the amount of top end that passes.

If this preamp is from a Rockette 30 or similar then it's highly likely it will be very bright. I did some research for member *Jungle Jim* Posting here; http://www.ssguitar.com/index.php?topic=3647.0
Jim  found some of the Caps with no value were not on his circuit and this dramatically changes the end result. Without them the amp will most likely sound very harsh.
A simulation of his circuit reveals the tone is very bright, I'd research the whole circuit before a major renovation. 8|

Phil.

Phatt, You are totally right, the rockette 30 is the subject of topic. I read all posts pointing to Jungle Jim`s hiss problem, and also share that issue with him... BUT, i found some interesting sentences, maybe problem related, on some other forum:

Quote:
I 'warmed up' my Rockette quite a bit by replacing a resistor and a capacitor in the input-circuit just before the first op-amp (allowing more high frequencies to flow to ground before getting amplified). I'm guessing Stewart Ward does a similar thing when he talks about taming the treble of the amp. Very simple and effective mod that will only cost you half a pound in parts. But you have to be able to read a schematic (they are on the Award-Session website) and locate the parts on the print, de-solder the old parts and solder the new parts in. It didn't take me more then 30 minutes though and I am very pleased with the result: a fuller tone and no more overly-bright trebles. But this has nothing to do with the RetroTone mod, as that concerns the power-amp and negative feedback circuit, 'current feedback' Stewart calls it.

And another one quote:
Look at the first op-amp after the input. There's a 100k resistor and a 10nF cap in series. I changed those to 47k and 220nF and liked the result a lot! (Got this from a Sessionette 75 user.) After that mod you can cleary hear that now it's the reverb that adds some hi-freq 'hiss' or 'sizzle' and not anymore the pre-amp.

End of quotes.

I have no problem with hiss, nor with tone, but think the desired fender tone stack could improve this little amp, which have very good response, transparent sound, etc... I understand that wrong or bad topology with perfect tone stack mean nothing... :)

LTSpice sim of Fender tonestack with source impedance swept 0 to 50k x5k steps attached.

If we think of the situation as a voltage divider, the source impedance Zsrc being the top impedance and the entire tonestack being the lower element; and that the source impedance is actually resistive and not frequency selective; then it follows that simply changing the source impedance will only change the absolute amplitude of the frequency selective contour imposed by the tonestack, not the shape, and that this will be true for all settings of the tonestack controls.

QuoteTone circuits are just there for tone trim by the user they Do Not (on there own) dictate the Tone, as That is the sum of the whole circuit not just knobs on the panel.

YES.
This very  central fact is so often overlooked by people wanting to alter the sound of their amp by focusing only on the tone stack.

All your advice helped me a lot and a lot of them I learned .. As it was obviously that i not enough professional use LTspice ...  :loco

Thanks Roly for that observation...

Let me explain you what is my aim... Session Rockette 30 amp which i have is tonally very similar to fender amps.. Only reason for why i want to add original fender tone stack is because i want to controll mid range... I could instead 6K8 resistor put 10k potentiometre... But while modify TS circuitry, let's do a complete mod.. :)

Quote from: mladenuI could instead 6K8 resistor put 10k potentiometre

A bit of a fiddle in Tone Stack Calculator (http://www.duncanamps.com/tsc/download.html) suggests that if you want some real control over the Fender mid-scoop that you use a 50k Linear pot for your Middle control.

You could always do what I did!
Build an external tone box,, and just leave the existing one alone.  8|

Fender and similar tone stacks work like a big lump of jelly,,If you alter one R or C value it then tugs at another freq and although the tone calculator is a great help it's still only one part of the whole system and as such may or may not work in your amp. As mentioned before and noted by ENZO who is way more qualified than myself,, (thanks for the comment Enzo :tu:)
The whole system has to be taken into account.
An option;
Dave Reeves Hiwatt tone control is by far the best at mid control. :tu:

I've researched A LOT of tone stacks and the Hiwatt concept is about as good as it gets. I've built quite a few tone circuits based on Hiwatt idea in stand alone boxes as modifying the internals of amps is always a pain and likely to reduce the resale value if you bore to many extra holes in the front panel.  :-X
An external tone unit also gives you two tone control options and I've found that to be a big asset.

I had a chap come over with a brand new Fender Deville 212 and after I added some castors for him (they are very heavy) we plugged in for a quick jam.
He was impressed with the tone of my humble setup and asked How, what and why??? Needless to say I just plugged my simple tone box between his guitar and Amp and the difference was night and day.

Having said that It's no magic bullet and likely won't work well if the amp is already very harsh and bright.

The mod you mentioned, the leg from Neg input of U1 with the 220n and 47k leg to ground looks good on sims. That returns all the bottom end, though the gain does go UP quite a bit so that may cause issues if circuit noise is already a problem.

If you want my take on Dave Reeves HiWatt tone circuit it's here somewhere,, just search for PhAbbTone Ver 3.5
I may have an updated schematic coming soon as some noise still gets in as these hi z circuits are all prone to picking up noise.

With some gear it may work better after gain stages, like in the FX loop.
Every bit of gear is always slightly different so you have to experiment, especially if you want to hack an existing rig.
Phil.

Parametrics mate.   <3) :dbtu:

Quote from: Roly on April 25, 2015, 12:28:58 PM
Parametrics mate.   <3) :dbtu:

Yes Para EQ is brilliant but most of the guitar players I meet would struggle to spell Parametric,, let alone know how to use one,  :lmao:

I was going to mention the parametric type deep notch the Hiwatt produces.

while testing I did indeed test the PhAbbTone against my Alesis Para EQ and the effect is close. Of course a full parametric EQ would be a lot harder to build using hand drawn ink pen on the copper.
:duh
When I built most of the early Ptone boxes I did not have a laser printer to make iron-on PCB's but now I can make them a lot smaller.

As for the Ptone response, With bass and treble at full and mid off the notch is around 30 dB deep (from top off bass curve).

The Alesis has a claimed +/- 15 dB boost/cut which should do a similar job of tone shaping but the PhAbbtone even with it's fixed freq just seems to work better for guitar. <3)
In most of the fender tone circuits you are lucky to get ~10dB of mid dip and the deep notch is never apparent.

I also tested the fabled Dumble tone setup with tone shift switching. IMO, not worth the effort. xP
Phil.

Quote from: phatt on April 25, 2015, 07:38:10 AM
You could always do what I did!
Build an external tone box,, and just leave the existing one alone.  8|

I plan that :), because when i direct input guitar to return in, no hiss at all... thus all hiss is generated through preamp...  And external tone box will be bingo.. :) PhAbbTone with volume pot direct in return? And i will have clean amp..

Quote from: phatt on April 25, 2015, 07:38:10 AM
An option;
Dave Reeves Hiwatt tone control is by far the best at mid control. :tu:

If Hiwatt control contain Fenderish character?

Quote from: phatt on April 25, 2015, 07:38:10 AM
The mod you mentioned, the leg from Neg input of U1 with the 220n and 47k leg to ground looks good on sims. That returns all the bottom end, though the gain does go UP quite a bit so that may cause issues if circuit noise is already a problem.

Seems like Session preamp suffer noise problem because of sparkle characteristic and good response? :/ Or reason is not great topology... If that is true, another one reason for PhAbbTone.. ;)

Quote from: phatt on April 25, 2015, 07:38:10 AM
If you want my take on Dave Reeves HiWatt tone circuit it's here somewhere,, just search for PhAbbTone Ver 3.5
I may have an updated schematic coming soon as some noise still gets in as these hi z circuits are all prone to picking up noise.

If i understand, you have greater version than 3.5? I will wait for that.. Less noise, more want.. :D

Yes it will sound very Fender but that depends on your interpretation of a *Fender* sound. 8|

Bypassing preamp means you loose any OD effect but if you have some decent pedals and a tone control then you may find that more pleasing. I've done that trick a few times for local players who have struggled with there rigs, just a couple of pedals and a tone box bypassing the whole preamp.

Be aware that the Ptone does not add any distortion it's super clean but it does the classic big round bass and sparkle treble.

If you want the preamp and tone section to respond like a triode valve preamp then try *Loudthud's* design.
Here:
http://www.ssguitar.com/index.php?topic=3732.0

Just replace his tone stack with the Ptone circuit,
I've never tried his circuit but the idea looks like it will give a little half wave clipped edge to big notes emulating the classic triode rattle you get from valves.

As to noise /hiss and like issues,,
Even big name circuits can come with design flaws, just one tiny oversight in the layout of pcb can cause all sorts of excess noise to creep into the signal path.

Meantime pictures speak mountains, this screen shot is your Rockette 30 preamp with the tone section replaced with my HiWatt inspired Ptone.

The *yellow curve* is the standard Rockette tone response while the green curve is the PhAbbtone. Notice the deep mid notch. Unlike most of the other tone circuits which only tend to dip the mid with a shallow scoop this forms a deep narrow notch.

Both traces are taken with the tone controls at 90% while the mid on PhAbbTone is of course set low to show the full effect. in actual use it sounds good for me with treb around 12 o'clock, mid 9 o'clock Bass around 1 o'clock. your setup might be different as many other things alter response.
Phil.

Fendery?

I think it goes *beyond*  Fender in chime and sparkle, so much so that it kept that sound even when heavily overdriven, go figure.

Just listen to old WHO records, even better some live ones (there's a couple YT videos too).

The 8x12" 100W Marshall was developed specifically for Pete Townshend (his Dad was a close friend and bandmate of Jim Marshall, go figure), and yet he preferred Fenders, there are many pictures showing a Fender head on top of early Marshall cabinets, so he heartily embraced the Hiwatts when they became available.

Using Fender head:
(http://images.epiphone.com.s3.amazonaws.com/News/2015/FEBwhorockpaper.jpg)

early Marshall:
(http://news.bbc.co.uk/media/images/46465000/jpg/_46465477_who_manchester.jpg)

Hiwatt (and anti-gravity belt or something):
(https://livingiseasywitheyesclosed1.files.wordpress.com/2015/02/the-who-live.jpg)
including some tasty Sunn Coliseum 300W Bass heads.

Thanks *Jaun*,
Yes even Mark Huss notes the core difference that set Hiwatt's apart from the others was mainly due to the tone control setup. 8)

Here you go *mladenu*,
                                 I finally got my shed computer sound card working again so a PhAbbtone demo via a proper microphone.
Dead flat with no effects just strat copy> Ptone> Laney.
The bass may not sound as deep with small computer speakers but enough to give an idea of the tone range.
This is the latest unit I built so I'm adding the schematic which you asked for, Hope it meets your approval. 8|

Play around with different values if you wish, try R1 (100k will make it insane bright)
VR3 Bass can be 100k but don't go 500k unless you; 1/ have a real LOG taper pot. 2/ need more bass.
C5 is now 1n8 which stops the mid from dragging too much treble as you turn up.
Cheers, Phil.

Phill, you are marvelous! To mention J M Fahey too.. :) I saw PhAbbTone V4 schematic just after you attached, and via Line out jack from my Laptop through Return in to Session Rockette 30 amp heard awesome tone shaping.. All of this drive me to open some free tool and for the every first time go and try to design PCB layout for ypur PhAbbTone circuit... I know this is just a try, and sure contain many error, but if you have patience and desire, help me to made this acceptable... Well, please, spot the errors, and advice me what to change (sure, if i know how).. :)

Thanks Phill again for this updated circuit...

I have meny question especialy for you, but it will be time for that..

Cheers, Mladen

I'll assume you don't have a lot of experience at board design so this might help.
The pic attached is the actual PCB layout I just made.

Note how the output is well away from input.

Keep the track from Treble wiper to C6 and + input short as this is a High Z circuit and will be prone to noise issues if not careful.

As you will likely be doing this board at home then a big mistake with most pcb software is the pad and track sizes are set for a motherboard and although tiny tracks might look professional it's going to come to grief when you try to drill pads and even worse problems await when trying to solder. Don't make tracks and parts layout too close together as it's also asking for trouble.

I use KiCad to do this but just as easy with the free version of Eagle, just make sure you set Global parameters for tracks and pads.

My board is using 16mm metric pots and the spacing is 23mm which is about as close as you can go with the knobs that are available to me, any closer and you will first need to source those tiny narrow knobs.

BTW how are you going to make/print/drill the PCB?

I use a Laser printer and then a hot iron to melt the print onto the copper, great for home builders like me.

Also a picture of the box I used to make this one, it's an unused foot switch which saves me a lot of fussing to make the box which is the hardest part.
As it's on all the time I don't need the expensive 3 pole stomp switch and that also saves cost.

Have fun, Phil.

(http://s5.postimg.org/xruibfzx3/Ph_Abbtone_V4layout.png) (http://postimage.org/)
how do you print screen (http://postimage.org/app.php)

(http://s5.postimg.org/9mtstqfmf/Ph_Abbtone_V4.png) (http://postimage.org/)
free upload image (http://postimage.org/)

Phill, i have zero experience on pcb designing! As this "pcb layout" by me clearly shows it. :) It's supposed to be my first pcb production tryout.. So it would obviously wait since my layout is bad... :/ Or Phill, if you were kind, and if i don`t ask to much, you may pleased me with pcb layout, because i suspect i`ll make it in resonable time... :/

Thanks anyway...

I noticed that the schematic you first attached is different from PCB layout, and these changes i recorded quickly and half glimpsed.. Red one values are from PCB layout..

Regards, Mladen.

You are doing well just keep asking until it makes sense :dbtu:
Don't expect perfection on the first build in fact if the first build does not work when you throw the switch it's the best way to learn as once you find and understand those small mistakes it stays with  you and unlikely you will make that mistake again.

Years back I wanted to build a killer guitar amp,, foolishly kidding myself that it was not that hard as the instructions were clear enough. What could go wrong,, I can solder? :duh
Ha ha ,, It took me another 10 years before I finally built something worthwhile. All that was before I could even spell cOmputa let alone the amazing internet we have today so with the web and voluntary help from some seriously talented technicians who grace these forums you will likely get ahead way faster than myself.  :dbtu: :dbtu:

As to the different values;
Don't worry most values are not critical, I'll try to explain.
R10 can be any low value from say 10 to 50 Ohms it just helps isolate the supply from other pedals and can help noise.
Not all of those pedal power supplies are the same, some can bleed noise into the circuit. If you have a super clean supply you can delete it if you wish. C10, similar to above, DC filtering often any value from 10 to 100uF.

R5/6 is a voltage division for bias, again any value from 10k to 100k can be used as long as they are the same value to give the half rail (bias) supply.
The general rule of thumb is 1k Ohm per volt, so if you have 10VDC supply then 2x 4k7 resistors would work, lower values give a stiffer bias but pull more battery.

C12 filters the node of DC bias voltage,, can be any value from 10 to 100uF.
You will eventually come to understand which parts of a circuit require close tolerance and which ones are not so important.
I'm not sure about C11 but often used in split supplies systems sometimes right at the supply pins. As I'm trying make it as low noise as possible it can't hurt to add it.

Note:
     Always remember when trying to read schematics it's TWO circuits in one drawing as there is both DC and AC happening.
That is how amplifiers works, AC floating on DC.
You setup the DC so as to pass the best possible signal and if the electrons like your magic smoke design, with luck amplification might just happen. <3)

With discrete circuits (transistors) of old you had to do a lot of DC work before you got it right. Now with opamps even dummies like me can make cool stuff even without a slide rule. :lmao:
Oh R11 (2k2) does not go to ground that is to power the LED light. Choose R11 value to suit the LED you use as some are very bright and you may want a larger value to dull it down. I find those bright blue ones quite annoying on stage.

Now the AC, the signal you hear;

As the input of U1 is very high due to R4 being very large then even if C6 was 2nF it would still pass reasonable bass response. If R4 is a low value then you have to make C6 larger.
This is all to do with impedance and R/C maths. As long as R4 is at least 1 Meg then 10nF ~ 50nF will be fine.

To get the best from these high Z (High impedance) tone circuits the output has to be looking into a hi Z input otherwise the tone control will be severely degraded and will not be able to give the same performance.
**By far this is the most critical point of the whole circuit if R4 was 100k the tone would be dull and lifeless and hardly working.**

As with most passive tone circuits there is no actual GAIN or Boost, they can only subtract or cut but they suit guitar quite well. A 1 Volt signal swing going in might come out as only 300mVolts but that loss is the price you pay for good tone control. Being hi z and lossy in nature there is a signal noise penalty but care with layout and shielding it's fine. I'm loosing count now but I've built about 20 of these units for local muso's.

R5 (1k) works in combination with VR4 to set the gain, another maths equation you likely don't really need to know for this to work. Just know that larger values of VR4 will increase gain and smaller values of R5 will also increase gain. (if you want to understand more, then google opamp design rules as they are not hard to find)
C7 sets the bass roll-off point if the main amp has massive bass you can make that value smaller.

C8, rolls off top end. again this is going to depend on your gear, your pickups, your ears and even your taste in music more that what dictates a perfect circuit. :-X
In My Humble Experience, too much high frequency is a major reason for amplifier hiss and with hi gain now a standard part of most commercial guitar amps it can lead to a lot of hassles. as you have already heard the PhAbbtone it has more treble than you would ever need. The lower the value of C8 the more hi freq content will get through and the more hiss you will hear when distortion and hi gain pedals are added to the signal path.
So up to you? At least make it 100pF.

R6 (100 Ohms) is a safety backup for the output of the opamp, anywhere from 50 Ohms to 1k Ohm. RL is the load resistor. This little sucker helps to drain off capacitor buildup. It pays to have a load there to drain off any Dc when you switch the circuit, the dreaded pop when you stomp on a bypass switch. :grr

Just keep asking questions and even if I don't know the answer there are greater minds here that can step in and help you and also correct any stuffups I might make. 8)

BTW, How are you going to make the PCB?
Phil.

Phill, you gave me a remarkable hour of electronics. Much of it is now clear, and many answers i got. I used your screenshot and practically crossed out PCB layout...  ::) I would love very much if you pointing me to possible errors... Also, i plan to use METALFILM resistors, due to a lower tolerance, and for pF value ceramic capacitors, while for nF value Wima MKS2.. Is this acceptable or there are better solutions? One more thing, the only unknowns to me about layout is potentiometers dimensions like Lug size, Diameter and Spacing..  :loco I would ask you to write me a most suitable, and also their labels.. Believe that`ll be a no problem to find them by the label...

Thank you for everything so far and advance for your answers Phill!

EDIT: Oh, sorry Phill, i forgot to write that i`ll use your Printer-Iron method, as is simple enough.. :)

Regards, Mladen.

Nice thick track widths.  :dbtu:   Better for home etching, and generally there is no point in skimping on track widths where you don't have to.  The more copper you leave, the longer your etchant will last.

I'd suggest moving your jumper to the right, over to between C6 and C11 and nudge C6 left a bit, then you won't have such a squeeze under C6.

Try to get poly-(anything) rather than ceramic's if you can.  It's no big deal but they are better suited.

Thanks for suggestion Roly! :) Something like this? Very hard to find Poly Film, or any Poly- with pF values.. But i can try... What proper to choose for potentiometers? Which brand, diameter, Piher`s.. ?

Hey I'm impressed, good effort. :dbtu:
Q/ What software are you using to make the layout?
If I know that I might be able to give better advice.

Yes Roly is on the mark with wide tracks, especially around pads and even more so around pot pins as these are the only thing holding the whole PCB. Ideally you would use pots with an extra support bracket to support the pcb but I'm in no position to track down those for a home build which will never be abused but be careful once the pots are soldered as the pins don't like being bent much so get your case sorted and holes all drilled ready to mount.
 

Re pot pin-outs;
I'm using standard 16mm Alpha pots, often suppliers will have pdf files with all the dimensions you will need. Be warned, get the parts before you make a pcb and make sure they are going to fit.
Print out a test pcb on plain paper to reference the front edge of the pcb as they have to line up with the collar at base of thread. Never assume the model on the software to be exact.
Even though those pots all look similar there are many versions which are all slightly different.
Of course if you don't need to use pcb mounted pots then it matters little.

These are the Alpha pots I have used;
http://www.tube-town.net/ttstore/Potentiometer/Alpha-Potentiometer-16-mm-PCB/Potentiometer-Alpha-16-PCB-220k-log::4413.html?MODsid=galpd1drup2pglocpijk17pgh2

Regards to capacitors it will work with ceramic if that is all you can get.
C1 and C7 can be ceramic the rest can be green caps. but yes if you can get hold of poly film for C1 they are technically a better type for this situation,, though you won't hear much difference but may help with noise as ceramics tend to be micro-phonic. C7 not an issue just use a Ceramic.

FWIW, I scrounge a lot of junked electronic equipment for parts, a treasure trove of stuff can be found in almost any old El junk these days. For ceramics, greencaps and resistors Electronic junk is free parts supply store. I've had no need to purchase the fine shielded cable for years due. 8|

Take time with the software layout, I often spend a week or 2 just re-arranging the layout and it's amazing how often you stare at something for hours on end and after a good sleep it hits you that there is a better way to layout the tracks.

Yes Metal resistors are less noise prone than carbon so worth the extra cost.  :tu:

Regards to printing PCB.
Assign Full Density of ink, software should have a drop down menu for advanced setting somewhere. Make sure board is super clean.

I use those thin glossy pages from my wife's house and garden magazines. :-X
the print on the page is not plastic and won't bother the plastic ink of laser print.
(though don't print on heavy colured pages, just normal word print pages is not a problem)
The reason is the thin paper only takes a few miutes to roll off after a dunk in Hot water.
When I first tried this trick I used photo paper and it took hours to remove the damned paper.  :grr
(Disregard all that if you already know)
   
Phil.

Quote from: mladenuSomething like this?

Yep.   :dbtu:


I've done a lot of boards so I can get pretty close first time, but I still might spend hours tinkering with exact positions of components and tracks to share the available space around.  For a one-off home etch there is also no virtue in cramming everything into the smallest possible space - laminate ain't that expensive and you just make life hard for yourself with layout/build/debug.

There are a few tiny things I'd tinker, but meh, on the whole that's a pretty good layout  :dbtu:  (we just hope that all the tracks go where they should and nowhere else - I haven't checked it against Phil's circuit).

Ta Roly :tu:, Yep I checked the layout and mladenu you are lookin good. :dbtu:

Just note right before you etch add a big fat ink pen along the back like shown as you need an extra 2 common/ground points, One for the LED return and one for input common.

I like to add a fat copper pad as there is always something you forget usually a ground wire. I also at this point ink pen a bit extra around the pot pins (I've shown 2) and anything else that looks a bit suspect.
Don't over do it and don't use a water base pen.

I use a 1mm drill bit for holes (0.8mm is ideal but they break so easy)
You will also need 1.5mm drill for the pot pins.

Assuming a hand battery drill or similar is used;
Drill holes with pcb laid flat on a heavy block of clean flat wood and tape it down so it can't move.
Oh yeah should add,, lightly centre pop before you drill will help keep your bit from wandering off course.

Drill bit should be deep in the chuck with only 5mm or so exposed as drilling with a long shaft is asking for the drill to break.
Drill speed should be fast, a Dremel tool or similar is ideal for this as battery drills and like are rather slow and that actually will prematurely blunt the drill bit.

Believe it or not,, tiny drills like these need to go quite fast to cut properly.
Metal workshops often have a chart with all the drill sizes and the ideal speeds to ensure you don't spend half the day resharpening drill bits.
   
Phil.

An important point that needs to be stressed; just before you transfer give the copper a really good scrub with steel wool or similar so it is nice and bright, and don't touch the surface after cleaning (or you might get a lovely etched thumbprint).

Firstly .. You guys are my inspiration to end this thing exactly as it should be and I'm immensely grateful you for all of that!  :tu:  8|

Very appreciate your willingness and commitment to help me. In this I recognize myself .. Always felt good when someone transfer part of my knowledge and when that someone is happy because of that ...

To move on to answers!  :)

Phatt, I am on Mac OS X platform, and name of softwer I use is DIY Layout Creator, which is free, simple, and intuitive.. For my very small experience, is more than serviceable.  :cheesy:

Info link:
https://code.google.com/p/diy-layout-creator/ (https://code.google.com/p/diy-layout-creator/)

I have studied your suggestions in the attached picture, and here I upload revised PCB layout ... I hope that it is now a little bit better .. :)

Guys, will adopt all your suggestions and techniques in making PCB..

If there are objections or opportunities to improve the design, just shoot!  :cheesy: ;)

Regard, Mladen!

Quote from: mladenuVery appreciate your willingness and commitment to help me.

And well worth the price...   :lmao:


...um... title block/board ID - project/your name/date?

Currency profitable from banana republic!  :lmao:
I forgot to insert proper lug size for pots, like in alpha datasheet for 16mm diameter pots, and now is more safe, IMHO...

One more question Phill, pot related... On your schematic lugs on middle and bass pot are without connection, but on pcb is linked.. Is this regular?