Timmy + EP Booster combined build. Loss of volume and gain when both on!

[pawarit28]

Hi there,

I've wired up both the Timmy + EP Booster circuits as such. They work fine separately but not together.
There is a huge loss of volume, gain, and treble. Also, the EP Booster constantly experiences switch-popping even though .

I've tried separating the power supplies to each circuit but no change.

Can you guys spot any potential issues from the schematic? Thanks so much!

[Chris60601]

You can start by removing R1 (the pull down res) from Timmy

[induction]

From your schematic, it appears that you're combining the circuits so that they can't be switched separately. (i.e. They're either both on or both off, never one at a time.) Is this correct?

Regarding the switch pop from the EP booster: does that happen when the circuit is run independently, when it's combined with the Timmy, or both?

Have you tried connecting them in the opposite order (Timmy first)?

Can you post some photos?

[pawarit28]

Thanks induction :)

Sorry I didn't include the switching into the layout. I used this wiring (allows them to run independently):


The switch pop from the EP booster happens both independently and when combined.
I suspect it is R1 from the Timmy as Chris60601 said.

I have tried connecting them in the opposite order but I believe the output/input resistors (R1 of each circuit) will cause the same end effect.

Sorry I'm studying abroad at the moment and left the circuit back home a few days ago.

[pawarit28]

Thanks very much Chris!

I see now that the (R1 input resistor + 100ohm) is being connected in parallel with R12 resistor going to ground at the output of the EP booster circuit, causing all the signal to go to ground.

Could you also explain to me what is going on with the circuit/signal? I'd love to learn.
- What's the difference between having the input of the Timmy connected to a jack/cable?
- How is the switch pop from the EP booster be related to this?

Thanks again :)

[Chris60601]

My assumption was that you were going direct from out to in. If that
were the case, wouldn't need the pull down res in Timmy (in my mind)
But, using proper switching (as you have later shown) I would disregard
my comment.  - LOL, I assumed you were trying to kludge both designs
into one board - silly me.

[Frank_NH]

I would check the power supply.  I'm assuming you're using a wall wart or similar.  With both circuits engaged, is it possible that there is not enough current to supply both effects and their LEDs at the same time?  You could use your DMM to check voltages in the circuit when both effects are on.

I don't see an obvious reason otherwise why the two circuits can't operate together.

[Chris60601]

See - I read the schem "as is" assuming you were trying to combine both into one circuit/board.
You schem "should" include your switching so idiots like me, can read it correctly :)

But yeah, if you really are using proper switching, the 2 separate circuits should work just fine.
Definitely save yourself a migraine and DONT try to make one circuit out of both :)

Pardon my ignorance :)

[pawarit28]

No, its my bad! I was just a bit lazy to draw up the switching and wanted to focus on when they were BOTH on (i.e like the schematic). Sorry :)

[Chris60601]

Na - it was me. I tend to be too literal too often, lol

[pawarit28]

Thanks! Yup I'm using a wall wart. Could the current consumption really be that high?  I thought that this was pretty much equivalent to daisy-chaining pedals (which shouldn't be a problem).
I'll have a look with a DMM again :)

[induction]

That switching doesn't allow them to run independently, exactly. You have one main stomp that engages the entire circuit, and a second stomp that engages only the second circuit, but the second stomp only works when the first stomp is engaged. This means that you can have full bypass, the first circuit alone, or the first and second circuits in series. You can't engage the second circuit by itself. I wanted to clarify this before I ask more questions.

More questions:
1. From your schematic, it looks like the first circuit is the EP Booster, and the second is the Timmy. Is this correct?
2. When do you have the loss of volume? It sounds like EP Booster is good on its own, but when you engage the Timmy with the second stomp switch, the volume and gain suffer. Is that correct?
3. Did you test the Timmy separately?


Regarding switch pops: The Booster shouldn't pop as drawn. I suspect either the led or a leaky output cap. Test them separately. Disconnect the Booster led and see if it still pops. If that doesn't solve it, try replacing the output cap. Make sure it's oriented correctly. If it's backwards or defective, it will leak DC, which will cause pops.

The pulldown resistors are not likely the cause of your problems. They should be left alone.

I have a hypothesis, but it depends on the answers to the above questions.

[pawarit28]

You're right about that diagram. But since I am able to engage either pedal independently, I must be using this wiring actually. (sorry I gave you the wrong link)



1. The first circuit is the EP booster and the second is the Timmy, yes.

2a. Each pedal works great on its own (great boost in volume and gain). The EP has the switch pop whenever its engaged, but sonically its working fine. The Timmy works perfectly on its own without any switch pop.

2b. When I already have the Timmy on, then I engage the EP then i get switch pop and a loss of volume and gain. When i have the EP already on, then I engage the Timmy I also get the same losses but no switch pop.

3. Yes I have been using the Timmy on its own this whole time. sounds great + without any problems (not even switch pop).

Regarding switch pops: are you referring to the 10uF output cap near Q2 of the EP circuit?

Thank you again :)

[induction]

The 10u output cap is the one at the top of the layout. It's next to a 47u filter cap and spans the top four rows.

The predicted response depends on the settings of the pedals and amp, but in general having both circuits on should provide more distortion than either circuit alone. Boosting the input of the Timmy may or may not increase output volume, but should definitely increase saturation. Sending the output of the Booster to the Timmy may decrease output volume at some settings, but should always increase saturation. I don't have an EP Booster, but this is the behavior I find with any of my other boosters and my Timmy. So it does sound like something is wrong.

Both pedals together should only draw about 20 mA (unless you've done something crazy with the leds), which any properly functioning adapter should be able to handle (don't rule out a damaged adapter though).

My guess is some kind of build problem, and my suggestion is to post photos and voltages. Maybe we'll spot something.

[motterpaul]

Induction knows far more than most people here - but let me ask a simple question. How hard are you pushing the second pedal with the first?

If you are also getting a very noisy, hard to control sound, along with the loss of volume, it is possible that you are just putting so much gain into the second pedal that you are causing it to clip harder than it ever should.

The simple answer to that problem would be to back off the output volume of the first pedal and see if it sounds better. There should be a sweet spot where it is louder, but not out of control noisy.

Also - there is a difference between clean boosting (EP) a dirty pedal (Timmy), and dirty boosting a cleaner pedal. Either way might sound good if the volume levels of pedal one is kept down, but if you put too much into either pedal it can get funky.

Can I ask what the final goal is to be? Is it to boost after the Timmy for louder solos, for example? Or are you trying to push the Timmy harder with the EP to get more gain from the Timmy?