Could I get some feedback on this Buffer/Pick Up Simulator?

[carboncomp]

Hello,

Recently been getting into home recording and have had some wonderful help from the people on this forum, who are extremely welcoming to noobs like me!

So, I have this very edge case of wanting to ReAmp effects pedals, but rather old ones like fuzz and boosts that have a lower input impedance and really don't play nice with a buffer in front of them, and was trying to find a way to make a small versatile box that I could put in front of them to give me more options on pedal chain placement and a way they could sound a little bit better with DI out of the audio interface so have cobbled together this "Buffer Be Nice" circuit and could really do with someone smarter than me pointing out my errors, and explaining why its a terrible idea!

(oh, should probably explain, my thinking, simple jfet buffer into a tapped transformer to emulate a pickups and a simple tone and volume control)

 

[JohnRoberts]

Input buffer looks OK... running the transformer winding in series with rest of transformer floating will mainly look like an inductor (is that your plan?). The VOL1 pot to ground will draw DC current through the transformer but not much. It can make the wiper sound scratchy. Putting the, or another cap before the VOL1 pot might clear up the scratchy wiper. Polarity of the output electrolytic cap is backwards

JR

 

[carboncomp]

. running the transformer winding in series with rest of transformer floating will mainly look like an inductor (is that your plan?).

Thank you! Yes, its really just being used as an inductor with spec near to a single coil and humbucker depending on the switch

The VOL1 pot to ground will draw DC current through the transformer but not much. It can make the wiper sound scratchy. Putting the, or another cap before the VOL1 pot might clear up the scratchy wiper.

Thanks for heads up, is there any pros or cons in moving vs adding another, or just parts count?

Polarity of the output electrolytic cap is backwards

Well, that's embarrassing!

Sincerely thank you for the feedback!

 

[JohnRoberts]

Thanks for heads up, is there any pros or cons in moving vs adding another, or just parts count?

less parts is better generally better.

JR

 

[carboncomp]

Updated!

 

[sr1200]

I have a question about this, in trying to learn about circuits in general...
at the end here, he has a potential 250k pot followed by a 10ohm resistor and a cap thats grounded (470pf). When the pot is maxed (getting close to the 250k range), is that going to be a low pass filter that is going to knee around 1.3KHz or does that section only see the 10ohms? Being in series i would think that the resistance there would just be additive. My shoddy simulation software seems to follow my train of thought on this.

 

[JohnRoberts]

I have a question about this, in trying to learn about circuits in general...
at the end here, he has a potential 250k pot followed by a 10ohm resistor and a cap thats grounded (470pf). When the pot is maxed (getting close to the 250k range), is that going to be a low pass filter that is going to knee around 1.3KHz or does that section only see the 10ohms? Being in series i would think that the resistance there would just be additive. My shoddy simulation software seems to follow my train of thought on this.

The source impedance of a pot is the parallel resistance of the two pot element segments from wiper to each end. Worst case for a 250k pot is mid resistance (mod rotation for linear pot) 125k in parallel with 125k or 62.5k. The 10 ohm is insignificant wrt that LPF formed with 470 pF . Keep in mind the inductance of that transformer winding is also in series.

JR

 

[sr1200]

Sorry to hijack the thread here. So in just speaking about the pot. The way its wired now acts as sort of a voltage divider, had the wiper been tied to pin 3 then it's acting in the way i thought (where you get the full value of the pot)?