The "Woody": a cheap acoustic simulator

[Mark Hammer]

There is a BIG distance between this circuit and a true acoustic tone.  On the other hand, if it's buried in the back of the rhythm in a gig situation, and you can't afford a decent acoustic simulator pedal or piezo-equipped instrument, this doesn't do a half bad job for the amount of stuff involved.  Sounds great with a chorus and a touch of compression.

I posted an earlier version of the schematic that had a pinout error.  The new one posted is correct and functions as promised.

Find it at http://hammer.ampage.org

I'll see if I can post some sound clips soon.

[John G]

Mark,
Is the low impedence (10k) nessessary to achieve the sound or can a Hi Z (1M) non- inverting stage be used.
Thanx
John G

[Nasse]

A good circuit can save your day, and an excellent circuit can do even more.  

A fender-style guitar can sound quite like an acoustic one when playing rhytm with a live band trough a goodish amp. And with a little help from this kind of gadget you can bring it home, I believe.

Btw I just bought myself a digital multieffects processor, which has an acoustic simulator preset. Comparing it to your demo I think this time analog wins absolutely clearly.

[Gilles C]

Hey Mark,

Could you wait until I'm ready to build things again... before you come up with a new good sounding device  :cry:

Looks and sounds good.  

Cheers,

Gilles

[donald stringer]

I used to have an ac-2 and when I got a convincing sound it was always accompanied by an incredible hiss sound or noise was present. In your demo it almost had that page 12 string gibson thing happening, sounds good as is. The only bad  thing is I cant keep up with all these circuits that I want to build. This one will have to be put at the top of the list. I thinkboss accomplished some of there sound [at least in part ] by  filtering out the mids] and the only reason I know that  is because another electronics guitar player friend told me.

[Parade]

You know what would be nice?
To have a 12 string acoustic simulator. You could probably mix a harmonizer effect with an acoustic simulator effect. I havent tried this but it would be cool. I have always wanted to have a sound like that.

You could probably hook up. Boss HR-2 Harmonist and Boss AC-2 Acoustic Simulator

[Mark Hammer]

In simulating a 12-string, you need to remember that the 3 bass strings have an octave tacked onto them, where the 3 treble strings merely have the same pitch in unison (or is it 4+2, I forget). :oops:

This means that adding an octave shifted version of the same instrument to the basic sound would produce something which does not sound like a 12-string.  Its a lot harder to emulate acoustic instruments than you think!  I have to say that the Woody+chorus surprised me with respect to faking a 12 string.

Of course, if you had a split pickup that could deliver the lower strings to one processor and the higher strings to another, then maybe it could be done,but again, that's trickier and more technology intensive than what you suggested.

Good try, though.

[Nasse]

:oops: Sorry this comment is about off what you talk but just remembered one quick and dirty Eagles trick what was told in some guitar magazine. You dont need a processor or 12-string guitar in this trick: Just remove three lowest and thickest strings on your guitar and replace them with unwound thin trings and tune them E in same octave as highest, A and D octave higher than normal. If you have old suitable guitar around for this purpose for some song or track this could work, of course it is thin in the bass side but may sound clearer in the final mix.

Cheers

[AL]

I think that trick is called Nashville tuning.  I think Steve Earl just called it High Strung Guitar.  It's a really interesting sound and can be used to good effect in select instances.  Uncle Tupelo/Jay Farrar may have used that a few times.

AL

[Aharon]

After listening to the sample and comparing with a commercial unit(Zoom,yes I know,don't go there)it sounds considerably better to my ears,definetly a must do.
One question Mark,is you prototype diferent?,did I detect a lower part count in the picture?.
regards
Aharon

[Paul Marossy]

Is the LM4136 just a quad opamp?

[Gil]

Sounds great ! Is there any layout avaliable for it ?

BTW, Mark, I noticed that use used the same DPDT that I generally use, and which makes me LOTS of problems... Do you encounter the same problems with yours ?

Thanks.

[Marcos - Munky]

Is there any layout avaliable for it ?

Not yet, but wait a few days :lol:!! Me and Tomboy are working on one.

[Bill Bergman]

I like it !!

[Mark Hammer]

The 4136 is a low noise quad op-amp.  There is nothing special or critical about it in this application.  Like the document says, you can use anything you want - duals, quads, whatever.  It is probably important to have lownoise op-amps for the input stage and the highpass filter since whatever comes through them or is *generated* by them will be boosted, and you want this thing to produce harmonics of valid music/signal content not spurious blips.  Beyond that, though, the choice is yours.  Munky/Marcos has corresponded with me regarding the particulars of the layout he is working on.  I forget whether the layout will be based on a 4136 or TL074/84/64/LM324 pinout.  Both of these are quads, but the pinout is somewhat different.

I think the only thing different bertween the schematic and what I used for the demo was a little more gain in the output/mixer stage (not critical) and a feedback cap in the input and output stages just to keep the noise under control.  I think I rolled it off around 15khz or so.  I asked Marcos to stick some extra pads in for those who want the option of rolling off the ultra-highs.

It pleases me immensely that a shot in the dark yields something that some folks who've been around the DIY block a few times find build-worthy.  Kind of nice as well to generate interest in something that doesn't sound like a torture chamber and isn't a fuzz.  I like those things too - don't get me wrong - but with 6083 possible circuits to choose from, where does a fella/gal start?

PS: If you make the cap values a bit smaller in the highpass filter so as to raise the cutoff frequency a bit, you can probably also use it as a standalone "exciter" circuit for adding a bit more sizzle to mic'd acoustic instruments.

[Paul Marossy]

Sign me up for a copy of the layout when it's done

[Marcos - Munky]

I use the LM4136 in my layout. When Tomboy finish the redraw, I will post here.

[Bill Bergman]

Where's the layout

[Mark Hammer]

If you're desparate, there's a *perfboard* layout in the zipfile...heh, heh.  It's how I made two of them.  The hardest part is having fine enough needle-nose pliers to wrap the resistor leads around the IC socket pins.  Well, maybe that and figuring out where you put the end-cutters under that pile of paper and crap.

[Marcos - Munky]

I think the layout will be online in this week, it's almost finished.