Pick up simulator

[SprinkleSpraycan]

https://photos.app.goo.gl/oQt7MACcEXywygBx8

I want to add a pick simulator to a Roland Double Beat clone.

I've breadboarded both the amz and one from aion fx proteus, which is essentially the same as the eqd eruptor one too.

The amz p.s. works great, I like the ability to tune it with the 25k pot and it's passive!

The other circuit, buffer included, doesn't seem to offer me better sound, in fact I think it sounds worse. What are the advantages of the more complicated and active design?

[Rob Strand]

You shouldn't restrict yourself to using those circuit's part for part.   They are both essential trying to do the same thing.   The thing is there's no exact answer.

There is an assumption in the AMZ circuit that there is a buffer or low impedance circuit driving the pickup simulator.  From a pickup simulator point of view it makes no sense to drive a pickup into a pickup simulator.

A more flexible platform is:
- Keep the buffer.  make sure it is biasing OK
- Try both inductor taps
- Try different caps 330pF to 1nF is a good range.
  470pF is probably something more in the middle.
- Keep the 25k pot

The capacitor value emulates the cable capacitance.  There's plenty of old posts with more details on cable capacitance.  The capacitance is proportional to the length of cable so you can't expect emulate a 3m and 5m long cable simultaneously.

The 25k pot is a simple way to tweak the sound.

Despite what values actually emulate a pickup + cable certain pedals will simply sound a bit better by playing around with the pickup sim circuit values.

[Mark Hammer]

If I may ask, WHY do you want to add the pickup simulator to the front of the Double Beat?

[SprinkleSpraycan]

If I may ask, WHY do you want to add the pickup simulator to the front of the Double Beat?

It doesn't play well when it's not first in the chain. I don't mind old school fuzz circuits being sensitive but I want this one to get its crap together and mingle further down the board. 

[Mark Hammer]

If I may ask, WHY do you want to add the pickup simulator to the front of the Double Beat?

It doesn't play well when it's not first in the chain. I don't mind old school fuzz circuits being sensitive but I want this one to get its crap together and mingle further down the board. 

Are there ANY places "further down the chain" where it behaves well?  It seems like the issue is not one of requiring a pickup simulator, but rather feeding it from a more suitable impedance.

[SprinkleSpraycan]

If I may ask, WHY do you want to add the pickup simulator to the front of the Double Beat?

It doesn't play well when it's not first in the chain. I don't mind old school fuzz circuits being sensitive but I want this one to get its crap together and mingle further down the board. 

Are there ANY places "further down the chain" where it behaves well?  It seems like the issue is not one of requiring a pickup simulator, but rather feeding it from a more suitable impedance.

Interesting. I've always thought once you passed the first pedal, buffers compressors etc low input impedence pedals were going to sound less than desirable.

Basically no matter where I place it (besides absolute first) the gain control ceases to do much. It's stuck at full gain.

I'm gonna start another thread with the schematic for a more inclusive q & a about the circuit so far.

[mark2]

What do you think is the purpose of that 1k / 1nF LPF (160kHz) at the end of the Proteus one?

[mark2]

Also, is there a downside to omitting the resistance that Jack's article adds with a 25k pot? The Aion Proteus only has about 1k + the coil.

[PRR]

A real "pickup" is a coil, cable capacitance, and two kinds of stray resistance.

Leaving parts out won't save many pennies, and will give some other response.

[mark2]

Yes, I guess going back to the article it's clearly there to simulate a real pickup.

In retrospect I think I was moreso wondering why the Homewrecker bazz fuss omits those and simply uses a coil. I tried it both ways and can hear differences (and prefer the plain coil), but couldn't articulate why and what those differences were.

[Rob Strand]

Yes, I guess going back to the article it's clearly there to simulate a real pickup.

In retrospect I think I was moreso wondering why the Homewrecker bazz fuss omits those and simply uses a coil. I tried it both ways and can hear differences (and prefer the plain coil), but couldn't articulate why and what those differences were.

*If* the pedal has a relatively low input impedance then the inductor will be the main part shaping the response.   If the series resistance is high enough then that will have an effect as well.   However the effect of the added caps would be minimal.

Ideally you start-out with the complete pickup sim then after that you work out what parts have no/little effect on the pedal and you can pull those out.

In loose terms:  Suppose you have a 10k input impedance pedal.   At 20kHz (10kHz) you need a cap large than 800pF (1.6nF) to compete with the 10k pedal impedance.  So the 470pF cap on a pickup sim probably isn't going to do much.  You should not interpret this as the pick-up sim should have a large cap.  The pickup sim matches an existing physical object.  If the pedal input impedance was 20k then maybe the 470pF cap will have a small effect.

[PRR]

...prefer the plain coil

So do the plain coil. The "Standard Pickup" is a good practical solution to amp-ing strings but not necessarily the perfect sound for all situations.