Using the runoffgroove splitter blend schematic to make an active ABY pedal?

[spectraljulian]

That is, with two inputs, one output, blend switch.   I've encountered some problems though (detailed at the end.) 



I omitted the Input/Send part, since this is not a loop, but a two input ABY mixer. 

I wired the switches like this:

AB switch:  (each line is one pole of the switch and both throws)
LED A- Ground- LED B
B - To Input 2 (Green return on Schematic) - A
A - To Y switch - B

Y Switch:
unwired - LED A - LED B
ground - To Input 1 (red return on Schematic)  - From A/B switch
From A/B switch - to output jack - blend output

I soldered 1 meg pulldown resistors to the input and output jacks so that the A/B switch wouldn't pop. 

I've encountered a couple of problems:

When the Y switch is activated and the blend is turned all the way towards input 1 (red on the schematic), Iget unity (or slightly above unity) gain and the tone is significantly better than the true-bypass tone.  I'm wondering if this is because of the pulldown resistors, the cable length (about 10 feet), or some other unseen problem.  When the Y switch is off, the circuit is completely disconnected (with the exception of ground) from the input currently in use as well as the output. 

Next problem: input 2 is below unity when the blend knob is turned all the way to the left.  Fiddling with the phase switch doesn't seem to fix it.  In fact, all fiddling with the phase switch seems to do is make it even quieter in one position. 

[spectraljulian]

I took out the phase switching circuit and that seems to improve the response of the 2nd channel very well, and the blend is working very well now.

Though as soon as I took the circuit apart I started second guessing myself and wondering if I had wired something wrong. 

Anyways, I think what I'll do is change the A/B switch to this, so that the buffer is always active. 

LED A- Ground- LED B
B - To Input 2 (Green return on Schematic) - A
Pin 7 - To Y switch - Pin 1

Then I'll replace the blend knob with two 500kA pots that fade the outputs following the capacitors of pin 1 and pin 7 to ground, each followed by a 47ohm resistor to the blend out. 

[good air]

No one will help you.  This place is filled with a bunch of sarcastic pricks that have no desire to help anyone who plan on using the projects discussed in ACTUAL real-life musical ways.  They'll build them on their breadboards, or build something to sell to someone else because they can't think of circuits themselves. They're merely the equivalent to the chinese knock-offs of brand name pedals.  I've searched the forum top to bottom with questions regarding splitters and aby boxes, even started a new post.  Most, like your post, goes unanswered, including mine.  Which leads me to believe the people here are a bunch of assholes with their best reply being "look it up! its been asked before!"  No regard for conversation, they all have "text book minds" and a shitty attitude caused they have a shitty life. 

I wish you luck with your splitter, and if you get it up and running, try to figure out a way to have dedicated gain knobs for each input, I'd really appreciate it after my question about that went unanswered for a month. 

[petemoore]

  Starting with a clear schematic is recommended for a complex build.
  Working to grasp what the circuit is, the only vague probability, a 50/50 chance phase cancellation...at least needs to be calculated as correct.
  The + opamp stages [all are + inputs] all are non-inverting, it's the Jfet stage that has me stumped.
  Go look it up whether the Jfet source is inverting ! [or wait a few, PRR and others just know this for certain, and will be glad to chime in and help us out.
  A readable schemetic...I tried to envision what is going on but got lost on a number of the changes from what is shown.
  As I understand it you want to build a 2 input mixer but with a balance control instead of 2 volume/faders.
  Other than doing the typical debugs such as signal path verifications and voltage bias measurements, note that the signal phase can cancel if not 'corrected' once straying from what is shown [IIRC there was related text in the SB article about phase/out of phase].
  Other good reads about mixer/bypass/looping at GEO: the parallelizer.
  I'll try to check in soon to see how this goes.
  I'm thinking the problem with ''2'' is either a phase deal or a simple debug.

 
 

[spectraljulian]

I took out the phase switching circuit and that seems to improve the response of the 2nd channel very well, and the blend is working very well now.

Though as soon as I took the circuit apart I started second guessing myself and wondering if I had wired something wrong.  

Anyways, I think what I'll do is change the A/B switch to this, so that the buffer is always active.  

LED A- Ground- LED B
B - To Input 2 (Green return on Schematic) - A
Pin 7 - To Y switch - Pin 1

Then I'll replace the blend knob with two 500kA pots that fade the outputs following the capacitors of pin 1 and pin 7 to ground, each followed by a 47ohm resistor to the blend out.  

I don't think that's quite the case.  Posting on here doesn't always get someone to come in and magically solve my problems, but it helps me go through the thought process of dealing with them and how to work around them on my own if nobody answers me.  

I've decided that I found the phase switch to be unnecessary, so I rewired that side of the op-amp to resemble the other side, and it works like a charm now.  I'm out of 500kA knobs, so I've got to order some, and put them to fade each signal to ground before the mixing cap so then I have individual controls.  


What are your needs?  Since I'm working on a build right now I'll try to help you in whatever way I can. 

[Morocotopo]

Spectraljulian, it would be better if you post a complete schematic/drawing of your circuit, the written explanation is hard to follow, then we would be able to help you better.

Good air, no one has the obbligation to help you here. Usually someone will, but it may be the case that no one will, because they didn´t catch your post, or they didn´t know the answer to your questions. A few times one of my posts had no reply, well, bad luck, try next time... If you don´t like the way the forum works, don´t participate in it. It´s not nice to call people assh*les. If the answer is "look it up", then look it up! What´s the big deal?

[spectraljulian]

I think I'm good now, so no need.