DIY Effects

[kyboo]

@DolganoFF

I tend to break my circuits into smaller independent parts. These PC simulation programs go sometimes bonkers. I haven't exactly figured why, I just read that it has to with transients, especially at the beginning of simulations. So just to be on the safe side, I keep logical parts separate. I just make sure that input, output impedances are as they should. Like low output impedance goes into filters, etc. If you really want, at the end, you can put them together before making a pedal by using sub-circuits. So I would put a power supply related stuff to a separate circuit. Those caps can create transients and you don't really need that part for your filter anyway.

That gain pot works for sure It is just that I think there are other wirings which might give you some benefits and don't need any other components. Let me think about your case. That taper to the ground wiring works for non-inverting opamp inputs.

I agree as well, as you pointed out, it is more than valuable to look outside of guitar pedals diy forums, topics. Sometimes, I just stay puzzled about myths being created around it. Whereas in the reality, guitar circuits are, more often then not, very basic comparing to hi-fi or studio gear. However, it is interesting to see some witty simplifying solutions. Like Rothwell Love Squeeze compressor.

P.S.: I am just a hobbyist, so if there is any real engineer, please have mercy

Edited August 25, 2014 by kyboo

[kyboo]

BTW this is a good book on the topic 'Electronics for guitarists' http://www.amazon.co.uk/Electronics-Guitarists-Denton-J-Dailey/dp/1461440866/ref=sr_1_1?ie=UTF8&qid=1408967044&sr=8-1

[kyboo]

@DolganoFF

Try the schematic I attached. R4+POT_2K5+R5 can't be bigger then Rf(10K), otherwise the inverting gain opamp might be rendered unstable. Gain ratio can be computed like this:

(Rf*Rpg)/(Rin*(Rin+Rpg))

where Rpg is the pot resistance to the ground. Rin is R4(1K)+R5(2K)+(2K5-Rpg).

However, I am not 100% sure whether it will work in your state variable filter. I am not familiar with it but I would say that it should.

EDIT: R4 is not needed.

[attachment=170126:basschat_diy1.png]

Edited August 25, 2014 by kyboo

[DolganoFF]

Yep, good remark on stability, to avoid the problems I've chosen only between the "unity-gain stable" opamps, they help to stay stable even with low gains.
I'll have separate volumes on the outputs so not having signal going to 0 is allright here (due to not referenced to ground gain pot).

You're right on transient analysis, putting ideal caps in parallel with ideal voltage sources may be tricky to analyze for simulation software (because of infinite current at the start). As far as my experiments go, I didn't have problems with this in LTSpice yet, but I'll try to remember your advice if this thing pops up some day!

[KingBollock]

Well, I am having no bloody luck with blender circuits at all. I have built the paralooper, both the bass and the full ranger versions, and a couple of others, and none of them have worked and I really don't know why. Though I rather suspect my current fragile state of mind might have something to do with it.

As the end result with each one was the same I decided to try to narrow it down to common parts, the sockets that I have set up in a box for testing. I built another one of those little split n blend circuits that I put in my Big Muff thing, because I know it works. And it did indeed work... Bugger!

The main reason I don't want to use the split n blend is because I wasn't terribly happy with it in the Big Muff, but I found it played ball better when the effect volume was at 50%. I also discovered that the Musket that I have built into the same box and also goes through the blend, leaves the phase inverted because of its five gain stages, whereas the Big Muff only has four, this causes the volume to drop when the blend knob is at 50%.
When I talked about this earlier in this thread, I wondered about adding an LPB1 to add volume but was told that it inverts the phase. Now I am thinking this could be exactly what I need. I could use it in the Musket as a phase inverter. I could also use it in the dual loop, blend, order switcher pedal I am currently struggling with. It seemed such a simple idea when I thought of it... Am I talking bollocks again? There is a very obvious reason this won't work, isn't there?

I really don't know why nothing is working properly, though. It seems anything I try to make using ICs just doesn't work. It is confusing and worrying.

[paul_5]

I built the Bass Paralooper too and it didn't work. It;s not just you, I think it's a dicky circuit.

I've not found a blend circuit that I'm happy with yet, and I've built probably 5 or 6. It's a bit of a minefield really.

[KingBollock]

I did end up putting the Split n Blend and an LPB-1 together. It actually works as I thought it would, which, lately, is highly unusual... The only side effect is that the loop gets boosted when the LPB-1 is engaged. Which shouldn't be a surprise really, but it has a volume pot and if used carefully could be quite useful.
I am going two build another and put them in a box. Since the plan was always to have three footswitches (loops 1 & 2, order switcher), four knobs (volume and blend for each loop) and two toggle switches, I can keep trying to build a better version and just swap it out if I succeed.

I just need to figure out why I fail so hard with ICs. Even incredibly simple stuff like the Noisy Cricket, Ruby and Smoky amps won't work for me, though I did get them to work on breadboard. The main difference being that I breadboard from schematics but follow others' layouts for the vero. But I have looked closely at those layouts and can't see anything wrong and they have been verified by others. I have also used DIY Layout Creator to design vero layouts from the schematics. I socket the ICs and work on an anti-static mat connected to earth so as not to damage them, and like I said, they work on breadboard. I just seem to be getting something fundamentally wrong when trying to use them on vero and it is worrying that it has been so long and I just can't see it.

Some of the mini amps are even simpler than the blend and LPB-1, and before I started trying to use ICs the far more complicated circuits, including the dual Big Muff and Musket, that I had to redesign a bit, worked fine first time. It just seems to be the inclusion of an IC that throws me. I did do some stuff with ICs on breadboards in college, and replaced some while doing work experience in electrical repair shops, but that was all over twenty years ago. The only difference is the use of sockets, but I have tested them to make sure the IC legs are definitely in contact with the circuit.

I think I might put something really simple together and post pics on here, see if anyone can spot the problem. I can't post any of my current bad builds because I have made a right mess of them while trying to figure them out.

[ahpook]

[quote name='KingBollock' timestamp='1409916723' post='2544548']
I think I might put something really simple together and post pics on here, see if anyone can spot the problem. I can't post any of my current bad builds because I have made a right mess of them while trying to figure them out.
[/quote]

It's a real shame you have no luck with IC, maybe kick off with a klon buffer ?

[KingBollock]

[quote name='ahpook' timestamp='1409929332' post='2544705']
It's a real shame you have no luck with IC, maybe kick off with a klon buffer ?
[/quote]
I don't currently have any TL071s and with the luck I am having I am reluctant to order any. I have TL074s, LM396N4s and LM741s. I do have a few other ICs that came in a sort of starter set that I bought to get a stash started, but they don't look very useful.

I'm not going to stop trying with ICs, I'm sure it's something stupidly obvious.

[KingBollock]

[quote name='paul_5' timestamp='1409781855' post='2543419']
I built the Bass Paralooper too and it didn't work. It;s not just you, I think it's a dicky circuit.

I've not found a blend circuit that I'm happy with yet, and I've built probably 5 or 6. It's a bit of a minefield really.
[/quote]
I am actually quite happy with what I have ended up with, considering. It's very simple but it seems to work. I won't know how useful it actually is until I have it boxed up and start using it in my pedalboard. I haven't tried it with a non-inverting pedal in the loop yet.

This is what I ended up with: [url="http://freespace.virgin.net/alison.jackson/list/ElectronicProjects/BlendLoopBoost.pdf"]BlendLoopBoost[/url]

I've put a battery clip in there because there isn't a DC jack to use. I wouldn't use a battery, though, it distorts if it gets less than 9v. I might even try it with 12v.

Edited September 5, 2014 by KingBollock

[ahpook]

[quote name='KingBollock' timestamp='1409929789' post='2544715']
I don't currently have any TL071s and with the luck I am having I am reluctant to order any.
[/quote]

If you PM me your address I'll send you a couple of 072s. The layout of 072-based klon clone at the tagboard effects blog deffo works as I've built a couple.

[KingBollock]

[quote name='ahpook' timestamp='1409931602' post='2544745']


If you PM me your address I'll send you a couple of 072s. The layout of 072-based klon clone at the tagboard effects blog deffo works as I've built a couple.
[/quote]
Thank you for the very kind offer. I am going to carry on with other stuff for now, I am fairly happy with the blender I made so I'm in now hurry. I will come back to ICs when I think I can get my head around it (I am still a bit muggy headed after rather nasty news a few weeks ago, it has effected me rather badly and I tend to dwell on that sort of stuff). I seem to be putting in an order with Bitsbox every month at the moment, I shall tag some on to the next one, or the one after that. Again, thank you.

[KingBollock]

I just rescued an old 12v transformer, one that was knackered but got thrown in a drawer, instead of the bin, for just such an occasion. It was just a transformer and bridge rectifier, no filter caps at all, and no regulator. So I fitted a regulator and a cap either side. While I was looking for suitable cap values I found plenty of schematics but none of them agreed on values, certainly not for the big cap. I saw mention of 1uf per mA, but it was said that this allows for a 1v ripple and in a 9v supply that is rather a lot I think.

Has anyone here built a PSU for effect pedals? What cap values should I be looking at? Is there an upper limit beyond which it makes no difference?

I have a couple of other transformers knocking about that I would like to sort out. I also have plans to make a multi PSU using three transformers, each with two secondaries, to run my pedalboard in the future.

[ahpook]

I had a go at a Run-Off Groove Grace Drive today, with some bassier caps.

I used the vero from Runoffgroove [url="http://tagboardeffects.blogspot.co.uk/2013/01/runoffgroove-grace-overdrive.html"]here[/url], but tweaked it slightly to give it a bit more space as I was just trying the circuit out.

Here's my 'roomier' version - the same as the ROG one as far as I can tell, but if anyone spots anything, do let me know.

[url="https://flic.kr/p/p6J6sN"][/url]

I used a 12k load resistor instead of a 15k as I had one to hand and a 2n5258.

It works OK...but I'm not overjoyed with the sound. Just a bit farty for my tastes.

I'll go over the circuit tomorrow to see if I've made any obvious errors in the construction. Still, a nice little project for a quiet afternoon. I may not go the whole hog and box it up...see how it goes.

Edited September 7, 2014 by ahpook

[ahpook]

[quote name='KingBollock' timestamp='1409958163' post='2545077']
Has anyone here built a PSU for effect pedals? What cap values should I be looking at? Is there an upper limit beyond which it makes no difference?
[/quote]

No, but I've got a 12v transformer and some voltage regulators - I've been meaning to have a go, but mains scares me.

[KingBollock]

[quote name='ahpook' timestamp='1410048583' post='2545723']


No, but I've got a 12v transformer and some voltage regulators - I've been meaning to have a go, but mains scares me.
[/quote]
If you've got an unregulated 12v wall wart you can just make an inline filter/regulator in a separate box, just to get started.

[ahpook]

[quote name='KingBollock' timestamp='1410050179' post='2545728']
If you've got an unregulated 12v wall wart you can just make an inline filter/regulator in a separate box, just to get started.
[/quote]

Good idea !

[ahpook]

Update on the Grace Overdrive I built yesterday. I decided to try different values of coupling capacitor between the FET and the LM386. Very small values seemed to tame the fart a bit (I ended up with 47nF), but still not great.

I suppose I [i]have[/i] to build a smokey amp now with this spare 386

[paul_5]

FWIW I've never really rated dirt boxes based on the 386.

If you want to build a small amp then the TDA2822M does a much better job. It's a dual amp, but it can be bridged to run in mono, which also makes it louder.

Here's the schematic I used for mine.

[url="http://s1221.photobucket.com/user/paul_510/media/TDA2822schematic_zps30735c62.jpg.html"][/url]

Edited September 7, 2014 by paul_5

[ahpook]

[quote name='paul_5' timestamp='1410094321' post='2545999']
FWIW I've never really rated dirt boxes based on the 386.

If you want to build a small amp then the TDA2822M does a much better job. It's a dual amp, but it can be bridged to run in mono, which also makes it louder.

Here's the schematic I used for mine.

[url="http://s1221.photobucket.com/user/paul_510/media/TDA2822schematic_zps30735c62.jpg.html"][/url]
[/quote]

Cool, what's the maximum power output ?

I just croc-clipped a speaker to the output of the grace pedal to see what it would sound like - it needed to be pretty fuzzed-up to get any real output, but it's was a pretty cool lo-fi 60s fuzz.

Think I'll leave the LM386 as an experiment

[paul_5]

[quote name='ahpook' timestamp='1410094494' post='2546004']
Cool, what's the maximum power output ?
[/quote]

Dunno, depends on the DC supply.

I just finished on of these...

[URL=http://s1221.photobucket.com/user/paul_510/media/DODFX25_rev8a_zpsfb574c07.png.html][IMG]http://i1221.photobucket.com/albums/dd471/paul_510/DODFX25_rev8a_zpsfb574c07.png[/IMG][/URL]

…and it's pretty cool. I've hardwired mine to the LPF setting and have added a volume knob, but other than that it's a good little project.

[jetofuj]

I'm sort of oldschool when it comes to dirt boxes and always though about using two classic things with bass. First is Rangie style germanium booster with range control to boost not only treble, but also mids and bass. Second is modified Fuzz Face - fuzz fixed at maxed, and instead of fuzz control, there is a pre-gain control to mimic rolling down your guitar's volume knob. Of course it cuts bass a bit, but still works great even in heavy mix.

[ahpook]

[quote name='jetofuj' timestamp='1411250212' post='2557941'] I'm sort of oldschool when it comes to dirt boxes and always though about using two classic things with bass. First is Rangie style germanium booster with range control to boost not only treble, but also mids and bass. Second is modified Fuzz Face - fuzz fixed at maxed, and instead of fuzz control, there is a pre-gain control to mimic rolling down your guitar's volume knob. Of course it cuts bass a bit, but still works great even in heavy mix. [/quote]

Very nice indeed - super neat wiring.

Can I ask, what tone control did you use before the Ge booster ? - I have a spare one made up from a kit that I dug out the other day.

[jetofuj]

Thanks! 4700pF and 100nF caps with 100K pot.

[ahpook]

[quote name='jetofuj' timestamp='1411409721' post='2559276']
Thanks! 4700pF and 100nF caps with 100K pot.
[/quote]

Nice one. Ta.