Simple MN3007 Chorus Circuit?

[ziggy]

Hey folks,

I am brand new to building pedals, brand new to this forum ... but do have a little electronics background.

Was just searching around the net as I wanted to build a real small chorus pedal. I have a relatively cheap chorus pedal at the moment and only use the "depth" side of it which gives a fuller sound to my Ovation ... so was wanting to build a simpler and much smaller unit really with just a single control depth function running off a 9-volt battery.

Whilst searching, I saw lots of posts about Boss Chorus pedals to the effect "get the MN3007 chip, its the best and you won't be able to get them soon as they are discontinued and there are lots of fakes around ... yada yada yada"  ... so without much further research (i.e. just a cursory check that the Boss pedals have a depth function) ... and my usual impulsive behaviour ... I just (panic) bought the MN3007 & MN3101 pair from Doctor Tweek ... then thought "hmmm ... can I actually build what I want with this"?

I then found one circuit with that chip and it looked very complex ... but I think it was using all of the features of the chip with a bit more added on!

Was hoping even to build it first maybe on a breadboard, test it was all ok and then commit it to a PCB and enclosure.

I have the panasonic datasheet that has a sample application with about 4 op-amps to produce what they call an "echo effect generation circuit" ... but not sure whether that is really what I am after.

Can anyone give me any pointers? Can I build a fairly simple "depth" chorus effect with the MN3007? Are there any simple circuits out there explaining how to do this?

Any help appreciated

Thanx

Ziggy

[stecykmi]

madbean's pork barrel is right up your alley, i think. simple, 2-knob control and a fairly low parts count (for a chorus effect). for the record, it's based off the boss ce-2 chorus.

[RobA]

madbean's pork barrel is right up your alley, i think. simple, 2-knob control and a fairly low parts count (for a chorus effect). for the record, it's based off the boss ce-2 chorus.

And if you really wanted to just have the depth knob, you could replace the rate knob with a trim pot.

[ziggy]

Hmmm ... over 40 resistors ... nearly 25 caps .. and a few other odds & ends ... that is not a "low parts count" in my books ... I am thinking I may have bit off more than I can chew :-(

Understand I could replace the "rate" knob with a trim pot ... but wondering how much of that circuit I actually need for just a "depth" function ... with that many parts can't see my fitting it into a small enclosure either :-(

[kothoma]

Yup, the Pork Barrel.

It may look complex, but you really need all that stuff. It's the minimum to get a great chorus sound with these chips.

You could also build the Tonpad Corrrral Chorus, but with Madbean's layout you can use 5mm box caps where Tonepad's has 7.5mm spacing.

No need to breadboard and reinvent the wheel.
Forget the sample application, no swirl, no depth.

To say the truth, you could also try this: http://www.hollis.co.uk/john/zombie.jpg.
But it uses a CD4046 instead of your MN3101 and as it has less filtering it is a bit more noisy.

[madbean]

The John Hollis Zombie chorus is very low parts count and great sounding. However, it is pretty noisy...enough so that I would not recommend it unless you are willing to accept that. There are some tweaks to the circuit available on DIYSB, but I've tried them with no luck in reducing noise.

I suggest instead going with the Little Angel chorus. It is very low parts count and sounds great. Doesn't use the MN3007, but don't let that fool you. It's a righteous chorus.

You can easily find info on it through Google.

[LaceSensor]

If you want my mind, dont waste time on the Little Angel, the Pork Barrell is far nicer.
Just bite the bullet, do one part at a time, and get the job done.

A 60 part project is not really harder than a 20 part project, just take your time.

The results are well worth it...

[Mike B.]

+1 for the Pork Barrel. It's really not as difficult as it looks, fits in a 125B enclosure, and you can't beat the CE-2 circuit for analog lushness.

[LaceSensor]

+1 for the Pork Barrel. It's really not as difficult as it looks, fits in a 125B enclosure, and you can't beat the CE-2 circuit for analog lushness.

Fits in a a 1590B....

[jkokura]

Yeah, Chorus is like Delay - you need a higher parts count to make it happen. It's why they tend to be more expensive. BBD chips require quite a bit of filtering, and that requires high parts counts.

So, your first post stipulates an MN3007 circuit, but by doing so, you've automatically booked yourself into a high parts count.

The CE-2 circuit really was a homerun circuit. There's no sense in going for anything else. The MN3005 has been applied in many different circuits, but really, the MN3007 is it's best in that CE-2 chorus.

Jacob

[juansolo]

Pork Barrel (CE-2) or Bajaman's Small Clone would be my choices.

[RobA]

Hmmm ... over 40 resistors ... nearly 25 caps .. and a few other odds & ends ... that is not a "low parts count" in my books ... I am thinking I may have bit off more than I can chew :-(

Understand I could replace the "rate" knob with a trim pot ... but wondering how much of that circuit I actually need for just a "depth" function ... with that many parts can't see my fitting it into a small enclosure either :-(

The CE-2 really isn't that hard to build. I think it's the second pedal I built. I did it the first time using a self etched board which had a bit of noise in it. I then redid it using the Pork Barrel and it came out really well. If you have a good soldering iron and take it slow, it's not bad. The layout is nice to work with and the instructions are good.

You might want to look into doing a boost or preamp pedal first to get used to the process. They are usually very easy to build and can be great for adding a bit of sparkle or tone shaping to your guitar.

A modulation pedal that is pretty simple to build and I think sounds nice on acoustic is the Smoothie (Phase 45). It might be a good choice as a warmup build for the CE-2 and would provide a nice useful pedal as well. The only difficulty with the Phase 45 is getting the matched JFET's, but there are a variety of solutions to that problem too.

[Stomptown]

I'm currently working on a PCB for the EHX small clone chorus. I'm pretty sure there are less components than the CE-2 but not by much! I would agree with Brian though; the little angel would be a nice low count alternative if you can go without the mn3007. Personally though, I would Jump in and build a 3007 chorus. Just socket your parts!

[juansolo]

Small Clone vs CE-2 (Pork Barrel).

[ziggy]

Folks,

Thanks for all your posts, you have all been a big help.

I am going to press on with the pork barrell ... may take me some time as I need to get a few more parts and other odds and ends ... but going to give it a go!

Will let you know how I get on ...

Thanx

ziggy