BAJA JVM overdrive pedal 040218

jhergonz · Post by **jhergonz** » 03 Dec 2018, 02:56

[quote="GeoffroyLux" when turning the gain pot to zero there is no sound at all.
Is that' normal?[/quote]

yes, it is normal, but you may put a resistor between the vbias and the pin 1 of gain pot if you want. in that way there will always be a sound.

GeoffroyLux · Post by **GeoffroyLux** » 13 Dec 2018, 06:50

Thx a lot

Ok I will let it like that, It doesn't bother me how the gain pot works

just curious if it was linked to my switch oscillation problem

So I'm still looking for a solution to this oscillation problem

Any advice?

Optical · Post by **Optical** » 14 Dec 2018, 21:55

osciallation is probably from the wiring. Either certain things too close to each other on the layout or wires extending from the board picking up noise.

GeoffroyLux · Post by **GeoffroyLux** » 22 Dec 2018, 20:46

Hi Optical,

Thx for your help, but I'm almost certain it's not a wiring problem
I know this kind of problem when in/out leads are too close.
In fact It's not really an oscillation, it's more like squeal/buzz,
this happened whatever position of the gain pot is, zero to max

I didn't box it, I always testing the effect out of the box before

Willypp · Post by **Willypp** » 23 Dec 2018, 07:49

Ok, I've finally done a demo. It's a bit long and boring, plus I apologise for the junk playing in advance. I really should invest in a looper for demoing this stuff.

Edit: Doesn't look like it embeds youtube vids, so here's the link:

karul · Post by **karul** » 23 Dec 2018, 13:58

it doesn't work with "https:" address. just change it to “http:“ - erase the "s" and that's it.

Ichabod_Crane · Post by **Ichabod_Crane** » 24 Dec 2018, 08:39

It sounds very good. A nice crunch with really a lot of gain.

Willypp · Post by **Willypp** » 24 Dec 2018, 08:58

Yeah, it works pretty well.

Ichabod_Crane · Post by **Ichabod_Crane** » 25 Dec 2018, 09:13

I'd like to see more about the EQ!

Willypp · Post by **Willypp** » 25 Dec 2018, 09:58

The eq is 2 of attached layout, one the crunch, and one on the OD channel. Wouldn't bother with doing that, just stick a single layout on the main output. Use the first one if you want to keep the eq in the chain, use the second one followed by a volume pot if you want to set it up to be bypassable.

Ichabod_Crane · Post by **Ichabod_Crane** » 26 Dec 2018, 08:45

Thanks, but probably I had to say "I'd like to LISTEN more about the EQ".

I don't want to ask you another video.

jhergonz · Post by **jhergonz** » 09 Jan 2019, 08:02

Willypp wrote:Ok, I've finally done a demo. It's a bit long and boring, plus I apologise for the junk playing in advance. I really should invest in a looper for demoing this stuff.

Edit: Doesn't look like it embeds youtube vids, so here's the link:

many thanks to this video! Now im also curious about How the eq affects the tone. But maybe I should be the one to build and hear it myself.

Willypp · Post by **Willypp** » 10 Jan 2019, 00:41

The easiest way would be to go to 3.32 where it's OD2 flat out, and then to 3.49 where I switch in the eq and compare the two tones. It's fairly drastic.

GeoffroyLux · Post by **GeoffroyLux** » 14 Mar 2019, 08:20

Hi guys!

I tried to figure out with my squeal problem
(I built the first layout from Tagboard Fx)

I disconnected the leads 1,4 and 7 to switch 1 one by one to find the bad one.
Problem comes from the lead sw1-7, so I connected directly to the BC547 base ans it's working great.
But I'm not sure if it's correct compare to Bajaman's schematic

GeoffroyLux · Post by **GeoffroyLux** » 17 Mar 2019, 18:13

In da box!

Ichabod_Crane · Post by **Ichabod_Crane** » 18 Mar 2019, 08:40

GeoffroyLux wrote:Hi guys!

I tried to figure out with my squeal problem
(I built the first layout from Tagboard Fx)

I disconnected the leads 1,4 and 7 to switch 1 one by one to find the bad one.
Problem comes from the lead sw1-7, so I connected directly to the BC547 base ans it's working great.
But I'm not sure if it's correct compare to Bajaman's schematic

Yes, I have to say there's something I don't understand, too. I'm looking the schematic and the layout.
Looking at the layout I guess you fix the problem jumpering a 2.2k resistor, but I'm confused. You got squeal when the switch is open or close? Because I expect no difference where the switch links if it's open. But also I'm figuring that you got the squeal when the switch is open because you don't bypass that gain stage getting more gain, and so more inclined to squeal.
Anyway, did you notice really no difference in the sound, except the squeal?

Thanks for sharing!

GeoffroyLux · Post by **GeoffroyLux** » 19 Mar 2019, 18:27

Ok I'm not a specialist so maybe I will tell you something wrong ^_^

The "squeal" who was more like an alarm who's screaming like hell, happened when the 7th and 8th lugs were connected
So when the 3PDT was on down position.

Now I could notice differences in the 3 positions
But I still have a slight sound when gain is CCW but it's disappear when I turn it CC
Anyway volume is cut when gain is zero so it doesn't matter

GeoffroyLux · Post by **GeoffroyLux** » 19 Mar 2019, 18:27

Ok I'm not a specialist so maybe I will tell you something wrong ^_^

The "squeal" who was more like an alarm who's screaming like hell, happened when the 7th and 8th lugs were connected
So when the 3PDT was on down position.

Now I could notice differences in sound on the 3 positions.

I still have a slight weird sound (kind of hum) when gain is CCW but it's disappear when I started to turn it CC.
Anyway volume is cut when gain is zero so it doesn't matter

GeoffroyLux · Post by **GeoffroyLux** » 22 Mar 2019, 08:05

Ok after playing it a bit I could tell it's still not perfect .

I still have noise

when switch 1 is engaged on lugs 1+2/4+5/7+8 (down position for me)

Here's a sample of the noise

salin3 · Post by **salin3** » 07 Nov 2020, 17:38

albru80 wrote: ↑21 May 2018, 15:32 You can use a 4PDT switch and separate the outputs.
This should fix it.

Hi,

I can't see where the SW 1 - 11 goes, I don't find where the OUT is on the layout.
Can you help me figure it out ?

Thanks !!!

BAJA JVM overdrive pedal 040218 [documentation]