can i turn the tonepad smallclone into a flanger???

[axr]

i've been thinking of this, but dont  know how to do it, thanks.

[Claus H]

Well you could you have to figure out a way to add some feedback to your BBD.. You could try to add a 33K resistor to the inverting input of IC1A connect a capacitor of 220nF to this and connect to the point marked D.. Not sure this will work but it will add some feedback to the BBD it might be too much..

Well later..


Claus H

[Chico]

If you search this forum and the tonepad build reports, you will find a lot on this subject, I would assume.

The bottom line from my experience is that if you are looking for additional "shades" of chorus, this pedal is a great candidate for modding.  If you want an ADA jet flanger sound, you will likely be better off starting with a different circuit.

Modding is cool, but sometimes the original design and/or layout imposes limitations that are not worth working around.  For example, it is short order to add a switch to slow down the lfo to flanger approved lfo sweep rates.  It is also possible to shorten the delay time to get closer to flanger approved ranges.   There is a ton of information on these mods at tonepad.  You can also add a regeneration control as noted above.  In the end, I did all these mods and ended up with a tone that hinted at a flanger, but failed to nail those metallic, swooshy flange tones that I desired.

There are many on this forum way more qualified than I to address this issue, but I suspect one  problem inherent in this design is that there is no buffer between the 4047 and the delay (MN3007).  As such, as frequency of the PLL increases, capacitive effects of the clock inputs to the delay chip will start to round off the nice square clock pulses from the 4047 such that, at some point, the clocks will become unusable.  This undesirable because these high frequencies is where the flanging matters most, I think.  This limitation also affects the sweep of the lfo as the delay times become shorter.  This is another factor that defines a flanger.

For example, to drive the MN3007 down to 1 ms, you need a reliable clock of approximately 1mhz.  For a flanger, you may even prefer that your delay sweep shorter than that (e.g., into the microsecond range).  
The 4047 is certainly capable of such clock frequencies, but I doubt that a 4047 could directly drive an MN3007 at 1 mhz.

Now there are many chips that would make a suitable buffer between the 4047 and the MN3007, e.g., cd4041, cd4049 come to mind, but if you already have a layout and the circuit built, trying to insert a buffer may introduce more problems than it is worth.  Layout is critical when dealing with high frequency signals, thus you run the risk of introducing clicks in the audio.

My advice is to try the easy mods, see if you personally like them in the context of your rig and enjoy the pedal for what it is, a nice chorus.  

Then, set your sights on a flanger project.  There are several out there.

Happy building...and modding.

Best regards

Tom

[Claus H]

BBD Calculation...

Delay time = 51.2ms

BBD stages = 1024

Clock: 0.5 * (1 / (0.0512 / 1024)) = 10kHz

Bandwidth: depens on what BBD you are using 10kHz / 3 = 3.333kHz

Or am I way off.. 1ms would be 512Khz Clock..

Claus H

[Chico]

You are correct, Claus, thanks for the correction.  Times like these remind me of the importance of never leaving home without my trusty datasheets.

Best regards

Tom

[Claus H]

No prob Tom..

Glad to help..

Claus H

[Chico]

OK, just for kicks, I scoped the clock on my small clone build.  (per my mods described at tonepad).  Essentially, I added a control I call Girth - (sounds more interesting than manual) to set the base delay on my small clone.  At max delay, my clock is running at 16.667 Khz.  As you can imagine, with the low order filter on this circuit, whine is a plenty.  It is not unbearable if the lfo is turnned off, but this box was never meant as a slapback delay.  As I turn the Girth down, I run through a sweet range of chorus sounds, then passing through, I approach approximately 151.51 Khz where the clock rising edge begins seriously curving.  Shortly thereafter, the clock quickly loses voltage and begins to resemble sin/triangle.  At frequencies over approximately 178Khz, the lfo stops functioning.  Even when it does function, when set to maximum depth, the sweep from the lfo causes the clock to range from 178k to 125Khz.  Not very impressive for a flanger, and it explains why I hear "flanger like" character that is really weak.  I am hitting the 3 ms range but the sweep just does not extend far enough.  That also explains why my Regen is subtle at best.

That said, when the Girth is set to within the chorus range, the amount of sweep is sufficient that I can get into all sorts of wierd pitch bending madness.

In view of these observations, I think that anyone desiring to mod a small clone to a flanger should take a long and hard look at the clock driver/lfo.

In this regard, try taking a look at the Hollis UltraFlanger at Geofex for ideas.

Best regards

Tom

[Claus H]

http://www.morleypedals.com/sfbes.pdf

This maybe a good one to clone... Looks simple..

Claus H