Escobedo Octap!

[ghiekorg]

Hi everyone,
I just added to my list the Escobedo Octap! but i would like to fit it into a 1590A (the one from EffectsLayout is too big), so i searched for schematics and i found this (on the left) and i made a PCB (on the right).



I managed to make the fit but once i finished i realized it was completely something else from the EffectsLayout one 



I have then a couple of question:
1- Are they just 2 different versions of the same pedal, right?
2- Do you have a schematic of the EffectsLAyout version? There are a couple of thread here talking about that but the links are all broken. Ok, probably i can quickly pull it out from the PCB but here comes my third question:
3- Is my PCB correct? Specifically I am not sure about the couple of JFETs: the D and the S have to be connected DD-SS (like on the EffectsLayout PCB) or DS-DS (like mine)? I still can't read schematics properly so i don't know if the D is always "up" and the S is always "down".

Thank you guys

[11-90-an]

Your "volume" would actually be a "bias" control... the volume knob can be off-board wired, with your board output to lug 3, ground to lug 1, and the "ckt out" that you connect to your footswitch to lug 2. if what I said make sense...

1. they ARE the same pedal but you named your bias knob into volume, so you can change that...  , also, the EffectsLayouts one has a reverse polarity protection diode and a 47uF decoupling cap... you can add them if you  want. Isn't part of the part of the original schem, but good in practice.

2. refer to 1.

3. follow the effectslayouts one for this. it seems that you have to look at polarity and stuff, but I don't know so we'll wait for an expert to come along and explain...

[ghiekorg]

the volume knob can be off-board wired, with your board output to lug 3, ground to lug 1, and the "ckt out" that you connect to your footswitch to lug 2. if what I said make sense...

Makes sense. So: output>3, ground>1 new output>2. I will try to modify the board so maybe i can board mount it too.

3. follow the effectslayouts one for this. it seems that you have to look at polarity and stuff, but I don't know so we'll wait for an expert to come along and explain...

I will. I just would like to understand this thing of ups and downs. I have the same problem with  pots. I still don' get if the lower one is always lug 1 or it depends if the lug 2 comes from left or right...

Thanks a lot

[11-90-an]

I have the same problem with  pots. I still don' get if the lower one is always lug 1 or it depends if the lug 2 comes from left or right...

Same...

Most of the time I just
1. assume
2. test it on breadboard

or

3. ask   

[ghiekorg]

3. ask   

Exactly i bought a breadboard now, should arrive soon.

I prepared a 1590A version of the octup starting from EL's layout. I could manage to do the fit (with 1 jumper and if there are not errors, i double checked and it seems good to me) but the whole length with board mounted pots is 5cm, so probably the components will end up in the jack's space. I should have starter to plan it thinking of the pots upside down, it would have worked. Still it's possible to put the pots upside down on the components side (is there enough space?) or just wire them (that should work easy).

Is there a way to use a SPDT switch to turn the pedal on (with no LED)? I have an ON/OFF/ON that i don't need atm and i would like to keep this as small as possible

[duck_arse]

pots - clockwise is always clockwise. 1 can be wherever you say.

fets - in the pedal building world, all the jfets you or I will use can interchange their Drain with their Source. if you want D-D and S-S, fine, but D-S is same as S-D. just make sure you know where the gate is.

[ghiekorg]

Thanks duck_arse

I meant in the schematic, how can i know which is 1 (that usually goes to ground?) and which is 3?

if you want D-D and S-S, fine, but D-S is same as S-D.

So i can just use DD-SS or DS-DS and won't change anything? SO here all three are correct?

[duck_arse]

what does the pot do? volume control? so one end is no signal and the other full volume, that should be easy to work out. or rheostat connection - short the wiper to one or other lug, which lug only depends on if you want clockwise rotation = resistance decreasing or the opposite. no sign of 1, 2 or 4.

the function in the schematic [with a few clues, like the "increase" arrow, and sometimes the ccw marked] should tell you which end is up in the physical.

fets - yessir. there's your 3.

[ghiekorg]

i get your point, i think we talked already about 1-2-3 and how much you don't like them
My problem is that often i can't really say what's going on in a schematic, so the function is not always so clear to me. That's when 123 comes handy.

Back to the pedal: I just ordered the components, this time i went for the suggested ukelectronic (so far i tried mouser, musikding, banzai and ukelectronic). The site is a bit weird sometimes but they had almost everything i needed. I had to take 2N5458s instead of 57s and i went for a MPSA14.

I will now prepare the print layout, if anyone wants to check the layout i posted above... feel free

[ghiekorg]

Sorry if i answer my own post... i just remembered about the need of a boost in front of it (so it says).
To do that i had the idea of placing a JHS minibomb (the smallest i could find atm) on the same board (but without changing it i guess) or as a optional board inside the enclosure.

https://3.bp.blogspot.com/-sNeClkwdxJI/VgV7DRTcKZI/AAAAAAAAGHA/Y8WcFsbIFW8/s1600/JHS%2BMiniBomb.png

The idea is to use the booster full-on removing the pot and replace it with a resistor (or maybe better go like halfway?) and then regulate the volume with the volume control of the octaver. Questions are:
1- Would it work?
2- is it enough to connect the OUT of the booster with the IN of the octaver?
3- can they share the same ground and +9V? That would save me some space
4- looking at the layout a complete turn CCW gives the max boost. Is it then correct to replace the pot with a 1M resistor as showed in green?

5- I don't have a 5.1k, would it make a big difference a 4.7k or a 5.6k (i could go parallel but i wanna save space)?
6- wait. is the volume of the octup controlling the overall volume or just the volume of the upper octave? 

Thank you guys <3

[11-90-an]

1- Would it work?

Yes, but not as you think..

2- is it enough to connect the OUT of the booster with the IN of the octaver?

Yessir

3- can they share the same ground and +9V? That would save me some space

Yep

4- looking at the layout a complete turn CCW gives the max boost. Is it then correct to replace the pot with a 1M resistor as showed in green?

Honestly, It makes more sense to me to leave it as a pot. making the bias control instead if a pot to 2 10k resistors in series from +9v to GND.... then connect the 1M to the middle... or even small trimpot would be good...

If you really want to scrap the boost pot in the minibomb, you probably should tack a 1k resistor across where lug 2 and 3 of the pot should be, and tack say a 100k resistor from lug 1 and lug 2. Basically, this forms a voltage divider, just like the original pot. so, tweak the 100k resistor, (making the value smaller) until you get a reasonable boost that you like. (note that it should already be connected to the octap! so you would hear how both circuits interact.)

- I don't have a 5.1k, would it make a big difference a 4.7k or a 5.6k (i could go parallel but i wanna save space)?

You can probably get away with using a 5.6k

6- wait. is the volume of the octup controlling the overall volume or just the volume of the upper octave? 

overall volume..

p.s. nice layout! 

[ghiekorg]

Yes, but not as you think..

Actually before sleeping i thought "mm maybe i should just leave the booster pot there... and have it as 3rd control" so i made the layout and when i was in bed i thought "mm maybe i can add a switch to cut off the octaver so i can have just a clean boost if i want to". So i just made another layout for it
i just placed a SPDT ON/ON switch between  the OUT of the bomb and the IN of the octup; the signal from the boost is the lug 2, while the final OUT and the IN of the octaver are lugs 1 and 3. So position 1-2 connects the boost's OUT to the final OUT, while position 2-3 connects boost's OUT with octaver's IN. Makes sense?) I am starting to feel like it won't  fit into a 1590A anymore...
Also: are 2x 4001 necessary? they both do the same thing, can i just get rid of one?

[11-90-an]

i just placed a SPDT ON/ON switch between  the OUT of the bomb and the IN of the octup; the signal from the boost is the lug 2, while the final OUT and the IN of the octaver are lugs 1 and 3. So position 1-2 connects the boost's OUT to the final OUT, while position 2-3 connects boost's OUT with octaver's IN. Makes sense?)

So from what I'm getting... you can switch from bomb into octap or both in parallel? I don't know, but there might be some unwanted sound cancellation...

I do have a feeling that the bias knob won't do anything significant and just might be a waste of space, but please prove me wring... ... 

Also: are 2x 4001 necessary? they both do the same thing, can i just get rid of one?

Just one should do fine...

[ghiekorg]

I was thinking more in series. The only shared parts are +9V and and 0V. In one position the boost is on and is bypasses the whole octaver. On the other positionyou have boost+octaver in series (boost first then octaver, of course)... At least that's what i was aiming to

About the bias: I have no clue about his usage... I would happily take it out as well, it could save some space inside the enclosure so i can place the switch... I will make a version without it now

Here is a versione without the second 4001 and 3 knobs

[ghiekorg]

making the bias control instead if a pot to 2 10k resistors in series from +9v to GND.... then connect the 1M to the middle

You mean like that?

[11-90-an]

making the bias control instead if a pot to 2 10k resistors in series from +9v to GND.... then connect the 1M to the middle

You mean like that?

Yep

I was thinking more in series. The only shared parts are +9V and and 0V. In one position the boost is on and is bypasses the whole octaver. On the other positionyou have boost+octaver in series (boost first then octaver, of course)... At least that's what i was aiming to

Sorry, my bad.. didn't read properly...

[duck_arse]

Sorry if i answer my own post... i just remembered about the need of a boost in front of it (so it says).
To do that i had the idea of placing a JHS minibomb (the smallest i could find atm) on the same board (but without changing it i guess) or as a optional board inside the enclosure.

https://3.bp.blogspot.com/-sNeClkwdxJI/VgV7DRTcKZI/AAAAAAAAGHA/Y8WcFsbIFW8/s1600/JHS%2BMiniBomb.png

The idea is to use the booster full-on removing the pot and replace it with a resistor (or maybe better go like halfway?) and then regulate the volume with the volume control of the octaver. Questions are:
1- Would it work?
2- is it enough to connect the OUT of the booster with the IN of the octaver?
3- can they share the same ground and +9V? That would save me some space
4- looking at the layout a complete turn CCW gives the max boost. Is it then correct to replace the pot with a 1M resistor as showed in green?

5- I don't have a 5.1k, would it make a big difference a 4.7k or a 5.6k (i could go parallel but i wanna save space)?
6- wait. is the volume of the octup controlling the overall volume or just the volume of the upper octave? 

Thank you guys <3

I'll play silly - where is the circuit diagram for this? why that 100k resistor? and, when you draw the arrow in green on the pot, a gain pot, call the arrow clockwise, not counterclockwise. I know what it looks like, but you are drawing on the back of the pot, and clockwise is always clockwise, and it's rare for a gain pot to decrease gain as rotated clockwise.

see, that ccw lug is in the same place on the pot, looking at the back or the front. so you can't have an arrow going ccw if it points to the cw lug. does any of this make sense?

[duck_arse]

so are you keeping the bias pot? if so, you probably want to test it first, so you can get an idea of the usable range, then you can add padding/stop resistors, an maybe use a smaller value pot for better dialabillity.

please - collect all your thoughts on paper in the form of a circuit diagram, and then show it here - then you point - this, that, something other, and we nod our heads. and we can make sense of yr layouts.

[ghiekorg]

where is the circuit diagram for this?

I actually just copied EL layout and i modified it, as it's verified. I then found this one https://easyeda.com/normal/MINI_BOMB_JHS_ETSEFFECTS-ddacd9871df145c09744e7b023f82d9e but they don't match (to my eyes at least).

clockwise is always clockwise

Here i can't understand... If i look at the shaft i have to rotate CW to get gain, alright, but if i look at the back the rotation itself remains CW but i will see it as CCW. My arrow was just helping me while thinking "which lugs are "connected" when i have 100% gain?" so i drew the arrow and it shows that lugs 2 and 3 (or we can call them wiper and CW lug)

so are you keeping the bias pot?

no... i think it will get too tight with 3 pots (i already have to make 2 1590A with 2 and 3 pots as soon as i have the components... so better stay out of other annoying projects I will probably have to check the 5.1k resistor and the last 100nF cap as i understood from some comments they are quite important for tone and output volume

collect all your thoughts on paper in the form of a circuit diagram

haha i can't i can barely read them... I can give it a try but probably it will be more wrong than the layout. i also don't know any software (DIYLC is not really handy for moving things around...) i will have alook online

Thanks a lot

[duck_arse]

that circuit ^ you found is very wrong. I still don't understand the 100k in the mini bomb thing.