need some suggestions for a 1 in, 3 out buffered splitter.....

Started by pinkjimiphoton, April 11, 2020, 03:26:21 PM

Previous topic - Next topic

pinkjimiphoton

for guitar synth use.... i'm taking an ancient aria pro II thor guitar and making it a midi controller... but with a twist. its the only guitar i own that has room for both a roland gk2a AND a roland gk-1 midi pickup between the bridge pickup and bridge. so the plan is to make up a monstrosity that will allow me to run both modern 13 pin roland stuff, archaic 24 pin roland stuff, and a guitar signal by itself simultaneously.
the thor has an onboard 30db boost. it runs off a 9v battery. i'm ME. forget the math, or anything to do with it or even smell like it. no idea to how much voltage that would be coming from the guitar, but i imagine it would be less than 4.5v point to point. probably wrong.
remember, i am a monkey with a breadboard and no actual EE knowledge. i can make a mean fuzzbox if the moon shines brightly and the wolfbane blooms....
so anyways, i need a simple easy buffer circuit that i can use to take the 1/4" output of the guitar to a strap-mounted breakout box, then have that one input be buffered and split to three different outputs... one to drive my marshall straight, one for the gr300, and one for the gr30 or 09 or whatever... so i can feed guitar into both midi pickups. this will require still three cords, obviously, and a bit of ridiculousness, but i'm committed to doing it. ;) all the grounds need to be connected to prevent loops in the system, trying to split the straight guitar off can be a nitemare... hum city.

so i found this:



it says its flat from 30-24k which should be plenty of frequency range for my purposes... but i am an idiot and a luddite...

i see where it has a voltage divider for vcc. i see where it says to vcc. what i don't get, is where the hell does the 9volts go in? and isn't vcc supposed to be half voltage? sorry for the no doubt dumb questions, but, like, you guys know me, right? ;)

i'm thinking 9v to pin 4 and ground to pin 11 to run this, i don't think i understand what the heck i'm supposed to do. but i figure this is a good candidate for a simple way to do it... i could fit this and the 4 jacks in a 1590a or b easily to mount on my strap, and then i can make the venerable and the modern beasts join together in sweet electron love.

help a pinkster out, and buy his dumbass a clue, won't ya?? ;)

advice sought and appreciated, and as always, extra points for comical insanity. and explaining it to me like you would a lobotomized  chimpanZee...

or am i an idiot <likely> and i just need to apply 9v to r4 and pin 4? 

see? told ya i'm a dummy ;)
  • SUPPORTER
"When the power of love overcomes the love of power the world will know peace."
Slava Ukraini!
"try whacking the bejesus outta it and see if it works again"....
~Jack Darr

antonis

Not enough coffee, Jimi..??  :icon_lol:

R4 & R5 are voltage divider resistors and R3 is Vcc/2 non-inverting bias resistor..
R1 is Gain resistor (set gain together with R2)

Setting +9V everywhere is Vcc should be a simple and effective brainstorm diffuser.. :icon_wink:

P.S.
To make you feel better, Vcc arrows should point at reverse direction.. :icon_redface:
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

PRR

Multiple problems here.

There's 4V of DC on the outputs. It would be polite to cap-block that.

Audio gain of 10, on 9V supply, will probably clip. Is this a buffer or an amplifier?

There is almost NO case for the three extra opamps. The one opamp can drive a couple dozen typical stage loads with grear isolation.

100k is high enough to add hiss in stage work.
  • SUPPORTER


pinkjimiphoton

#4
Quote from: PRR on April 11, 2020, 08:02:01 PM
Multiple problems here.

There's 4V of DC on the outputs. It would be polite to cap-block that.

hi paul ;)
yeah, that i thought was obvious... was mostly curious where the heck to hook up the 9v.


Quote
Audio gain of 10, on 9V supply, will probably clip. Is this a buffer or an amplifier?

be a buffer. i need one in, 3 out split independently. that way, i still have my guitar signal, and one guitar signal buffered to drive each synth pickup with.  this way, my guitar knobs control the master "guitar" signal independently of the synthesizers, which will each be discreet as well. i need to buffer the signals independently, cuz i'm dealing with guitar level, as well as each synth. it has to be able to be really simple, and really small... planning to fit it in a 1590a hopefully, and mount it on my guitar strap. there will be an input with a switching jack  for the normal guitar output, and then three outputs... one for the gk1, one for the gk2, and one basically a pass thru for the straight guitar signal. i assume all 3 signals need buffering from each other. its important that all three circuits share a ground as well to prevent ground loop hums.
its kinda more complex than usual stompbox fare; but not really.

bottom line, need a one in 3 out buffered splitter. i've seen jack orman's jfet one, but it will take up more room than what i plan on doing... its kinda hairbrained, and looking at various possibilities, including mounting it IN the guitar, and adding a stereo end pin output jack to break out the cables to feed the synth pickups with. both the gk1 and gk2 pickups have inputs for the "straight" guitar so you can mix between guitar, synth, or both. but again, to use both kinds at the same time is gonna require jumping thru some hoops.

doing it with a single  tl084 and the couple passives in this, i could easily fit this plus two 1/4" and two 8th" jacks and still stuff a 9 volt inside a 1590a i think.



Quote
There is almost NO case for the three extra opamps. The one opamp can drive a couple dozen typical stage loads with grear isolation.

yeah, i get that as a driver, but that doesn't help me in this case... i need to not drive an fx chain, i need to buffer the output of the guitar and split it three ways, while having the guitar knobs control the guitar signal to all three outputs. ;)


Quote
100k is high enough to add hiss in stage work.

perhaps i should go 10k? i was planning to use the onboard stock pots in the guitar, which are the predictable b500k

i appreciate the guidance help and advice!
  • SUPPORTER
"When the power of love overcomes the love of power the world will know peace."
Slava Ukraini!
"try whacking the bejesus outta it and see if it works again"....
~Jack Darr

pinkjimiphoton

Quote from: mth5044 on April 11, 2020, 08:17:24 PM
Yeh?

http://www.muzique.com/lab/splitter.htm

thanks matt,
i am familiar with this circuit as well, but its gonna take a lot more space to pull off than a single chip with a couple passives deadbugged onto it

  • SUPPORTER
"When the power of love overcomes the love of power the world will know peace."
Slava Ukraini!
"try whacking the bejesus outta it and see if it works again"....
~Jack Darr

PRR

Vcc has never been "half" that I know of.

Older than most folks here: a 'grounded'-base transistor has collector going to Vcc, Emitter to Vee, and Base to Vbb. If literally grounded-base then Vbb is ground; often Vbb was a moving bias for gain control.

You really want me to break out the crayons?


All I see tells me you want UNITY gain. A TLO7* strapped unity gain has output impedance around 0.3 Ohms at the top of the guitar band. 2K isolation resistors make >70dB return loss. Two of your toys can be dead-short and the third will still get signal. If a "destination" mistakenly becomes a source (all them wires look alike), you will hear it, very faintly, probably not so you can tell when the desired source is playing.
  • SUPPORTER

pinkjimiphoton

thanks for breaking out the crayons for me. i needed that. ;)
this is like i said, totally above my limited feeble paygrade. i can make a fuzz outta damn near anything, but if its actual electronic-ing, i'm a babe in the woods.

i'll go back to licking the windows of my short bus now... thanks, paul

i actually "get" what ya say now. i'll give it a shot. i don't need to have the guitar volume independent from the three outputs, so this may be perfect.
  • SUPPORTER
"When the power of love overcomes the love of power the world will know peace."
Slava Ukraini!
"try whacking the bejesus outta it and see if it works again"....
~Jack Darr