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Messages - madbean

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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.


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.

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)

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.

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.

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?

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.

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.

Open Discussion / Re: 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.

Build Reports / Re: Mandroid build
« on: February 07, 2018, 08:11:59 PM »
If it helps, I can check to see if I have a spare chip. I'd be happy to send it to you.

Build Reports / Re: Mandroid build
« on: February 07, 2018, 07:09:57 PM »
Sorry about that. I will change the doc to exclude that. You should be able to return the Vellman kit, I hope!

Open Discussion / Re: Did the forum ever get a donate button?
« on: February 05, 2018, 09:28:41 AM »
Donut button:

Open Discussion / Does anyone have one of these dual pots?
« on: February 04, 2018, 11:50:16 AM »
Anyone have one of these dual concentric 9mm pots? I need some measurements from it: spacing between the two rows of pins and length/width of the green casing (area where the pins are, don't need the height of the casing). In mm, if you can.


It's been over a week since I did my test package to Canada and still not a single update in tracking. I've got two more packages to mail out as a test. So far, I am not impressed. I'm trying to keep positive about this but all the data from this thread seems to indicate there might be no getting around the incredible price increase. I'm still getting international orders but there is a noticeable dip in sales. I feel pretty bad for folks who just want to order a board or two and end up having to pay an equal price in shipping. It's just nonsense. At the same time, a process that is cheaper which results in spotty/no tracking at all is no way to run a business. Rock, meet hard place. This, coupled with the sudden and recent demise of free shipping from my PCB manufacturer is a strong indicator that there are going to be a lot of challenges for MBP going forward.

How Do I? Beginner's Paradise. / How to instantly improve your soldering
« on: February 03, 2018, 07:52:34 PM »
I put off getting one of these for a long time, but I received it as a gift for Christmas and I have to say it has proved to be a tremendous help in soldering. I wear glasses for working at the computer and for soldering and the addition of a magnified light has made a huge difference for me. I'm getting better joints with less solder. And, I can actually see what I'm doing a lot better!

There are probably cheaper ones out there, but this is what I have:

I found that the color temperature on the stock bulb was way too cool for me, so I replaced it with this:

The replacement bulb is much better on my eyes!

(of course, I am not shilling for this equipment)

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