Ginger Bass overdrive... 1N5818 crucial?

[Buzz]

Hi All.

I'm wanting to make an overdrive / distortion pedal particularly for bass guitar. After a lot of reading around I'm pretty keen on the Ginger pedal, courtesy of Ronoffgroove.

The Ginger has two clipping stages, one with LEDs and the other with 1N5158 Shotkkys.

Are the 5158s crucial for the function of the pedal, or could they be replaced by standard Si or Ge Diodes? ( 1N4148 / 1N60 etc )

I wouldn't mind if they changed the 'flavour' a bit, I just want to keep as much bottom end as possible.

http://www.runoffgroove.com/ginger.html

Cheers.

[GibsonGM]

Neat looking schematic...you could TRY other diodes, but I have a feeling they chose the Schottky's for their particular characteristics.   You could end up with something pretty neat, or something that just sucks!
I'd just order them up, 5 cents each and all that...get yourself a bunch of other goodies at the same time!  )     

Guys like AMZ, Runoffgroove - they play with parts in their designs enough so that if they're calling form this TYPE of component, there is certainly a reason...

[Mike Burgundy]

shottky's are very fast and have a very low forward voltage. Ge might get close as far as forward voltage is concerned, Si will be very different. First glance looks like the LEDs are used more like limiter stages, and the Schottky's add the brunt of distortion.  GGM has the ticket - get them and stick them in, see how you like it, then experiment.

[Buzz]

Cool.

I've got all the other bits. I might chuck it on the bread board with some 1N60s and 1N34as.

That will give me something to play with while I wait for the Shottkys to arrive.

Thanks guys.

[jimilee]

Is there a strip board layout for this or a fabbed board?

[Buzz]

No, jimilee, haven't found either.

I was going to use pad per hole or knock up my own vero for this. I hadn't decided yet.

If I go for the vero I'll share the layout.

[bluebunny]

Rick Holt (frequencycentral) did a PCB for this.  Try dropping him a line.

BTW, regarding those 1N5818s - this from the runoffgroove web page:

each stage has a pair of clipping diodes at the gate to avoid hard clipping in the JFET stages

[Buzz]

OK, I've sourced my 1N5158s. All good.

I was going to put together a vero layout, but then decided it was time to take the next DIY step and etch my own board.

I impulse bought a kit that I saw on *special* by Kemo Electronic. It's got the starting bits I need... some ferric chloride powder, some pieces of board, tray, tweezers etc...

I've got some PnP blue... all good.

Here's where I hit my wall.... laser printers.

I've heard Brother brand laser printers are not the best for etching process.

Guess what brand my friends own? Yup. So I thought I might go out and buy one. All the ones I could afford were, once again, Brother printers.

Has anyone here had success with Brother printers?

And more importantly, how can I tell if the transfer has worked before the acid bath?

[Jopn]

And more importantly, how can I tell if the transfer has worked before the acid bath?

After you transfer to the board, you'll see your toner stuck onto the copper.  Double check and do any necessary touch ups with an etch resist marker before tossing it in the acid.

[Buzz]

And more importantly, how can I tell if the transfer has worked before the acid bath?

After you transfer to the board, you'll see your toner stuck onto the copper.  Double check and do any necessary touch ups with an etch resist marker before tossing it in the acid.

Thanks.

I've heard of the toner flaking off after going into the bath ( on other posts in this forum ). Is there any way to insure it's secure?

If I gave it a light scratch with my fingernails, say, would that be a good test?

[Buzz]

Hey guys, sorry to dig this one out of the grave, but here goes.

I managed to learn to etch PCBs and made the ROG ginger and have been using it for about three months now.

I love it. Big time. Apart from my tuner, it is the only pedal on my bass setup.

Here's the "thing". Works fine with a wall wart. Works fine with a battery too, but only a new battery. Couple of hours playing with a new battery and the output volume starts to drop below unity. So it needs ( guessing here ) 9v + to function.

Here's the next "thing". It doesn't go big over unity gain ( volume kinda gain ) so to get the sound I want the volume control is set to 100%, the gain ( dist ) up to about 90%, bass at 100 and tone at about 90. All cool, I'm getting the sound I want. But I would like some headroom.

Would I get improvements on these issues if I ran it off a 12 or 18v power supply? Or would it make bugger all difference once I  (re) bias the fets?

[ggedamed]

At higher voltage supply the JFETs' gain will be bigger. You might like the result. I fit at least 18V on overy JFET dirt box I make. Just check the datasheet for the safe operation limits.

I'm a bit surprised though. The Ginger schematic shows that all the crunch is done after the tone-stack, so you should have plenty of signal - one common-source amplifier stage and a SRPP. The final (2N5088) stage is a 2nd order Sallen-Key LPF and it should not have any significant signal loss. Hmm, I should breadboard it...

[Buzz]

Ah the breadboard... I think I'll build another one on the board and do an A/B comparison to make sure I'm getting what I should out of this circuit.

I'll have a look at the jfet data sheets and see if they're good for 18v. Better have a poke around in the box and check the voltage rating of the caps, too.

[duck_arse]

buzz, what is the voltage drop across the 68R at +9V?

when we going to have that diode conversation?

[Buzz]

9.01v going in 8.53v coming out.

Our diode discussion will have to wait a bit. Too hot to put a brew down atm.

At the 2N5088 I'm getting:

C  8.53v
B  3.76v
E  3.278v.

Double checked my biased fets, Both have 6v at Drain.

[Buzz]

I also had a listen to the sound samples at ROG. They pretty much match the sounds i'm getting.

I'm wondering if putting a 2N5089 in place of the 5088 at the end of the circuit might get me some more output. Hmmmm....

[duck_arse]

well the drop across the 68R says you're only drawing 7mA, so unless you're using megawatt leds and an acme battery from woolworths, the battery should last more'n a couple of hours. do you have a battery voltage reading from when the volume drops?

and with Q3 and 4 in front of the output buffer, there should be a fair whack of output. do you have any oscilloscope type viewing devices?

[Buzz]

Gotta admit that I may have exaggerated the couple of hours thing... It was a fresh Duracell gold top three months ago, I always use a PSU in rehearsal and have only played via the battery on a few occasions.

I have the battery I pulled out of it, I'll check it's volts at a better time.

I don't have an oscilloscope.

I've still got to put this circuit on the breadboard and do an A/B test. Good place to start.

The reason I'm messing with the ginger again is to make it a part of a new project.

I use this pedal as an always on tone shaper. It doesn't need a stomp switch and it doesn't need to be on the stage floor. I thought it would be good to put this in a box that could also incorporate  a DI  and possibly a compressor. Something that can sit on top of my amp head.

The compressor would just be for a sharper attack. I made a nice ross clone, it does the attack job but I don't like the noise it adds when I'm not hitting a string. I'm prepared to leave it out but I'm currently building an Engineer's thumb to see if it does the job better. I'll put it in the pedal chain when done and see how it goes.

So at the end of the day the whole project will be made from scratch. Something like this.... Input - Ginger - ET - splitter/buffer - DI / output. All in one slab.

Is a buffer all I need for a DI?

If it works out that the ginger I currently have is doing all it is supposed to do I might add a boost after the ET.

The school holidays are over in a couple of weeks... maybe then I'll get several consecutive minutes to rub together and make some progress.

[ggedamed]

Make yourself an audio probe, like here or here. You'll never know how you lived without it.

2N5088 is working as a voltage follower in the Ginger circuit - it has a voltage gain of almost 1 (around 0.992 with your voltages). Its job is to isolate the low-pass filter and to lower the output impedance. Changing it with a 2N5089 will make no difference.

Usually the compresor comes first in the chain. But YMMV.

[Buzz]

Ah, showing my newbieness  many fold.

I thought the 5088 was a recovery stage. I should have researched your terms earlier and got the drift. All the required info was there.

Compressor before ginger makes sense. Having already built both as stand alone pedals I'll give it a work out and see what I like.

Gotta work out what's required for a DI ( apart from the jack... )

Google here I come!

( and ghetto probe on the way )