Greetings earthlings :)

bluzeyonecat · April 15, 2015, 12:29:45 PM

...so..a keyboard player walks into a guitar pedal forum and.....

It does sound like the start of a joke doesn't it?

Its true though. And Im glad I found yas. Been playing for 28 years.. Been playing professionally for about 15 minutes.

Actually about 15 years. As a hobby I got into diy synths with inevitably led me to op amps and eventually here. I look forward to building your 741 project and make my Rhodes patch a bit meaner. Already learned alot from you. Nice to meet all of you.

bluzeyonecat · April 15, 2015, 12:32:43 PM

Supposed to be "greetings earthlings" btw. Sometimes smartphones..aren't.

bool · April 15, 2015, 12:35:25 PM

Money Makes The World Go Round

Ice-9 · April 15, 2015, 12:36:48 PM

Welcome to the forum bluzeyonecat, lots here to find and some synth stuff is about as well.

bluzeyonecat · April 15, 2015, 12:46:12 PM

Thank you very much. I fixed the title. Guess you could call it my first stompbox mod?

Quackzed · April 15, 2015, 12:47:18 PM

Quote...so..a keyboard player walks into a guitar pedal forum and.....

... just as the door behind him closes, sees he is in a room packed full of old beardy emaciated guitar players staring at him in mute surprise...
The keyboard player, not missing a beat, smiles and exclaims, " Don't worry boys, I bought the KEYS!!!"

*HURRRRRAAAAAYYYYYY!!!!!*

blackieNYC · April 15, 2015, 01:14:04 PM

Half of us are just trying to make our guitar sound like a synth!
Have fun!

Perrow · April 15, 2015, 02:42:22 PM

... not to mention that the owner of this forum usually plays keyboard

Mark Hammer · April 15, 2015, 03:05:57 PM

The links between what happens here, and analog modular synth, are, and have historically been, quite strong. Keep in mind that many of us older farts got our start with PAiA gear and have continued with MFOS stuff, more recently.

So you're in good company.

C'mon in, the water's fine.

bluzeyonecat · April 18, 2015, 11:09:36 AM

Thank you all for the warm welcome. I managed to build some cool oscillator circuits but am stumbling a bit with a distortion pedal.
First, what is this -v business? Some schematics say you need it, others say just bring it to ground. Are they both right?

Secondly, since my output on the keyboard is hotter than guitar, should I change the resistor size on the input for the pedal? I've experimented with some basic circuits and found alot of overdrive at the start. I would rather see it clean and add the grit with pot in the feedback loop. Thank you for your time. Now lets rock some China Grove!

mth5044 · April 18, 2015, 11:16:01 AM

-V really depends on the circuit. If it's not grounded, there is a good chance it uses a bipolar power supply, like +/- 9V or +/-15V, etc. Have a link to any particular circuits? I have built a scarce few synth pedals, but I've mod'd them all to run on a bipolar power supply for more headroom. You could also just increase the supply from 9V to 18V, leaving ground where it is, and if there are any Vref they would double as well (4.5V to 9V).

You can also put a pad on the input, as you were saying with resistance. An input volume pot could be used too to dial in how hard your are hitting the circuit since synths seem to have line level outputs. You could also make an external, active pad to run your synth in to before a whole bunch of pedals so you don't have to fuss with the input on all of them.

Welcome to the forum!

bluzeyonecat · April 18, 2015, 11:18:05 AM

....come to thunk, we all had a little grit from pot in our feedback loop from time to time!

bluzeyonecat · April 18, 2015, 11:34:31 AM

Thank you Matt. That clears it up a bit. Is virtual ground really solid enough to work with? I've added a 100uf cap to it with hopes to secure it. I am working with a 9v circuit.

Two terms you mentioned I need a little studying. "Headroom" & "Pad" . I know what a pad is in "synthology" but your talking of something different. Thank you for your help.

China Grove got em dancing, wuddaya say we launch into "Misty Mountain Hop"? *dialing up the wurly*

bluzeyonecat · April 18, 2015, 12:07:15 PM

Does this look like an accurate way to create -v from a single supply? http://m.instructables.com/id/How-to-create-voltage-using-one-power-supply/
Also, Im currently following the schem. from your Introduction in the IC based fuzz section which seems to use it differently. Prior to that, I've seen it hooked up to pin 3 on non-inverting circuits. I've tried that with poor results. Thank you for your time.

Derringer · April 18, 2015, 12:49:44 PM

welcome to the forum

in order to get a bipolar power supply (+ and - voltage), it seems that most folks around here like to employ the use of charge pump like the MAX1044 or ICL7660SCPA etc.

here's a nice description of how to use a MAX1044 for bipolar supply http://www.geofex.com/circuits/+9_to_-9.htm

and here's a project from MadBeanPedals called the road rage that can be designed to give you all sorts of voltages from a 9V source
http://www.madbeanpedals.com/projects/RoadRage/docs/RoadRage_2015.pdf

search for "Charge Pump" and I'm sure you'll find lots of options

mth5044 · April 18, 2015, 01:19:25 PM

Quote from: bluzeyonecat on April 18, 2015, 11:34:31 AM
Thank you Matt. That clears it up a bit. Is virtual ground really solid enough to work with? I've added a 100uf cap to it with hopes to secure it. I am working with a 9v circuit.

Two terms you mentioned I need a little studying. "Headroom" & "Pad" . I know what a pad is in "synthology" but your talking of something different. Thank you for your help.

China Grove got em dancing, wuddaya say we launch into "Misty Mountain Hop"? *dialing up the wurly*

There are probably better technical definitions. but I refer to headroom as the amount of voltage you can swig through a pedal before it clips. So if you have a TL072 running off a 9V supply referenced to 4.5V, you can only input a signal that swings MAYBE 6V (1.5V to 7.5V), or maybe less, before you clip the opamp as it can only do signals with less voltage than what it's powered by. There are 'rail to rail' opamps that can swing almost it's entire power supply.

A pad is something you use to bring down or pad the input volume, be it two resistors, a potentiometer, etc.

The Road Rage Derringer posted is great. If you want a simple +/-15V supply, check out link below. No need to mess with mains wiring, a 16V *AC* adapter works well. You can mod circuits to run on higher voltage for more headroom if you need to using the charge pumps pr whatever, but take note that the charge pumps can only put out a small amount of milliamps, so plan accordingly.

bluzeyonecat · April 18, 2015, 10:19:33 PM

Thanks alot guys! Gonna do some fishing. Really appreciate your time.

amptramp · April 19, 2015, 10:23:26 AM

Earthlings? Since when did we allow earthlings to join this forum?

bluzeyonecat · April 19, 2015, 11:37:42 AM

Now I know I'm in the right house!

anotherjim · April 19, 2015, 11:53:28 AM

A mean Rhodes patch huh?
You know, there's all those painstakingly recorded samples sets out there and usually someone moans about the sound of one or other. Usually "not enough bite when I dig in". But you probably know that half of the sound was due to whatever the piano was played through and the following chain.
So, amp sims would be a good place to start, since guitar amps were & still are commonly used with EP's.
Runoffgroove have many suitable designs.

News:

Greetings earthlings :)