BAJA JVM overdrive pedal 040218

Ichabod_Crane · Post by **Ichabod_Crane** » 22 May 2018, 07:37

Thanks for the layout, albrus80.

Thanks, ppfai, but we need another layout to add all that extra part, or I was wrong?

If the new version of the albrus80 works fine, how we hope, I think we can be satisfied.

Willypp · Post by **Willypp** » 22 May 2018, 09:26

I think I can see where Albrus80 was going with the 4pdt and separating the outputs, but I'm already using one so I can have LED indication indication for the Crunch/OD selection.

Ichabod_Crane · Post by **Ichabod_Crane** » 22 May 2018, 15:17

I see. In the schematic we miss a switch, indeed. I'm gonna draw it later.

ppfai · Post by **ppfai** » 22 May 2018, 16:06

Ichabod_Crane wrote:Thanks for the layout, albrus80.

Thanks, ppfai, but we need another layout to add all that extra part, or I was wrong?
If the new version of the albrus80 works fine, how we hope, I think we can be satisfied.

If I start doing 3 mode, I will add extra section for OD1/OD2. It give same result but easy to wiring each section.
sorry for my bad english.

Ichabod_Crane · Post by **Ichabod_Crane** » 22 May 2018, 18:12

Do you think you can build a new layout, ppfai? Or I'm misunderstanding and it's easy modify the current layout?

Anyway, the layout is correct, and of course, working and verified except that issue of the two volumes. Probably beacuse are connected together.

Instead, I noticed some of mistake in the schematic. A part of the Crunch/OD switch and a part of the OD1/OD2 switch are missing. Further the drive pots are not connected in the layout (else, I suspect, we should get a sort of the same effect that willy got with the two volume pots).

So, we actually have a DPDT for the OD1/OD2 Switch and already a 3PDT for the Crunch/OD2 Switch. None problem to add the led to the OD1/OD2 Switch using a 3PDT, but what about the Crunch/OD?
A 5PDT fooswitch?

No kidding! Maybe a relais swicth system? Maybe it's still a bit complicated. What about a millenium bypass to turn ON and OFF the led?

I need to think about it, I can't do it now, and I don't even know if it's a possible solution.

Willypp · Post by **Willypp** » 23 May 2018, 11:02

Ichabod, I'm not sure what the purpose of your extra switching is doing on my schematic - your switch 2-4,5,6 is superfluous as your switch 2-7,8,9 will take the OD1/2 out the circuit.. The correction posted by sixthfloor should work as it switching out the volumes for Crunch/OD. I think it might be too late for me to fix it in my build.

I can replace that 3pdt with a 4pdt and switch between the outputs of the dpdt EQ switches, but I really don't have the space to add a couple of channel volume pots. It would take the channels interfering with each other out of it though. I can't see myself building this one again either!

Ichabod_Crane · Post by **Ichabod_Crane** » 23 May 2018, 13:40

Of course I might get in some mistake, but those switches I added is those I see in the veroboard layout.
Unless I misunderstanding how the work channels I see in my schematic (that I see in the veroboard layout) that the blue switch swap the OD1 and the OD2 portion. The blue switch swap the Crunch/OD1-OD2, through the IC1c and IC1d and swap the last stages for the Volume controls.

PS the Switch 2-5,4,6 was already draw in the schematic. Look also the veroboard layout: Switch 1-8,7,9.

I'll be happy if we can simplify, somehow.

Willypp · Post by **Willypp** » 24 May 2018, 00:22

Looking closer, you have switch 2-5,4,6 duplicated just above switch 3-5,4,6. That doesn't need to be there.

Ichabod_Crane · Post by **Ichabod_Crane** » 24 May 2018, 08:00

I think I get what you mean, maybe, but I just follow the veroboard layout, and correctly I guess. Just make attention because I kept the original switch number in the schematic but in the layout the number are mismatched.
Here's the layout: http://www.freestompboxes.org/viewtopic ... 20#p270683
Of course we can discuss about the utility of the switch, the real core of the discussion, but I hope that all this complicated switching systes is clear.
In the schematic we have four switches:
- 3PDT - Bypass (Green)
- 3PDT - Crunch/OD (Red)
- DPTD - OD/OD2 (Blue)
- SPST - Orange/Red Mode (no color)
The DPDT for OD1/OD2 is to avoid that the two pots are connected, I get it's the same reason you got the two volumes control interactive. (The author of the layout should tell us something more.)
To separate the two Volume pots we can use a switch as you draw early, maybe the SW-2, 4, 5, 6 in the schematic is really redundant as you said, I mean the one after the 2k2 resistor (in the layout: SW1-8, 7, 9), in this case we have the solution.

It will be ok to jumper those connection and use that row of the switch (now free) in the final part of the schematic to separate the volumes.

Probably I can't explain well how I would, it could be just a misunderstanding between us.

Willypp · Post by **Willypp** » 03 Jun 2018, 11:55

The knobs have arrived. Demo one day...

Ichabod_Crane · Post by **Ichabod_Crane** » 04 Jun 2018, 07:52

Nice!

Do you have some new ideas about the Crunch/OD swicth? (The Red one I draw in the schematic.)

Willypp · Post by **Willypp** » 06 Jun 2018, 12:56

You could use a crunch/OD 4dpt to switch between the Crunch and OD sections at the output but you loose the ability to have LED indication for that. If I were to build it again, I'd jumper across the OD and Crunch outputs to the main output, ignoring/leaving off the volumes, go to a single eq section, and a single master volume. There's only a tiny variation in volumes across the 3 channels.

It's a bit of a moot point, I've finished mine and I don't plan on returning to this build. I think my schematic that I modified should work, but I would move sw2 - poles 5,4,6 to after the channel volumes and before the main output, not before the final channel stages like I currently have it.

Nefi_fatobene · Post by **Nefi_fatobene** » 07 Jun 2018, 07:03

Willy, so do you suggest use this layout (download/file.php?id=31018&mode=view) and put de eq before the level pot?

Ichabod_Crane · Post by **Ichabod_Crane** » 07 Jun 2018, 14:18

This layout download/file.php?id=31018&mode=view is disappeared from Guitar FX, I guess.

Willpp, that you would do with the switch it's exaclty what I'd do, so we can have a free row on that 4PDT switch and use the LED. I just hope we don't prejudice the correct behavior of the circuit with this mod (I expect not, but...). Of course I'd include the LPB-1 with the EQ for more vesatility.

Thanks.

Willypp wrote:The knobs have arrived. Demo one day...

Demo!

Willypp · Post by **Willypp** » 10 Jun 2018, 10:10

Nefi_fatobene wrote:Willy, so do you suggest use this layout (download/file.php?id=31018&mode=view) and put de eq before the level pot?

If you want to use the eq w/LPB1 w/volume pot that I posted earlier, I would do this:

"Level 3" of the layout goes to the input of the eq/lpb1
The output of the LPB1 (pin 2 on the pot) goes to "Level 2" on the layout
"Out" on the layout goes to your bypass switch as per normal.

This means you would be using the eq/lpb1 as your master volume control....

Ichabod_Crane · Post by **Ichabod_Crane** » 10 Jun 2018, 14:12

Nefi_fatobene · Post by **Nefi_fatobene** » 10 Jun 2018, 22:55

Great!! Thanks!!

Nefi_fatobene · Post by **Nefi_fatobene** » 13 Jun 2018, 13:54

Willypp, I'm excited to listen to your demo!!

jhergonz · Post by **jhergonz** » 14 Jun 2018, 19:00

can't wait

please let us hear it.

GeoffroyLux · Post by **GeoffroyLux** » 29 Nov 2018, 09:08

Hi guys!

First thx to Bajaman, Albru80 and all the others who contributed to traced this schematic

I built this from Albru80's layout

I used BC547 and 2SK117
It sounds great but I still have a problem when Switch 1 OD1 is engaged (1/2,4/5 and 7/8 lugs)
I get a huge oscillation, it varies when turning the gain pot.

Something else I noticed, when turning the gain pot to zero there is no sound at all.
Is that' normal?

Thx for your help

BAJA JVM overdrive pedal 040218 [verified]