Blender with Phase Inverter

[isaiahtruj]

I found this schematic by Brian Cheyne/Signal Cheyne Audio and decided to have a go at creating a layout for it. However I'm getting a volume drop even when I try the circuit with 2n5458's. Attached is the schem and the layout I made, can anyone see anything that would cause a volume drop? I'm pulling my hair out trying to figure out whats wrong

[antonis]

1. Bring both Q1 & Q2 4k7 resistors directy on respective Sources (right before 100nF caps)..

2. Delete  Inverter 1M resistor (the one right after 100nF input cap) or make it 470k and place it between non-inverting input (+) and VR (optional, for input bias current cancellation..)
Delete 100nF input cap, also..
(Q2 ouput cap serves for it..)

[isaiahtruj]

1. Bring both Q1 & Q2 4k7 resistors directy on respective Sources (right before 100nF caps)..

2. Delete  Inverter 1M resistor (the one right after 100nF input cap) or make it 470k and place it between non-inverting input (+) and VR (optional, for input bias current cancellation..)
Delete 100nF input cap, also..
(Q2 ouput cap serves for it..)

Thank you for the input, I appreciate it! I tried bringing the 4k7 resistors directly to source and the volume drop didn't change ) :
Also there's a cut under 2m2 which separates the input cap from that other 100n Q2 output cap

[antonis]

Did you also delete the 1M & 100nF mentioned above..??

[iainpunk]

those Jfets are missing their Emitter resistors to ground.
should probably be around 5K from both jfets to ground.


i also strongly believe that the following mixer is superior. it has a quirk tho, the bottom op amp goes from quiet to double over the pot's travel but the top op amp is quiet with the pot in the middle, but has both normal and inverted output on both ends of travel, using an attenuverter


cheers, Iain

[isaiahtruj]

Did you also delete the 1M & 100nF mentioned above..??

I replaced the inverter 1m with a 470k from + to Vr and still no change, also there is a cut that separates the input cap from the jfet cap so they don't cancel each other out

[isaiahtruj]

those Jfets are missing their Emitter resistors to ground.
should probably be around 5K from both jfets to ground.


i also strongly believe that the following mixer is superior. it has a quirk tho, the bottom op amp goes from quiet to double over the pot's travel but the top op amp is quiet with the pot in the middle, but has both normal and inverted output on both ends of travel, using an attenuverter


cheers, Iain

I'm not sure which pin of a DSG would be equivalent to an emitter, also that circuit looks like something I'd want to try, does it use two separate op amps?

[iainpunk]

those Jfets are missing their Emitter resistors to ground.
should probably be around 5K from both jfets to ground.


i also strongly believe that the following mixer is superior. it has a quirk tho, the bottom op amp goes from quiet to double over the pot's travel but the top op amp is quiet with the pot in the middle, but has both normal and inverted output on both ends of travel, using an attenuverter


cheers, Iain

I'm not sure which pin of a DSG would be equivalent to an emitter, also that circuit looks like something I'd want to try, does it use two separate op amps?

that should have been called the drain... oops
i would recommend a dual op amp like the TL072. keep in mind that one of the pots in quiet in the middle. also, this schematic comes from an old project i did a few years ago, some adaptations may be needed. (i used a +10 and -5 supply, and the attenuverter side is where a complex feedback loop terminated.)

[iainpunk]

sorry i forgot to say:

welcome to the forum