Component values for saturation switch?

[ledvedder]

Hi guys! I figured I'd ask here, since I know many of you have much more experience with this than myself. I added a saturation switch to my JCA22H this weekend. I'm not a big fan of it. It adds way more gain than I'd ever uses, drops the volume pretty significantly (I knew it would drop, but didn't expect this much), and seems to increase bass too much.

I'm just curious what diode and component values work best for you guys. I know the lower the voltage on the diodes, the more saturation and volume drop occurs. I'd like something similar to what my Chupacabra's 80s Era switch did.

 

[scottosan]

The MPSA06 is pretty low. You may want to buy some various value diodes between 10v-20v.

 

[ledvedder]

I've ordered a few different diodes to try. Does the cap or resistor value change anything. I'm currently using a 10k resistor with a 0.1uF cap.

The diodes I've ordered are 1N4749A, 1N968B, and UF5408.

 

[SpiderWars]

The UF5408 is not a zener. You need zener diodes. Like scottosan said, try 10v up to even 24v. I like 4x MPSA06 connected BE-EB-BE-EB (think Roadrunner cartoon...beeb-beeb).

And I wouldn't mess with the 10K. But the 0.1uF is often 0.22uF or even a little higher. But that is probably not an issue.

 

[ledvedder]

The UF5408 is not a zener. You need zener diodes. Like scottosan said, try 10v up to even 24v. I like 4x MPSA06 connected BE-EB-BE-EB (think Roadrunner cartoon...beeb-beeb).

And I wouldn't mess with the 10K. But the 0.1uF is often 0.22uF or even a little higher. But that is probably not an issue.

What effect would changing to 0.22uF have?

Yep, I read somewhere about the UF5408 rectifier being used in saturation designs.

 

[ledvedder]

The UF5408 is not a zener. You need zener diodes. Like scottosan said, try 10v up to even 24v. I like 4x MPSA06 connected BE-EB-BE-EB (think Roadrunner cartoon...beeb-beeb).

And I wouldn't mess with the 10K. But the 0.1uF is often 0.22uF or even a little higher. But that is probably not an issue.

I have some MPSA06 lying around. So, I'd just use 4 in place of the 2 zeners that are in it now?

 

[SpiderWars]

Yes, when connected base to emitter they are like a zener but apparently clip a little differently. That setup I mentioned above is still a lot but less than just 2 of them. Chris Merren mentioned in a VERY old post (Plexi Palace or something) that he had seen that setup in an actual Jose so I tried it and it stuck.

 

[ledvedder]

I've seen some saturation switches with a resistor in parallel to the diodes or transistors. What effect does the resistor add?

 

[ledvedder]

Yes, when connected base to emitter they are like a zener but apparently clip a little differently. That setup I mentioned above is still a lot but less than just 2 of them. Chris Merren mentioned in a VERY old post (Plexi Palace or something) that he had seen that setup in an actual Jose so I tried it and it stuck.

So, do you connect the 4 MPSA06's in series? One after the other?

 

[SpiderWars]

Yep, and it won't matter which end is connected to ground since it is BE-EB-BE-EB either way.

 

[ledvedder]

Yep, and it won't matter which end is connected to ground since it is BE-EB-BE-EB either way.

OK cool! So, just to be clear, since this is new to me... They're not in parallel, the way that 2 zeners would be connected?

 

[SpiderWars]

Yes, in series. You can connect the zeners in series too.

 

[ledvedder]

This is one I've tried, but it's too much saturation than I'd like. It's 2 MPSA06's with a 1M resistor in parallel. I don't know what the resistor does.

 

[SpiderWars]

The resistor is in place of the 1M MV that "usually" would be there. The resistor (or pot) is necessary for it to work properly.

You need the other stuff, the only thing you need to swap out are the clippers themselves.

 

[ledvedder]

The resistor is in place of the 1M MV that "usually" would be there. The resistor (or pot) is necessary for it to work properly.

You need the other stuff, the only thing you need to swap out are the clippers themselves.

OK, because I have another saturation mod that doesn't have a resistor in parallel with the zener diodes. That's one that I don't like. It adds way too much gain and extra bass.

 

[SpiderWars]

Is it in parallel with a MV?

 

[scottosan]

OK, because I have another saturation mod that doesn't have a resistor in parallel with the zener diodes. That's one that I don't like. It adds way too much gain and extra bass.

For the 1 you have without the 1M in parallel, you could try adding a 1.5k between the clippers and ground. This is how it’s done on the Helios

 

[psychodave]

Also, a little solder goes a long way. ?

 

[ledvedder]

For the 1 you have without the 1M in parallel, you could try adding a 1.5k between the clippers and ground. This is how it’s done on the Helios

What would the resistor do?

Sorry for all the newbie questions. It's just that I don't have all of these components and values laying around. And I can't run up to my local Radio Shack anymore. I have to order online, where they want to charge $8 to ship a couple 50 cent components.

Is there anything like an amplifier "component pack" that I could get to have all of this stuff on hand?

 

[SpiderWars]

Is there anything like an amplifier "component pack" that I could get to have all of this stuff on hand?

No, you over-stock yourself over years of buying 10 when you only need 1. Then you die with a bunch of extra shit. Sorry bro, that's just the way it goes...this is the path you have chosen.