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Messages - madbean

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1
Output and input are in phase.

2
General Questions / Re: Pork Barrel Blend
« on: February 23, 2018, 08:54:23 PM »
This kind of setup would work better because it operates by sending either the dry signal or wet signal to (virtual) ground and doesn't require changing anything in the output stage.

When the Blend pot is in the middle you have equal amounts of dry/wet
Turning it clockwise grounds the dry path so you get vibrato
Turning it counter clockwise grounds the wet so you get straight dry signal

3
General Questions / Re: Pork Barrel Blend
« on: February 23, 2018, 08:28:49 PM »
You will need to use those 47k resistors rather than omit them otherwise the output will distort badly as you turn it to the highest and lowest settings on the pot. Instead, attach wires to the blue and red spots, a 47k on the other end of each wire and then the other end of the 47k to lugs 1 and 3 resp. And, still attach the wiper to green.

Blue -----wire-----47k-----lug3
lug2-----wire----- Green
Red -----wire----47k-----lug1

Not sure if 100k pot is enough - might have to use 250k.

So we need the resistors to avoid clipping the IC input. Makes sense. Thanks!

Would you expect the additional resistance from the pot to reduce the overall output? Can we gain up the IC with a value change somewhere?

Well that's a good point. Yeah, overall the output is going to be reduced depending on where the blend knob is set. You can offset that by changing values with R11, R10, C5 and C6. What exact values would be best I don't know - but you would want to scale them up equally otherwise you are going to change the overall frequency response. Another thing I though of - R26 is DC coupled by C17 but R9 is not DC coupled. So, you'd also probably have to a 100n cap before R9 to avoid scratchiness on the pot.

Whether or not all this is worth the effort is up to you. It's possible to do a better blend knob but it requires more parts and a ton of off-board wiring to do it. An alternative to all this would be to simply leave R9 in place and put a 100k or 250k pot in series with R26. This would allow you to reduce the chorus level. But, it won't let you change the dry level for vibrato type effect. To do that you would have to lift R9 with a switch. In fact, the very early versions of the Pork Barrel had both of these mods but I ditched them when I went down to a 1590B layout.

4
General Questions / Re: Pork Barrel Blend
« on: February 23, 2018, 08:10:33 PM »
You will need to use those 47k resistors rather than omit them otherwise the output will distort badly as you turn it to the highest and lowest settings on the pot. Instead, attach wires to the blue and red spots, a 47k on the other end of each wire and then the other end of the 47k to lugs 1 and 3 resp. And, still attach the wiper to green.

Blue -----wire-----47k-----lug3
lug2-----wire----- Green
Red -----wire----47k-----lug1

Not sure if 100k pot is enough - might have to use 250k.

5
Tech Help - Projects Page / Re: 3PRR Voltage Regulator Orientation
« on: February 22, 2018, 08:27:42 PM »
It will put out some heat, but probably not enough to damage the cap next to it.  Most of the heat will get absorbed and emitted by the heat sink which is on the other side. Your pin orientation is correct.

6
Open Discussion / Re: Don't forget to hug your dog today....
« on: February 22, 2018, 07:06:33 PM »
I say don't wait too long to get another dog. Having other pets around when you lose one helps tremendously. Plus, you can pay back some of that love you got from the last one by rescuing one in need.

7
Mods / Re: Quick question, 4:1 & phase
« on: February 20, 2018, 02:25:13 PM »
Yes, the 4:1 output is out of phase with its input. Something I try to avoid with most projects but this one obviously not.

I would not do it exactly as shown on the Muzique schematic. There's no need for a high input impedance into the added "buffer" stage since you already have a nice low impedance output from the previous stage. Using 10k resistors instead of 1M gets the job done and with less potential noise. Only "bad" thing about the schem below is both pin7 and pin2 of the added IC will be sitting at 4.5v, so a bi-polar 1uF for C3 would be a better choice. However, you could change it to 220n or even jumper through it.

One last possible mod if you are feeling crazy - make R19 a 100kA volume control instead. That would give you a master volume for the signal/compression mix. It's something I would have liked to put in the 4:1 but there was no room on the PCB.

8

But what I don't understand is why a voltage divider is used extensively in circuit design, but the PT2399 seems to want the steady 5v?

The simple answer is it's the safest choice to use given that the PT2399 has a very narrow range of voltage tolerance. As already mentioned, it requires a minimum of 4.5v and it will continue to operate up to about 6v. Over that, it might simply stop working or worse, damage it. A voltage divider is completely dependent on the voltage provided to the circuit. A regulator only requires about 3v minimum over the voltage it regulates to operate. You would not be doing yourself any favors by saving $0.15 on a regulator since the possibility for damage outweighs it.


9
Sure! It's actually quite easy:

- Use some 0000 steel wool and gently sand the copper areas in a cross-hatch fashion. This will lightly scratch the underlying PCB material but that's okay - step 3 fixes that.
- Use Acetone to clean the entire surface until the paper towel comes away clean.
- Do 1 to 2 light coats of clear spray over the surface. This seals the copper, prevents oxidation and will magically remove any light surface scratches.

(BTW - all my faceplates are done on black FR-4 which is the least forgiving. This method works really well on it)

10
Lots of pedals can be adapted for bass if you are willing to experiment. A good rule of thumb is to factor up capacitance values by a factor of 2 to 10. Particularly input coupling caps and tone/filtering caps. For example, if an input cap is 22n or 47n, go up to 220n or 470n. Another example: active gain stage like the TS where the mid frequencies are clipped centered at 720Hz by a 4k7 and 47n cap. Change the cap to 220n or 470n. Use the formulas excel workbook posted here to figure out frequency response.

But, this is just a starting point. One drawback with trying to fit a guitar pedal with a bass rig is so many bass guitars are active these days. So, lowering circuit input impedance can actually be a benefit rather than a drawback.

Someday I will design a few projects just for bass. I really should....even though I've been playing guitar for almost 30 years a lot of my gigging experience was a bass player. Maybe someone can hip us to some existing bass pedal projects out there now.

11
One more benefit I thought of - if you don't have fume extraction the glass serves as a pretty good buffer between your face and solder fumes.

12
General Questions / Re: electronic drum kit?
« on: February 16, 2018, 12:26:54 PM »
Are you talking about one of the pad triggers? A lot of them use piezos for triggers which should be easy to replace. Or is it part of the sound module?

13
General Questions / Re: Relay bypass power supply issue
« on: February 16, 2018, 09:09:23 AM »
We had a similar problem with our switching system with Function FX. Our setup is slightly different but we found that rather than running the regulator after the DC filtering used for the audio portion, tying it directly to the PS with a 1N4001 in series with the regulator input fixed the problem. Also, you can try incorporating a temporary mute at the circuit output if you haven't done so. And, also check to see if your LED switching on/off is contributing.

14
Build Reports / Re: Triumvirate
« on: February 12, 2018, 07:55:34 PM »
Bottom mounted jacks? You maniac!

Looks good. Glad you did the treble mod.

15
Open Discussion / Re: Pedalpcb.com demos ?
« on: February 08, 2018, 08:47:58 PM »
My Organ Donor fired right up. Sounds very cool! The octaves are a bit warbly but that's a limitation of the FV-1, not the design itself. It does decent polyphony, as well. I really like it with some clean tone mixed in - good for nice fat leads (if I could play any). Thanks for making the project available, BuGG! It's a very well put together project.

My FV-1 soldering wasn't quite as clean as it could be; I actually put it on last so it was a bit of a chore manuevering the iron around the parts.

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