Really Smooth Overdrive!

roseblood11 · Post by **roseblood11** » 29 Sep 2011, 08:55

Correct. Replace the 100k with a pot and a small fixed resistor in series.
And you can try any clipping diodes - use sockets...

mictester · Post by **mictester** » 29 Sep 2011, 23:00

gght wrote:I know this is an old thread, but... I am intrigued. I am wondering if a gain control would be as simple as a pot and a fixed resistor in parallel with the diodes, ala a tubescreamer? I just never have liked using the guitar volume to control pedal gain. is Mictester still around? Also, did anyone try LEDs as clippers here?

Thanks!
gght

I'm still here!

Just replace the 100k resistor with (say) 10k in series with a 220k pot. with the pot wired as a variable resistor. With the pot at the centre position, the gain will be (virtually) the same as the fixed resistor - using a higher value pot allows a bigger range of gain, from very little to really screaming. There's little point in changing the diodes to LEDs (try it if you want - it'll work) - you'll just get a bigger output (because the conduction voltage of the LEDs is higher), and slightly harsher distortion because of the more abrupt start of conduction (at least with most normal LEDs).

Remember - the values I publish are just a known-good starting point. Please feel free to tweak away!

gght · Post by **gght** » 30 Sep 2011, 04:18

Thanks! Since I don't have the ability to produce a board, and would rather not mess with the other methods, I'm gonna see if I can con, errrr bribe someone to etch a board to build this. If anyone is willing and able, please speak up. I will pay, not looking for a freebie. (I would love to DIY, but my free time is extremely limited, so I semi-DIY as best I can. )

Maybe germ diodes, rather than LEDs? I just found some nice sounds from an SD-1 conversion to the CJOD found here in another thread.

I am after the sound of a Laney Lionheart L5T, a great sounding amp. If you haven't heard it, check out the youtube clips. Since the Laney runs about $900, thought I would try this instead!

Thanks again.
gght

roseblood11 · Post by **roseblood11** » 30 Sep 2011, 09:21

It's easy to make a veroboard layout with DIYLC...
Maybe I'll draw one next weekend, but I'll use a RC4136N (a quad version of 4558), which has a different pinout than TL074 and other common types. Maybe two dual opamps would be better anyway, because you could use different types for the buffers (maybe NE5532AP) and for the distortion stages (I prefer 4558 or LM833, OPA2134 etc there).

geiristudio · Post by **geiristudio** » 01 Oct 2011, 13:34

I'd love a vero layout for this, thanks!

mictester · Post by **mictester** » 02 Oct 2011, 01:43

gght wrote:Thanks! Since I don't have the ability to produce a board, and would rather not mess with the other methods, I'm gonna see if I can con, errrr bribe someone to etch a board to build this. If anyone is willing and able, please speak up. I will pay, not looking for a freebie. (I would love to DIY, but my free time is extremely limited, so I semi-DIY as best I can. )

Maybe germ diodes, rather than LEDs? I just found some nice sounds from an SD-1 conversion to the CJOD found here in another thread.

I am after the sound of a Laney Lionheart L5T, a great sounding amp. If you haven't heard it, check out the youtube clips. Since the Laney runs about $900, thought I would try this instead!

Thanks again.
gght

If you use germanium diodes, the output levels will be a lot lower - you'll have to give the final op-amp buffer stage a gain of about 3.5 to get the same levels as with silicon diodes. I have built these with germanium diodes, but there really wasn't a great change in sound - you have to remember that the input filter stage shaves off a lot of the harmonic energy before the clipper section, and the tone filter shaves off even more afterwards. Even using silicon diodes, it lives up to the billing as "really smooth"!

Incidentally, two well-known guitarists have recently started using (virtually unmodified) versions of this box in preference to their overpriced Cornish copies of Big Muffs. They find that the tones are smoother and the pedal is less hissy...

phatt · Post by **phatt** » 02 Oct 2011, 11:55

I can vouch for the RSO as I did test it out and having breadboard tested it,,,,Lets just say you could do a lot worse with vastly more complex circuits.

I wish I had more time to play around with things like this but alas life gets in the way of the best laid plans.

And NO I don't work for mictester..
Phil

gght · Post by **gght** » 03 Oct 2011, 17:01

Thanks for all the input. Because life does get in the way of these things am making a deal for a couple of etched boards as we speak.

Gght

Chugs · Post by **Chugs** » 05 Oct 2011, 16:04

I had nothing to do today so I sat around making vero layouts. Here is Mictester's Really Smooth Overdrive.

mictester · Post by **mictester** » 05 Oct 2011, 19:19

Nice one!

roseblood11 · Post by **roseblood11** » 05 Oct 2011, 20:54

Nice, but 23 holes is too much to use a 1590b enclosure. But I don't see a simple way to reduce it to 21...

HEAD · Post by **HEAD** » 05 Oct 2011, 23:33

I've built one yesterday using mictesters layout posted here. Indeed very Santana like sounding or like played with an fixed wah in front of an overdrive - especialy with a compressor in front of it - good lead sound. The only withdraw is that it sounds a bit "cheap" - I mean it sounds like a most diode clippers do, which is kinda artificial to me at least. But could be worse.

Thanks again, mictester!

gght · Post by **gght** » 06 Oct 2011, 00:35

Glad to hear Mictester's layout works! Got 2 boards ordered! One thing that is confusing me, The schema shows five 10uF caps yet the parts list only has three, and I assume the layout is the same? What am I missing?

Thanks!

Gght

bubstance · Post by **bubstance** » 06 Oct 2011, 05:13

Well, one of the missing 10uF caps is used for the LED indication in the schematic, which is not on board. The other isn't really necessary since there is already a 10uF cap on 9v.

phatt · Post by **phatt** » 06 Oct 2011, 11:57

HEAD wrote:I've built one yesterday using mictesters layout posted here. Indeed very Santana like sounding or like played with an fixed wah in front of an overdrive - especialy with a compressor in front of it - good lead sound. The only withdraw is that it sounds a bit "cheap" - I mean it sounds like a most diode clippers do, which is kinda artificial to me at least. But could be worse.
Thanks again, mictester!

Hello HEAD,
Just use an old fashioned *Passive* type tone circuit *INFRONT of the RSO and it may change your whole concept of how distortion works,, winky.
without a tone circuit in the right place all those fuzz boxes leave you wanting MORE.

Try my PhAbbTone,, Schematic here;
https://www.freestompboxes.org/viewtopic ... 28&t=12135 (half way down page).

Member Johno did a diy layout for this circuit, not sure if it still exists?

I get the impression Johno likes it

Phil.

asperix · Post by **asperix** » 16 Oct 2011, 18:25

I built one with some minor mods. Changed the 330k in op amp 2 feedback path to 150k. Replaced the 100k in op amp 3 feeback path to A250k pot w/4K7 in series. Clippers go out to a switch. Also used OPA4134 opamp. Sounds nice.

Really like the wha-ish sound. What to modify to play with the resonant frequency there? I'd like to sweep that resonant peak up/down until I find the perfect spot for me.

What needs to be changed on op amp 4 to make a little bit louder output to compensate for the different clippers on a switch?

danke!

HEAD · Post by **HEAD** » 17 Oct 2011, 09:36

Try something like this. I also found it had bit too less output.

HEAD · Post by **HEAD** » 14 Dec 2011, 13:09

Hi,

here is my little christmas contribution. I did a little refining/improvement work based up on Chris RSO layout.
1.) The ouput was too low with the tone controll dimed. So I added a bit gain to the last opa stage (~3x). For the schematic look at the post above - though I changed the 10k to 47k (which gave me ~10x gain which was a tat too much for my taste).
2.) I added the missing 10µF cap at vref since the circuit otherwise started to oscillate with the added gain in the last op stage.
3.) Cap spacing for the electorlytics was choosen a bit too tight for my taste. So I fixed that as we had enough space using your standard 1590B style enclosure which gives you ~56mm usable width.
4.) Pots spacing was also a bit too tight if you want to use pcb mounted pots, a good looking design and knobs with a biiger diameter than 14mm.
5.) I added a trim pot to adjust the gain of the distortion part. There's a via on the pcb right in the middle of the trim pot. Drill that big enough for being able to adjust the gain with a screw driver while the pcb is upside down in your enclosure.
I think that's it. Enjoy and feel free to comment and improve!

Cheers
Helge

meffcio · Post by **meffcio** » 14 Dec 2011, 16:17

Great Dude, I love professionaly made pdf project files. Certainly goes to my to-do list.
And of course big thanks to mictester for the main project.

Anyway, standard question - did anybody try it with bass guitar? I'm looking for a good bass tone suitable for playing some metal. I tried some fuzzes blended with clean bass, some distortions (actually modded Rat on low gain setting works well), but I'm still looking for a sound that reminds of just an overdriven tube amp, or smth.. You know, not that much of distortion in the sound, just a little bit of harshness, still retaining overall character of the guitar. Since that one here is believed to be smooth, I thought that maybe that will do. So, anybody has a bass guitar and this circuit built?

sjturbo · Post by **sjturbo** » 26 Feb 2014, 01:47

Has Chuggs vero layout been verified for the RSO? I know Phatt has breadboarded it has anyone else built the pedal using the vero layout?

Really Smooth Overdrive! [documentation]